High-toughness new energy automobile part bonding resin and preparation method thereof

Abstract

The invention relates to high-toughness new energy automobile part bonding resin and a preparation method thereof, and belongs to the technical field of high polymer materials. The resin comprises the following components: an aromatic epoxy-siloxane block copolymer, alicyclic epoxy resin, a bifunctional group hybrid hyperbranched toughening agent, a silane coupling agent, a titanate coupling agent, hydrophobic fumed silica, an amino-terminated dendritic curing agent, an alicyclic amine curing agent, an ionic liquid modified imidazole accelerant and the like. The aromatic epoxy-siloxane block copolymer is prepared by reacting two intermediates, a coupling agent and dibutyltin dilaurate, wherein the intermediates are prepared from raw materials in a specific ratio. The bifunctional group hybrid hyperbranched toughening agent is prepared by the following steps: reacting trimethylolpropane, epsilon-caprolactone and dibutyltin dilaurate, then reacting with aminated nano boron nitride and toluene-2, 4-diisocyanate in sequence, and carrying out end-capping modification by using diethanol amine. The ionic liquid modified imidazole accelerant is 1-ethyl-3-methylimidazole chloride salt modified 2-ethyl-4-methylimidazole, and the ionic liquid modified imidazole accelerant is 1-ethyl-3-methylimidazole chloride salt modified 2-ethyl-4-methylimidazole.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a high-toughness bonding resin for new energy vehicle parts and its preparation method. Background Technology

[0002] With the explosive growth of the global new energy vehicle industry, lightweighting, high safety, and long lifespan have become the core development demands of the industry. As a key supporting material, bonding resin plays an irreplaceable role in vehicle assembly.

[0003] New energy vehicles place stringent demands on the application scenarios of bonding resins. In the field of power batteries, bonding resins must be used to fix cell modules, conduct heat through liquid cooling plates, and seal the casing, while withstanding high and low temperature shocks and vibrations during charge and discharge cycles. As the core actuator, the drive motor requires its rotor magnetic material bonding and stator potting to withstand high temperature and high torque conditions. In addition, the bonding of heterogeneous materials in components such as door systems, sensors, and cockpit controllers must balance lightweighting and structural stability. All these scenarios require bonding resins to possess excellent bonding strength, weather resistance, and environmental adaptability.

[0004] Current mainstream bonding resins include epoxy resin, silicone, and polyurethane, but they all have significant performance shortcomings. Traditional epoxy resin has high bonding strength but insufficient toughness, making it prone to brittleness under the vibration and impact of vehicle operation, affecting the reliability of component connections; silicone resin has good flexibility but limited bonding strength, making it difficult to meet the load-bearing requirements of structural components; solvent-based adhesives face the problem of VOC emission control.

[0005] Lightweight and integrated design further exacerbates the contradiction between toughness requirements. New energy vehicles widely use heterogeneous materials such as aluminum, steel, and composite materials, and the bonding resin needs to adapt to the differences in the thermal expansion coefficients of different substrates to maintain interface integrity during temperature cycling. At the same time, the compact design of core components such as battery packs and electronic control systems requires the bonding resin to simultaneously undertake multiple functions such as bonding, thermal conduction, and sealing, making it difficult for traditional materials to balance the synergistic relationship between strength and toughness.

[0006] Therefore, it is necessary to improve and develop high-toughness bonding resins that combine high bonding strength, high impact resistance, and environmental compliance to solve the problem of reliable connection of new energy vehicle parts. Summary of the Invention

[0007] To address the problem that existing bonding resins used for bonding new energy vehicle components still struggle to comprehensively improve bond strength, impact resistance, and toughness, this invention provides a high-toughness bonding resin for new energy vehicle components and its preparation method. Through a multi-component synergistic design, including aromatic epoxy-siloxane block copolymers, alicyclic epoxy resins, bifunctional hybrid hyperbranched toughening agents, amino-terminated dendritic curing agents, alicyclic amine curing agents, and ionic liquid-modified imidazole accelerators, this invention overcomes the bottleneck of traditional bonding resins' inability to simultaneously achieve strength, toughness, weather resistance, and environmental friendliness. The specific technical solution is as follows:

[0008] A high-toughness bonding resin for new energy vehicle parts is composed of component A and component B mixed in a mass ratio of 100:(28-32). Component A includes the following raw materials in parts by mass: 80-90 parts of aromatic epoxy-siloxane block copolymer, 35-45 parts of alicyclic epoxy resin, 18-25 parts of bifunctional hybrid hyperbranched toughening agent, 8-12 parts of silane coupling agent, 0.4-0.8 parts of titanate coupling agent, 0.5-1.0 parts of hydrophobic fumed silica, 0.3-0.5 parts of defoamer, 0.2-0.4 parts of leveling agent, and 5-10 parts of neopentyl glycol diglycidyl ether. Component B includes the following raw materials in parts by mass: 25-30 parts of amino-terminated dendritic curing agent, 15-20 parts of alicyclic amine curing agent, and 0.8-1.5 parts of ionic liquid modified imidazole accelerator. The general chemical formula for aromatic epoxy-siloxane block copolymers is: HO-[E] x -L-[S] y -L-[E] x -OH, where: [E] x It is an aromatic epoxy segment, E is the repeating unit -O-C6H4-C6H4-O-CH2-CH(OX)-CH2-, X is the covalent bonding site of the linker L; x is the degree of polymerization, 5≤x≤15; [S] y The structure consists of siloxane segments, where S is the repeating unit -Si(CH3)2-O-, y is the degree of polymerization (20≤y≤30), and L is the linking group. The core structure is -CH2CH2CH2-O-Si(OC2H5)2-CH2CH2CH2-NCO-O-, which is a covalently bridged structure between aromatic epoxy segments and siloxane segments. The molecular end group is hydroxyl -OH, and the segments are ordered alternating blocks without random copolymerization. The general chemical formula for bifunctional group-hybridized hyperbranched toughening agents is: Core-([P] n -TDI-NH-BNNS) m -([P] n -Cap) 3-m In the formula: Core represents the core structure, specifically the trifunctional core of trimethylolpropane -C(CH2OH)3-; [P]n The structure consists of polyether ester branches, where P is a repeating ε-caprolactone ring-opening polymerization unit with the structure -O-(CH2)5-CO-; n is the degree of polymerization, 5≤n≤8; NH-BNNS is an aminated boron nitride nano-hybrid unit, where BNNS is a nano-hexagonal boron nitride sheet connected to TDI via covalent bonds between amino groups; TDI is a toluene-2,4-diisocyanate-derived coupling bridge with the structure -O-CO-NH-C6H3(CH3)-NCO-, and bifunctional groups are bonded to the polyether ester branches [P]. n With NH-BNNS; Cap is a diethanolamine-derived end-capping group, which is covalently linked to the unreacted isocyanate group of TDI via an amino group, with the structure -NH-CH2CH2OH; m is the number of branches of the grafted inorganic hybrid unit BNNS, 1≤m≤2, and the remaining 3-m branches are end-capped with diethanolamine; The general chemical formula of the terminal amino dendritic curing agent is: G2-PAMAM-NH2, where PAMAM is a polyamide-amine branching unit with the structure H2N-CH2CH2-NH-CO-CH2CH2-[-NH-CH2CH2-NH-CO-CH2CH2-]2-NH2; G2 is a second-generation polyamide-amine dendritic macromolecule with a core structure of ethylenediamine H2N-CH2CH2-NH2, which is the starting core of the branching reaction. The branching unit is a polyamide-amine with the structure -CH2CH2-CO-NH-CH2CH2-NH-, which achieves secondary branching through amide and amine bonds; the molecular end groups are 8 primary amino groups -NH2; the branching method is that the two amino groups of the ethylenediamine core are primary branching sites, each of which is grafted with 1 polyamide-amine unit to form 4 secondary branching sites, and then each of these sites is grafted with 1 more polyamide-amine unit, ultimately forming 8 terminal primary amino groups; The aromatic epoxy-siloxane block copolymer is prepared by reacting reaction solution A, reaction solution B, a binder, and dibutyltin dilaurate in a mass ratio of (14-16):(9-11):(2-3):(0.015-0.018), followed by the addition of hydroquinone to terminate the reaction and adjusting the viscosity to 8000 mPa·s-9000 mPa·s. Reaction solution A is prepared by reacting 4,4'-dihydroxybiphenyl, tetrabutylammonium bromide, and a 40wt%-42wt% sodium hydroxide aqueous solution in epichlorohydrin in a mass ratio of (50-55):(2-3):(50-55), followed by vacuum distillation to 10%-15% of the volume. Reaction solution B is octamethylcyclotetrasiloxane. The reaction was carried out with 1,3-bis(3-glycidyl etheroxypropyl)tetramethyldisiloxane and tetramethylammonium hydroxide silanoate at a mass ratio of (200-220):(15-18):(0.4-0.6); the tetramethylammonium hydroxide silanoate was prepared by reacting 25wt% tetramethylammonium hydroxide aqueous solution, hexamethyldisiloxane, and anhydrous methanol at a mass ratio of 10:(22-25):(55-58) and then distilling under reduced pressure; the connecting agent was prepared by reacting 3-isocyanate propyltriethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, and dibutyltin dilaurate at a mass ratio of 10:(10.2-10.3):(0.003-0.005). The bifunctional hybrid hyperbranched toughening agent is prepared by ring-opening polymerization of trimethylolpropane, ε-caprolactone, and dibutyltin dilaurate in a mass ratio of (10-12):(55-65):(0.08-0.12), followed by reaction with 0.8-0.9 times the mass of trimethylolpropane of aminated nano-boron nitride and 1.3-1.5 times the mass of trimethylolpropane of toluene-2,4-diisocyanate. The mixture is then end-capped with 0.8-1 times the mass of trimethylolpropane of diethanolamine, diluted with ethyl acetate, washed, and distilled under reduced pressure to obtain a product with a viscosity of 12000 mPa·s to 15000 mPa·s. The aminated nano-boron nitride is prepared by modifying nano-hexagonal boron nitride with γ-aminopropyltriethoxysilane. The ionic liquid modified imidazole promoter is obtained by reacting 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone in a mass ratio of 10:(8.5-9):(120-150) and drying the resulting solid.

