Polyurethane structural adhesive and preparation method thereof

Abstract

The invention relates to the technical field of polyurethane structural adhesives, in particular to a polyurethane structural adhesive and a preparation method thereof.The polyurethane structural adhesive comprises a component A and a component B. The component A is prepared from, by weight, 20-40 parts of diisocyanate, 1-3 parts of a chain extender, 0.5-2 parts of a thixotropic agent and 5-10 parts of filler; the component B is prepared from the following raw materials in parts by weight: 20-80 parts of polyol, 4-6 parts of double-end hydroxypropyl silicone oil, 1-3 parts of a chain extender, 0.1-0.25 part of a catalyst and 5-10 parts of filler; the filler is composed of carbon fibers and carbon nanotubes according to the weight part ratio of (4-6): 1, by adopting the formula, the prepared polyurethane structural adhesive can meet the performance requirements in multiple aspects of adhesion, impact resistance, insulation and the like while the density is reduced and the heat-conducting property is improved, and the service life of the polyurethane structural adhesive is prolonged. Therefore, the battery can well adapt to the trend that new energy batteries develop towards the direction of high energy density, high safety and light weight.

Description

Technical Field

[0001] The present application relates to the technical field of polyurethane structural adhesives, and more specifically, to a polyurethane structural adhesive and a preparation method thereof. Background Art

[0002] As new energy batteries develop towards high energy density and high safety, adhesive materials need to have higher performance. Adhesive materials are not only about improving bonding strength, but also meeting the battery's requirements for high temperature resistance and corrosion resistance. Among them, polyurethane structural adhesive can form a strong bond with a variety of materials, including metals, plastics and composite materials. This enables it to adapt to components of different materials inside the battery, ensuring the reliability and stability of the bond, and maintaining a good connection between the battery cell and other components even in environments with battery vibration and impact. At the same time, polyurethane structural adhesive has good chemical corrosion resistance, heat resistance, impact resistance, thermal conductivity and insulation properties, making it a commonly used material for bonding battery cells in new energy batteries.

[0003] However, as new energy batteries develop towards lightweight, the density of polyurethane structural adhesives needs to be reduced, which usually means reducing the content of high-density components in the material, or adding some lightweight fillers to replace some of the original heavy components. For example, using low-density polymer segments, introducing porous structures or adopting lightweight fillers. However, the battery generates a lot of heat during operation, and these lightweight components often perform poorly in terms of thermal conductivity. Good thermal conductivity requires the material to have an efficient heat conduction path. Generally, materials with good thermal conductivity need to contain components with high thermal conductivity coefficients, such as metal fillers (such as aluminum powder, copper powder, etc.), ceramic fillers (such as alumina, boron nitride, etc.) or some polymer segments with high crystallinity. The addition of these components will increase the density of the material, which is contrary to the goal of lightweighting. Therefore, how to reduce the density of polyurethane structural adhesives while maintaining or even improving their thermal conductivity has become an urgent problem to be solved. Summary of the Invention

[0004] In order to solve the problem that polyurethane structural adhesive cannot meet the requirements of lightweight and high thermal conductivity at the same time, the present application provides a polyurethane structural adhesive and a preparation method thereof.

[0005] In a first aspect, the present application provides a polyurethane structural adhesive, which adopts the following technical solution: A polyurethane structural adhesive comprises component A and component B, wherein component A is prepared by comprising the following raw materials in parts by weight: 20-40 parts of diisocyanate 1-3 parts of chain extender 0.5-2 parts of thixotropic agent 5-10 parts filler Component B is prepared by including the following raw materials in parts by weight: 20-80 parts of polyol 4-6 parts of double-terminal hydroxypropyl silicone oil 1-3 parts of chain extender 0.1-0.25 parts of catalyst 5-10 parts of filler; The filler is composed of carbon fibers and carbon nanotubes in a weight ratio of (4-6):1.

[0006] By adopting the above technical solution, the prepared polyurethane structural adhesive can reduce density and improve thermal conductivity while taking into account the performance requirements of high temperature resistance, aging resistance, impact resistance, insulation, etc., so that it can well adapt to the development trend of new energy batteries towards high energy density, high safety and lightweight.

