A fluorosilane-modified pvdf coating and a method for preparing the same

Abstract

The application belongs to the technical field of PVDF coating and specifically relates to a fluorosilane modified PVDF coating and a preparation method thereof. The PVDF coating comprises the following raw materials in weight fractions: 50-60 parts of polyvinylidene fluoride, 8-10 parts of amino-grafted fluorine-based polyether modified polysiloxane, 5-8 parts of tridecafluoro octyl trimethoxysilane or / and, 5-10 parts of hydrophobic nano-silicon dioxide and 1-2 parts of corrosion inhibitor. The fluorosilane modification technology and scientific formula design solve the defects of weak adhesion, single function and insufficient corrosion resistance of the traditional PVDF coating. The coating reaches the industry leading level in adhesion (5B level), self-cleaning property (contact angle > 150°) and corrosion resistance (1000 hours of salt spray without failure), and is suitable for long-term protection requirements in harsh environments such as buildings, automobiles and industrial equipment.

Description

Technical Field

[0001] This invention belongs to the field of PVDF coating technology, specifically relating to a fluorosilane-modified PVDF coating and its preparation method. Background Technology

[0002] Polyvinylidene fluoride (PVDF) is a high-performance fluoropolymer with the chemical formula -(CH2-CF2)-n-, polymerized from vinylidene fluoride monomers. This material combines the excellent corrosion resistance and high-temperature resistance of fluoroplastics with the easy processability of thermoplastics. PVDF coatings are high-performance fluorocarbon coatings, using PVDF resin as the main film-forming substance. Due to their excellent chemical properties, they are widely used in building exteriors, bridge protection, automotive coatings, and industrial equipment.

[0003] However, traditional PVDF coatings still suffer from problems such as insufficient adhesion, limited functionality, and poor synergy in complex scenarios, which restricts their application in high-end and harsh environments. Specifically, this manifests in the following aspects: (1) Insufficient coating adhesion: Due to its non-polar molecular structure, PVDF has a low surface energy and weak adhesion to the substrate, which easily leads to peeling and cracking of the coating during long-term use. This problem is the most significant technical bottleneck in the practical application of traditional PVDF coatings. (2) Traditional coatings often focus on a certain performance, such as corrosion resistance or weather resistance, while neglecting the balance and synergy of other performances, such as self-cleaning efficiency. (3) PVDF coatings are prone to performance degradation in harsh environments, with weak corrosion resistance, resulting in a shortened coating life. Summary of the Invention

[0004] In view of the shortcomings of existing traditional PVDF coatings, such as weak adhesion, limited functionality, and insufficient corrosion resistance, this invention provides a fluorosilane-modified PVDF coating and its preparation method.

[0005] To achieve the above objectives, in one aspect, the present invention provides a fluorosilane-modified PVDF coating, comprising the following raw materials in weight fractions:

[0006] 50-60 parts of polyvinylidene fluoride

[0007] 8-10 parts of amino-grafted fluoropolyether modified polysiloxane or / and 5-8 parts of tridecafluorooctyltrimethoxysilane, 5-10 parts of hydrophobic nano-silica

[0008] 1-2 parts corrosion inhibitor.

[0009] A further improvement to this scheme is the preparation method of the amino-grafted fluoropolyether modified polysiloxane as follows.

[0010] (1) Fluoro-based polyether modified polysiloxane pretreatment

[0011] Dissolve fluoropolyether-modified polysiloxane in toluene at a concentration of 20-30 wt% and stir until completely dissolved. The reaction temperature is 60-70℃, the stirring speed is 300-400 rpm, and the reaction time is 1-2 hours.

[0012] (2) Hydrolysis of silane coupling agents

[0013] Mix 3-aminopropyltrimethoxysilane with deionized water, and add 0.5-1 wt% acetic acid to catalyze hydrolysis; the reaction temperature is 25-30℃, the time is 30-60 minutes, and the volume ratio of 3-aminopropyltrimethoxysilane to deionized water is 1:1-1.2.

[0014] (3) Amino grafting reaction

[0015] The fluoropolyether-modified polysiloxane solution obtained in step (1) is mixed with the hydrolysate obtained in step (2), and 0.1-0.3 wt% acetic acid is added to the total system mass for reaction. The reaction temperature is 70-80℃, the stirring speed is 400-500 rpm, the reaction time is 6-8 hours, and the entire process is protected by nitrogen. The molar ratio of the fluoropolyether-modified polysiloxane in step (1) to the 3-aminopropyltrimethoxysilane in step (2) is 1:1-1.2.

[0016] The corrosion inhibitor is benzotriazole or benzotriazole corrosion inhibitor microcapsules.

