High-weatherability polyurethane structural adhesive and preparation method thereof

Abstract

This invention belongs to the field of polyurethane structural adhesive technology, and provides a high weather-resistant polyurethane structural adhesive and its preparation method. The polyurethane structural adhesive is prepared by mixing and curing component A and component B in a mass ratio of 100:95-105. Component A, by weight, includes the following raw materials: 15-20 parts of vegetable oil polyol, 30-40 parts of polycarbonate diol, 15-25 parts of polycaprolactone diol, 3-6 parts of modified nano-titanium dioxide, 0.5-3.5 parts of chain extender, 0.01-0.2 parts of catalyst, 0.8-1.5 parts of silane coupling agent, and 1-2 parts of dehydrating agent. Component B, by weight, includes the following raw materials: 40-55 parts of isophorone diisocyanate, 20-30 parts of polyether polyol, 3-5 parts of nano-alumina, 8-12 parts of hexagonal boron nitride, 1-3 parts of plasticizer, and 1-2 parts of dehydrating agent.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane structural adhesive technology, specifically relating to a high weather-resistant polyurethane structural adhesive and its preparation method. Background Technology

[0002] Polyurethane structural adhesives are a class of high-performance adhesives with polyurethane prepolymer as the main component. They possess excellent elasticity, abrasion resistance, low-temperature flexibility, and good adhesion to various substrates, and are widely used in automotive manufacturing, building curtain walls, rail transportation, and new energy battery packaging. Polyurethane structural adhesives typically consist of a polyol component and an isocyanate component, which cure by undergoing a cross-linking reaction after mixing to form a three-dimensional network structure. Based on the curing mechanism, they can be divided into two main categories: single-component moisture-curing type and two-component reactive type. Among them, two-component polyurethane structural adhesives have advantages such as fast curing speed, wide performance adjustment range, and good storage stability, and dominate industrial applications.

[0003] In recent years, with the continuous expansion of application fields, especially under long-term outdoor exposure or extreme climatic conditions, the weather resistance of polyurethane structural adhesives has faced severe challenges. Existing polyurethane structural adhesives generally suffer from insufficient weather resistance. The urethane groups, ester bonds, or ether bonds in their molecular structure are highly susceptible to hydrolysis, thermo-oxidative degradation, or photoaging reactions under the synergistic effects of long-term exposure to humidity, heat, oxygen, ultraviolet radiation, and rapid temperature changes. This leads to molecular chain breakage or excessive cross-linking of the adhesive, macroscopically manifested as a significant decrease in bond strength, material brittleness or pulverization, ultimately resulting in structural failure. For example, in the bonding applications of new energy vehicle power batteries, where battery operating temperatures can reach approximately 60°C and are accompanied by vibration, ordinary polyurethane structural adhesives show significant strength degradation after long-term heating, posing safety hazards. In the construction field, polyurethane sealants also face long-term bond failure problems due to ultraviolet aging and humid heat cycling.

[0004] To improve the aging resistance of polyurethane, the industry has conducted some in-depth research and exploration. For example, adding fillers such as fumed silica can delay thermo-oxidative aging, but the introduction of a single filler has limited effect on improving overall weather resistance. Other methods involve introducing polyols or isocyanates with specific structures to improve high-temperature and aging resistance, but these formulations are complex and do not adequately address the improvement of UV radiation resistance. Furthermore, some technical solutions focus on improving thermal conductivity or flame retardancy, failing to comprehensively balance overall weather resistance, including resistance to damp heat, UV radiation, and thermo-oxidative aging, while maintaining high strength.

[0005] Therefore, developing a polyurethane structural adhesive that possesses both high strength and the ability to maintain stable performance over long periods under harsh environments such as ultraviolet radiation and high / low temperature shocks remains a pressing technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a high weather-resistant polyurethane structural adhesive and its preparation method, so as to solve the technical problem of insufficient weather resistance of polyurethane structural adhesives in the prior art.

