Epoxy vinyl resin with high ultraviolet aging resistance as well as preparation method and application of epoxy vinyl resin

Abstract

The invention relates to the technical field of high polymer materials, in particular to epoxy vinyl resin (VER) with high ultraviolet aging resistance and a preparation method and application thereof. The preparation method comprises the following steps: (S1) reacting diisocyanate with 4-hydroxybenzophenone (4-HBP) to synthesize an isocyanate-terminated precursor; (S2) mixing the precursor with a VER matrix, and adding a catalyst and a diisocyanate curing agent; and (S3) curing by adopting a stepped heating program to obtain a final product. According to the invention, diisocyanate has dual functions: on one hand, diisocyanate reacts with 4-HBP to form an isocyanate-terminated precursor, and the isocyanate-terminated precursor reacts into a VER network in a chemical bond manner; on the other hand, as a curing agent of the VER, the curing agent reacts with hydroxyl in the VER to form a final and functionalized three-dimensional cross-linked network, so that full curing is realized. According to the method, the problem that the micromolecular ultraviolet absorbent is easy to migrate and lose is effectively solved, and the ultraviolet aging resistance and durability of the resin are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to an epoxy vinyl resin with high UV aging resistance, its preparation method and application, and particularly to a modification method and the resulting material by grafting 4-hydroxybenzophenone (4-HBP) UV absorption units into a VER crosslinking network via specific diisocyanates through chemical bonding. Background Technology

[0002] Vinyl ester resin (VER) is a high-performance thermosetting resin produced by reacting epoxy resin with unsaturated monobasic acid (such as methacrylic acid). It combines the excellent mechanical properties, adhesion and chemical resistance of epoxy resin with the good processability of unsaturated polyester and is widely used in composite materials, corrosion protection engineering, electronics and electrical fields.

[0003] However, the VER molecular structure contains unsaturated double bonds and aromatic rings, making it prone to photo-oxidation under long-term ultraviolet radiation. This leads to yellowing, surface chalking, loss of gloss, and a sharp decline in mechanical properties. This problem severely limits the application of VER in long-term outdoor exposure scenarios such as wind turbine blades, outdoor building materials, and vehicle shells. Therefore, improving the UV aging resistance of VER is an important research direction for expanding its application prospects.

[0004] Currently, common methods for improving the UV aging resistance of polymer materials mainly include adding UV absorbers, UV shielding agents, or antioxidants. Among these, adding small-molecule UV absorbers (such as benzophenones and benzotriazoles) is the simplest and most economical industrial method for UV modification. However, small-molecule UV absorbers are prone to migration, volatilization, or precipitation during material use, leading to a significant decrease in UV resistance over time. Furthermore, the precipitated additives may cause environmental pollution.

[0005] To address the migration problem of small molecule additives, researchers have explored various chemical modification methods. CN 121471684A discloses a polymer composite material for wind turbine blade cables, composed of a polymer matrix, reinforcing materials, polymer modifiers, and functional additives. The functional additives consist of UV stabilizers, antioxidants, silane coupling agents, and nano-titanium dioxide (TiO2), with each component uniformly dispersed in the matrix through physical blending. However, the UV stabilizers in this system are still dispersed in small molecule form, posing a risk of migration, volatilization, or precipitation during long-term outdoor use, leading to a decline in UV resistance over extended service life.

[0006] CN121182324A discloses an epoxy resin insulating coating with high toughness and high resistance to ultraviolet aging, and its preparation method. The coating consists of TiO2@PDA@BTA nanomaterials, epoxy resin, and a curing agent. By sequentially constructing a polydopamine layer and a benzotriazole layer on the surface of the nano-TiO2, full-band coverage is achieved by utilizing the absorption capabilities of TiO2 and BTA for different wavelengths of ultraviolet light. However, this system relies on the design and synthesis of complex multi-layered core-shell nanoparticles. The preparation process involves multiple steps, including reaction, ultrasonic dispersion, centrifugal washing, and drying, making the process relatively cumbersome and costly.

