Corrosion-resistant waterborne polyurethane as well as preparation method and application thereof

Abstract

The invention relates to the field of coating production, and discloses corrosion-resistant waterborne polyurethane which comprises waterborne polyurethane and fluorinated graphene dispersed in the waterborne polyurethane, and the mass ratio of the waterborne polyurethane to the fluorinated graphene is 100: (0.1-0.5); the waterborne polyurethane is fluorine modified waterborne polyurethane; the fluorinated graphene is subjected to surface treatment by a silane coupling agent, and the fluorine content in the fluorinated graphene before surface treatment by the silane coupling agent is 20-50 at%, on one hand, the fluorinated graphene is modified by the silane coupling agent, so that the surface energy of the fluorinated graphene is reduced; on the other hand, fluorine modification is conducted on waterborne polyurethane, and it is found in the actual testing process that the dispersing capacity of fluorinated graphene in polyurethane is further improved.

Description

Technical Field

[0001] This application relates to the field of coating production technology, and in particular to a corrosion-resistant waterborne polyurethane, its preparation method, and its application. Background Technology

[0002] There are various methods for corrosion protection of metallic materials. Using coatings to isolate the metal substrate from direct contact with the corrosive environment, thereby achieving corrosion prevention, is currently the most common and convenient method. Waterborne polyurethane, as an environmentally friendly material, is one of the most widely used resins in waterborne coatings due to its high flexibility, excellent corrosion and chemical resistance, and strong adhesion to substrates.

[0003] However, compared to traditional solvent-based coatings, water-based coatings contain more hydrophilic groups in their molecules, resulting in poor water resistance and significantly limiting their actual anti-corrosion effect. To improve the anti-corrosion performance of water-based coatings, efforts should first be made to improve the coating's water resistance.

[0004] Graphene is a two-dimensional material with good heat and chemical resistance, and it can effectively protect metals in hot air at 200°C. Fluorinated graphene, while inheriting the two-dimensional structure of graphene, also possesses the insulation, hydrophobicity, good thermal stability, and excellent wear resistance of fluorinated graphene. When combined with polymer materials, it retains the inherent properties of fluorinated graphene while also incorporating the advantages of polymer materials, making this combination undoubtedly more promising for applications.

[0005] However, due to the high surface energy of fluorinated graphene and the low surface energy of waterborne polyurethane, the dispersion effect of fluorinated graphene in waterborne polyurethane is significantly affected, and the two are not easy to form a stable and uniform mixed system after mixing.

[0006] The problem this solution aims to solve is: how to provide a stable and uniform hybrid system of fluorinated graphene and waterborne polyurethane. Summary of the Invention

[0007] The purpose of this application is to provide a mixed system of fluorinated graphene and waterborne polyurethane with good dispersion stability. On the one hand, this application reduces the surface energy of fluorinated graphene by modifying it with a silane coupling agent. On the other hand, it modifies the waterborne polyurethane with fluorine. In actual testing, it was found that this further improves the dispersion ability of fluorinated graphene in polyurethane.

[0008] To achieve the above objectives, this application discloses a corrosion-resistant waterborne polyurethane, comprising waterborne polyurethane and fluorinated graphene dispersed in the waterborne polyurethane, wherein the mass ratio of the waterborne polyurethane to the fluorinated graphene is 100:0.1 to 0.5;

[0009] The waterborne polyurethane is a fluorine-modified waterborne polyurethane;

[0010] The fluorinated graphene is fluorinated graphene that has been surface-treated with a silane coupling agent, and the fluorine content in the fluorinated graphene before surface treatment with the silane coupling agent is 20-50 at.