[0007] The objective of this invention can be achieved through the following technical solutions: The first aspect of this invention provides a high weather-resistant polyurethane structural adhesive, wherein the polyurethane structural adhesive is prepared by mixing and curing component A and component B in a mass ratio of 100:95-105; Component A comprises the following raw materials by weight: 15-20 parts of vegetable oil polyol, 30-40 parts of polycarbonate diol, 15-25 parts of polycaprolactone diol, 3-6 parts of modified nano titanium dioxide, 0.5-3.5 parts of chain extender, 0.01-0.2 parts of catalyst, 0.8-1.5 parts of silane coupling agent, and 1-2 parts of dehydrating agent; Component B comprises the following raw materials by weight: 40-55 parts of isophorone diisocyanate, 20-30 parts of polyether polyol, 3-5 parts of nano alumina, 8-12 parts of hexagonal boron nitride, 1-3 parts of plasticizer, and 1-2 parts of dehydrating agent.

[0008] In some embodiments of the present invention, the modified nano-titanium dioxide in component A is prepared by the following steps: S1. Dissolve dopamine hydrochloride in Tris-HCl buffer, then add nano-titanium dioxide, sonicate for 20-30 min, stir for 12-16 h, after the reaction is complete, wash with deionized water, centrifuge, freeze dry and grind to obtain pretreated titanium dioxide. S2. Pretreated titanium dioxide, phosphorus oxychloride, and triethylamine were added to tetrahydrofuran and ultrasonically dispersed for 1–1.5 h to obtain a mixture. 4,4-Diaminodiphenylmethane was dissolved in tetrahydrofuran and then added dropwise to the mixture over 1 h. The mixture was stirred and reacted for 24–26 h. After the reaction was completed, the mixture was purified sequentially with tetrahydrofuran and deionized water. Finally, it was dried under reduced pressure at 80°C for 24 h to obtain modified nano-titanium dioxide.

[0009] In some embodiments of the present invention, the ratio of dopamine hydrochloride, Tris-HCl buffer, and nano-titanium dioxide in S1 is 1.38–1.42 g: 300 mL: 0.66–0.68 g; the ratio of pretreated titanium dioxide, phosphorus oxychloride, triethylamine, and tetrahydrofuran in S2 is 0.50–0.55 g: 0.31–0.32 g: 0.24–0.25 g: 100 mL; and the ratio of 4,4-diaminodiphenylmethane and tetrahydrofuran is 0.66–0.67 g: 30 mL.

[0010] The aforementioned technical solution, due to the UV shielding effect and photocatalytic antibacterial effect of nano-titanium dioxide, can effectively prevent the photo-oxidative degradation of polyurethane, endowing the polymer with antibacterial and antifungal properties. This further improves the weather resistance of polyurethane materials and extends their outdoor service life. It can also strengthen and toughen the polymer, improving its tensile strength, hardness, and wear resistance. However, nano-titanium dioxide has a high surface energy and poor compatibility with polymers, resulting in poor stability and dispersibility in the matrix, thus severely affecting the polymer's performance. Therefore, to address these shortcomings, this invention first coats nano-titanium dioxide particles with dopamine to obtain a polydopamine coating layer. The catechol groups and amino groups of polydopamine reduce the surface energy of the particles, improving their wettability and dispersion stability in the polymer. Furthermore, phosphorus oxychloride and 4,4-diaminodiphenylmethane were used as modifiers to perform flame-retardant functionalization modification on polydopamine-coated titanium dioxide. By grafting N and P elements after coating, not only can the compatibility with polyurethane be improved and the interfacial bonding be enhanced, but the flame-retardant effect and mechanical properties can also be taken into account, thereby improving the flame-retardant properties, mechanical properties and thermal stability of polyurethane structural adhesive.

[0011] In some embodiments of the present invention, the vegetable oil polyol in component A is hydrogenated epoxidized soybean oil.

[0012] In some embodiments of the present invention, the chain extender in component A is one of 1,4-butanediol, triethanolamine, glycerol, ethylene glycol, E100, and E300.

[0013] In some embodiments of the present invention, the catalyst in component A is one of bismuth neodecanoate, zinc neodecanoate, and zinc isooctanoate.