[0007] Carbon fiber and carbon nanotubes are both materials with high thermal conductivity. The combination of the two can form an efficient heat conduction path, allowing heat to be conducted quickly, dissipating the heat generated by the battery in a timely manner, reducing the internal temperature of the battery, and improving the heat dissipation efficiency and performance of the battery. This makes up for the problem of decreased thermal conductivity that may result from reduced density, allowing the polyurethane structural adhesive to maintain lightweight while still having good thermal conductivity. Compared with traditional high-density fillers, carbon fiber and carbon nanotubes have relatively low density while providing high thermal conductivity, which can reduce the overall density of the polyurethane structural adhesive to a certain extent. Among them, the low density of carbon fiber is used to reduce the overall density of the polyurethane structural adhesive. Carbon fiber has thermal conductivity, but its thermal conductivity is limited. By adding an appropriate amount of carbon nanotubes, its thermal conductivity is increased without increasing the density of the polyurethane structural adhesive.

[0008] The high strength and high modulus of carbon fibers and carbon nanotubes enhance the mechanical properties of polyurethane structural adhesives. Under battery vibration and impact, the modified polyurethane structural adhesive is better able to withstand stress and maintain a secure connection between the battery cell and other components. This helps improve battery stability and reliability, reducing the risk of battery failure due to bonding failure. The inherent flexibility of the polyurethane structural adhesive, combined with the reinforcing effects of carbon fibers and carbon nanotubes, imparts a high degree of strength while also possessing a certain degree of elasticity. This property allows it to adapt to the subtle deformations of internal battery components during charging and discharging, further improving the reliability and durability of the bond.

[0009] Preferably, the carbon fiber is modified carbon fiber, which is prepared by the following method: 1) Grinding the carbon fiber to 10-100 nm, then placing it in an environment with a temperature of 500-700° C., and firing it for 2-3 hours. During the firing process, spraying sodium hydroxide solution every 30 minutes, with the weight of each spraying being 1-2 times that of the carbon fiber, after the firing is completed, placing it in a sodium hydroxide solution at a temperature of 5-10° C., cooling, filtering, washing with water, and drying to obtain pretreated carbon fiber; 2) Mixing the pretreated carbon fiber with a long-chain alcohol, heating it to 120-140° C. under nitrogen conditions, maintaining heating for 2-3 hours, cooling, centrifuging, washing, and drying to obtain modified carbon fiber.

[0010] After the carbon fiber is ground to nanometer size, the specific surface area is greatly increased. During the firing process, sodium hydroxide solution is sprayed to etch the surface of the carbon fiber, further increasing its surface active sites. These active sites can undergo esterification reaction with long-chain alcohols, so that the long-chain alcohols are grafted to the surface of the carbon fiber, significantly improving the compatibility of the carbon fiber with the polyurethane structural adhesive matrix, uniformly dispersing it in the colloid, reducing agglomeration, and giving full play to its thermal conductivity and other properties. The modified carbon fiber is combined with carbon nanotubes to fill the polyurethane structural adhesive. The carbon nanotubes have excellent one-dimensional thermal conductivity, and the modified carbon fiber cooperates with the carbon nanotubes like nodes to form a stable and efficient three-dimensional thermal conductive network. Heat can be quickly conducted through this network, effectively reducing the internal temperature of the battery and improving heat dissipation efficiency.

[0011] The density of modified carbon fiber is low. Under the premise of ensuring the thermal conductivity of polyurethane structural adhesive, the use of this low-density filler combination can significantly reduce the density of structural adhesive, which is in line with the development trend of lightweight new energy batteries and is conducive to improving battery energy density and cruising range.

[0012] After the modified carbon fiber is added, the bonding force between the carbon fiber and the polyurethane matrix can be enhanced. When subjected to external force, it can effectively disperse stress, prevent the generation and expansion of cracks, improve the impact resistance and flexibility of the polyurethane structural adhesive, while maintaining a certain strength, enhancing the comprehensive mechanical properties of the structural adhesive, ensuring good connection between the battery cell and other components, and extending the battery life.

[0013] Preferably, the weight ratio of the carbon fiber to the long-chain alcohol is 1:(2-3).

