Benzimidazole functionalized waterborne polyurethane as well as preparation method and application thereof

Abstract

The invention discloses benzimidazole functionalized waterborne polyurethane as well as a preparation method and application thereof. The benzimidazole functionalized waterborne polyurethane is prepared from the following raw materials in parts by weight: 50 to 105 parts of polyurethane prepolymer, 5 to 8.5 parts of chain extender, 2 to 4 parts of cross-linking agent, 0.3 to 0.6 part of corrosion inhibitor, 20 to 40 parts of diluent, 2 to 5 parts of neutralizer and 140 to 240 parts of deionized water. According to the invention, the ultraviolet absorption functional monomer and the corrosion inhibitor are firmly bonded to a polyurethane main chain or side chain in a chemical bond manner, so that a coating is endowed with lasting ultraviolet resistance, excellent corrosion resistance and excellent mechanical properties. Benzimidazole functionalized waterborne polyurethane with a double-crosslinking structure is constructed through a three-step method, the process is reasonable, the conditions are mild, and the prepared waterborne polyurethane has excellent mechanical properties, ultraviolet resistance and corrosion resistance and is suitable for the field of high-performance metal protection and outdoor weather-resistant coatings.

Description

Technical Field

[0001] This invention relates to the field of coating compositions, specifically to a benzimidazole-functionalized waterborne polyurethane, its preparation method, and its application. Background Technology

[0002] Waterborne polyurethane, with its advantages of being environmentally friendly and having low volatility, has become a substitute for traditional solvent-based polyurethane and is used in the corrosion protection of metal surfaces. However, waterborne polyurethane contains a large number of hydrophilic groups, resulting in poor water and chemical resistance, and it cannot effectively block water, oxygen, and corrosive ions. Furthermore, in practical applications, waterborne polyurethane is easily damaged by ultraviolet radiation. Ultraviolet light can trigger a photo-oxidation reaction in the polyurethane matrix, leading to chalking, discoloration, loss of gloss, and decreased mechanical properties of the coating, ultimately causing it to fail. Therefore, developing a waterborne polyurethane with excellent UV resistance and corrosion resistance is crucial.

[0003] Chinese invention patent CN116554777B discloses a method for preparing a rigid, self-healing, water-based, environmentally friendly anti-flash rust coating of polyurethane. By using a conjugated grafting method, benzimidazole is attached to the side chains of polyurethane to form a conjugated benzimidazole structure, effectively preventing flash rust on the metal substrate during film formation. However, it does not have UV resistance. Chinese invention patent CN112876932B discloses a coating with long-lasting color-fixing properties and its preparation method, using a polymer latex with two closely related -NH groups. - Groups can interact with pigments containing C=O and / or =N. - and / or -O - The groups generate strong hydrogen bonds and complexation, which can stabilize organic pigments in the hydrophobic part of the particles, allowing the coating to maintain its color for a long time under continuous strong light. However, it cannot achieve both corrosion resistance and UV resistance at the same time. Summary of the Invention

[0004] To develop a waterborne polyurethane with excellent UV resistance and corrosion resistance, the first aspect of the present invention provides a benzimidazole-functionalized waterborne polyurethane, the raw materials for which, by weight, comprise: 50-105 parts of polyurethane prepolymer, 5-8.5 parts of chain extender, 2-4 parts of crosslinking agent, 0.3-0.6 parts of corrosion inhibitor, 20-40 parts of diluent, 2-5 parts of neutralizer, and 140-240 parts of deionized water.

[0005] In one embodiment, the polyurethane prepolymer is a polyurethane prepolymer modified with ultraviolet-absorbing monomers.

[0006] In one embodiment, the raw materials for preparing the polyurethane prepolymer include at least polyether polyol, polyisocyanate, ultraviolet-absorbing functional monomer and catalyst.