[0014] In some embodiments of the present invention, the silane coupling agent in component A is one of silane coupling agent KH-550 and silane coupling agent KH-560.

[0015] In some embodiments of the present invention, the dehydrating agents in both component A and component B are molecular sieves.

[0016] In some embodiments of the present invention, the polyether polyol in component B is PPG-2000.

[0017] In some embodiments of the present invention, the plasticizer in component B is one of the following: DOTP, PEA, and ATBC.

[0018] A second aspect of this invention provides a method for preparing a high weather-resistant polyurethane structural adhesive, comprising the following steps: Step 1: Add vegetable oil polyol, polycarbonate diol, and polycaprolactone diol to a reaction vessel, heat to 100-120℃ and stir for 1.5-3 hours, cool to 60-80℃ and continue stirring for 0.5-1 hours, finally add chain extender, catalyst, silane coupling agent and dehydrating agent, continue stirring for 0.5-1 hours, discharge under nitrogen protection to obtain component A; Step 2: Add isophorone diisocyanate and polyether polyol to the reactor, heat to 80-85℃, stir for 2-3 hours, and after the NCO content reaches the theoretical value, adjust the NCO content to 18%-22%, cool to 50-60℃, add plasticizer to the reactor, stir for 0.5-1 hours, then add nano zinc oxide, hexagonal boron nitride and dehydrating agent, continue stirring for 0.5-1 hours, discharge under nitrogen protection to obtain component B; Step 3: Mix component A and component B to obtain the final product.

[0019] The beneficial effects of this invention are: This invention achieves a significant improvement in material performance through the synergistic design of components A and B. Component A, mainly composed of polycarbonate diol and polycaprolactone diol, endows the polyurethane matrix with excellent hydrolysis resistance, oxidation resistance, and mechanical strength. Simultaneously, the introduction of vegetable oil polyols enhances environmental friendliness and flexibility while ensuring reactivity. Component B, with alicyclic isophorone diisocyanate as its core, provides the adhesive with excellent resistance to yellowing and UV radiation due to its saturated structure. Crucially, component B incorporates nano-alumina and hexagonal boron nitride. Their synergistic effect not only rapidly dissipates interfacial heat through highly thermally conductive fillers, delaying high-temperature aging, but also effectively improves the structural adhesive's resistance to corrosion, thus solving the anti-aging problem of polyurethane structural adhesives during long-term outdoor use and extending their service life.

[0020] This invention also provides a modified nano-titanium dioxide. Addressing the issues of easy agglomeration and poor compatibility with the matrix in nano-titanium dioxide, this invention first coats the nanoparticles with polydopamine, utilizing its abundant catechol groups and amino groups to significantly reduce the surface energy and introduce reactive sites. Subsequently, through graft modification with phosphorus oxychloride and 4,4-diaminodiphenylmethane, N and P flame-retardant elements are successfully bonded to the particle surface. This significantly improves the dispersion stability of inorganic fillers in organic polyols, avoiding agglomeration defects, and allows the UV-shielding effect of titanium dioxide itself to enhance the weather resistance and antibacterial and antifungal properties of the polyurethane structural adhesive. Furthermore, the introduced N and P elements promote char formation during combustion, endowing the structural adhesive with excellent flame-retardant properties, achieving an integration of mechanical reinforcement, weather resistance, and flame retardancy.