[0017] A further improvement to this scheme, the preparation method of hydrophobic nano-silica, is as follows:

[0018] Vaporized nano-SiO2 and perfluorooctyltrichlorosilane were mixed in ethanol at a molar ratio of 1:1.5-2, the pH was adjusted to 2.0-5.0, and after stirring and reacting, hydrophobic SiO2 was obtained by centrifugation and drying.

[0019] The gaseous nano-SiO2 particles have a diameter of 20-50 nm, the reaction temperature is 50-70℃, the reaction time is 4-6 hours, and the mass-volume ratio (g:ml) of gaseous nano-SiO2 to ethanol is 1:3-5.

[0020] On the other hand, the present invention provides a method for preparing fluorosilane-modified PVDF coatings, comprising the following steps: (1) dissolving polyvinylidene fluoride in supercritical CO2 solvent to form a uniform resin solution;

[0021] (2) Add amino-grafted fluoropolyether modified polysiloxane or / and tridecafluorooctyltrimethoxysilane, hydrophobic nano silica, benzotriazole or benzotriazole corrosion inhibitor microcapsules in sequence, and disperse by ultrasonication;

[0022] The polyvinylidene fluoride (PVDF) content is 50-60 wt%, the amino-grafted fluorinated polyether modified polysiloxane and tridecafluorooctyltrimethoxysilane content is 8-10 wt%, the hydrophobic nano silica content is 5-10 wt%, and the benzotriazole or benzotriazole corrosion inhibitor microcapsules content is 1-2 wt%.

[0023] In step (1), the temperature of the supercritical CO2 is 50-65℃, the pressure is 15-20MPa, the dissolution time is 2-3 hours, and the concentration of polyvinylidene fluoride is 50-60wt%. The ultrasonic dispersion time is 30-60 minutes and the frequency is 40-60kHz.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) This invention proposes an innovative solution based on fluorosilane modification technology. By regulating the interfacial reaction between fluorosilane and PVDF matrix and using supramolecular interface construction technology, a novel multifunctional coating is developed. This technology can significantly enhance coating adhesion and interfacial stability, and integrate multiple functions such as self-cleaning, anti-fouling, and anti-corrosion, breaking through the performance bottleneck of traditional coatings.

[0026] (2) The amino groups (-NH2) in amino-grafted fluoropolymer polyether-modified polysiloxane form a strong interfacial bond with the CF bonds in the PVDF molecular chain through hydrogen bonding, effectively overcoming the insufficient adhesion problem caused by the non-polar structure of traditional PVDF coatings. Adhesion tests all achieved the highest level (5B). The uniform dispersion of hydrophobic nano-SiO2 further optimized the coating microstructure, reduced defects, and enhanced the bonding strength between the coating and the substrate. Furthermore, by providing tridecafluorooctyltrimethoxysilane modification, it synergistically improves adhesion with other raw materials, enhancing its application prospects.

[0027] (3) After being modified with perfluorooctyltrichlorosilane, the hydrophobic nano-silica is covered with a low surface energy perfluorinated chain. The amino-grafted component enhances the density of the coating and reduces micropores, further synergistically improving the hydrophobic effect. The coating obtained by this invention forms a superhydrophobic surface with a contact angle >150°, allowing water droplets to roll off quickly (roll-off angle ≤5°), thus achieving a self-cleaning function.

[0028] (4) The corrosion inhibitor of this invention suppresses chemical corrosion and employs microencapsulation technology. The benzotriazole corrosion inhibitor microcapsules slowly release active ingredients into the coating, inhibiting electrochemical corrosion over a long period. Furthermore, hydrophobic SiO2 reduces the surface energy of the coating, decreases water vapor adsorption, and blocks the penetration of corrosive media, forming a hydrophobic barrier. The strong bonding between the amino-grafted components and PVDF, along with the uniform dispersion of nano-SiO2, forms a defect-free, dense protective layer. Under the action of the system, the corrosion resistance time reaches 1000 hours in a salt spray test without rust or bubbles.

[0029] (5) The synergistic effect of amino-grafted fluorosilane, hydrophobic nano-SiO2 and corrosion inhibitor microcapsules realizes the three-in-one functional integration and synergy of "interface strengthening - hydrophobic barrier - long-term corrosion inhibition".

[0030] (6) The method of the present invention uses supercritical CO2 solvent to dissolve PVDF and combines ultrasonic dispersion technology to ensure uniform dispersion of each component and avoid the influence of traditional solvent residue on performance. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention are clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] All raw materials used in the following embodiments of the present invention are commercially available. The polyvinylidene fluoride (PVDF) is HSV900, provided by Guangzhou Hongcheng Plastics Co., Ltd. The fluoropolymer-modified polysiloxane is MDH, provided by Hubei Maidehao Biotechnology Co., Ltd. The fumed nano-SiO2 is selected from Shandong Kasong New Materials Co., Ltd. The perfluorooctyltrichlorosilane CAS number is 78560-45-9.