[0011] Preferably, the preparation method of the fluorinated graphene after surface treatment with a silane coupling agent is as follows:

[0012] Step A1: Hydrolyze the silane coupling agent to obtain a silane coupling agent hydrolysate;

[0013] Step A2: Fluorinated graphene is ultrasonically dispersed in ethanol to obtain a dispersion of fluorinated graphene;

[0014] Step A3: Add the hydrolysate of the silane coupling agent obtained in step 1 to the dispersion of fluorinated graphene at a mass ratio of 10 to 15:1. Then, heat the mixture in a constant temperature oil bath at 75 to 90°C for 3 to 6 hours. After cooling and centrifugation, collect the precipitate and wash it to obtain fluorinated graphene that has undergone surface treatment with the silane coupling agent.

[0015] Preferably, the silane coupling agent is selected from at least one of KH550 and KH560.

[0016] Preferably, the preparation method of the fluorine-modified waterborne polyurethane is as follows: mixing adipic acid-based polyester polyol, fluorinated diol, aliphatic diisocyanate and pre-chain extender solution, heating, and carrying out polymerization reaction under nitrogen protection; after cooling, adding a neutralizing agent to carry out neutralization reaction; then adding water to carry out dispersion and emulsification; then adding ethylenediamine to carry out post-chain extension reaction, and filtering to obtain fluorine-modified waterborne polyurethane;

[0017] The fluorinated diol is prepared by the following method:

[0018] Step 1: Polymerize a fluorinated monohydric alcohol and an aliphatic diisocyanate at a molar ratio of 1:1 to 1.2 to obtain an intermediate;

[0019] Step 2: The intermediate is polymerized with diethanolamine to obtain a fluorinated diol, and the molar ratio of diethanolamine to aliphatic diisocyanate in step 1 is 1:1 to 1.2.

[0020] Preferably, step 1 specifically involves: mixing a fluorinated monohydric alcohol, an aliphatic diisocyanate, and a catalyst, and heating the mixture to 60–80°C for 1.5–2 hours to obtain an intermediate;

[0021] The catalyst is selected from at least one of dibutyltin dilaurate and stannous octoate;

[0022] Step 2 specifically involves reacting the intermediate obtained in step 1 with diethanolamine at -10 to 0°C for 5 to 12 minutes to obtain a fluorinated diol.

[0023] Preferably, the adipic acid-based polyester polyol is selected from any one of polytetrahydrofuran, polypropylene glycol, polyethylene glycol, and polycaprolactone;

[0024] The aliphatic diisocyanate is selected from any one of isophorone diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate;

[0025] The pre-chain extender solution is selected from any one of 2,2-dimethylolpropionic acid solution, dimethylolbutyric acid solution, sodium ethylenediamine ethanesulfonate solution, N-methyldiethanolamine solution, and triethanolamine solution.

[0026] Preferably, the mass ratio of the adipic acid-based polyester polyol, aliphatic diisocyanate, fluorinated diol, pre-chain extender solution, neutralizer, and ethylenediamine is 2.2–3.7: 5.0–8.3: 0.9–2: 5.6–10.0: 0.7–1.4: 0.6–0.8.

[0027] The concentration of the pre-chain extender in the pre-chain extender solution is 0.15–0.3 g / mL.

[0028] In addition, this application also discloses a method for preparing the above-mentioned corrosion-resistant waterborne polyurethane, characterized in that fluorinated graphene that has been surface-treated with a silane coupling agent is dispersed into fluorine-modified waterborne polyurethane to obtain corrosion-resistant waterborne polyurethane.

[0029] In addition, this application also discloses the application of corrosion-resistant waterborne polyurethane coatings as described above.

[0030] The beneficial effects of this application are:

[0031] This application provides a mixed system of fluorinated graphene and waterborne polyurethane with good dispersion stability. On the one hand, this application reduces the surface energy of fluorinated graphene by modifying it with a silane coupling agent. On the other hand, it modifies the waterborne polyurethane with fluorine. In actual testing, it was found that this further improves the dispersion ability of fluorinated graphene in polyurethane. Detailed Implementation

[0032] The present invention will now be clearly and completely described in conjunction with embodiments thereof. It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0033] Pentafluorobutanol, CAS number 54949-74-5;

[0034] Isophorone diisocyanate, CAS number 4098-71-9;

[0035] Lysine diisocyanate, CAS number 45172-15-4;

[0036] Dimethylolbutyric acid, CAS number 10097-02-6;

[0037] Stannous octoate, CAS number 301-10-0;

[0038] Diethanolamine, CAS number 111-42-2;

[0039] Fluorinated graphene was purchased from Shandong Zhongshan Optoelectronic Materials Co., Ltd.