[0021] This invention provides a method for preparing a high-weather-resistant polyurethane structural adhesive. The method involves separately mixing raw materials to form component A and component B, and then mixing components A and B together to ensure the product's storage stability. The resulting polyurethane structural adhesive exhibits excellent weather resistance, thermal stability, and superior mechanical and flame-retardant properties. It is suitable for applications with stringent requirements for weather resistance and reliability, such as outdoor building curtain walls, photovoltaic module encapsulation, and automotive body structure bonding, and has broad application prospects. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Preparation Example Preparation Example 1 This preparation example provides a modified nano-titanium dioxide, and the preparation steps are as follows: S1. Dissolve 1.38g of dopamine hydrochloride in 300mL of Tris-HCl buffer, then add 0.66g of nano titanium dioxide, sonicate for 25min, stir for 12h, after the reaction is complete, wash with deionized water, centrifuge, freeze dry and grind to obtain pretreated titanium dioxide. S2. Add 0.50g of pretreated titanium dioxide, 0.31g of phosphorus oxychloride and 0.24g of triethylamine to 100mL of tetrahydrofuran and disperse by ultrasonication for 1h to obtain a mixture. Dissolve 0.66g of 4,4-diaminodiphenylmethane in 30mL of tetrahydrofuran and then add it dropwise to the mixture over 1h. Stir and react for 24h. After the reaction is complete, purify the mixture by tetrahydrofuran and deionized water in sequence, and finally dry it under reduced pressure at 80°C for 24h to obtain modified nano-titanium dioxide.

[0024] Preparation Example 2 The only difference from Preparation Example 1 is that: S1. Dissolve 1.42g of dopamine hydrochloride in 300mL of Tris-HCl buffer, then add 0.68g of nano titanium dioxide, sonicate for 25min, stir for 12h. After the reaction is complete, wash with deionized water, centrifuge, freeze dry and grind to obtain pretreated titanium dioxide.

[0025] Preparation Example 3 The only difference from Preparation Example 1 is that: S2. Add 0.55g of pretreated titanium dioxide, 0.32g of phosphorus oxychloride and 0.25g of triethylamine to 100mL of tetrahydrofuran and sonicate for 1h to obtain a mixture. Dissolve 0.67g of 4,4-diaminodiphenylmethane in 30mL of tetrahydrofuran and then add it dropwise to the mixture over 1h. Stir and react for 24h. After the reaction is complete, purify the mixture sequentially with tetrahydrofuran and deionized water. Finally, dry the mixture under reduced pressure at 80°C for 24h to obtain modified nano-titanium dioxide.

[0026] Example Example 1 This preparation example provides a high weather-resistant polyurethane structural adhesive and its preparation method: A high weather-resistant polyurethane structural adhesive, wherein the polyurethane structural adhesive is prepared by mixing and curing component A and component B in a mass ratio of 100:95; Component A comprises the following raw materials by weight: 15 parts hydrogenated epoxidized soybean oil, 30 parts polycarbonate diol, 15 parts polycaprolactone diol, 3 parts modified nano titanium dioxide from Preparation Example 1, 0.5 parts 1,4-butanediol, 0.01 parts bismuth neodecanoate, 0.8 parts silane coupling agent KH-550, and 1 part molecular sieve. Component B comprises the following raw materials by weight: 40 parts isophorone diisocyanate, 20 parts polyether polyol, 3 parts nano alumina, 8 parts hexagonal boron nitride, 1 part plasticizer DOTP, and 1 part molecular sieve.

[0027] A method for preparing a high weather-resistant polyurethane structural adhesive includes the following steps: Step 1: Add vegetable oil polyol, polycarbonate diol, and polycaprolactone diol to a reaction vessel, heat to 100℃ and stir for 1.5h, cool to 60℃ and continue stirring for 0.5h, finally add chain extender, catalyst, silane coupling agent and dehydrating agent, continue stirring for 0.5h, discharge under nitrogen protection to obtain component A; Step 2: Add isophorone diisocyanate and polyether polyol to the reactor, heat to 80°C, stir for 2 hours, and after the NCO content reaches the theoretical value, adjust the NCO content to 18%, cool to 50°C, add plasticizer to the reactor, stir for 0.5 hours, then add nano zinc oxide, hexagonal boron nitride and dehydrating agent, continue stirring for 0.5 hours, discharge under nitrogen protection to obtain component B; Step 3: Mix component A and component B to obtain the final product.

[0028] Example 2 The only difference from Example 1 is that: The modified nano-titanium dioxide in Preparation Example 1 was replaced with the modified nano-titanium dioxide in Preparation Example 2, with the amount of each component remaining the same.