[0007] CN121045871A discloses a sandwich-structured broad-spectrum ultraviolet absorber, its preparation method, and its applications. This absorber uses aminated graphene oxide as the "surface" and benzotriazole-based ultraviolet absorbers as "discrete points," self-assembling through hydrogen bonding and π-π bond interactions to form a "discrete point / surface / discrete point" sandwich structure. However, this system relies on the non-covalent interaction between graphene oxide and the ultraviolet absorber. This physical adsorption may desorb during long-term use due to solvent erosion, temperature changes, or mechanical stress, leading to the gradual detachment of the ultraviolet absorber.

[0008] CN 120590896A discloses a high-temperature and weather-resistant epoxy resin adhesive and its preparation method. This adhesive achieves a synergistic improvement in high-temperature resistance, UV aging resistance, and toughening by physically blending multiple functional components, including hydrogenated bisphenol F type epoxy resin, silicone phenyl glycidyl ether epoxy resin, dicyandiamide-imidazolium composite curing agent, and graphene aerogel-modified nano-alumina. However, this system relies on the complex compounding of multiple functional components, and the interfacial bonding between the filler and the resin matrix is ​​mainly physical. Under long-term high-temperature or harsh environments, there is a risk of interfacial degradation, affecting the durability and service life of the adhesive.

[0009] In summary, although some progress has been made in the research of UV-resistant epoxy vinyl resins in the prior art, it is still difficult to obtain a modification method that combines the following properties: (1) long-lasting and stable UV resistance without the problem of small molecule additive migration; (2) simple modification process that is compatible with the existing VER curing process; (3) improving UV resistance without sacrificing the mechanical properties and thermal stability of the resin; (4) readily available raw materials, controllable cost, and suitable for large-scale production. Summary of the Invention

[0010] To address the technical problems of insufficient UV resistance in existing physical blending methods and complex processes in other chemical modification methods, this invention provides a high-UV-resistant epoxy vinyl resin, its preparation method, and its applications. The core concept of this invention lies in selecting a suitable diisocyanate as a "molecular bridge," first reacting it with the phenolic hydroxyl groups of 4-HBP to generate a prepolymer (precursor) retaining an isocyanate group (-NCO) at one end; then, this precursor with externally linked 4-HBP is mixed with the VER matrix, and the remaining -NCO on the precursor undergoes an urethane reaction with the hydroxyl groups (-OH) on the VER chain, thereby anchoring the 4-HBP units to the final VER crosslinking network through strong chemical bonds (urethane bonds). This method is based on a common VER curing process, is simple in steps, effectively prevents the migration and loss of UV absorbers, and achieves long-lasting UV resistance.

[0011] Furthermore, through extensive experiments, the inventors discovered that among numerous diisocyanates, isophorone diisocyanate (IPDI) exhibits a significant difference in reactivity between its two -NCO groups, enabling it to more efficiently and selectively generate a well-defined monoadduct precursor with 4-HBP. Moreover, its alicyclic structure itself endows the resin with excellent resistance to yellowing, making it the preferred embodiment of this invention.

[0012] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing an epoxy vinyl resin with high UV aging resistance, characterized by comprising the following steps: (S1) Precursor preparation: 4-HBP was reacted with a diisocyanate compound to synthesize a precursor with -NCO at the end; (S2) Mixing and modification: The precursor obtained in step (S1) is mixed with the VER matrix, and a diisocyanate compound is added to the mixture as a curing agent and catalyst; (S3) Curing and molding: The mixture obtained in step (S2) is cast and cured using a stepped heating program to obtain the epoxy vinyl resin with high UV aging resistance.

[0013] Preferably, in step (S1), the molar ratio of the diisocyanate compound to 4-HBP is 1:1.

[0014] Preferably, in step (S1), the diisocyanate compound is IPDI.

[0015] Preferably, in step (S1), the curing agent is dibutyltin dilaurate (DBTDL).

[0016] Preferably, in step (S2), the amount of the precursor added is 5%-30% by mass percentage of the total mass of the finally cured resin, and more preferably 8%-15%.