[0009] Furthermore, in the bonding resin, the silane coupling agent is KH-560; the defoamer is BYK-A530; the leveling agent is BYK-331; and the alicyclic amine curing agent is isophorone diamine.

[0010] Furthermore, in the bonding resin, the preparation method of the aromatic epoxy-siloxane block copolymer includes: under nitrogen protection, mixing 50-55 parts by mass of 4,4'-dihydroxybiphenyl, 350-370 parts by mass of epichlorohydrin, and 2-3 parts by mass of tetrabutylammonium bromide; adding 50-55 parts by mass of sodium hydroxide aqueous solution at 70-75°C; stirring and reacting at 75-78°C for 3-4 hours; adjusting the pH to 6.5-7.5 with deionized water; and distilling under reduced pressure to obtain reaction solution A; under nitrogen protection, mixing 200-220 parts by mass of octamethylcyclotetrasiloxane, 15-18 parts by mass of 1,3-bis(3-glycidyl ether oxypropyl)tetramethyldisiloxane, and 0.4-0.6 parts by mass of tetramethylammonium hydroxide silicon. The alkoxides were mixed and stirred at 105℃~115℃ for 5h~6h. The temperature was then raised to 145℃~155℃ and held for 30min~40min. The mixture was then cooled to obtain reaction solution B. Under nitrogen protection, reaction solution A, reaction solution B, linker, and dibutyltin dilaurate were mixed in a mass ratio of (14~16):(9~11):(2~3):(0.015~0.018). The mixture was stirred at 60℃~65℃ for 2h~2.5h. The temperature was then raised to 92℃~98℃ and stirred for 2.5h~3h. The mixture was then cooled to 60℃~65℃, hydroquinone was added, and the mixture was stirred for 1h~1.5h. The temperature was then lowered, and the viscosity was adjusted to 8000mPa·s~9000mPa·s to obtain an aromatic epoxy-siloxane block copolymer.

[0011] In the above-mentioned method for preparing aromatic epoxy-siloxane block copolymers, the concentration of the sodium hydroxide aqueous solution is 40wt% to 42wt%; the vacuum distillation is carried out to 10% to 15% of the volume; the amount of hydroquinone added is 0.3% to 0.4% of the mass of reaction solution A; the hydroquinone is dissolved and diluted with 4 to 5 times the amount of acetone before being added; and the viscosity is adjusted with neopentyl glycol diglycidyl ether.

[0012] In the above-mentioned method for preparing aromatic epoxy-siloxane block copolymers, the method for preparing tetramethylammonium hydroxide silanolate includes the following steps: mixing 25wt% tetramethylammonium hydroxide aqueous solution, hexamethyldisiloxane, and anhydrous methanol in a mass ratio of 10:(22-25):(55-58) under a flowing nitrogen atmosphere, stirring at below 10°C, adding hexamethyldisiloxane dropwise, stirring and reacting at 10°C-15°C for 4-5 hours, and distilling under reduced pressure to obtain tetramethylammonium hydroxide silanolate; In the above-mentioned method for preparing aromatic epoxy-siloxane block copolymers, the preparation method of the linker includes the following steps: under nitrogen protection, 3-isocyanate propyltriethoxysilane, 3-glycidyl ether propyltriethoxysilane, and dibutyltin dilaurate are mixed in a mass ratio of 10:(10.2~10.3):(0.003~0.005), stirred at 40℃~50℃ for 2h~3h, heated to 65℃~70℃ and stirred for 1.5h~2h, cooled to obtain a reaction solution, anhydrous magnesium sulfate is added for drying, filtered, and the filtrate is distilled under reduced pressure to obtain the linker.

[0013] Furthermore, in the bonding resin, the preparation method of the bifunctional group hybrid hyperbranched toughening agent includes: under nitrogen protection, trimethylolpropane, ε-caprolactone, and dibutyltin dilaurate are mixed in a mass ratio of (10-12):(55-65):(0.08-0.12), stirred at 110-120°C for 3-4 hours, cooled to 65-70°C, aminated nano-boron nitride is added and dispersed evenly, toluene-2,4-diisocyanate is added dropwise, stirred at 80-85°C for 2-2.5 hours, cooled to 65-70°C, diethanolamine is added dropwise, stirred for 3-3.5 hours, cooled, diluted with ethyl acetate, washed with hydrochloric acid aqueous solution, washed with deionized water until neutral, separated, and the organic phase is taken, distilled under reduced pressure, and cooled to obtain a bifunctional group hybrid hyperbranched toughening agent with a viscosity of 12000 mPa·s-15000 mPa·s.

[0014] In the preparation method of the above-mentioned bifunctional group hybrid hyperbranched toughening agent, the amount of aminated boron nitride nanoparticles added is 0.8 to 0.9 times the mass of trimethylolpropane; the amount of toluene-2,4-diisocyanate added is 1.3 to 1.5 times the mass of trimethylolpropane; the amount of diethanolamine added is 0.8 to 1 times the mass of trimethylolpropane; the amount of ethyl acetate added is 10 to 12 times the mass of trimethylolpropane; and the concentration of the hydrochloric acid aqueous solution is 5 wt% to 6 wt%.

[0015] In the preparation method of the above-mentioned bifunctional group hybrid hyperbranched toughening agent, the preparation method of the aminated nano boron nitride includes: adding nano hexagonal boron nitride to anhydrous ethanol containing 4wt% to 6wt% γ-aminopropyltriethoxysilane at a solid-liquid mass ratio of 1:(15-20), dispersing evenly, refluxing, filtering, washing the filter cake, and vacuum drying to obtain aminated nano boron nitride.

[0016] Furthermore, in the bonding resin, the preparation method of the ionic liquid modified imidazole accelerator includes: mixing 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone in a mass ratio of 10:(8.5-9):(120-150), stirring and reacting at 50℃-55℃ for 5-6 hours, allowing to stand and cool to room temperature, filtering, washing the filter cake with acetone, then washing with deionized water, and vacuum drying to obtain the ionic liquid modified accelerator.

[0017] The preparation method of the above-mentioned high-toughness bonding resin for new energy vehicle parts includes the following steps: Component A is prepared by mixing according to the formula of component A; component B is prepared by mixing according to the formula of component B; components A and B are stored separately, and when used, they are stirred and mixed evenly according to the ratio and degassed under vacuum.