[0029] Example 3 The only difference from Example 1 is that: The modified nano-titanium dioxide in Preparation Example 1 was replaced with the modified nano-titanium dioxide in Preparation Example 3, with the amount of each component remaining the same.

[0030] Example 4 The only difference from Example 1 is the ratio of components A and B in the polyurethane structural adhesive: The polyurethane structural adhesive is prepared by mixing and curing component A and component B in a mass ratio of 100:95-105.

[0031] Example 5 The only difference from Example 1 is the amount of components A and B in the polyurethane structural adhesive: Component A comprises the following raw materials by weight: 20 parts hydrogenated epoxidized soybean oil, 40 parts polycarbonate diol, 25 parts polycaprolactone diol, 6 parts modified nano titanium dioxide from Preparation Example 1, 3.5 parts 1,4-butanediol, 0.2 parts bismuth neodecanoate, 1.5 parts silane coupling agent KH-550, and 2 parts molecular sieve. Component B comprises the following raw materials by weight: 55 parts isophorone diisocyanate, 30 parts polyether polyol, 5 parts nano alumina, 12 parts hexagonal boron nitride, 3 parts plasticizer DOTP, and 2 parts molecular sieve.

[0032] Example 6 The only difference from Example 1 is the preparation method of the polyurethane structural adhesive: A method for preparing a high weather-resistant polyurethane structural adhesive includes the following steps: Step 1: Add vegetable oil polyol, polycarbonate diol, and polycaprolactone diol to a reaction vessel, heat to 120°C and stir for 1 hour, cool to 80°C and continue stirring for 0.5 hours, finally add chain extender, catalyst, silane coupling agent and dehydrating agent, continue stirring for 0.5 hours, discharge under nitrogen protection to obtain component A. Step 2: Add isophorone diisocyanate and polyether polyol to the reactor, heat to 85°C, stir for 3 hours, and after the NCO content reaches the theoretical value, adjust the NCO content to 22%, cool to 50°C, add plasticizer to the reactor, stir for 0.5 hours, then add nano zinc oxide, hexagonal boron nitride and dehydrating agent, continue stirring for 0.5 hours, discharge under nitrogen protection to obtain component B; Step 3: Mix component A and component B to obtain the final product.

[0033] Comparative Example Comparative Example 1 The only difference from Example 1 is that modified titanium dioxide is not added to component A: Component A comprises the following raw materials by weight: 15 parts hydrogenated epoxidized soybean oil, 30 parts polycarbonate diol, 15 parts polycaprolactone diol, 0.5 parts 1,4-butanediol, 0.01 parts bismuth neodecanoate, 0.8 parts silane coupling agent KH-550, and 1 part molecular sieve.

[0034] Comparative Example 2 The only difference from Example 1 is that: In Preparation Example 1, the modified nano-titanium dioxide was replaced with nano-titanium dioxide, while the amount of nano-titanium dioxide remained the same.

[0035] Comparative Example 3 The only difference from Example 1 is that component B does not contain nano-alumina and hexagonal boron nitride. Component B comprises the following raw materials by weight: 40 parts isophorone diisocyanate, 20 parts polyether polyol, 1 part plasticizer DOTP, and 1 part molecular sieve.

[0036] Comparative Example 4 The only difference from Example 1 is that nano-alumina is not added to component B: Component B comprises the following raw materials by weight: 40 parts isophorone diisocyanate, 20 parts polyether polyol, 8 parts hexagonal boron nitride, 1 part plasticizer DOTP, and 1 part molecular sieve.

[0037] Comparative Example 5 The only difference from Example 1 is the ratio of components A and B in the polyurethane structural adhesive: The polyurethane structural adhesive is prepared by mixing and curing component A and component B in a mass ratio of 100:85.