[0007] In one embodiment, the raw materials for preparing the polyurethane prepolymer include at least 30-50 parts by weight of polyether polyol, 20-50 parts by weight of polyisocyanate, 0.1-1 parts by weight of UV-absorbing functional monomer and 1-10 parts by weight of catalyst.

[0008] In one embodiment, the raw materials for preparing the polyurethane prepolymer include at least 30-50 parts by weight of polyether polyol, 22-44 parts by weight of polyisocyanate, 0.3-0.6 parts by weight of UV-absorbing functional monomer and 4-7 parts by weight of catalyst.

[0009] In one embodiment, the raw materials for preparing the polyurethane prepolymer include at least 40 parts by weight of polyether polyol, 30 parts by weight of polyisocyanate, 0.42 parts by weight of UV-absorbing functional monomer and 5.5 parts by weight of catalyst.

[0010] In one embodiment, the number average molecular weight of the polyether polyol is 1000-3000.

[0011] In one embodiment, the number average molecular weight of the polyether polyol is 2000.

[0012] In one embodiment, the polyether polyol is polytetrahydrofuran ether diol.

[0013] In one embodiment, the polyisocyanate is isoflurane diisocyanate.

[0014] In one embodiment, the catalyst is dibutyltin dilaurate.

[0015] In one embodiment, the ultraviolet absorption functional monomer is a benzotriazole ultraviolet absorber.

[0016] In one embodiment, the benzotriazole-based ultraviolet absorber includes at least one of 2-(2H-benzotriazole-2-yl)-4,6-di(1-methyl-1-phenylethyl)phenol, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chloro-2H-benzotriazole, 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol, 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-tert-octylphenol], 2-[2-hydroxy-3-tert-butyl-5-(2-hydroxyethyl)phenyl]-2H-benzotriazole, and 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole.

[0017] In one embodiment, the benzotriazole ultraviolet absorber is a reactive benzotriazole ultraviolet absorber.

[0018] In one embodiment, the crosslinking agent includes an internal crosslinking agent and an external crosslinking agent, wherein the weight ratio of the internal crosslinking agent to the external crosslinking agent is (0.5-2):(1-3).

[0019] In one embodiment, the weight ratio of the internal crosslinking agent to the external crosslinking agent is (0.92-1.53):(1.2-2).

[0020] In one embodiment, the weight ratio of the inner crosslinking agent to the outer crosslinking agent is 1.22:1.6.

[0021] In one embodiment, the internal crosslinking agent includes at least one of trimethylolpropane, pentaerythritol, ethylene glycol, 1,4-butanediol, and dipropylene glycol.

[0022] In one embodiment, the internal crosslinking agent is trimethylolpropane.

[0023] In one embodiment, the external crosslinking agent includes at least one of 3-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-epoxypropoxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0024] In one embodiment, the external crosslinking agent is 3-aminopropyltriethoxysilane.

[0025] In one embodiment, the chain extender comprises a combination of 1,4-butanediol and 2,2-dihydroxymethylbutyric acid.

[0026] In one embodiment, the weight ratio of 1,4-butanediol to 2,2-dihydroxymethylbutyric acid is (1.5-2.5):(3.53-5.88).

[0027] In one embodiment, the weight ratio of 1,4-butanediol to 2,2-dihydroxymethylbutyric acid is 2:4.7.

[0028] In one embodiment, the 2,2-dihydroxymethylbutyric acid is 2,2-dihydroxymethylbutyric acid pre-dissolved in a solvent.

[0029] In one embodiment, the 2,2-dihydroxymethylbutyric acid is 2,2-dihydroxymethylbutyric acid pre-dissolved in N,N-dimethylacetamide.

[0030] In one embodiment, the corrosion inhibitor comprises at least a benzimidazole structure, and the corrosion inhibitor comprises at least one of 2-aminobenzimidazole or 2-mercaptobenzimidazole.

[0031] In one embodiment, the corrosion inhibitor is 2-aminobenzimidazole.

[0032] In one implementation, the diluent includes, but is not limited to, acetone.