[0033] Example 1:

[0034] Preparation of amino-grafted fluoropolyether-modified polysiloxane:

[0035] (1) Fluoro-based polyether modified polysiloxane pretreatment

[0036] Fluoropolymer-modified polysiloxane was dissolved in toluene at a concentration of 20 wt%. The reaction temperature was 60°C, the stirring speed was 300 rpm, and the reaction time was 1 hour, stirring until completely dissolved.

[0037] (2) Hydrolysis of silane coupling agents

[0038] 3-Aminopropyltrimethoxysilane was mixed with deionized water at a volume ratio of 1:1, and 0.5 wt% acetic acid was added to catalyze hydrolysis. The reaction temperature was 25 °C, and the reaction time was 30 minutes.

[0039] (3) Amino grafting reaction

[0040] Fluoropolymer-modified polysiloxane was mixed with 3-aminopropyltrimethoxysilane at a molar ratio of 1:1, and 0.1 wt% acetic acid was added to the mixture for reaction. The reaction temperature was 70℃, the stirring speed was 400 rpm, the reaction time was 6 hours, and nitrogen gas was used for protection throughout the process.

[0041] (4) The reaction solution was centrifuged (3000-4000 rpm, 20 minutes) to remove unreacted monomers, and then dried to obtain the product.

[0042] The amino content was 1.5 mmol / g using acid-base titration.

[0043] The above process can achieve efficient amino grafting of fluorinated polyether modified polysiloxane, and when combined with polyvinylidene fluoride (PVDF), the interfacial bonding strength can be significantly improved through hydrogen bonding between -NH2 and CF bonds.

[0044] Example 2:

[0045] Preparation of amino-grafted fluoropolyether-modified polysiloxane:

[0046] (1) Fluoro-based polyether modified polysiloxane pretreatment

[0047] Fluoropolymer-modified polysiloxane was dissolved in toluene at a concentration of 30 wt%. The reaction temperature was 70°C, the stirring speed was 400 rpm, and the reaction time was 2 hours, stirring until completely dissolved.

[0048] (2) Hydrolysis of silane coupling agents

[0049] 3-Aminopropyltrimethoxysilane was mixed with deionized water at a volume ratio of 1:1.2, and 1 wt% acetic acid was added to catalyze hydrolysis. The reaction temperature was 30°C, and the reaction time was 60 minutes.

[0050] (3) Amino grafting reaction

[0051] Fluoropolymer-modified polysiloxane was mixed with 3-aminopropyltrimethoxysilane at a molar ratio of 1:1.2, and 0.3 wt% acetic acid was added to the mixture for reaction. The reaction temperature was 80℃, the stirring speed was 500 rpm, the reaction time was 8 hours, and nitrogen gas was used for protection throughout the process.

[0052] (5) The reaction solution was centrifuged (3000-4000 rpm, 20 minutes) to remove unreacted monomers, and then dried to obtain the product.

[0053] The amino content was 1.2 mmol / g using acid-base titration.

[0054] The following is an example using the product of Example 1.

[0055] Example 3: Preparation of hydrophobic nano-silica

[0056] Vaporized nano-SiO2 and perfluorooctyltrichlorosilane were mixed in ethanol at a molar ratio of 1:1.5-2. The pH was adjusted to 2.0-5.0 with acetic acid. After stirring and reacting, the mixture was centrifuged and dried to obtain hydrophobic SiO2.

[0057] The particle size of the gas-phase nano-SiO2 is 20-50nm, the reaction temperature is 50-70℃, the reaction time is 4-6 hours, and the mass-volume ratio (g:ml) of gas-phase nano-SiO2 to ethanol is 1:3-5.

[0058] Its contact angle was measured and found to be >150°.

[0059] In the example below, using these parameters, vapor-phase nano-SiO2 (particle size 20-50 nm) and perfluorooctyltrichlorosilane (molar ratio 1:1.5) were mixed in ethanol, the pH was adjusted to 3 with acetic acid, and the mixture was stirred at 50°C for 6 hours. After centrifugation and drying, hydrophobic SiO2 was obtained, with a measured contact angle of 155°.

[0060] Example 4:

[0061] Preparation of fluorosilane-modified PVDF coatings:

[0062] PVDF was dissolved in supercritical CO2 (temperature 60℃, pressure 18MPa) and stirred for 2 hours until completely dissolved. The concentration of polyvinylidene fluoride was 55wt%.