[0018] The present invention provides a high-toughness bonding resin for new energy vehicle parts and its preparation method, which has the following beneficial effects: I. The bonding resin of this invention, through multi-component synergistic design and structural hybridization modification, overcomes the bottleneck of traditional bonding resins in simultaneously achieving strength, toughness, weather resistance, and environmental friendliness. It exhibits balanced mechanical properties, combining high bonding strength with high impact resistance; excellent weather resistance, adapting to extreme environments such as high and low temperature cycling and humidity changes while maintaining interface structural stability; environmental compliance, with a solvent-free formulation significantly reducing VOC residue and meeting emission control requirements; and broad applicability, compatible with heterogeneous substrates such as aluminum, steel, and composite materials, suitable for bonding needs in various scenarios such as power batteries, drive motors, and cockpit controllers.

[0019] II. Preparation of Aromatic Epoxy-Siloxane Block Copolymers: Aromatic epoxy segments are achieved through a dedicated catalyst and linker of tetramethylammonium hydroxide siloxane salt, providing high strength and heat resistance, and precise chemical bonding with siloxane segments, introducing flexibility and reducing internal stress. This avoids phase separation defects and reduces thermal stress at the interface of heterogeneous substrates. Viscosity adjustment and reaction condition control during the preparation process ensure the stability of the copolymer structure and performance.

[0020] III. In the preparation of bifunctional hybrid hyperbranched toughening agents, aminated boron nitride nanoparticles form an organic-inorganic hybrid structure, which exerts an anti-crack effect; terminal functional groups participate in the curing reaction, improving interfacial compatibility and thermal stability; during preparation, the toughening agent agglomeration is avoided by precisely controlling the monomer ratio, reaction temperature and dispersion method, so as to achieve a balance between multi-scale toughening and strength.

[0021] IV. The compounding of terminal amino dendritic curing agent and alicyclic amine curing agent forms a gradient cross-linking network, which takes into account both cross-linking strength and chain segment flexibility; the ionic liquid modified imidazole accelerator improves the solubility and dispersibility of traditional accelerators, enhances curing catalytic efficiency, reduces curing temperature, reduces internal stress concentration, and promotes the full reaction of low molecular weight substances, thereby reducing VOC residues; the reaction temperature, washing and drying processes during preparation ensure the purity and activity of the modified imidazole accelerator.

[0022] Fifth, the solvent-free formulation design and the catalytic effect of the ionic liquid modifier accelerator synergistically reduce low molecular weight volatile organic compounds (VOCs) and improve mechanical properties and environmental resistance through complete curing, thus avoiding the conflict between environmental protection and performance.

[0023] In summary, the rigid and flexible segments of aromatic epoxy-siloxane block copolymers, along with the gradient crosslinking network of the composite curing system, form a synergistic effect of rigid support and flexible buffering, resolving the contradiction between the strength and brittleness, and toughness and weakness of traditional resins. An appropriate amount of bifunctional hybrid hyperbranched toughening agent enhances toughness through energy absorption and crack inhibition, while also improving interfacial stability and weather resistance by participating in the curing reaction, achieving toughening without sacrificing strength and stability without reducing flexibility. Detailed Implementation

[0024] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0025] Definitions: Example 1 A high-toughness bonding resin for new energy vehicle parts is prepared by mixing component A and component B in a mass ratio of 100:30. Component A is prepared from the following raw materials in parts by mass: 85 parts of aromatic epoxy-siloxane block copolymer, 40 parts of alicyclic epoxy resin, 22 parts of bifunctional hybrid hyperbranched toughening agent, 10 parts of silane coupling agent, 0.65 parts of titanate coupling agent, 0.75 parts of hydrophobic fumed silica, 0.4 parts of defoamer, 0.3 parts of leveling agent, and 7.5 parts of neopentyl glycol diglycidyl ether. Component B is prepared from the following raw materials in parts by mass: 27 parts of amino-terminated dendritic curing agent, 18 parts of alicyclic amine curing agent, and 1.2 parts of ionic liquid modified imidazole accelerator. The silane coupling agent is KH-560; the defoamer is BYK-A530; the leveling agent is BYK-331; and the alicyclic amine curing agent is isophorone diamine.

[0026] The preparation method of aromatic epoxy-siloxane block copolymers includes: under nitrogen protection, mixing 52 parts by mass of 4,4'-dihydroxybiphenyl, 360 parts by mass of epichlorohydrin, and 2.5 parts by mass of tetrabutylammonium bromide, heating to 72°C, adding 53 parts by mass of 41wt% sodium hydroxide aqueous solution at a rate of 0.6 mL / min, stirring at 220 rpm for 3.5 h in a temperature range of 75°C–78°C, cooling to 35°C, washing three times with deionized water until the pH of the aqueous phase is 7.0, and distilling under reduced pressure at 45°C–50°C to 12% by volume (recovering excess epichlorohydrin) to obtain reaction solution A; under nitrogen protection, mixing 210 parts by mass of octamethylcyclotetrasiloxane, 17 parts by mass of 1,3-bis(3-glycidyl ether oxypropyl)tetramethyldisiloxane, and 0.5 parts by mass of tetramethylammonium hydroxide silanolate, and heating at 105°C–50°C. The reaction mixture was stirred at 220 rpm for 5.5 h at 115 °C, then heated to 145 °C–155 °C and held for 35 min (to decompose the catalyst), and cooled to 60 °C to obtain reaction solution B. Under nitrogen protection, reaction solution A, reaction solution B, linker, and dibutyltin dilaurate were mixed in a mass ratio of 15:10:2.5:0.016 and stirred at 220 rpm for 2 h at 60 °C–65 °C, then heated to 180 rpm for 2.5 h at 92 °C–98 °C, and cooled to 62 °C. Hydroquinone (0.35% by mass of reaction solution A was added; hydroquinone was dissolved and diluted with 4.5 times its volume of acetone before addition), and stirred at 220 rpm for 1 h. The mixture was then cooled to 28 °C, and the viscosity was adjusted to 8500 mPa·s with neopentyl glycol diglycidyl ether to obtain an aromatic epoxy-siloxane block copolymer.

[0027] The preparation method of tetramethylammonium hydroxide silanoate includes: mixing 25wt% tetramethylammonium hydroxide aqueous solution, hexamethyldisiloxane, and anhydrous methanol in a mass ratio of 10:23:56 under a flowing nitrogen atmosphere; adding hexamethyldisiloxane dropwise at a rate of 0.15 mL / min while stirring at 320 rpm below 10℃; after the addition is complete, stirring and reaction continue for 4.5 h in the temperature range of 10℃~15℃; then distilling under reduced pressure of -0.092 MPa for 4 h in the temperature range of 40℃~45℃; and finally cooling to room temperature to obtain tetramethylammonium hydroxide silanoate.

[0028] The preparation method of the linker includes the following steps: Under nitrogen protection, 3-isocyanate propyltriethoxysilane, 3-glycidyl ether propyltriethoxysilane, and dibutyltin dilaurate are mixed in a mass ratio of 10:10.3:0.004, stirred at 220 rpm for 2.5 h at a temperature range of 40℃~50℃, then heated to a temperature range of 65℃~70℃ and stirred at 220 rpm for 1.5 h, and then cooled to 22℃ to obtain a reaction solution. 5 wt% of powdered anhydrous magnesium sulfate is added to the reaction solution, and the mixture is stirred at 220 rpm and dried for 1 h. The mixture is then filtered, and the filtrate is distilled under reduced pressure at -0.092 MPa for 1.5 h at a temperature range of 60℃~65℃ to remove low-boiling substances, thus obtaining the linker.