[0017] Preferably, in step (S2), the curing agent is IPDI, and its total amount should be such that the ratio of the total number of moles of all -NCO in the system to the total number of moles of all -OH in the VER and precursor is (0.95-1.05):1.

[0018] Preferably, in step (S3), the stepped temperature curing procedure is as follows: first, cure at 30-60 ℃ for 8-12 h, preferably at 50 ℃ for 10 h; then, raise the temperature to 70-90 ℃ and cure for 2-4 h, preferably at 80 ℃ for 2 h; finally, raise the temperature to 90-110 ℃ and cure for 3-6 h, preferably at 100 ℃ for 4 h.

[0019] This invention also provides an epoxy vinyl ester resin with high UV aging resistance prepared by the above-described method. Furthermore, this invention provides the application of the above-described epoxy vinyl ester resin with high UV aging resistance in the preparation of outdoor composite materials (such as wind turbine blades, outdoor building components, vehicle housings, etc.).

[0020] The beneficial effects achieved by this invention include: Long-lasting and stable UV protection: 4-HBP is firmly fixed in the resin network through chemical bonding, which completely solves the problem of migration and precipitation of small molecule additives, resulting in long-lasting UV protection.

[0021] The process is simple and has good compatibility: This modification method is based on the universal urethane curing process of VER, which does not require complex equipment or significant changes to the existing production process, and is easy to implement and promote.

[0022] Excellent overall performance: Under optimal conditions, the modified resin can maintain or even optimize the mechanical strength, transparency and thermal stability of the matrix resin while achieving excellent resistance to ultraviolet aging.

[0023] The raw material selection has outstanding advantages: IPDI is used as a reaction bridge. Its unique reactivity and structural advantages enable the synthesis of precursors and the final resin performance to achieve the best balance, which is significantly better than other common diisocyanates (such as TDI and HDI). Attached Figure Description

[0024] Taking the IPDI system as an example, Figure 1 (a) Infrared spectrum; (b) Proton NMR spectrum, characterizing the precursor for the synthesis of UV aging absorber and isocyanate. Detailed Implementation Example

[0025] (S1) Synthesis of 4-HBP-IPDI precursor: A constant-pressure dropping funnel and a nitrogen inlet tube were installed in a dry 500 mL three-necked flask. Dry nitrogen was continuously introduced, and 8.48 g (0.0372 mol) of 4-HBP and 80 mL of anhydrous THF were added to the flask. The mixture was stirred in a 50 °C oil bath until 4-HBP was completely dissolved. Under vigorous stirring, 9.52 g (0.0428 mol) of IPDI was slowly added dropwise through the constant-pressure dropping funnel over 15 min, with the reaction temperature controlled at 50 °C. 0.54 g of DBTDL was added as a catalyst, and the mixture was stirred for 5 min. The reaction was continued with nitrogen purging and stirring for 12 h. The reaction mixture was transferred to a rotary evaporator, and THF was completely evaporated under a high vacuum in a water bath at ≤35 °C to obtain a viscous waxy solid, which was the 4-HBP-IPDI precursor, and stored in a desiccator for later use. Example

[0026] (S2) Resin Mixing and Modification: Accurately weigh 162.0 g of VER and 18.0 g of the 4-HBP-IPDI precursor prepared in step (S1) (10 wt% of the expected total resin mass of 180.0 g) and add them to a wide-mouth container. Mix at high speed using a mechanical stirrer for 15 min until a homogeneous mixture is formed. Keep stirring at a low temperature, and then, while continuing to stir, slowly add 8.10 g of IPDI as a curing agent (the amount of agent is 5 wt% of VER in the system), and continue stirring for 10 min to ensure the system is homogeneous. Example