[0014] By adopting the above technical solution, the amount of carbon fiber and long-chain alcohol is optimized, allowing the long-chain alcohol to fully contact the carbon fiber and undergo an esterification reaction. The long-chain alcohol can be evenly grafted onto the carbon fiber surface, achieving a high reaction conversion rate in a relatively short time, thereby improving production efficiency. The appropriate amount of long-chain alcohol grafting will not mask the thermal conductivity of the carbon fiber. At the same time, it can also enable the carbon fiber to be evenly dispersed in the polyurethane structural adhesive, better synergizing with the carbon nanotubes to form an efficient thermal conductivity path. Heat can be quickly transferred through the good contact between the carbon fiber and the carbon nanotubes, improving the thermal conductivity of the polyurethane structural adhesive. And under the premise of ensuring thermal conductivity, the addition of long-chain alcohol will not significantly increase the density of the polyurethane structural adhesive, which helps to achieve a balance between lightweight and high thermal conductivity of the structural adhesive.

[0015] Preferably, the polyol is composed of polyester polyol and polyether polyol in a weight ratio of (7-10):5.

[0016] By adopting the above technical solution and optimizing the type and dosage ratio of polyols, the density of the polyurethane structural adhesive is reduced. At the same time, the polyurethane structural adhesive has high strength while maintaining a certain degree of flexibility, which can adapt to the stress changes of batteries under different operating conditions and ensure stable bonding. This does not affect the heat dissipation performance of the polyurethane structural adhesive.

[0017] Preferably, the polyester polyol has a hydroxyl value of 10-500 mgKOH / g.

[0018] By adopting the above technical solution, the hydroxyl value of polyester polyol is optimized, and during the synthesis process of polyurethane structural adhesive, it can fully react with other ingredients such as diisocyanate to form a relatively stable polyurethane network structure, ensuring that the polyurethane structural adhesive has low density while also having good strength, bonding properties and heat dissipation properties.

[0019] Preferably, the hydroxyl value of the polyether polyol is 20-650 mgKOH / g.

[0020] By adopting this technical solution, the reaction with diisocyanate is more complete, forming a more stable polyurethane network structure. This reduces the density of the polyurethane structural adhesive while maintaining performance, contributing to battery lightweighting. Furthermore, the polyurethane structural adhesive maintains a certain strength while also possessing improved flexibility, effectively dispersing stress and improving impact resistance, thus reducing the risk of component damage when the battery is subjected to external forces.

[0021] Preferably, the double-terminal hydroxypropyl silicone oil has a hydroxyl content of 2-4.5% and a molecular weight of 500-5000.

[0022] By adopting the above technical solution, the hydroxyl content and molecular weight of the double-ended hydroxypropyl silicone oil are optimized. During the synthesis process of the polyurethane structural adhesive, it can fully react with the isocyanate group to form a stable chemical bond, thereby improving the uniformity of the network structure of the polyurethane structural adhesive, reducing the density of the polyurethane structural adhesive, and at the same time improving the flexibility of the polyurethane structural adhesive, so that it can better absorb and disperse stress when subjected to external force, reducing the occurrence of cracks caused by stress concentration.

[0023] Preferably, the thixotropic agent is composed of hydrogenated castor oil and oleic acid in a weight ratio of (2-4):1.

[0024] By adopting this technical solution and optimizing the type and dosage of thixotropic agents, the colloid viscosity is reduced, the fluidity is improved, and application is facilitated. Furthermore, the thixotropic agent enhances the bonding performance, heat resistance, and weather resistance of the polyurethane structural adhesive, maintaining its stable performance under various environmental conditions and extending the service life and bonding effectiveness of the polyurethane structural adhesive.

[0025] Preferably, component A further comprises 1-2 parts by weight of an antioxidant, wherein the antioxidant comprises one of tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol, 3,5-di-tert-butyl-4-hydroxyphenylpropionate octadecyl, tris(2,4-di-tert-butylphenyl) phosphite, 2,6-di-tert-butyl 4-methylphenol and bis(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.

[0026] By adopting the above technical solution, the antioxidant performance of the polyurethane structural adhesive is improved, the oxidation of the polyurethane structural adhesive is prevented, and its long-term stability and service life are greatly improved.

[0027] In a second aspect, the present application provides a method for preparing a polyurethane structural adhesive, which adopts the following technical solution: A method for preparing a polyurethane structural adhesive comprises the following steps: Prepare component A: Place diisocyanate, chain extender, thixotropic agent and filler into a stirred kettle and evacuate and stir for 1-2 hours. Control the mixing temperature at 50-60°C and the vacuum degree at -0.08 to -0.09 MPa to obtain component A. Prepare component B: put polyol, double-terminal hydroxypropyl silicone oil, chain extender, catalyst and filler into a stirred kettle and stir under vacuum for 1-2 hours. Control the mixing temperature at 50-60°C and the vacuum degree at -0.08 to -0.09 MPa to obtain component B; Mixing: Mix component A and component B to obtain polyurethane structural adhesive.