[0029] The preparation method of the bifunctional group-modified hyperbranched toughening agent includes: under nitrogen protection, trimethylolpropane, ε-caprolactone, and dibutyltin dilaurate are mixed at a mass ratio of 11:60:0.1, and reacted at a vacuum of -0.085 MPa, a temperature range of 110℃ to 120℃, and stirred at 220 rpm for 3.5 h to obtain a hydroxyl-terminated hyperbranched polyether ester prepolymer; the temperature is lowered to 68℃, and 0.85 times the mass of trimethylolpropane aminated boron nanonitride is added. The mixture is ultrasonically dispersed at 350 W for 35 min, and then, under stirring at 220 rpm, 1.4 times the mass of trimethylolpropane toluene-2,4-diisocyanate is added dropwise at a rate of 1.5 mL / min. Afterwards, the temperature was raised to 80℃~85℃ and the reaction was stirred at 280rpm for 2h to obtain a hybrid prepolymer. The temperature was then lowered to 68℃, and diethanolamine with a mass of 0.9 times that of trimethylolpropane was added dropwise at a rate of 1.5mL / min under stirring at 220rpm. The reaction was stirred at 280rpm for 3h. The temperature was then lowered to 26℃, and ethyl acetate with a mass of 11 times that of trimethylolpropane was added for dilution. The mixture was first washed twice with 5.5wt% hydrochloric acid aqueous solution, and then washed with deionized water until neutral. After separation, the organic phase was collected and subjected to vacuum distillation at 55℃~60℃ for 3h to remove ethyl acetate. The temperature was then lowered to 25℃ to obtain a bifunctional group hybrid hyperbranched toughening agent with a viscosity of 13500mPa·s.

[0030] The preparation method of aminated boron nitride nanoparticles includes: adding hexagonal boron nitride nanoparticles to anhydrous ethanol containing 5 wt% γ-aminopropyltriethoxysilane at a solid-liquid mass ratio of 1:18, stirring and dispersing evenly, refluxing at 70℃~75℃ for 3.5h, filtering, washing the filter cake three times with anhydrous ethanol, and vacuum drying at 92℃ for 12h to obtain aminated boron nitride nanoparticles.

[0031] The preparation method of ionic liquid modified imidazole accelerator includes: mixing 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone in a mass ratio of 10:8.7:130, stirring and refluxing at 220 rpm for 5.5 h in a temperature range of 50℃~55℃, allowing to stand and cool to room temperature, filtering, washing the filter cake twice with acetone at 4℃, and then washing with deionized water until no white precipitate of chloride ions is detected by silver nitrate in the washing liquid, and drying under vacuum at 78℃ for 9 h to obtain ionic liquid modified accelerator.

[0032] The preparation method of the above-mentioned high-toughness bonding resin for new energy vehicle parts includes the following steps: Component A is prepared by mixing according to the formulation of component A; component B is prepared by mixing according to the formulation of component B; components A and B are stored separately. When using, mix at 280 rpm for 12 minutes at a temperature below 30°C, degas under vacuum, and complete the sizing operation within 40 minutes.

[0033] Example 2 A high-toughness bonding resin for new energy vehicle parts is prepared by mixing component A and component B in a mass ratio of 100:28. Component A is prepared from the following raw materials in parts by mass: 90 parts of aromatic epoxy-siloxane block copolymer, 35 parts of alicyclic epoxy resin, 25 parts of bifunctional hybrid hyperbranched toughening agent, 8 parts of silane coupling agent, 0.8 parts of titanate coupling agent, 0.5 parts of hydrophobic fumed silica, 0.5 parts of defoamer, 0.2 parts of leveling agent, and 10 parts of neopentyl glycol diglycidyl ether. Component B is prepared from the following raw materials in parts by mass: 25 parts of amino-terminated dendritic curing agent, 20 parts of alicyclic amine curing agent, and 0.8 parts of ionic liquid modified imidazole accelerator. The silane coupling agent is KH-560; the defoamer is BYK-A530; the leveling agent is BYK-331; and the alicyclic amine curing agent is isophorone diamine.

[0034] The preparation method of aromatic epoxy-siloxane block copolymers includes: under nitrogen protection, mixing 50 parts by weight of 4,4'-dihydroxybiphenyl, 370 parts by weight of epichlorohydrin, and 2 parts by weight of tetrabutylammonium bromide, heating to 75°C, adding 55 parts by weight of 40wt% sodium hydroxide aqueous solution at a rate of 0.5 mL / min, stirring at 250 rpm for 3 h in a temperature range of 75°C to 78°C, cooling to 38°C, washing four times with deionized water until the pH of the aqueous phase is 6.5, and distilling under reduced pressure at a temperature range of 45°C to 50°C to 15% of the volume (recovering excess epichlorohydrin) to obtain reaction solution A; under nitrogen protection, mixing 200 parts by weight of octamethylcyclotetrasiloxane, 18 parts by weight of 1,3-bis(3-glycidyl ether oxypropyl)tetramethyldisiloxane, and 0.4 parts by weight of tetramethylammonium hydroxide silanolate, and heating at 105 °C. The reaction mixture was stirred at 250 rpm for 5 hours in a temperature range of 100℃ to 115℃. The temperature was then increased to 145℃ to 155℃ and maintained for 40 minutes (catalyst decomposition). The mixture was then cooled to 62℃ to obtain reaction solution B. Under nitrogen protection, reaction solution A, reaction solution B, the linker, and dibutyltin dilaurate were mixed in a mass ratio of 14:11:2:0.018. The mixture was stirred at 200 rpm for 2.5 hours in a temperature range of 60℃ to 65℃. The temperature was then increased to 92℃ to 98℃ and stirred at 150 rpm for 3 hours. The mixture was cooled to 60℃, and 0.4% (by weight) of hydroquinone (dissolved and diluted with 4 times the volume of acetone before addition) of reaction solution A was added. The mixture was stirred at 250 rpm for 1 hour and cooled to 30℃. The viscosity was adjusted to 8000 mPa·s using neopentyl glycol diglycidyl ether to obtain an aromatic epoxy-siloxane block copolymer.

[0035] The preparation method of tetramethylammonium hydroxide silanolate includes: mixing 25wt% tetramethylammonium hydroxide aqueous solution, hexamethyldisiloxane, and anhydrous methanol in a mass ratio of 10:22:55 under a flowing nitrogen atmosphere; adding hexamethyldisiloxane dropwise at a rate of 0.2 mL / min while stirring at 300 rpm below 10℃; after the addition is complete, stirring and reaction continue for 4 h in the temperature range of 10℃~15℃; followed by vacuum distillation at -0.095 MPa for 4 h in the temperature range of 40℃~45℃; and cooling to room temperature to obtain tetramethylammonium hydroxide silanolate.

[0036] The preparation method of the linker includes the following steps: Under nitrogen protection, 3-isocyanate propyltriethoxysilane, 3-glycidyl ether propyltriethoxysilane, and dibutyltin dilaurate are mixed in a mass ratio of 10:10.2:0.005, stirred at 200 rpm for 3 h in a temperature range of 40℃~50℃, then heated to a temperature range of 65℃~70℃ and stirred at 200 rpm for 2 h, and then cooled to 23℃ to obtain a reaction solution. 4 wt% of powdered anhydrous magnesium sulfate is added to the reaction solution, and the mixture is stirred at 250 rpm and dried for 1 h. The mixture is then filtered, and the filtrate is distilled under reduced pressure at -0.095 MPa for 1.5 h in a temperature range of 60℃~65℃ to remove low-boiling substances, thus obtaining the linker.

[0037] The preparation method of the bifunctional group hybrid hyperbranched toughening agent includes: under nitrogen protection, trimethylolpropane, ε-caprolactone, and dibutyltin dilaurate are mixed at a mass ratio of 12:55:0.12, and reacted at a vacuum of -0.08 MPa, a temperature range of 110℃ to 120℃, and stirred at 250 rpm for 3 h to obtain a hydroxyl-terminated hyperbranched polyether ester prepolymer; the temperature is lowered to 70℃, and 0.8 times the mass of trimethylolpropane aminated boron nanonitride is added, and the mixture is ultrasonically dispersed at 400W for 30 min. Under stirring at 250 rpm, 1.5 times the mass of trimethylolpropane toluene-2,4-diisocyanate is added dropwise at a rate of 1 mL / min. After the addition is complete, the mixture is heated... The mixture was heated to 80℃~85℃ and stirred at 250rpm for 2.5h to obtain a hybrid prepolymer. The temperature was then lowered to 65℃, and diethanolamine with a mass equal to that of trimethylolpropane was added dropwise at a rate of 1mL / min while stirring at 250rpm. The mixture was stirred at 250rpm for 3.5h. The temperature was then lowered to 24℃, and ethyl acetate with a mass equal to that of trimethylolpropane was added for dilution. The mixture was first washed twice with 6wt% hydrochloric acid aqueous solution, then washed with deionized water until neutral. After separation, the organic phase was collected and subjected to vacuum distillation at 55℃~60℃ for 3.5h to remove ethyl acetate. The temperature was then lowered to 22℃ to obtain a bifunctional group-modified hyperbranched toughening agent with a viscosity of 15000mPa·s.