[0033] In one implementation, the neutralizing agent includes, but is not limited to, triethylamine.

[0034] A second aspect of the present invention provides a method for preparing benzimidazole-functionalized waterborne polyurethane, comprising the following steps: Preparation of polyurethane prepolymer; The polyurethane prepolymer is cooled to 40-50℃, a chain extender is added, and the temperature is raised to 60-80℃ for 1-3 hours. Then an internal crosslinking agent is added, and the reaction is carried out at 60-80℃ for 0.5-1.5 hours to obtain a waterborne polyurethane with a double crosslinking structure. A corrosion inhibitor is added to a waterborne polyurethane with a double crosslinking structure, and the reaction is carried out for 1-3 hours. Then a diluent is added, the temperature is lowered to 35-45℃, a neutralizing agent is added, and the reaction is carried out for 20-40 minutes. Finally, under high-speed stirring, deionized water containing an external crosslinking agent is added for emulsification to obtain benzimidazole functionalized waterborne polyurethane.

[0035] As one embodiment, the preparation method of the polyurethane prepolymer includes the following steps: under nitrogen protection, polyether polyol and polyisocyanate are mixed and reacted, the reaction temperature is controlled at 60-80℃ for 1-2 hours, ultraviolet absorption functional monomer and catalyst are added, and the reaction is continued at 60-80℃ for 1-2 hours to obtain polyurethane prepolymer.

[0036] A third aspect of the present invention provides an application of benzimidazole-functionalized waterborne polyurethane for the preparation of UV-resistant and corrosion-resistant products.

[0037] Compared with the prior art, the present invention has the following beneficial effects: (1) The benzimidazole functionalized waterborne polyurethane of the present invention firmly bonds the UV-absorbing functional monomer and the corrosion inhibitor to the polyurethane main chain or side chain by chemical bond, thereby endowing the coating with durable UV resistance, excellent corrosion resistance and excellent mechanical properties.

[0038] (2) The benzimidazole functionalized waterborne polyurethane of the present invention uses trimethylolpropane and 3-aminopropyltriethoxysilane as internal and external crosslinking agents to construct a three-dimensional network structure with high crosslinking density. The resulting emulsion has excellent stability, and the coating formed has excellent mechanical properties, excellent corrosion resistance and long-lasting UV resistance.

[0039] (3) The benzimidazole functionalized waterborne polyurethane of the present invention chemically bonds ultraviolet absorption functional monomers and corrosion inhibitors into the polyurethane chain through molecular design, thereby achieving synergistic enhancement of ultraviolet resistance and corrosion resistance.

[0040] (4) The preparation method of benzimidazole functionalized waterborne polyurethane of the present invention constructs benzimidazole functionalized waterborne polyurethane with double crosslinking structure through a three-step method. The process is reasonable and the conditions are mild. The prepared waterborne polyurethane has excellent mechanical properties, UV resistance and corrosion resistance.

[0041] (5) The benzimidazole-functionalized waterborne polyurethane coating of the present invention has an impedance modulus of up to 4.35 × 10⁻⁶ at a frequency of 0.01 Hz. 6 Ω·cm², suitable for high-performance metal protection and outdoor weather-resistant coatings. Attached Figure Description

[0042] Figure 1 The graph shows the relationship between the impedance modulus and frequency of the coating prepared in Example 1. Figure 2 The graph shows the relationship between the transmittance and wavelength of the films prepared in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0043] Example 1 A benzimidazole-functionalized waterborne polyurethane, the raw materials for preparation include: polyurethane prepolymer, chain extender, crosslinking agent, corrosion inhibitor, diluent, neutralizer and deionized water.

[0044] The polyurethane prepolymer is a polyurethane prepolymer modified with ultraviolet-absorbing monomers.

[0045] The raw materials for preparing the polyurethane prepolymer include polyether polyol, polyisocyanate, ultraviolet absorption functional monomer and catalyst.