[0028] By adopting the above technical solution, vacuum stirring is used during the preparation of both components A and B. The vacuum environment effectively removes bubbles and impurities during the mixing process, allowing the components to fully contact and mix, forming a uniform system and ensuring the uniformity and stability of the mixture. This allows components A and B to form a uniform polyurethane network structure after mixing, improving bonding strength and thermal conductivity, and ensuring a stable connection between battery components.

[0029] In summary, this application has the following beneficial effects: 1. Prepared from a specific ratio of component A and component B raw materials, the diisocyanate, chain extender, thixotropic agent, and filler in component A interact with the polyol, bi-terminal hydroxypropyl silicone oil, chain extender, catalyst, and filler in component B. The filler is composed of carbon fibers and carbon nanotubes in a specific ratio. This combination reduces the density of the polyurethane structural adhesive while significantly improving its thermal conductivity, effectively dissipating heat from the battery, avoiding the decrease in thermal conductivity caused by reduced density, and meeting the high energy density and lightweight requirements of new energy batteries. Furthermore, the high strength and high modulus of carbon fibers and carbon nanotubes significantly enhance the mechanical properties of the polyurethane structural adhesive, ensuring it maintains a secure connection between the battery cell and other components under battery vibration and shock, improving battery stability and reliability, and reducing the risk of bond failure. Combined with other raw materials, the polyurethane structural adhesive improves its flexibility, possessing high strength and elasticity, adapting to the slight deformation of internal battery components during charging and discharging, further enhancing the reliability and durability of the bond. It also exhibits high-temperature resistance, aging resistance, and insulation properties, making it well suited to the development trend of new energy batteries. DETAILED DESCRIPTION Example

[0030] Example 1 A polyurethane structural adhesive is prepared by the following method: Preparation of component A: 200 g of diisocyanate (isophorone diisocyanate), 10 g of chain extender (1,4-butanediol), 10 g of antioxidant (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 5 g of thixotropic agent (white carbon black), and 50 g of filler were placed in a stirred kettle, vacuum-stirred for 1 h, and the mixing temperature was controlled at 50° C. and the vacuum degree was -0.08 MPa to obtain component A; Preparation of component B: 200 g of polyol (polycarbonate polyol), 40 g of double-terminal hydroxypropyl silicone oil, 10 g of chain extender (1,4-butanediol), 1 g of catalyst (dibutyltin dilaurate), and filler were placed in a stirred kettle and vacuum-stirred for 1 h. The mixing temperature was controlled at 50°C and the vacuum degree was -0.08 MPa to obtain component B; Mixing: Component A and component B are mixed in a weight ratio of 0.9:1 to obtain a polyurethane structural adhesive.

[0031] The hydroxyl content of the double-ended hydroxypropyl silicone oil is 4.5% and the molecular weight is 500.

[0032] The polycarbonate polyol had a hydroxyl value of 10 mgKOH / g and a molecular weight of 2,000.

[0033] The filler consists of carbon fibers (with an average particle size of 10 nm) and carbon nanotubes in a weight ratio of 4:1.

[0034] The difference between Example 2-3 and Example 1 is that the types, amounts and parameters of raw materials used to prepare the polyurethane structural adhesive are different. The specific differences are shown in Table 1: Table 1 Types, amounts and parameters of raw materials used in preparing polyurethane structural adhesives in Examples 1-3 Polycaprolactone polyol, hydroxyl value is 30mgKOH / g, molecular weight is 3000.

[0035] Glycerol polyether polyol, hydroxyl value is 20mgKOH / g, molecular weight is 3000.

[0036] Example 4 A polyurethane structural adhesive, the difference between this embodiment and embodiment 1 is that the carbon fiber is modified carbon fiber, which is prepared by the following method 1) 60 g of carbon fiber was ground to 10 nm, then placed in an environment at a temperature of 500 ° C and fired for 2 h. During the firing process, sodium hydroxide solution (mass fraction of 10%) was sprayed every 30 min, and the weight of each spraying was 120 g of carbon fiber. After the firing was completed, it was placed in a sodium hydroxide solution at a temperature of 5 ° C, cooled, filtered, washed with water, and dried to obtain pretreated carbon fiber; 2) The pretreated carbon fiber was mixed with 120 g of long-chain alcohol (stearyl alcohol), heated to 120° C. under nitrogen, kept heated for 2 h, cooled, centrifuged, washed and dried to obtain modified carbon fiber.