[0038] The preparation method of aminated boron nitride nanoparticles includes: adding hexagonal boron nitride nanoparticles to anhydrous ethanol containing 4wt% γ-aminopropyltriethoxysilane at a solid-liquid mass ratio of 1:20, dispersing evenly by ultrasonication, refluxing at 70℃~75℃ for 4h, filtering, washing the filter cake three times with anhydrous ethanol, and vacuum drying at 95℃ for 10h to obtain aminated boron nitride nanoparticles.

[0039] The preparation method of ionic liquid modified imidazole accelerator includes: mixing 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone in a mass ratio of 10:8.5:150, stirring and refluxing at 200 rpm for 6 h in a temperature range of 50℃~55℃, allowing to stand and cool to room temperature, filtering, washing the filter cake three times with acetone at 2℃, and then washing with deionized water until no white precipitate of chloride ions is detected by silver nitrate in the washing liquid, and vacuum drying at 75℃ for 10 h to obtain ionic liquid modified accelerator.

[0040] The preparation method of the above-mentioned high-toughness bonding resin for new energy vehicle parts includes the following steps: Component A is prepared by mixing according to the formulation of component A; component B is prepared by mixing according to the formulation of component B; components A and B are stored separately. When using, mix at 250 rpm for 15 minutes at a temperature below 30°C, degas under vacuum, and complete the sizing operation within 40 minutes.

[0041] Example 3 A high-toughness bonding resin for new energy vehicle parts is prepared by mixing component A and component B in a mass ratio of 100:32. Component A is prepared from the following raw materials in parts by mass: 80 parts of aromatic epoxy-siloxane block copolymer, 45 parts of alicyclic epoxy resin, 18 parts of bifunctional hybrid hyperbranched toughening agent, 12 parts of silane coupling agent, 0.4 parts of titanate coupling agent, 1.0 part of hydrophobic fumed silica, 0.3 parts of defoamer, 0.4 parts of leveling agent, and 5 parts of neopentyl glycol diglycidyl ether. Component B is prepared from the following raw materials in parts by mass: 30 parts of amino-terminated dendritic curing agent, 15 parts of alicyclic amine curing agent, and 1.5 parts of ionic liquid modified imidazole accelerator. The silane coupling agent is KH-560; the defoamer is BYK-A530; the leveling agent is BYK-331; and the alicyclic amine curing agent is isophorone diamine.

[0042] The preparation method of aromatic epoxy-siloxane block copolymer includes: under nitrogen protection, mixing 55 parts by weight of 4,4'-dihydroxybiphenyl, 350 parts by weight of epichlorohydrin, and 3 parts by weight of tetrabutylammonium bromide, heating to 70°C, adding 50 parts by weight of 42wt% sodium hydroxide aqueous solution at a rate of 0.8 mL / min, stirring at 200 rpm for 4 h in a temperature range of 75°C to 78°C, cooling to 30°C, washing three times with deionized water until the pH of the aqueous phase is 7.5, and distilling under reduced pressure at a temperature range of 45°C to 50°C to 10% of the volume (to recover excess epichlorohydrin) to obtain reaction solution A; under nitrogen protection, mixing 220 parts by weight of octamethylcyclotetrasiloxane, 15 parts by weight of 1,3-bis(3-glycidyl ether oxypropyl)tetramethyldisiloxane, and 0.6 parts by weight of tetramethylammonium hydroxide silanolate, and heating at 105°C. The reaction mixture was stirred at 200 rpm for 6 hours at a temperature range of ~115℃. The temperature was then increased to 145℃-155℃ and maintained for 30 minutes (catalyst decomposition), before being cooled to 58℃ to obtain reaction solution B. Under nitrogen protection, reaction solution A, reaction solution B, linker, and dibutyltin dilaurate were mixed in a mass ratio of 16:9:3:0.015. The mixture was stirred at 250 rpm for 2 hours at a temperature range of 60℃-65℃. The temperature was then increased to 92℃-98℃ and stirred at 200 rpm for 2.5 hours. The mixture was cooled to 65℃, and 0.3% (by weight) of hydroquinone (dissolved and diluted with 5 times the volume of acetone before addition) of reaction solution A was added. The mixture was stirred at 200 rpm for 1.5 hours, cooled to 25℃, and the viscosity was adjusted to 9000 mPa·s with neopentyl glycol diglycidyl ether to obtain an aromatic epoxy-siloxane block copolymer.

[0043] The preparation method of tetramethylammonium hydroxide silanolate includes: mixing 25wt% tetramethylammonium hydroxide aqueous solution, hexamethyldisiloxane, and anhydrous methanol in a mass ratio of 10:25:58 under a flowing nitrogen atmosphere; adding hexamethyldisiloxane dropwise at a rate of 0.1 mL / min while stirring at 350 rpm below 10℃; after the addition is complete, stirring and reaction continue for 5 h in the temperature range of 10℃~15℃; then distilling under reduced pressure of -0.09 MPa for 4.5 h in the temperature range of 40℃~45℃; and finally cooling to room temperature to obtain tetramethylammonium hydroxide silanolate.

[0044] The preparation method of the linker includes the following steps: Under nitrogen protection, 3-isocyanate propyltriethoxysilane, 3-glycidyl ether propyltriethoxysilane, and dibutyltin dilaurate are mixed in a mass ratio of 10:10.3:0.003, stirred at 250 rpm for 2 h in a temperature range of 40℃~50℃, then heated to a temperature range of 65℃~70℃ and stirred at 250 rpm for 1.5 h, and then cooled to 20℃ to obtain a reaction solution. 6 wt% of powdered anhydrous magnesium sulfate is added to the reaction solution, and the mixture is stirred at 200 rpm and dried for 1.5 h. The solution is then filtered, and the filtrate is distilled under reduced pressure at -0.09 MPa for 2 h in a temperature range of 60℃~65℃ to remove low-boiling substances, thus obtaining the linker.

[0045] The preparation method of the bifunctional group-modified hyperbranched toughening agent includes: under nitrogen protection, trimethylolpropane, ε-caprolactone, and dibutyltin dilaurate are mixed in a mass ratio of 10:65:0.08, and reacted at a vacuum of -0.09 MPa, a temperature range of 110℃ to 120℃, and stirred at 200 rpm for 4 h to obtain a hydroxyl-terminated hyperbranched polyether ester prepolymer; the temperature is lowered to 65℃, and 0.9 times the mass of trimethylolpropane aminated boron nanonitride is added, and the mixture is ultrasonically dispersed at 300 W for 40 min. Under stirring at 200 rpm, 1.3 times the mass of trimethylolpropane toluene-2,4-diisocyanate is added dropwise at a rate of 2 mL / min. The temperature was then raised to 80℃~85℃ and stirred at 300rpm for 2h to obtain a hybrid prepolymer. The temperature was then lowered to 70℃, and diethanolamine with a mass of 0.8 times that of trimethylolpropane was added dropwise at a rate of 2mL / min while stirring at 200rpm. The mixture was stirred at 300rpm for 3h and then cooled to 28℃. Ethyl acetate with a mass of 12 times that of trimethylolpropane was added for dilution. The mixture was first washed three times with 5wt% hydrochloric acid aqueous solution, and then washed with deionized water until neutral. After separation, the organic phase was collected and subjected to vacuum distillation at 55℃~60℃ for 3h to remove ethyl acetate. The temperature was then lowered to 28℃ to obtain a bifunctional group hybrid hyperbranched toughening agent with a viscosity of 12000mPa·s.

[0046] The preparation method of aminated boron nitride nanoparticles includes: adding hexagonal boron nitride nanoparticles to anhydrous ethanol containing 6wt% γ-aminopropyltriethoxysilane at a solid-liquid mass ratio of 1:15, dispersing evenly by ultrasonication, refluxing at 70℃~75℃ for 3h, filtering, washing the filter cake 4 times with anhydrous ethanol, and vacuum drying at 90℃ for 14h to obtain aminated boron nitride nanoparticles.