[0046] The polyether polyol is polytetrahydrofuran ether diol with a number average molecular weight of 2000, purchased from Zhongrun (Shandong) New Materials Co., Ltd.; the polyisocyanate is isoflurone diisocyanate; the catalyst is dibutyltin dilaurate; the ultraviolet absorption functional monomer is a reactive benzotriazole ultraviolet absorber, purchased from Chiguard Technology Co., Ltd., brand name Chiguard® R-455.

[0047] The crosslinking agent includes an internal crosslinking agent and an external crosslinking agent, wherein the internal crosslinking agent is trimethylolpropane and the external crosslinking agent is 3-aminopropyltriethoxysilane.

[0048] The chain extender comprises a combination of 1,4-butanediol and 2,2-dihydroxymethylbutyric acid.

[0049] The corrosion inhibitor is 2-aminobenzimidazole; the diluent is acetone; and the neutralizing agent is triethylamine.

[0050] A method for preparing benzimidazole-functionalized waterborne polyurethane includes the following steps: Preparation of polyurethane prepolymer: Under nitrogen protection, 30g of polyether polyol and 22.5g of polyisocyanate were mixed and reacted. The reaction temperature was controlled at 80℃ and the mixture was stirred at 360 rpm for 1h. 0.32g of UV-absorbing functional monomer and 3.75μL of catalyst were added, and the reaction was continued at 80℃ for 1h to obtain polyurethane prepolymer. The polyurethane prepolymer was cooled to 50°C, and 1.5g of 1,4-butanediol and 3.53g of 2,2-dimethylolbutyric acid, which were pre-dissolved in 6g of N,N-dimethylacetamide, were added. The mixture was heated to 70°C and reacted for 2 hours. Then, 0.92g of trimethylolpropane was added, and the mixture was reacted at 70°C for 1 hour to obtain a waterborne polyurethane with a double crosslinking structure. Add 0.32g of corrosion inhibitor to a waterborne polyurethane with a double crosslinking structure, react at 70℃ for 2 hours, then add 30mL of diluent, cool to 40℃, add 2.59g of neutralizer and react for 30min. Finally, under high-speed stirring at 1200rpm, slowly add 143g of deionized water containing 1.2g of external crosslinking agent and emulsify for 30min to obtain benzimidazole functionalized waterborne polyurethane.

[0051] Example 2 A benzimidazole-functionalized waterborne polyurethane, the specific implementation method is the same as in Example 1, except that: A method for preparing benzimidazole-functionalized waterborne polyurethane includes the following steps: Preparation of polyurethane prepolymer: Under nitrogen protection, 40g of polyether polyol and 30g of polyisocyanate were mixed and reacted. The reaction temperature was controlled at 80℃ and the mixture was stirred at 360 rpm for 1h. 0.42g of UV-absorbing functional monomer and 5μL of catalyst were added, and the reaction was continued at 80℃ for 1h to obtain polyurethane prepolymer. The polyurethane prepolymer was cooled to 50°C, and 2g of 1,4-butanediol and 4.7g of 2,2-dimethylolbutyric acid, which were pre-dissolved in 8g of N,N-dimethylacetamide, were added. The mixture was heated to 70°C and reacted for 2 hours. Then, 1.22g of trimethylolpropane was added, and the mixture was reacted at 70°C for 1 hour to obtain a waterborne polyurethane with a double crosslinking structure. Add 0.42g of corrosion inhibitor to a waterborne polyurethane with a double crosslinking structure, react at 70℃ for 2 hours, then add 30mL of diluent, cool to 40℃, add 3.45g of neutralizer and react for 30min. Finally, under high-speed stirring at 1200rpm, slowly add 190g of deionized water containing 1.6g of external crosslinking agent and emulsify for 30min to obtain benzimidazole functionalized waterborne polyurethane.