[0037] Example 5 A polyurethane structural adhesive, the difference between this embodiment and embodiment 1 is that the carbon fiber is modified carbon fiber, which is prepared by the following method 1) 60 g of carbon fiber was ground to 100 nm, then placed in an environment at a temperature of 700 ° C and fired for 3 h. During the firing process, 120 g of sodium hydroxide solution (mass fraction 10%) was sprayed every 30 min, and the weight of each spraying was twice that of the carbon fiber. After the firing was completed, it was placed in a sodium hydroxide solution at a temperature of 10 ° C, cooled, filtered, washed with water, and dried to obtain pretreated carbon fiber; 2) The pretreated carbon fiber was mixed with 180 g of long-chain alcohol (stearyl alcohol), heated to 140° C. under nitrogen, kept heated for 3 h, cooled, centrifuged, washed and dried to obtain modified carbon fiber.

[0038] Example 6 A polyurethane structural adhesive. The difference between this embodiment and embodiment 1 is that the polyol is composed of polyester polyol and polyether polyol in a weight ratio of 7:5.

[0039] The polyester polyol is a polycarbonate polyol having a hydroxyl value of 10 mgKOH / g and a molecular weight of 2000.

[0040] The polyether polyol is glycerol polyether polyol with a hydroxyl value of 20 mgKOH / g and a molecular weight of 3000.

[0041] Example 7 A polyurethane structural adhesive. The difference between this embodiment and embodiment 1 is that the polyol is composed of polyester polyol and polyether polyol in a weight ratio of 10:5.

[0042] The polyester polyol is a polycarbonate polyol having a hydroxyl value of 500 mgKOH / g and a molecular weight of 4000.

[0043] The polyether polyol is glycerol polyether polyol with a hydroxyl value of 650 mgKOH / g and a molecular weight of 5000.

[0044] Example 8 A polyurethane structural adhesive. This embodiment differs from embodiment 1 in that the thixotropic agent is composed of hydrogenated castor oil and oleic acid in a weight ratio of 2:1.

[0045] Example 9 A polyurethane structural adhesive. This embodiment differs from embodiment 1 in that the thixotropic agent is composed of hydrogenated castor oil and oleic acid in a weight ratio of 4:1.

[0046] Comparative Example Comparative Example 1 A polyurethane structural adhesive. The difference between this comparative example and Example 1 is that the filler is carbon fiber.

[0047] Comparative Example 2 A polyurethane structural adhesive. The difference between this comparative example and Example 1 is that the filler is carbon nanotubes.

[0048] Comparative Example 3 A polyurethane structural adhesive. The difference between this comparative example and Example 1 is that the filler is boron nitride.

[0049] Comparative Example 4 A polyurethane structural adhesive. The difference between this comparative example and Example 1 is that the double-terminal hydroxypropyl silicone oil in component B is replaced by polydimethylsiloxane.

[0050] Polydimethylsiloxane was purchased from Qingdao Baisenmao New Materials Co., Ltd., model BSM201.

[0051] Detection method / test method Density: Tested in accordance with ASTM D972 standard.

[0052] Shear bond strength: tested in accordance with ISO4587 standard.

[0053] Thermal conductivity test: Tested in accordance with ASTM 5470.

[0054] Elongation at break: tested in accordance with ASTM D 412.

[0055] Double 85 aging test: The samples were placed in an 85℃ / 85RH% environment for 1000h, and then their shear bond strength was tested. The experimental results are shown in Table 2: Table 2 Experimental data of Examples 1-9 and Comparative Examples 1-4 It can be seen from the experimental data of Example 1 and Comparative Examples 1-3 that in the present application, by using carbon fibers and carbon nanotubes in a specific proportion for polyurethane structural adhesive, the low density of the polyurethane structural adhesive can be reduced to achieve lightweighting. At the same time, it can also ensure that the polyurethane structural adhesive has good thermal conductivity, while taking into account both lightweight and high thermal conductivity, and the bonding performance, elasticity and aging performance are all improved, which can well adapt to the development trend of new energy batteries towards high energy density, high safety and lightweight.