[0047] The preparation method of ionic liquid modified imidazole accelerator includes: mixing 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone in a mass ratio of 10:9:120, stirring and refluxing at 250 rpm for 5 h in a temperature range of 50℃~55℃, allowing to stand and cool to room temperature, filtering, washing the filter cake twice with acetone at 6℃, and then washing with deionized water until no white precipitate of chloride ions is detected by silver nitrate in the washing liquid, and drying under vacuum at 80℃ for 8 h to obtain ionic liquid modified accelerator.

[0048] The preparation method of the above-mentioned high-toughness bonding resin for new energy vehicle parts includes the following steps: Component A is prepared by mixing according to the formulation of component A; component B is prepared by mixing according to the formulation of component B; components A and B are stored separately. When using, mix at 300 rpm for 10 minutes at a temperature below 30°C, degas under vacuum, and complete the sizing operation within 40 minutes.

[0049] Recommended curing schemes for the bonding resin in the above embodiments: after application, place at 25℃~30℃ and 40%~60%RH for 1h~2h, cure at 75℃~85℃ for 2h~3h, and cure at 105℃~115℃ for 1h~2h.

[0050] In the above embodiments, the general chemical formula of the aromatic epoxy-siloxane block copolymer is: HO-[E] x -L-[S] y -L-[E] x -OH, where: [E] x It is an aromatic epoxy segment, E is the repeating unit -O-C6H4-C6H4-O-CH2-CH(OX)-CH2-, X is the covalent bonding site of the linker L; x is the degree of polymerization, 5≤x≤15; [S] y It is a siloxane segment, S is the repeating unit -Si(CH3)2-O-, y is the degree of polymerization, 20≤y≤30; L is the linking group, the core structure is -CH2CH2CH2-O-Si(OC2H5)2-CH2CH2CH2-NCO-O-, which is a covalently bridged structure between aromatic epoxy segments and siloxane segments; the molecular end group is hydroxyl -OH, the segments are ordered alternating blocks, and there is no random copolymerization structure.

[0051] In the above embodiments, the general chemical formula of the bifunctional group hybrid hyperbranched toughening agent is: Core-([P] n -TDI-NH-BNNS) m -([P] n -Cap) 3-m In the formula: Core represents the core structure, specifically the trifunctional core of trimethylolpropane -C(CH2OH)3-; [P] nThe structure consists of polyether ester branches, where P is a repeating ε-caprolactone ring-opening polymerization unit with the structure -O-(CH2)5-CO-; n is the degree of polymerization, 5≤n≤8; NH-BNNS is an aminated boron nitride nano-hybrid unit, where BNNS is a nano-hexagonal boron nitride sheet connected to TDI via covalent bonds between amino groups; TDI is a toluene-2,4-diisocyanate-derived coupling bridge with the structure -O-CO-NH-C6H3(CH3)-NCO-, and bifunctional groups are bonded to the polyether ester branches [P]. n With NH-BNNS; Cap is a diethanolamine-derived end-capping group, which is covalently linked to the unreacted isocyanate group of TDI via an amino group, with the structure -NH-CH2CH2OH; m is the number of branches of the grafted inorganic hybrid unit BNNS, 1≤m≤2, and the remaining 3-m branches are end-capped with diethanolamine.

[0052] In the above embodiments, the general chemical formula of the terminal amino dendritic curing agent is: G2-PAMAM-NH2, where PAMAM is a polyamide-amine branching unit with the structure H2N-CH2CH2-NH-CO-CH2CH2-[-NH-CH2CH2-NH-CO-CH2CH2-]2-NH2; G2 is a second-generation polyamide-amine dendritic macromolecule with a core structure of ethylenediamine H2N-CH2CH2-NH2, which is the starting core of the branching reaction. The branching unit is a polyamide-amine with the structure -CH2CH2-CO-NH-CH2CH2-NH-, which achieves secondary branching through amide and amine bonds; the molecular end groups are 8 primary amino groups -NH2; the branching method is that the two amino groups of the ethylenediamine core are primary branching sites, each of which is grafted with 1 polyamide-amine unit to form 4 secondary branching sites, and then each of which is grafted with 1 polyamide-amine unit to finally form 8 terminal primary amino groups.

[0053] The raw material specifications and sources involved in the above embodiments are as follows: The alicyclic epoxy resin is poly[(2-epoxyethylene)-1,2-cyclohexanediol]2-ethyl-2-(hydroxymethyl)-1,3-propanediol ether, sourced from Wuhan Jixin Yibang Biotechnology Co., Ltd. The silane coupling agent is KH-560 with a purity of over 98%. The titanate coupling agent is sourced from Hubei Hongyunlong Biotechnology Co., Ltd., with a purity of over 99%. The hydrophobic fumed silica is sourced from Hubei Huifu Nanomaterials Co., Ltd., with a specific surface area of ​​170±30 m². 2 / g. Defoamer is BYK-A530. Leveling agent is BYK-331. Terminal amino dendritic curing agent is from Xiamen Aikema Chemical Co., Ltd., and epoxy resin dendritic curing agent is CYD-N1403. Alicyclic amine curing agent is isophorone diamine with a purity of over 99%. The median particle size of nano-hexagonal boron nitride is below 500nm and is from Hangzhou Jiupeng New Materials Co., Ltd. Neopentyl glycol diglycidyl ether, epichlorohydrin, tetrabutylammonium bromide, octamethylcyclotetrasiloxane, 1,3-bis(3-glycidyl etheroxypropyl)tetramethyldisiloxane, dibutyltin dilaurate, hydroquinone, hexamethyldisiloxane, anhydrous magnesium sulfate, trimethylolpropane, ε-caprolactone, diethanolamine, ethyl acetate, 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone all have a purity of over 99%. The purity of 4,4'-dihydroxybiphenyl, 3-glycidyl etheroxypropyltriethoxysilane, γ-aminopropyltriethoxysilane, 3-isocyanate propyltriethoxysilane, and toluene-2,4-diisocyanate is all above 98%.

[0054] Comparative Example 1 The difference from Example 1 is that the aromatic epoxy-siloxane block copolymer is changed to 35 parts and the alicyclic epoxy resin is changed to 90 parts.

[0055] Comparative Example 2 The difference from Example 1 is that the bifunctional group hybrid hyperbranched toughening agent is changed to 5 parts.

[0056] Comparative Example 3 The difference from Example 1 is that the bifunctional group hybrid hyperbranched toughening agent is changed to 40 parts.

[0057] Comparative Example 4 The difference from Example 1 is that in the preparation of the aromatic epoxy-siloxane block copolymer, tetramethylammonium hydroxide silanoate is replaced by dibutyltin dilaurate.

[0058] Comparative Example 5 The difference from Example 1 is that in the preparation of the aromatic epoxy-siloxane block copolymer, the linker is directly replaced by 3-isocyanate propyltriethoxysilane.

[0059] Comparative Example 6 The difference from Example 1 is that no ionic liquid modified imidazole accelerator is added to component B.

[0060] Comparative Example 7 The difference from Example 1 is that in component B, the ionic liquid modified imidazole accelerator is directly replaced by 2-ethyl-4-methylimidazolium.

[0061] The bonding resins prepared in the above embodiments and comparative examples were subjected to performance testing.

[0062] To ensure consistency in the experiments, the curing scheme for the resin was uniformly designed as follows: place at 25℃ and 50%RH for 1.5h, cure at 80℃ for 2.5h, and cure at 110℃ for 2h.

[0063] 1. Tensile bond strength test: The test was conducted according to GB / T 6329 "Determination of Tensile Strength of Butt Joints in Adhesives". The substrate consisted of a 25mm diameter 6061 aluminum alloy rod and a PA66 plastic rod, joined end-to-end, with an adhesive layer thickness of 0.15mm. After curing, the samples were conditioned at 25℃ and 50%RH for 24 hours. A universal testing machine was used to stretch the sample at a rate of 2mm / min until fracture. The tensile bond strength σ = P / A, where P is the maximum load (N) and A is the bond area. Five valid samples were used in each group, and the average value was taken. See Table 1 for the results.

[0064] 2. 180° peel strength test: The test was conducted according to GB / T 2790 "Adhesives - 180° Peel Strength Test Method". The substrate consisted of 6061 aluminum alloy sheet (150mm × 25mm × 1mm) and PET film (150mm × 25mm × 0.1mm), with an adhesive layer thickness of 0.05mm and a 50mm unbonded length left at the peel end. After curing, the samples were conditioned at 25℃ and 50%RH for 24 hours. A universal testing machine was used to perform 180° peels at a rate of 100mm / min. The peel strength was calculated as the average force (N) of the stable segment after subtracting the initial 25mm from the peel force-displacement curve, and then expressed as the force per unit width (kN / m). Five valid samples were used in each group, and the results were averaged (see Table 1).