[0052] Example 3 A benzimidazole-functionalized waterborne polyurethane, the specific implementation method is the same as in Example 1, except that: A method for preparing benzimidazole-functionalized waterborne polyurethane includes the following steps: Preparation of polyurethane prepolymer: Under nitrogen protection, 50g of polyether polyol and 43.75g of polyisocyanate were mixed and reacted. The reaction temperature was controlled at 80℃ and the mixture was stirred at 360 rpm for 1h. 0.53g of UV-absorbing functional monomer and 6.3μL of catalyst were added, and the reaction was continued at 80℃ for 1h to obtain polyurethane prepolymer. The polyurethane prepolymer was cooled to 50°C, and 2.5g of 1,4-butanediol and 5.88g of 2,2-dimethylolbutyric acid, which were pre-dissolved in 8g of N,N-dimethylacetamide, were added. The mixture was heated to 70°C and reacted for 2 hours. Then, 1.53g of trimethylolpropane was added, and the mixture was reacted at 70°C for 1 hour to obtain a waterborne polyurethane with a double crosslinking structure. Add 0.53g of corrosion inhibitor to a waterborne polyurethane with a double crosslinking structure, react at 70℃ for 2 hours, then add 30mL of diluent, cool to 40℃, add 4.32g of neutralizer and react for 30min. Finally, under high-speed stirring at 1200rpm, slowly add 238g of deionized water containing 3g of external crosslinking agent and emulsify for 30min to obtain benzimidazole functionalized waterborne polyurethane.

[0053] Comparative Example 1 A benzimidazole-functionalized waterborne polyurethane, the specific implementation method is the same as in Example 2, except that: A method for preparing benzimidazole-functionalized waterborne polyurethane includes the following steps: Preparation of polyurethane prepolymer: Under nitrogen protection, 40g of polyether polyol and 30g of polyisocyanate were mixed and reacted. The reaction temperature was controlled at 80℃ and the mixture was stirred at 360 rpm for 1h. 5μL of catalyst was added and the reaction was continued at 80℃ for 1h to obtain polyurethane prepolymer. The polyurethane prepolymer was cooled to 50°C, and 2g of 1,4-butanediol and 4.7g of 2,2-dimethylolbutyric acid, which were pre-dissolved in 8g of N,N-dimethylacetamide, were added. The mixture was heated to 70°C and reacted for 2 hours. Then, 1.22g of trimethylolpropane was added, and the mixture was reacted at 70°C for 1 hour to obtain a waterborne polyurethane with a double crosslinking structure. Add 0.42g of corrosion inhibitor to a waterborne polyurethane with a double crosslinking structure, react at 70℃ for 2 hours, then add 30mL of diluent, cool to 40℃, add 3.45g of neutralizer and react for 30min. Finally, under high-speed stirring at 1200rpm, slowly add 190g of deionized water containing 1.6g of external crosslinking agent and emulsify for 30min to obtain benzimidazole functionalized waterborne polyurethane.

[0054] Comparative Example 2 A benzimidazole-functionalized waterborne polyurethane, the specific implementation method is the same as in Example 2, except that: A method for preparing benzimidazole-functionalized waterborne polyurethane includes the following steps: Preparation of polyurethane prepolymer: Under nitrogen protection, 40g of polyether polyol and 30g of polyisocyanate were mixed and reacted. The reaction temperature was controlled at 80℃ and the mixture was stirred at 360 rpm for 1h. 0.42g of UV-absorbing functional monomer and 5μL of catalyst were added, and the reaction was continued at 80℃ for 1h to obtain polyurethane prepolymer. The polyurethane prepolymer was cooled to 50°C, and 2g of 1,4-butanediol and 4.7g of 2,2-dimethylolbutyric acid, which were pre-dissolved in 8g of N,N-dimethylacetamide, were added. The mixture was heated to 70°C and reacted for 2 hours. Then, 1.22g of trimethylolpropane was added, and the mixture was reacted at 70°C for 1 hour to obtain a waterborne polyurethane with a double crosslinking structure. After the waterborne polyurethane with a double crosslinking structure was cooled to 40°C, 3.45g of neutralizing agent was added and reacted for 30min. Finally, under high-speed stirring at 1200rpm, 190g of deionized water containing 1.6g of external crosslinking agent was slowly added and emulsified for 30min to obtain benzimidazole functionalized waterborne polyurethane.