[0040] 2,2-Dimethylolpropionic acid, CAS number 4767-03-7;

[0041] Polytetrahydrofuran was purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd., with a molecular weight of 600-700.

[0042] Polypropylene glycol was purchased from Haian Petrochemical Plant in Jiangsu Province, with a molecular weight of 700±50.

[0043] Example 1

[0044] Preparation method of fluorinated graphene:

[0045] Step A1: Mix KH550 with ethanol and water at a mass ratio of 3:1:1, and then incubate the mixture in a water bath at 45°C for 24 hours to obtain the hydrolysate of KH550.

[0046] Step A2: Fluorinated graphene (fluorine content of 25±3 at%) was ultrasonically dispersed in ethanol at a mass ratio of 1.5:100 to obtain a dispersion of fluorinated graphene.

[0047] Step A3: The hydrolysate of KH550 obtained in step A1 was added to the dispersion of fluorinated graphene at a mass ratio of 13:1 to silane coupling agent KH550. The mixture was then kept in a constant temperature oil bath at 85°C for 4 hours. After cooling, centrifugation, and collection and washing of the precipitate, fluorinated graphene with surface treatment by silane coupling agent was obtained.

[0048] Preparation of fluorinated diols:

[0049] Step 1: Mix pentafluorobutanol and acetone and heat to 70°C. Then add isophorone diisocyanate and stannous octoate and stir for 10 min. Then maintain the temperature at 70°C and react for 1.8 h to obtain the intermediate.

[0050] Furthermore, in step 1, the molar ratio of pentafluorobutanol to isophorone diisocyanate is 1:1.1, the mass ratio of acetone to pentafluorobutanol is 5:1, and the mass ratio of stannous octoate to pentafluorobutanol is 1:20.

[0051] Step 2: Cool the intermediate obtained in Step 1 to -6℃, then add diethanolamine to the intermediate and react for 20 min. Then evaporate acetone at 50℃ and 0.09 MPa vacuum to obtain a fluorinated diol. In Step 2, the molar ratio of diethanolamine to aliphatic diisocyanate in Step 1 is 1:1.1.

[0052] Preparation of corrosion-resistant waterborne polyurethane:

[0053] 2.2 g of polytetrahydrofuran, 5.0 g of isophorone diisocyanate, 0.9 g of fluorinated diol, and 5.6 g of 2,2-dimethylolpropionic acid solution (concentration 0.2 g / mL) were added to a 500 mL three-necked flask. The mixture was heated to 60 °C and stirred under nitrogen protection for 2 hours to carry out the polymerization reaction. After the reaction was completed, the system temperature was lowered to 40 °C, and 0.7 g of triethylamine was added for neutralization reaction for 30 minutes. Then, deionized water was added and the mixture was stirred at high speed to disperse until the emulsion was uniform.

[0054] Fluorinated graphene was then dispersed into the emulsion at a mass ratio of 100:0.3 (high-speed shear mixing at 2500 r / min for 1.5 h). 0.6 g of ethylenediamine was then added for a post-chain extension reaction for 45 minutes. After the reaction was completed, the mixture was filtered through a 200-mesh nylon screen to obtain corrosion-resistant waterborne polyurethane.

[0055] Example 2

[0056] Preparation method of fluorinated graphene:

[0057] Step A1: Mix KH550 with ethanol and water at a mass ratio of 3:1:1, and then incubate in a water bath at 45°C for 24 hours to obtain a hydrolysate of KH550.

[0058] Step A2: Fluorinated graphene (fluorine content 45±3at%) was ultrasonically dispersed in ethanol at a mass ratio of 1.5:100 to obtain a dispersion of fluorinated graphene.