[0065] 3. Impact strength test of simply supported beams: The impact test was conducted according to GB / T 1043.1 "Determination of Impact Properties of Simply Supported Beams in Plastics - Part 1". The mixed and degassed resin was cast into molds, cured, and then processed into 80mm × 10mm × 4mm unnotched specimens. A simply supported beam impact testing machine with a span of 62mm and a 2J pendulum was used for testing. The impact strength αk = W / (b × h) × 10 3 Where αk is the impact strength (kJ / m) 2 W represents the impact energy absorbed by the specimen during fracture (J), b represents the specimen width (10 mm), and h represents the specimen thickness (4 mm). Five valid specimens were used in each group, and the average value of the results was taken, as shown in Table 1.

[0066] 4. Tensile strength and elongation at break testing: Tests were conducted according to GB / T 2567 "Test Methods for Properties of Resin Castings" and GB / T 1040.2 "Determination of Tensile Properties of Plastics". Type I dumbbell-shaped casting specimens were prepared with a gauge length thickness of 4 mm. After curing, the specimens were conditioned at 25℃ and 50%RH for 24 hours. A universal testing machine equipped with an extensometer was used to stretch the specimens at a rate of 5 mm / min until fracture. The maximum load and gauge length at fracture were recorded, and the tensile strength and elongation at break were calculated. Five valid specimens were used in each group, and the results were averaged (see Table 1).

[0067] 5. Tensile bond strength retention rate test after high and low temperature cycling: The specimens used in the tensile bond strength test were subjected to the same cyclic conditions as those used in the test, according to GB / T 2423.22 "Environmental Testing - Part 2: Test Methods - N: Temperature Change": -40℃ for 2 hours, 25℃ for 0.5 hours, 85℃ for 2 hours, and 25℃ for 0.5 hours, constituting one cycle, for a total of 50 cycles. After each cycle, the tensile bond strength was tested according to the standard method. The tensile bond strength retention rate was calculated as (σ1 / σ0) × 100%, where σ0 is the initial tensile bond strength and σ1 is the tensile bond strength after the high and low temperature cycles. Five valid specimens were used in each group, and the average value of the results was taken, as shown in Table 1.

[0068] 6. Detection of volatile organic compound content: The test was conducted according to GB / T 33372-2020, "Limits of Volatile Organic Compounds in Adhesives". A suitable amount of the pre-cured adhesive sample was taken and the total volatile organic compound content was determined using headspace gas chromatography-mass spectrometry (HS-GC-MS). The sample was injected for analysis after being held at 120℃ for 60 min. The VOC content in Examples 1 to 3 was all below 30 g / L.

[0069] Table 1. Test Results (Average Values) Examples 1 to 3, through precise formulation and synergistic design, demonstrate the dual advantages of comprehensive performance and environmental friendliness. A system combining aromatic epoxy-siloxane block copolymers and bifunctional hybrid hyperbranched toughening agents achieves a balance between rigidity and toughness, with high strength retention after high and low temperature cycling, meeting the bonding requirements of new energy vehicle components. Simultaneously, relying on a composite curing accelerator system and a solvent-free formulation, the VOC content is effectively reduced to below 30 g / L. Fine-tuning the proportions of each component adapts to different scenarios, balancing mechanical properties, weather resistance, and environmental friendliness.

[0070] In Comparative Example 1, the reduction of aromatic epoxy-siloxane block copolymer and the increase of alicyclic epoxy resin disrupted the balance between rigidity and flexibility. The insufficient flexible segments of siloxane led to increased internal stress. The alicyclic epoxy homopolymer was more brittle and its compatibility with siloxane decreased. The microphase separation size increased, the interface defects increased, and the thermal expansion coefficient adaptability deteriorated, resulting in a significant decrease in bond strength, toughness, and high and low temperature cycling retention.

[0071] In Comparative Example 2, the bifunctional group hybrid hyperbranched toughening agent was insufficient: the amount of toughening agent was insufficient, and an effective interpenetrating toughening network could not be formed. The toughening and chain segment entanglement effects were weak. The interfacial bonding points and crack inhibition effects provided by the amino-modified nano boron nitride were insufficient, and the impact energy was difficult to absorb, resulting in a decrease in impact strength, elongation at break and peel strength. The ability to resist microcrack propagation under high and low temperature cycling was weakened.

[0072] In Comparative Example 3, the bifunctional group hybrid hyperbranched toughening agent was excessive: the excessive toughening agent occupied the epoxy crosslinking sites, reduced the crosslinking density of the system, and the decrease in crosslinking density led to the sacrifice of strength, and the tensile strength and adhesive strength decreased; the aminated nano boron nitride was prone to agglomeration to form stress concentration points, and microcracks were easily generated under external force; although the toughness index (impact strength, elongation at break) increased slightly, the integrity of the crosslinking network was destroyed, the structural stability deteriorated, and the high and low temperature cycling retention rate was significantly reduced.

[0073] In Comparative Example 4, tetramethylammonium hydroxide silanolate was replaced by dibutyltin dilaurate: Tetramethylammonium hydroxide silanolate is a dedicated catalyst for the ring-opening polymerization of siloxanes. Dibutyltin dilaurate has low catalytic efficiency and poor selectivity, resulting in irregular polysiloxane segment structure and wide molecular weight distribution. It has poor block polymerization effect with aromatic epoxy segments, resulting in severe phase separation. The rigid-flexible synergistic advantage of the block copolymer is lost, and all mechanical properties and weather resistance are greatly reduced.

[0074] In Comparative Example 5, the binder was replaced by 3-isocyanate propyltriethoxysilane alone: ​​the original binder achieved precise chemical bonding between the epoxy segment and the siloxane segment through bifunctional groups. However, 3-isocyanate propyltriethoxysilane alone could only react with the hydroxyl groups of the siloxane and could not form a stable bond with the epoxy groups. As a result, the two segments were only bonded by physical entanglement and weak interfacial interaction, resulting in severe phase separation and the formation of isolated phase regions. There was no synergistic effect, the bonding force at the adhesive interface decreased significantly, and the mechanical properties deteriorated across the board. The phase region interface was prone to cracking under high and low temperature cycling, and the retention rate was the lowest.

[0075] In Comparative Example 6, without the addition of ionic liquid modified imidazole accelerator: the curing reaction depends on the activity of the amine curing agent itself, the reaction is slow at low temperature, the area of ​​incomplete curing increases, the uniformity of the crosslinking network is poor, and local stress concentration occurs, resulting in a decrease in impact strength, elongation at break and bond strength; insufficient curing degree leads to insufficient interfacial chemical bonding, deterioration of environmental resistance, and a decrease in high and low temperature cycle retention rate.

[0076] In Comparative Example 7, the ionic liquid modified imidazole accelerator was replaced by pure 2-ethyl-4-methylimidazolium. Pure 2-ethyl-4-methylimidazolium has poor solubility and dispersibility in epoxy systems, and is prone to local aggregation, resulting in uneven curing reaction. Excessive local crosslinking leads to the formation of brittle micro-regions, while insufficient local crosslinking leads to insufficient strength. The absence of ionic liquid makes the compatibility between the accelerator and the resin worse, weakens the effect of improving interfacial bonding, and results in lower toughness and high and low temperature cycling retention rates than in the examples.