[0038] Comparative Example 6 The only difference from Example 1 is the amount of components A and B in the polyurethane structural adhesive: Component A comprises the following raw materials by weight: 10 parts hydrogenated epoxidized soybean oil, 30 parts polycarbonate diol, 3 parts modified nano titanium dioxide from Preparation Example 1, 0.5 parts 1,4-butanediol, 0.01 parts bismuth neodecanoate, 0.8 parts silane coupling agent KH-550, and 1 part molecular sieve. Component B comprises the following raw materials by weight: 40 parts isophorone diisocyanate, 20 parts polyether polyol, 3 parts nano alumina, 8 parts hexagonal boron nitride, 1 part plasticizer DOTP, and 1 part molecular sieve.

[0039] Comparative Example 7 The only difference from Example 1 is the amount of components A and B in the polyurethane structural adhesive: Component A comprises the following raw materials by weight: 30 parts polycarbonate diol, 15 parts polycaprolactone diol, 3 parts modified nano-titanium dioxide from Preparation Example 1, 0.5 parts 1,4-butanediol, 0.01 parts bismuth neodecanoate, 0.8 parts silane coupling agent KH-550, and 1 part molecular sieve. Component B comprises the following raw materials by weight: 65 parts isophorone diisocyanate, 15 parts polyether polyol, 3 parts nano alumina, 8 parts hexagonal boron nitride, 1 part plasticizer DOTP, and 1 part molecular sieve.

[0040] Comparative Example 8 The only difference from Example 1 is the preparation method of the polyurethane structural adhesive: A method for preparing a high weather-resistant polyurethane structural adhesive includes the following steps: Step 1: Add vegetable oil polyol, polycarbonate diol, and polycaprolactone diol to a reaction vessel, heat to 80°C and stir for 1.5 hours, cool to 50°C and continue stirring for 0.5 hours, finally add chain extender, catalyst, silane coupling agent and dehydrating agent, continue stirring for 0.5 hours, discharge under nitrogen protection to obtain component A; Step 2: Add isophorone diisocyanate and polyether polyol to the reactor, heat to 75°C, stir for 2 hours, and after the NCO content reaches the theoretical value, adjust the NCO content to 18%, cool to 40°C, add plasticizer to the reactor, stir for 0.5 hours, then add nano zinc oxide, hexagonal boron nitride and dehydrating agent, continue stirring for 0.5 hours, discharge under nitrogen protection to obtain component B; Step 3: Mix component A and component B to obtain the final product.

[0041] Performance testing The following performance tests were performed on the polyurethane structural adhesives prepared in Examples 1 to 6 and Comparative Examples 1 to 8: (1) Tensile strength and elongation at break: The tensile strength and elongation at break of the polyurethane structural adhesive were tested according to GB / T 1040.1-2006, and the average value of three tests was taken. (2) Hardness performance: According to GB / T 531 According to the 1999 standard, the tensile strength and elongation at break of polyurethane structural adhesives are tested. (3) Flame retardant performance: According to GB / T 2408 The 2008 standard tests the flame retardant properties of polyurethane structural adhesives. The test results are shown in Table 1.

[0042] Table 1

[0043] As can be seen from Table 1, the polyurethane structural adhesives prepared in Examples 1 to 6 have excellent tensile strength, elongation at break, hardness and flame retardancy.

[0044] (4) Aging performance test: PET adhesive strength test method: 3003 aluminum / PET insulating film / 3003 aluminum overlap method, that is, there is a layer of PET insulating film in the middle of the aluminum plate overlap surface, and the adhesive layer is between the PET insulating film and the aluminum plate. The adhesive layer cannot overflow the PET insulating film and contact the aluminum plate and adhesive layer on the other side. 3003 aluminum adhesive strength test: 3003 aluminum / 3003 aluminum overlap method test. The above test results are shown in Table 2.

[0045] Table 2

[0046] As can be seen from Table 2, the polyurethane structural adhesives prepared in Examples 1 to 6 have excellent aging resistance.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. It should be understood that, in the various embodiments of this application, the sequence number of each process does not imply a sequential order of execution; some or all steps may be performed in parallel or sequentially; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0048] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application are available on the market or can be prepared by existing methods.