[0059] Step A3: Add the hydrolysate of KH550 obtained in step A1 to the dispersion of fluorinated graphene at a mass ratio of 10:1 for silane coupling agent KH550 to fluorinated graphene. Then, heat in a constant temperature oil bath at 75°C for 6 hours. After cooling, centrifugation, and collection and washing of the precipitate, fluorinated graphene with surface treatment by silane coupling agent is obtained.

[0060] Preparation of fluorinated diols:

[0061] Step 1: Mix pentafluorobutanol and acetone and heat to 70°C. Then add isophorone diisocyanate and stannous octoate and stir for 10 min. Then maintain the temperature at 70°C and react for 1.8 h to obtain the intermediate.

[0062] Furthermore, in step 1, the molar ratio of pentafluorobutanol to isophorone diisocyanate is 1:1.1, the mass ratio of acetone to pentafluorobutanol is 5:1, and the mass ratio of stannous octoate to pentafluorobutanol is 1:20.

[0063] Step 2: Cool the intermediate obtained in Step 1 to -6℃, then add diethanolamine to the intermediate and react for 20 min. Then evaporate acetone at 50℃ and 0.09 MPa vacuum to obtain a fluorinated diol. In Step 2, the molar ratio of diethanolamine to aliphatic diisocyanate in Step 1 is 1:1.1.

[0064] Preparation of corrosion-resistant waterborne polyurethane:

[0065] 3.7 g of polytetrahydrofuran, 8.3 g of isophorone diisocyanate, 2 g of fluorinated diol, and 10 g of 2,2-dimethylolpropionic acid solution (concentration 0.2 g / mL) were added to a 500 mL three-necked flask. The mixture was heated to 60 °C and stirred under nitrogen protection for 2 hours to carry out the polymerization reaction. After the reaction was completed, the system temperature was lowered to 40 °C, and 1.4 g of triethylamine was added for neutralization reaction for 30 minutes. Then, deionized water was added, and the mixture was stirred at high speed to disperse until the emulsion was uniform.

[0066] Fluorinated graphene was then dispersed into the emulsion at a mass ratio of 100:0.1 (high-speed shear mixing at 2500 r / min for 1.5 h). 0.8 g of ethylenediamine was then added for a post-chain extension reaction for 45 minutes. After the reaction was completed, the mixture was filtered through a 200-mesh nylon screen to obtain corrosion-resistant waterborne polyurethane.

[0067] Example 3

[0068] Preparation method of fluorinated graphene:

[0069] Step A1: Mix KH550 with ethanol and water at a mass ratio of 3:1:1, and then incubate in a water bath at 45°C for 24 hours to obtain a hydrolysate of KH550.

[0070] Step A2: Fluorinated graphene (fluorine content of 35±3 at%) is ultrasonically dispersed in ethanol at a mass ratio of 1.5:100 to obtain a dispersion of fluorinated graphene.

[0071] Step A3: Add the hydrolysate of KH550 obtained in step A1 to the dispersion of fluorinated graphene at a mass ratio of 15:1 for silane coupling agent KH550 to fluorinated graphene. Then, heat in a constant temperature oil bath at 85°C for 4 hours. After cooling, centrifugation, and collection and washing of the precipitate, fluorinated graphene with surface treatment by silane coupling agent is obtained.

[0072] Preparation of fluorinated diols:

[0073] Step 1: Mix pentafluorobutanol and acetone and heat to 70°C. Then add isophorone diisocyanate and stannous octoate and stir for 10 min. Then maintain the temperature at 70°C and react for 1.8 h to obtain the intermediate.

[0074] Furthermore, in step 1, the molar ratio of pentafluorobutanol to isophorone diisocyanate is 1:1.1, the mass ratio of acetone to pentafluorobutanol is 5:1, and the mass ratio of stannous octoate to pentafluorobutanol is 1:20.