[0056] It can be seen from the experimental data of Example 1 and Comparative Example 4 that the addition of an appropriate amount of double-ended hydroxypropyl silicone oil is beneficial to improving the thermal conductivity, elasticity, aging resistance and bonding performance of the polyurethane structural adhesive.

[0057] It can be seen from the experimental data of Examples 1 and 4-5 that modifying carbon fibers by the method of the present application can effectively reduce the ether content of polyurethane structural adhesive while also improving its thermal conductivity, elasticity, aging resistance and bonding performance.

[0058] It can be seen from the experimental data of Examples 1 and 6-7 that by using polyester polyol and polyether polyol in a specific ratio, the thermal conductivity, elasticity, aging resistance and bonding performance of the polyurethane structural adhesive can be improved, while its density can be slightly reduced.

[0059] It can be seen from the experimental data of Examples 1 and 8, and Examples 4 and 9 that the thermal conductivity, elasticity, aging resistance and bonding performance of the polyurethane structural adhesive can be improved by using hydrogenated castor oil and oleic acid in a specific ratio.

[0060] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A polyurethane structural adhesive, characterized in that: The method comprises component A and component B, wherein component A is prepared by comprising the following raw materials in parts by weight: 20-40 parts of diisocyanate 1-3 parts of chain extender 0.5-2 parts of thixotropic agent 5-10 parts filler Component B is prepared by including the following raw materials in parts by weight: 20-80 parts of polyol 4-6 parts of double-terminal hydroxypropyl silicone oil 1-3 parts of chain extender 0.1-0.25 parts of catalyst 5-10 parts of filler; The filler is composed of carbon fibers and carbon nanotubes in a weight ratio of (4-6):

1.

2. The polyurethane structural adhesive according to claim 1, characterized in that: The carbon fiber is a modified carbon fiber, which is prepared by the following method: 1) Grind the carbon fiber to 10-100nm, then place it in an environment with a temperature of 500-700℃ and burn it for 2-3h. During the burning process, spray sodium hydroxide solution every 30min, and the weight of each spray is 1-2 times that of the carbon fiber. After the burning is completed, place it in a sodium hydroxide solution with a temperature of 5-10℃, cool, filter, wash with water, and dry to obtain pretreated carbon fiber; 2) The pretreated carbon fiber is mixed with a long-chain alcohol, heated to 120-140° C. under nitrogen conditions, maintained for 2-3 hours, cooled, centrifuged, washed and dried to obtain the modified carbon fiber.

3. The polyurethane structural adhesive according to claim 2, characterized in that: The weight ratio of the carbon fiber to the long-chain alcohol is 1:(2-3).

4. The polyurethane structural adhesive according to claim 1, characterized in that: The polyol is composed of polyester polyol and polyether polyol in a weight ratio of (7-10):

5.

5. The polyurethane structural adhesive according to claim 4, characterized in that: The polyester polyol has a hydroxyl value of 10-500 mgKOH / g.

6. The polyurethane structural adhesive according to claim 4, characterized in that: The hydroxyl value of the polyether polyol is 20-650 mgKOH / g.

7. The polyurethane structural adhesive according to claim 1, characterized in that: The double-terminal hydroxypropyl silicone oil has a hydroxyl content of 2-4.5% and a molecular weight of 500-5000.

8. The polyurethane structural adhesive according to claim 1, characterized in that: The thixotropic agent is composed of hydrogenated castor oil and oleic acid in a weight ratio of (2-4):

1.

9. The polyurethane structural adhesive according to claim 1, characterized in that: Component A also includes 1-2 parts by weight of an antioxidant, wherein the antioxidant includes one of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate, tris(2,4-di-tert-butylphenyl) phosphite, 2,6-di-tert-butyl 4-methylphenol and bis(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.

10. A method for preparing the polyurethane structural adhesive according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: Prepare component A: Place diisocyanate, chain extender, thixotropic agent and filler into a stirred kettle and evacuate and stir for 1-2 hours. Control the mixing temperature at 50-60°C and the vacuum degree at -0.08 to -0.09 MPa to obtain component A. Prepare component B: put polyol, double-terminal hydroxypropyl silicone oil, chain extender, catalyst and filler into a stirred kettle and stir under vacuum for 1-2 hours. Control the mixing temperature at 50-60°C and the vacuum degree at -0.08 to -0.09 MPa to obtain component B; Mixing: Mix component A and component B to obtain polyurethane structural adhesive.

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