Claims

1. A high-toughness bonding resin for new energy vehicle parts, characterized in that, It is composed of component A and component B mixed in a mass ratio of 100:(28-32); component A includes the following raw materials in parts by mass: 80-90 parts of aromatic epoxy-siloxane block copolymer, 35-45 parts of alicyclic epoxy resin, 18-25 parts of bifunctional hybrid hyperbranched toughening agent, 8-12 parts of silane coupling agent, 0.4-0.8 parts of titanate coupling agent, 0.5-1.0 parts of hydrophobic fumed silica, 0.3-0.5 parts of defoamer, 0.2-0.4 parts of leveling agent, and 5-10 parts of neopentyl glycol diglycidyl ether; component B includes the following raw materials in parts by mass: 25-30 parts of amino-terminated dendritic curing agent, 15-20 parts of alicyclic amine curing agent, and 0.8-1.5 parts of ionic liquid modified imidazole accelerator; The general chemical formula for aromatic epoxy-siloxane block copolymers is: HO-[E] x -L-[S] y -L-[E] x -OH, where: E is the repeating unit -O-C6H4-C6H4-O-CH2-CH(OX)-CH2-, X is the covalent bonding site of the linker L; 5≤x≤15; S is the repeating unit -Si(CH3)2-O-, 20≤y≤30; L is the linking group, and the core structure is -CH2CH2CH2-O-Si(OC2H5)2-CH2CH2CH2-NCO-O-; The general chemical formula for bifunctional group-hybridized hyperbranched toughening agents is: Core-([P] n -TDI-NH-BNNS) m -([P] n -Cap) 3-m In the formula: Core represents the core structure, with the structural formula -C(CH2OH)3-; [P] n The structure is a polyether ester branched chain, P is a repeating ε-caprolactone ring-opening polymerization unit with the structure -O-(CH2)5-CO-; 5≤n≤8; NH-BNNS is an aminated nano-boron nitride hybrid unit, covalently linked to TDI through an amino group; TDI structure is -O-CO-NH-C6H3(CH3)-NCO-; Cap is a diethanolamine-derived end-capping group; 1≤m≤2; The general chemical formula of the terminal amino dendritic curing agent is: G2-PAMAM-NH2, where PAMAM has the structure H2N-CH2CH2-NH-CO-CH2CH2-[-NH-CH2CH2-NH-CO-CH2CH2-]2-NH2; G2 is a second-generation polyamide-amine dendritic macromolecule with an ethylenediamine core, which is the starting core for the branching reaction. The branching unit is a polyamide-amine with the structure -CH2CH2-CO-NH-CH2CH2-NH-, which achieves secondary branching through amide and amine bonds; the molecular end groups are 8 primary amino groups; the branching method is that the two amino groups of the ethylenediamine core are primary branching sites, each of which is grafted with one polyamide-amine unit to form 4 secondary branching sites, and then each of these sites is grafted with one more polyamide-amine unit, ultimately forming 8 terminal primary amino groups; The ionic liquid modified imidazole promoter is a solid obtained by reacting 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone in a mass ratio of 10:(8.5-9):(120-150) and then drying it.

2. The high-toughness bonding resin for new energy vehicle parts according to claim 1, characterized in that, The silane coupling agent is KH-560; the defoamer is BYK-A530; the leveling agent is BYK-331; and the alicyclic amine curing agent is isophorone diamine.

3. The high-toughness bonding resin for new energy vehicle parts according to claim 1, characterized in that, The preparation method of the aromatic epoxy-siloxane block copolymer includes: under nitrogen protection, mixing 50-55 parts by mass of 4,4'-dihydroxybiphenyl, 350-370 parts by mass of epichlorohydrin, and 2-3 parts by mass of tetrabutylammonium bromide; adding 50-55 parts by mass of sodium hydroxide aqueous solution dropwise at 70-75°C; stirring and reacting at 75-78°C for 3-4 hours; adjusting the pH to 6.5-7.5 with deionized water; and distilling under reduced pressure to obtain reaction solution A; under nitrogen protection, mixing 200-220 parts by mass of octamethylcyclotetrasiloxane, 15-18 parts by mass of 1,3-bis(3-glycidyl etheroxypropyl)tetramethyldisiloxane, and 0.4-0.6 parts by mass of tetramethylammonium hydroxide silanolate. The reaction mixture was stirred at 105℃~115℃ for 5h~6h, then heated to 145℃~155℃ and held for 30min~40min, and then cooled to obtain reaction solution B. Under nitrogen protection, reaction solution A, reaction solution B, binder, and dibutyltin dilaurate were mixed in a mass ratio of (14~16):(9~11):(2~3):(0.015~0.018), stirred at 60℃~65℃ for 2h~2.5h, heated to 92℃~98℃ and stirred for 2.5h~3h, then cooled to 60℃~65℃, hydroquinone was added, and the mixture was stirred for 1h~1.5h. The temperature was then lowered, and the viscosity was adjusted to 8000mPa·s~9000mPa·s to obtain an aromatic epoxy-siloxane block copolymer.

4. The high-toughness bonding resin for new energy vehicle parts according to claim 3, characterized in that, The concentration of the sodium hydroxide aqueous solution is 40wt% to 42wt%; the vacuum distillation is carried out to 10% to 15% of the volume; the amount of hydroquinone added is 0.3% to 0.4% of the mass of reaction solution A; the hydroquinone is dissolved and diluted with 4 to 5 times the amount of acetone before being added; the viscosity is adjusted with neopentyl glycol diglycidyl ether.

5. The high-toughness bonding resin for new energy vehicle parts according to claim 3, characterized in that, The preparation method of the binder includes the following steps: under nitrogen protection, 3-isocyanate propyltriethoxysilane, 3-glycidyl ether propyltriethoxysilane, and dibutyltin dilaurate are mixed in a mass ratio of 10:(10.2~10.3):(0.003~0.005), stirred at 40℃~50℃ for 2h~3h, heated to 65℃~70℃ and stirred for 1.5h~2h, cooled to obtain a reaction solution, anhydrous magnesium sulfate is added for drying, filtered, and the filtrate is distilled under reduced pressure to obtain the binder.

6. The high-toughness bonding resin for new energy vehicle parts according to claim 1, characterized in that, The preparation method of the bifunctional group hybrid hyperbranched toughening agent includes: under nitrogen protection, trimethylolpropane, ε-caprolactone, and dibutyltin dilaurate are mixed in a mass ratio of (10-12):(55-65):(0.08-0.12), stirred at 110℃-120℃ for 3-4 hours, cooled to 65℃-70℃, aminated nano-boron nitride is added and dispersed evenly, toluene-2,4-diisocyanate is added dropwise, stirred at 80℃-85℃ for 2-2.5 hours, cooled to 65℃-70℃, diethanolamine is added dropwise, stirred for 3-3.5 hours, cooled, diluted with ethyl acetate, washed with hydrochloric acid aqueous solution, washed with deionized water until neutral, separated, and the organic phase is taken, distilled under reduced pressure, and cooled to obtain a bifunctional group hybrid hyperbranched toughening agent with a viscosity of 12000 mPa·s-15000 mPa·s.

7. The high-toughness bonding resin for new energy vehicle parts according to claim 6, characterized in that, The amount of aminated boron nitride nanoparticles added is 0.8 to 0.9 times the mass of trimethylolpropane; the amount of toluene-2,4-diisocyanate added is 1.3 to 1.5 times the mass of trimethylolpropane; the amount of diethanolamine added is 0.8 to 1 times the mass of trimethylolpropane; the amount of ethyl acetate added is 10 to 12 times the mass of trimethylolpropane; and the concentration of the hydrochloric acid aqueous solution is 5 wt% to 6 wt%.

8. The high-toughness bonding resin for new energy vehicle parts according to claim 6, characterized in that, The preparation method of the aminated boron nitride nanoparticles includes: adding hexagonal boron nitride nanoparticles to anhydrous ethanol containing 4wt% to 6wt% γ-aminopropyltriethoxysilane at a solid-liquid mass ratio of 1:(15-20), dispersing evenly, refluxing, filtering, washing the filter cake, and vacuum drying to obtain aminated boron nitride nanoparticles.

9. The high-toughness bonding resin for new energy vehicle parts according to claim 1, characterized in that, The preparation method of the ionic liquid modified imidazole accelerator includes: mixing 1-ethyl-3-methylimidazolium chloride, 2-ethyl-4-methylimidazolium, and acetone in a mass ratio of 10:(8.5-9):(120-150), stirring and reacting at 50℃-55℃ for 5-6 hours, allowing to stand and cool to room temperature, filtering, washing the filter cake with acetone, then washing with deionized water, and vacuum drying to obtain the ionic liquid modified accelerator.

10. A method for preparing the high-toughness bonding resin for new energy vehicle parts according to claim 1, characterized in that, Includes the following steps: Component A is prepared by mixing according to the formula of component A; component B is prepared by mixing according to the formula of component B; components A and B are stored separately, and when used, they are stirred and mixed evenly according to the ratio and degassed under vacuum.

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