[0075] Step 2: Cool the intermediate obtained in Step 1 to -6℃, then add diethanolamine to the intermediate and react for 20 min. Then evaporate acetone at 50℃ and 0.09 MPa vacuum to obtain a fluorinated diol. In Step 2, the molar ratio of diethanolamine to aliphatic diisocyanate in Step 1 is 1:1.1.

[0076] Preparation of corrosion-resistant waterborne polyurethane:

[0077] 3g of polytetrahydrofuran, 7g of isophorone diisocyanate, 1.5g of fluorinated diol and 8.5g of 2,2-dimethylolpropionic acid solution (concentration 0.2g / mL) were added to a 500mL three-necked flask, heated to 60℃, and stirred under nitrogen protection for 2 hours for polymerization. After the reaction was completed, the system temperature was lowered to 40℃, and 1g of triethylamine was added for neutralization reaction for 30 minutes. Then, deionized water was added and the mixture was stirred at high speed until the emulsion was uniform.

[0078] Fluorinated graphene was then dispersed into the emulsion at a mass ratio of 100:0.5 (high-speed shear mixing, rotation speed of 2500 r / min, mixing time of 1.5 h). 0.7 g of ethylenediamine was then added for a post-chain extension reaction for 45 minutes. After the reaction was completed, the mixture was filtered through a 200-mesh nylon screen to obtain corrosion-resistant waterborne polyurethane.

[0079] Comparative Example 1

[0080] The process is basically the same as in Example 1, except that the preparation method of the corrosion-resistant waterborne polyurethane is as follows: 3.1 g of polytetrahydrofuran, 5.0 g of isophorone diisocyanate and 5.6 g of 2,2-dimethylolpropionic acid solution (concentration of 0.2 g / mL) are added to a 500 mL three-necked flask, heated to 60 °C, and stirred under nitrogen protection for 2 hours for polymerization; after the reaction is completed, the system temperature is lowered to 40 °C, and 0.7 g of triethylamine is added for neutralization reaction for 30 minutes; then deionized water is added and the mixture is stirred at high speed until the emulsion is uniform.

[0081] Fluorinated graphene was then dispersed into the emulsion at a mass ratio of 100:0.3 (high-speed shear mixing, rotation speed of 2500 r / min, mixing time of 1.5 h). 0.6 g of ethylenediamine was then added for a post-chain extension reaction for 45 minutes. After the reaction was completed, the mixture was filtered through a 200-mesh nylon screen to obtain an aqueous polyurethane emulsion.

[0082] Comparative Example 2

[0083] The process is basically the same as in Example 1, except that the preparation method of the corrosion-resistant waterborne polyurethane is as follows: 3.1 g of polytetrahydrofuran, 5.0 g of isophorone diisocyanate and 5.6 g of 2,2-dimethylolpropionic acid solution (concentration of 0.2 g / mL) are added to a 500 mL three-necked flask, heated to 60 °C, and stirred under nitrogen protection for 2 hours for polymerization. After the reaction is completed, the system temperature is lowered to 40 °C, and 0.7 g of triethylamine is added for neutralization reaction for 30 minutes. Then, deionized water is added and the mixture is stirred at high speed until the emulsion is uniform. Then, 0.6 g of ethylenediamine is added for post-chain extension reaction for 45 minutes. After the reaction is completed, the mixture is filtered through a 400-mesh nylon screen to obtain the polyurethane emulsion.

[0084] Comparative Example 3

[0085] It is basically the same as Comparative Example 1, except that fluorinated graphene with a fluorine content of 10±3at% is used instead of fluorinated graphene with a fluorine content of 25±3at%.

[0086] Performance testing

[0087] 1. Corrosion resistance test: Neutral salt spray test (NSS) and acetic acid salt spray test (AASS) were conducted in accordance with GB-T10125-2012 (Artificial Atmosphere Corrosion Test Salt Spray Test), with steel as the reference sample;

[0088] 2. Water Contact Angle Test: The coating was prepared into a film on tinplate. After the film dried, a static water contact angle meter (SDC-100) was used to evaluate the hydrophobicity of the sample surface. 2 μL of deionized water was dropped onto the sample surface, and the static contact angle formed by the droplet on the coating surface was measured. The experiment was repeated 5 times, and the average value was taken.