[0049] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and all technical features and optional technical features of this application can be combined to form new technical solutions.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high weather-resistant polyurethane structural adhesive, characterized in that, The polyurethane structural adhesive is prepared by mixing and curing component A and component B in a mass ratio of 100:95-105. Component A comprises the following raw materials by weight: 15-20 parts of vegetable oil polyol, 30-40 parts of polycarbonate diol, 15-25 parts of polycaprolactone diol, 3-6 parts of modified nano titanium dioxide, 0.5-3.5 parts of chain extender, 0.01-0.2 parts of catalyst, 0.8-1.5 parts of silane coupling agent, and 1-2 parts of dehydrating agent; Component B comprises the following raw materials by weight: 40-55 parts of isophorone diisocyanate, 20-30 parts of polyether polyol, 3-5 parts of nano alumina, 8-12 parts of hexagonal boron nitride, 1-3 parts of plasticizer, and 1-2 parts of dehydrating agent.

2. The high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, The modified nano-titanium dioxide in component A is prepared by the following steps: S1. Dissolve dopamine hydrochloride in Tris-HCl buffer, then add nano-titanium dioxide, sonicate for 20-30 min, stir for 12-16 h, after the reaction is complete, wash with deionized water, centrifuge, freeze dry and grind to obtain pretreated titanium dioxide. S2. Pretreated titanium dioxide, phosphorus oxychloride, and triethylamine were added to tetrahydrofuran and ultrasonically dispersed for 1–1.5 h to obtain a mixture. 4,4-Diaminodiphenylmethane was dissolved in tetrahydrofuran and then added dropwise to the mixture over 1 h. The mixture was stirred and reacted for 24–26 h. After the reaction was completed, the mixture was purified sequentially with tetrahydrofuran and deionized water. Finally, it was dried under reduced pressure at 80°C for 24 h to obtain modified nano-titanium dioxide.

3. The high weather-resistant polyurethane structural adhesive according to claim 2, characterized in that, In S1, the ratio of dopamine hydrochloride, Tris-HCl buffer, and nano-titanium dioxide is 1.38–1.42 g: 300 mL: 0.66–0.68 g; in S2, the ratio of pretreated titanium dioxide, phosphorus oxychloride, triethylamine, and tetrahydrofuran is 0.50–0.55 g: 0.31–0.32 g: 0.24–0.25 g: 100 mL; and the ratio of 4,4-diaminodiphenylmethane and tetrahydrofuran is 0.66–0.67 g: 30 mL.

4. The high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, In component A, the vegetable oil polyol is hydrogenated epoxidized soybean oil.

5. The high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, The chain extender in component A is one of 1,4-butanediol, triethanolamine, glycerol, ethylene glycol, E100, and E300.

6. The high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, The catalyst in component A is one of bismuth neodecanoate, zinc neodecanoate, and zinc isooctanoate.

7. The high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, The silane coupling agent in component A is one of silane coupling agent KH-550 or silane coupling agent KH-560.

8. The high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, Both component A and component B contain molecular sieves as the dehydrating agents.

9. The high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, The polyether polyol in component B is PPG-2000; the plasticizer in component B is one of the following: DOTP, PEA, or ATBC.

10. The method for preparing a high weather-resistant polyurethane structural adhesive according to claim 1, characterized in that, Includes the following steps: Step 1: Add vegetable oil polyol, polycarbonate diol, and polycaprolactone diol to a reaction vessel, heat to 100-120℃ and stir for 1.5-3 hours, cool to 60-80℃ and continue stirring for 0.5-1 hours, finally add chain extender, catalyst, silane coupling agent and dehydrating agent, continue stirring for 0.5-1 hours, discharge under nitrogen protection to obtain component A; Step 2: Add isophorone diisocyanate and polyether polyol to the reactor, heat to 80-85℃, stir for 2-3 hours, and after the NCO content reaches the theoretical value, adjust the NCO content to 18%-22%, cool to 50-60℃, add plasticizer to the reactor, stir for 0.5-1 hours, then add nano zinc oxide, hexagonal boron nitride and dehydrating agent, continue stirring for 0.5-1 hours, discharge under nitrogen protection to obtain component B; Step 3: Mix component A and component B to obtain the final product.

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