[0027] The mixture obtained from (S2) was transferred to a vacuum drying oven and slowly evacuated to above -0.095 MPa at room temperature, maintaining this pressure for 15 min to degas. The degassed resin was then slowly poured into a flat mold pre-coated with a release agent. The mold was placed in a forced-air drying oven and cured according to the following procedure: cured at 50°C for 8 h → increased to 80°C at a rate of 1 °C / min. Set the temperature to ℃ and cure for 3 hours at this temperature → continue to increase the temperature to 100℃ at a rate of 1℃ / min. Curing temperature: ℃, 3 h. After curing, turn off the oven power and allow the sample to cool naturally to room temperature (approximately 4 h or more). Demold and cut into standard test strips, denoted as VER-IPDI-4-HBP-10wt%. Example

[0028] The 4-HBP-IPDI precursor was prepared according to the method of Example 1, except that in step (S1), the amount of 4-HBP was changed to 16.97 g and the amount of IPDI was changed to 19.03 g. Then, the mixture and modification were carried out according to the method of Example 2, except that the amount of VER was 144.0 g and the amount of precursor was 36.0 g (accounting for 20% of the expected total resin mass of 180 g). Finally, the curing and post-treatment were carried out according to the method of Example 3, and the resulting sample was designated as VER-IPDI-4-HBP-20 wt%. Example

[0029] The 4-HBP-IPDI precursor was prepared according to the method of Example 1, except that in step (S1), the amount of 4-HBP was changed to 25.45 g, and the amount of IPDI was changed accordingly to 28.55 g. Then, the mixture and modification were carried out according to the method of Example 2, except that the amount of VER was 126.0 g, and the amount of precursor was 54.0 g (accounting for 30% of the expected total resin mass of 180 g). Finally, the curing and post-treatment were carried out according to the method of Example 3, and the resulting sample was denoted as VER-IPDI-4-HBP-30 wt%.

[0030] No 4-HBP or precursor was added. 180.0 g of VER was weighed, and 9 g of IPDI (an equivalent amount required for complete curing) was added, along with an equal proportion of DBTDL catalyst (0.54 g, 0.1 wt%). After mixing and degassing, the mixture was cured using the same stepwise procedure as in Example 3. The resulting sample was denoted as VER / IPDI.

[0031] A physical blending method was used. 162.0 g of VER and 8.48 g of 4-HBP powder (the same 4-HBP content as in the precursor of Example 1) were weighed and heated and stirred until 4-HBP was completely dissolved or uniformly dispersed in VER. After cooling, 9 g of IPDI curing agent and 0.54 g of DBTDL catalyst, equal in amount to Comparative Example 1, were added. After mixing and degassing, the mixture was cured using the same stepwise procedure as in Example 3. The resulting sample was designated VER / 4-HBP / IPDI.

[0032] The precursor was prepared according to the method of Example 1, except that in steps (S1) and (S2), all IPDI was replaced with an equimolar amount of 2,4-toluene diisocyanate (2,4-TDI). Then, the mixture was modified according to the method of Example 2 (the amount of precursor was the same as in Example 2), and finally, the curing and post-treatment were carried out according to the method of Example 3. The resulting sample was designated as VER-2,4-TDI-4-HBP.

[0033] The precursor was prepared according to the method of Example 1, except that in steps (S1) and (S2), all IPDI was replaced with an equimolar amount of 2,6-toluene diisocyanate (2,6-TDI). Then, the mixture was modified according to the method of Example 2 (the amount of precursor was the same as in Example 2), and finally, the curing and post-treatment were carried out according to the method of Example 3. The resulting sample was designated as VER-2,6-TDI-4-HBP.

[0034] The precursor was prepared according to the method of Example 1, except that in steps (S1) and (S2), all IPDI was replaced with an equimolar amount of diphenylmethane diisocyanate (MDI). Then, the mixture was modified according to the method of Example 2 (the amount of precursor was the same as in Example 2), and finally, the curing and post-treatment were carried out according to the method of Example 3. The resulting sample was designated as VER-MDI-4-HBP.

[0035] The precursor was prepared according to the method of Example 1, except that IPDI in steps (S1) and (S2) was completely replaced with an equimolar amount of hexamethylene diisocyanate (HDI). Then, the mixture was modified according to the method of Example 2 (the amount of precursor was the same as in Example 2), and finally, the curing and post-treatment were carried out according to the method of Example 3. The resulting sample was designated as VER-HDI-4-HBP.