[0089] The test results are shown in Table 1:

[0090] Table 1

[0091] Group Contact angle (°) Mass loss - NSS / g / m2 Mass loss amount - AASS / g / m2 Appearance of waterborne polyurethane emulsion Example 1 125.6 31.5 10.7 Graphene exhibits no aggregation. Example 2 122.3 32.8 11.3 Graphene exhibits no aggregation. Example 3 128.4 29.1 9.8 Graphene exhibits no aggregation. Comparative Example 1 105.1 42.4 23.5 Graphene exhibits significant aggregation. Comparative Example 2 116.2 40.5 20.3 / Comparative Example 3 119.5 36.5 15.4 Graphene shows no obvious aggregation. steel reference specimen / 45.3 25.8 /

[0092] Results analysis:

[0093] 1. As can be seen from the observation of Examples 1-3, when some process parameters in the preparation process of waterborne polyurethane are slightly adjusted, the contact angle and corrosion resistance of Examples 1-3 fluctuate, but the fluctuation range is relatively small.

[0094] 2. Further observation of Comparative Example 1 shows that when the fluorinated diol in the waterborne polyurethane of Comparative Example 1 was omitted and the same mass of polytetrahydrofuran was used as a supplement, the contact angle of Comparative Example 1 decreased significantly, indicating that its hydrophobicity was weakened. This may be related to the decrease in the total fluorine content in the waterborne polyurethane. Furthermore, the corrosion resistance of the waterborne polyurethane also showed a downward trend. In addition, graphene showed agglomeration in the emulsion.

[0095] It is evident that the use of fluorinated diols may enhance the dispersibility of fluorinated graphene in emulsions;

[0096] Further observation of Comparative Example 2 shows that when the use of fluorinated graphene is omitted, the hydrophobicity and corrosion resistance of Comparative Example 2 also show a significant downward trend.

[0097] Furthermore, in conjunction with the reference samples, it can be seen that Comparative Example 1, which uses fluorinated graphene, and Comparative Example 2, which uses fluorinated diol, both showed varying degrees of improvement in corrosion resistance compared to the reference samples. However, the improvement in corrosion resistance of Example 1 compared to the reference sample exceeded the sum of the improvements of Comparative Examples 1 and 2 compared to the reference samples. This indicates that there is a synergistic effect between fluorinated graphene and fluorinated diol, which further enhances the corrosion resistance of polyurethane.

[0098] Further observation of Comparative Example 3 shows that when the fluorine content of fluorinated graphene is reduced, the fluorinated graphene in the polyurethane emulsion prepared in Comparative Example 3 does not show obvious agglomeration. As the fluorine content of fluorinated graphene increases, the content of its high-energy carbon-fluorine bonds increases, leading to an increase in its surface energy. Therefore, fluorinated graphene with high fluorine content is more difficult to disperse in aqueous polyurethane. The experiment of Comparative Example 3 shows that when the fluorinated diol is omitted in the preparation process of aqueous polyurethane, it can ensure the dispersion effect of graphene with low fluorine content. However, combined with Comparative Example 1, it cannot guarantee the dispersion effect of graphene with high fluorine content.

[0099] Therefore, it can be seen that waterborne polyurethane prepared from fluorinated diols can further enhance its ability to disperse fluorinated graphene with high fluorine content.

[0100] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A corrosion-resistant waterborne polyurethane, characterized in that, It includes waterborne polyurethane and fluorinated graphene dispersed in waterborne polyurethane, wherein the mass ratio of waterborne polyurethane to fluorinated graphene is 100:0.1 to 0.5; The waterborne polyurethane is a fluorine-modified waterborne polyurethane; The fluorinated graphene is fluorinated graphene that has been surface-treated with a silane coupling agent, and the fluorine content in the fluorinated graphene before surface treatment with the silane coupling agent is 20-50 at.