[0055] Performance testing 1. Corrosion resistance test: The benzimidazole-functionalized waterborne polyurethane prepared in the examples and comparative examples was uniformly coated on a 3 cm × 2 cm tinplate sheet, dried at room temperature for 4 days, and then placed in a constant temperature drying oven at 40 ℃ for 3 days to achieve a thickness of 1 mm. After complete curing, electrochemical impedance spectroscopy was performed using a three-electrode system of an electrochemical workstation in a 3.5 wt% NaCl aqueous solution. The impedance modulus value at 0.01 Hz was measured.

[0056] Preparation of benzimidazole-functionalized waterborne polyurethane films The benzimidazole-functionalized waterborne polyurethane prepared in the examples and comparative examples was slowly poured into a polytetrafluoroethylene mold and dried at room temperature for 4 days. Then it was placed in a constant temperature drying oven at 40 °C and dried for 3 days. The film thickness was 1 mm. After it was completely cured into a film, it was taken out of the mold to obtain a benzimidazole-functionalized waterborne polyurethane film.

[0057] 2. UV Resistance Test: The UV resistance of the prepared benzimidazole-functionalized waterborne polyurethane film was studied using a DU800 UV / Vis spectrophotometer (Beckman Coulter). The UV transmittance of the WPU film in the wavelength range of 200 nm to 800 nm was measured. The test results are shown in the figure below. Figure 2 .

[0058] 3. Tensile strength: The mechanical properties of the benzimidazole-functionalized waterborne polyurethane film were evaluated using an electronic universal testing machine (AGS-H). The film was shaped into dumbbell-shaped strips of 30 mm × 4 mm × 1.5 mm, and the testing rate was 50 mm / min.

[0059] 4. Water Absorption Rate: The water resistance of the benzimidazole-functionalized waterborne polyurethane film was evaluated by testing its water absorption rate. A 10 mm × 10 mm sample was prepared from the fully cured film and its initial mass was denoted as M1. After immersion in distilled water for 24 hours, its mass was denoted as M2. The water absorption rate was then calculated using the following formula:

[0060] The performance test results are shown in Table 1.

[0061] Table 1

[0062] The coating prepared in Example 1 exhibits an impedance modulus as high as 3.02 × 10⁻⁶ at 0.01 Hz. 6 The film exhibits excellent corrosion protection capabilities with a transmittance exceeding 75% in the visible light range (400-760 nm), indicating its superior transparency. Throughout the ultraviolet spectrum, including the UVC (200-280 nm), UVB (280-320 nm), and UVA (320-400 nm) bands, the film demonstrates excellent UV protection performance with a transmittance of 0. The impedance modulus versus frequency relationship of the coating prepared in Example 1 is shown in the figure. Figure 1 The relationship between the transmittance and wavelength of the thin film prepared in Example 1 is shown in the figure. Figure 2 .

[0063] The coating prepared in Example 2 exhibits an impedance modulus as high as 4.35 × 10⁻⁶ at 0.01 Hz. 6 Ω·cm 2 It exhibits excellent corrosion protection capabilities. The film prepared in Example 2 has a transmittance of 0 in the ultraviolet band of 200-400 nm, showing excellent shielding effect. In addition, the transmittance in the visible light region (400-800 nm) exceeds 75%, demonstrating excellent transparency.

[0064] The coating prepared in Example 3 exhibits an impedance modulus as high as 5.16 × 10⁻⁶ at 0.01 Hz. 6 Ω·cm 2It exhibits excellent corrosion protection capabilities. The film prepared in Example 3 has a transmittance of 0 in the ultraviolet band of 200-400 nm, showing excellent shielding effect. In addition, the transmittance in the visible light region (400-800 nm) exceeds 75%, demonstrating excellent transparency.