[0036] The precursor was prepared according to the method of Example 1, except that in steps (S1) and (S2), all IPDI was replaced with an equimolar amount of dicyclohexylmethane diisocyanate (HMDI). Then, the mixture was modified according to the method of Example 2 (the amount of precursor was the same as in Example 2), and finally, the curing and post-treatment were carried out according to the method of Example 3. The resulting sample was designated as VER-HMDI-4-HBP.

[0037] Experimental Example 1 Structural characterization of precursors and cured resins Figure 1 The infrared spectrum (a) and proton NMR spectrum (b) of the 4-HBP-IPDI precursor are shown in Figure 1 (a). As can be seen from Figure 1 (a), at 3145 cm⁻¹... -1 The stretching vibration of the phenolic hydroxyl group at 4-HBP occurs. After the reaction, the phenolic hydroxyl group is almost completely reacted and consumed to form a new chemical bond. The values ​​at 1745 and 3339 cm⁻¹ are significant. -1 Strong C=O and NH peaks appear at 2270 cm⁻¹. -1 The intensity of the -NCO peak decreased significantly, and... Figure 1(b) The phenolic hydroxyl group -OH completely disappeared at 10.52 ppm, and the characteristic NH peak of the urethane bond appeared at 7.56 ppm, proving that all hydroxyl groups had reacted. This confirmed the precursor and the synthesis.

[0038] Experiment Example 2 Basic mechanical testing project Tensile strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Example 3 78.5 14.2 Example 4 76.3 13.8 Example 5 72.1 12.5 Comparative Example 1 76.8 14.0 Comparative Example 2 65.4 10.3 Comparative Example 3 70.5 11.8 Comparative Example 4 71.2 12.0 Comparative Example 5 69.8 11.5 Comparative Example 6 68.5 11.2 Comparative Example 7 73.5 12.8 Table 1 shows the tensile strength and impact strength test results of different samples. As can be seen from Table 1, the tensile strength of Example 3 (10 wt% precursor addition) is 78.5 MPa, and the impact strength is 14.2 kJ / m². 2 Compared with Comparative Example 1 (blank sample, without 4-HBP), the pressure was 76.8 MPa and the capacitance was 14.0 kJ / m³. 2 The slight improvement indicates that the appropriate introduction of 4-HBP not only did not impair the mechanical properties of VER, but also slightly increased the strength due to the introduction of the rigid 4-HBP structure.

[0039] Comparing different precursor addition amounts, as the precursor addition amount increased from 10 wt% (Example 3) to 20 wt% (Example 4) and 30 wt% (Example 5), the tensile strength decreased from 78.5 MPa to 76.3 MPa and 72.1 MPa respectively, and the impact strength decreased from 14.2 kJ / m 2 It decreased successively to 13.8 kJ / m 2 and 12.5 kJ / m 2 This is because excessive precursor introduces too many flexible segments, leading to a slight decrease in resin crosslinking density. Furthermore, the 4-HBP molecule itself is quite rigid, and excessive introduction can disrupt the regularity of the network structure. Therefore, a precursor addition of 10-20 wt% is the preferred range.

[0040] Comparative Example 2 (physical blending method) had a tensile strength of 65.4 MPa and an impact strength of 10.3 kJ / m. 2 Compared to Comparative Example 1, the mechanical properties decreased by 18.5% and 31.8%, respectively, while Comparative Example 3 showed even greater decreases of 16.7% and 27.5%, respectively. This is because the small molecule 4-HBP in physical blending is dispersed in a free state within the resin network, disrupting the network's integrity. Furthermore, migration and aggregation may occur during curing, forming localized defects and leading to a significant decrease in mechanical properties. This fully demonstrates the advantages of chemical grafting in maintaining mechanical properties.