2. The corrosion-resistant waterborne polyurethane according to claim 1, characterized in that, The preparation method of the fluorinated graphene after surface treatment with a silane coupling agent is as follows: Step A1: Hydrolyze the silane coupling agent to obtain a silane coupling agent hydrolysate; Step A2: Fluorinated graphene is ultrasonically dispersed in ethanol to obtain a dispersion of fluorinated graphene; Step A3: Add the hydrolysate of silane coupling agent obtained in step A1 to the dispersion of fluorinated graphene at a mass ratio of 10 to 15:

1. Then, heat in a constant temperature oil bath at 75 to 90°C for 3 to 6 hours. After cooling, centrifugation, and collection and washing of the precipitate, fluorinated graphene with surface treatment by silane coupling agent is obtained.

3. The corrosion-resistant waterborne polyurethane according to claim 2, characterized in that, The silane coupling agent is selected from at least one of KH550 and KH560.

4. The corrosion-resistant waterborne polyurethane according to claim 1, characterized in that, The preparation method of the fluorine-modified waterborne polyurethane is as follows: adipic acid-based polyester polyol, fluorinated diol, aliphatic diisocyanate and pre-chain extender solution are mixed, heated and polymerized under nitrogen protection; after cooling, a neutralizing agent is added for neutralization; then water is added for dispersion and emulsification; then ethylenediamine is added for post-chain extension reaction, and after filtration, fluorine-modified waterborne polyurethane is obtained. The fluorinated diol is prepared by the following method: Step 1: Polymerize a fluorinated monohydric alcohol and an aliphatic diisocyanate at a molar ratio of 1:1 to 1.2 to obtain an intermediate; Step 2: The intermediate is polymerized with diethanolamine to obtain a fluorinated diol, and the molar ratio of diethanolamine to aliphatic diisocyanate in step 1 is 1:1 to 1.

2.

5. The corrosion-resistant waterborne polyurethane according to claim 4, characterized in that, Step 1 specifically involves mixing a fluorinated monohydric alcohol, an aliphatic diisocyanate, and a catalyst, and heating the mixture to 60–80°C for 1.5–2 hours to obtain an intermediate. The catalyst is selected from at least one of dibutyltin dilaurate and stannous octoate; Step 2 specifically involves reacting the intermediate obtained in step 1 with diethanolamine at -10 to 0°C for 5 to 12 minutes to obtain a fluorinated diol.

6. The corrosion-resistant waterborne polyurethane according to claim 1, characterized in that, The adipic acid-based polyester polyol is selected from any one of polytetrahydrofuran, polypropylene glycol, polyethylene glycol, and polycaprolactone. The aliphatic diisocyanate is selected from any one of isophorone diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate; The pre-chain extender solution is selected from any one of 2,2-dimethylolpropionic acid solution, dimethylolbutyric acid solution, sodium ethylenediamine ethanesulfonate solution, N-methyldiethanolamine solution, and triethanolamine solution.

7. The corrosion-resistant waterborne polyurethane according to claim 1, characterized in that, The mass ratio of the adipic acid-based polyester polyol, aliphatic diisocyanate, fluorinated diol, pre-chain extender solution, neutralizer, and ethylenediamine is 2.2–3.7: 5.0–8.3: 0.9–2: 5.6–10.0: 0.7–1.4: 0.6–0.

8. The concentration of the pre-chain extender in the pre-chain extender solution is 0.15–0.3 g / mL.

8. A method for preparing the corrosion-resistant waterborne polyurethane according to any one of claims 1-7, characterized in that, Fluorinated graphene, after surface treatment with a silane coupling agent, is dispersed into fluorine-modified waterborne polyurethane to obtain corrosion-resistant waterborne polyurethane.

9. Application of the corrosion-resistant waterborne polyurethane coating as described in any one of claims 1-7.