[0065] The coating prepared in Comparative Example 1 has an impedance modulus of 1.05 × 10⁻⁶ at 0.01 Hz. 5 Ω·cm 2 The transmittance of the film prepared in Comparative Example 1 was significantly higher (over 50%) in the 200-400 nm ultraviolet band, indicating poor shielding performance.

Claims

1. A benzimidazole-functionalized waterborne polyurethane, characterized in that, The raw materials for preparation include, by weight: 50-105 parts of polyurethane prepolymer, 5-8.5 parts of chain extender, 2-4 parts of crosslinking agent, 0.3-0.6 parts of corrosion inhibitor, 20-40 parts of diluent, 2-5 parts of neutralizer, and 140-240 parts of deionized water.

2. The benzimidazole-functionalized waterborne polyurethane according to claim 1, characterized in that, The polyurethane prepolymer is a polyurethane prepolymer modified with ultraviolet-absorbing monomers.

3. The benzimidazole-functionalized waterborne polyurethane according to claim 2, characterized in that, The raw materials for preparing the polyurethane prepolymer include at least polyether polyol, polyisocyanate, ultraviolet-absorbing functional monomer and catalyst.

4. The benzimidazole-functionalized waterborne polyurethane according to claim 3, characterized in that, The crosslinking agent includes an internal crosslinking agent and an external crosslinking agent, and the weight ratio of the internal crosslinking agent to the external crosslinking agent is (0.5-2):(1-3).

5. The benzimidazole-functionalized waterborne polyurethane according to claim 4, characterized in that, The internal crosslinking agent includes at least one of trimethylolpropane, pentaerythritol, ethylene glycol, 1,4-butanediol, and dipropylene glycol.

6. The benzimidazole-functionalized waterborne polyurethane according to claim 4, characterized in that, The external crosslinking agent includes at least one of 3-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-epoxypropoxypropyltrimethoxysilane, and vinyltrimethoxysilane.

7. The benzimidazole-functionalized waterborne polyurethane according to claim 1, characterized in that, The corrosion inhibitor comprises at least a benzimidazole structure, and the corrosion inhibitor comprises at least one of 2-aminobenzimidazole or 2-mercaptobenzimidazole.

8. A method for preparing benzimidazole-functionalized waterborne polyurethane according to any one of claims 4-7, characterized in that, Includes the following steps: Preparation of polyurethane prepolymer; The polyurethane prepolymer is cooled to 40-50℃, a chain extender is added, and the temperature is raised to 60-80℃ for 1-3 hours. Then an internal crosslinking agent is added, and the reaction is carried out at 60-80℃ for 0.5-1.5 hours to obtain a waterborne polyurethane with a double crosslinking structure. A corrosion inhibitor is added to a waterborne polyurethane with a double crosslinking structure, and the reaction is carried out for 1-3 hours. Then a diluent is added, the temperature is lowered to 35-45℃, a neutralizing agent is added, and the reaction is carried out for 20-40 minutes. Finally, under stirring, deionized water containing an external crosslinking agent is added for emulsification to obtain benzimidazole functionalized waterborne polyurethane.

9. The preparation method according to claim 8, characterized in that, The preparation method of the polyurethane prepolymer includes the following steps: under nitrogen protection, polyether polyol and polyisocyanate are mixed and reacted, the reaction temperature is controlled at 60-80℃ for 1-2 hours, ultraviolet absorption functional monomer and catalyst are added, and the reaction is continued at 60-80℃ for 1-2 hours to obtain polyurethane prepolymer.

10. An application of the benzimidazole-functionalized waterborne polyurethane according to any one of claims 1-7, characterized in that, It is used in the preparation of products that are resistant to ultraviolet radiation and corrosion.

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