[0041] Compared with different diisocyanate systems, the mechanical properties of Example 3 (IPDI system) are significantly better than those of Comparative Examples 3 (2,4-TDI), 4 (2,6-TDI), 5 (MDI), 6 (HDI), and 7 (HMDI). The tensile strength of the IPDI system is 78.5 MPa, which is 7.3-10.0 MPa higher than that of Comparative Examples 3-7, and the impact strength is 1.4-3.0 kJ / m higher. 2 This is because the two -NCO groups in the IPDI molecule have significantly different reactivity, allowing it to more selectively react with 4-HBP to form well-defined precursors, resulting in a more regular and dense cross-linked network. In contrast, while the aromatic ring structures in TDI and MDI molecules are relatively rigid, their reactivity is less selective, easily generating polysubstituted byproducts, leading to uneven network structures. HDI, being a straight-chain aliphatic molecule, is too flexible and has a lower cross-linking density. Although HMDI is also alicyclic, its symmetrical structure is less conducive to forming a regular network compared to the asymmetrical structure of IPDI. Therefore, the IPDI system has a significant advantage in maintaining good mechanical properties.

[0042] Experimental Example 3 Accelerated UV aging performance testing According to GB / T 16422.3-2014 standard, UVB fluorescent ultraviolet lamps were used, with an irradiance of 0.76 W / m². 2 Cyclic conditions: 8 h light exposure (60 ℃) / 4 h condensation (50 ℃) The samples were aged at ℃ for 1000 h. The retention rate of mechanical properties and yellowing index of the aged samples were tested, and the results are shown in Table 2.

[0043] project Tensile strength retention rate (%) Impact strength retention rate (%) Yellowing index ΔE Example 3 92.5 90.3 2.2 Example 4 94.2 92.1 1.5 Example 5 95.8 93.5 1.2 Comparative Example 1 58.3 52.7 16.7 Comparative Example 2 70.1 65.4 7.5 Comparative Example 3 80.5 78.2 5.8 Comparative Example 4 82.3 79.5 5.2 Comparative Example 5 69.8 68.1 6.5 Comparative Example 6 68.5 66.8 6.8 Comparative Example 7 82.5 80.2 4.5 Example 3 (10 wt%) showed that the tensile strength retention rate and impact strength retention rate after aging reached 92.5% and 90.3%, respectively, and the yellowing index ΔE was only 2.2, indicating that chemical grafting of 4-HBP endowed VER with excellent UV aging resistance. As the precursor addition increased from 10 wt% to 30 wt%, the tensile strength retention rate after aging gradually increased from 92.5% to 95.8%, the impact strength retention rate increased from 90.3% to 93.5%, and the yellowing index ΔE decreased from 2.2 to 1.2, showing a clear positive correlation between the addition amount and UV resistance. This indicates that the more 4-HBP UV absorption units chemically grafted into the VER network, the stronger its shielding and absorption effect on UV light, and the more effectively it can inhibit photo-oxidation reactions, delaying the degradation and yellowing of the resin matrix. It is worth noting that even when the addition amount reaches 30 wt% (Example 5), the mechanical property retention rate after aging remains above 93%, and ΔE is only 1.2, which fully demonstrates that the UV absorber fixed by chemical bonding will not migrate or be lost during long-term aging and can continuously and stably play an anti-UV protection role.

[0044] Comparative Example 1 (blank sample) showed retention rates of only 58.3% and 52.7% after aging, with a ΔE as high as 16.7, exhibiting obvious yellowing. Comparative Example 2 (physical blend) showed retention rates of 70.1% and 65.4% after aging, with a ΔE of 7.5. Although better than the blank sample, it was far lower than the chemically grafted sample, demonstrating that the small molecule 4-HBP in the physical blend migrated and was lost during the aging process, leading to a decrease in the UV protection effect.

[0045] Compared with different diisocyanate systems, the UV resistance of Example 3 (IPDI) was significantly better than that of Comparative Examples 3-7, with a retention rate 10.0-24.0 percentage points higher and a ΔE 2.6-4.6 lower. This is because the two -NCO groups in the IPDI molecule have significantly different reactivity, allowing it to more selectively react with 4-HBP to form a well-defined precursor. The resulting cross-linked network is more regular and dense, effectively hindering the penetration of UV light and the diffusion of free radicals. Simultaneously, the alicyclic structure of IPDI itself exhibits excellent resistance to yellowing and is less prone to photo-oxidation reactions to form chromophores under UV irradiation.

[0046] In contrast, the aromatic rings in TDI (Comparative Examples 3-4) and MDI (Comparative Example 5) molecules are prone to photooxidation under ultraviolet light irradiation, generating chromophores such as quinone structures, leading to severe yellowing (ΔE 5.2-6.5). Although HDI (Comparative Example 6) is aliphatic and does not contain aromatic rings, its linear structure is too flexible, resulting in a low crosslinking density. Ultraviolet light can easily penetrate into the network and cause degradation, resulting in poor UV resistance (ΔE 6.8). HMDI (Comparative Example 7), also alicyclic, exhibits better yellowing resistance than aromatic and aliphatic molecules (ΔE 4.5), but its symmetrical structure results in a less regular network than the asymmetric structure of IPDI, and its UV resistance is still lower than that of the IPDI system. Therefore, IPDI, with its unique reaction selectivity and alicyclic structure, has a significant advantage in terms of UV aging resistance.

Claims

1. A method for preparing an epoxy vinyl resin with high UV aging resistance, characterized in that, Includes the following steps: (S1) A terminal isocyanate precursor was synthesized by reacting a diisocyanate compound with 4-HBP. (S2) The precursor obtained in step (S1) is mixed with the VER matrix, and diisocyanate is added as a curing agent, wherein the diisocyanate is preferably isophorone diisocyanate (IPDI). (S3) The mixture obtained in step (S2) is cast and cured using a stepped heating program to obtain the high UV resistance VER.

2. The preparation method according to claim 1, characterized in that, Step (S1) specifically involves: dissolving 4-HBP in an anhydrous organic solvent, adding diisocyanate dropwise to the solution under an inert atmosphere and in the presence of a catalyst, and controlling the reaction temperature at 50 °C; reacting for 6-16 h after the addition is complete; removing the solvent after the reaction is complete to obtain the terminal isocyanate precursor; wherein the molar ratio of 4-HBP to IPDI is 1:

1.

3. The preparation method according to claim 2, characterized in that, The anhydrous organic solvent is one of anhydrous tetrahydrofuran, anhydrous acetone, or anhydrous N,N-dimethylformamide; the catalyst is dibutyltin dilaurate.

4. The preparation method according to claim 1, characterized in that, In step (S2), the amount of the precursor added is 5%-40% by mass percentage of the total mass of the finally cured resin.

5. The preparation method according to claim 1, characterized in that, In step (S2), the total amount of the diisocyanate compound curing agent is determined such that the ratio of the total moles of isocyanate groups (-NCO) to the total moles of all hydroxyl groups (-OH) in the VER and precursor is (0.1-1.1):

1.

6. The preparation method according to claim 1, characterized in that... The diisocyanate may also be selected from one or more of 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and dicyclohexylmethane diisocyanate (HMDI).

7. The preparation method according to claim 1, characterized in that, In step (S3), the stepped temperature curing procedure is as follows: first, cure at 30-60 ℃ for 6-16 h, preferably at 50 ℃ for 10 h; then, increase the temperature to 70-90 ℃ at a rate of 0.5-1.5 ℃ / min, and cure at this temperature for 2-4 h, preferably at 80 ℃ for 2 h; finally, continue to increase the temperature to 90-120 ℃ and cure for 3-6 h, preferably at 100 ℃ for 4 h.

8. A VER with high resistance to ultraviolet aging, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the high UV aging resistance VER prepared by the preparation method according to any one of claims 1 to 7 in the preparation of outdoor composite material products.

10. The application according to claim 8, characterized in that, The outdoor composite material products include wind turbine blades, outdoor building components, or vehicle shells.

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