[0063] Amino-grafted fluorinated polyether-modified polysiloxane, hydrophobic nano-silica, and benzotriazole corrosion inhibitor microcapsules were added sequentially, stirred, and ultrasonically dispersed for 30 minutes at a frequency of 50 kHz. The composition of the microcapsules was: polyvinylidene fluoride 55 wt%, amino-grafted fluorinated polyether-modified polysiloxane 9 wt%, hydrophobic nano-silica 7 wt%, and benzotriazole corrosion inhibitor microcapsules 1.5 wt%.

[0064] The benzotriazole corrosion inhibitor microcapsules were prepared as follows:

[0065] Sodium benzotriazole (BTA·Na) was mixed with ZIF-8 at a mass ratio of 1:2, stirred and encapsulated at 60°C for 12 hours, and the particle size distribution was 1-5 μm.

[0066] Example 5:

[0067] The difference from Example 4 is that tridecafluorooctyltrimethoxysilane, hydrophobic nano-silica, and benzotriazole corrosion inhibitor microcapsules were added sequentially, stirred, and ultrasonically dispersed for 30 minutes at a frequency of 50 kHz. The polyvinylidene fluoride (PVDF) had a mass fraction of 55 wt%, tridecafluorooctyltrimethoxysilane 9 wt%, hydrophobic nano-silica 7 wt%, and benzotriazole corrosion inhibitor microcapsules 1.5 wt%.

[0068] Example 6:

[0069] The difference from Example 4 is that amino-grafted fluorinated polyether modified polysiloxane, hydrophobic nano-silica, and benzotriazole were added sequentially, and the mixture was stirred and ultrasonically dispersed for 30 minutes at a frequency of 50 kHz. The mass fraction of polyvinylidene fluoride was 55 wt%, the mass fraction of amino-grafted fluorinated polyether modified polysiloxane was 9 wt%, the mass fraction of hydrophobic nano-silica was 7 wt%, and the mass fraction of benzotriazole was 1.5 wt%.

[0070] Example 7:

[0071] The difference from Example 4 is that amino-grafted fluorinated polyether modified polysiloxane, tridecafluorooctyltrimethoxysilane, hydrophobic nano silica, and benzotriazole corrosion inhibitor microcapsules were added sequentially and then ultrasonically dispersed.

[0072] The composition includes 55 wt% polyvinylidene fluoride, 4.5 wt% amino-grafted fluorinated polyether modified polysiloxane and 4.5 wt% tridecylfluorooctyltrimethoxysilane, 7 wt% hydrophobic nano-silica, and 1.5 wt% benzotriazole or benzotriazole corrosion inhibitor microcapsules.

[0073] Example 8:

[0074] Unlike Example 4, no amino-grafted fluoropolyether modified polysiloxane was added.

[0075] Example 9:

[0076] Unlike Example 4, hydrophobic nano-silica was not added.

[0077] Example 10:

[0078] The difference from Example 4 is that unmodified nano-silica was added.

[0079] Example 11:

[0080] Unlike Example 4, no corrosion inhibitor was added.

[0081] Example 12:

[0082] The difference from Example 4 is that the amino-grafted fluoropolyether modified polysiloxane is replaced with fluoropolyether modified polysiloxane.

[0083] Example 13: Performance Testing

[0084] The obtained coating is uniformly applied to the substrate surface using an electrostatic spraying device, with the wet film thickness controlled at 80-100 μm. The product is then obtained by baking at 80℃ for 1 hour, followed by annealing at 120℃ for 2 hours.

[0085] Experiments were conducted on the products of Examples 4-12, and a blank group (products containing only polyvinylidene fluoride coating) was set up.

[0086] Example 14: Adhesion Performance Test

[0087] The cross-cut test (GB / T 9286-2021 "Paints and Varnishes Cross-cut Test") was used to evaluate the bonding strength between the coating and the substrate. The experimental results are shown in Table 1 below.

[0088] Table 1: Comparison of Adhesion Performance

[0089]

[0090]

[0091] The data above shows that Examples 4 / 7 / 11 exhibit the best results. The amino groups and CF bonds enhance interfacial bonding through hydrogen bonding, while the hydrophobic SiO2 improves uniformity, resulting in optimal adhesion. In Example 11, the absence of a corrosion inhibitor does not affect short-term adhesion, but long-term peeling is possible. Combining Examples 8 and 12, it can be seen that the lack of amino groups prevents hydrogen bonding, leading to extremely weak interfacial bonding and a significant decrease in adhesion.

[0092] Example 5 shows that tridecafluorooctyltrimethoxysilane can also improve adhesion, but not as significantly as amino-grafted fluoropolymer modified polysiloxane. Example 6 shows poor corrosion inhibitor dispersibility, but with little impact on adhesion. Example 9 shows decreased hydrophobicity, leading to decreased adhesion. Example 10 shows uneven dispersion of unmodified SiO2, resulting in numerous coating defects and a significant decrease in adhesion.

[0093] Example 15: Corrosion Resistance

[0094] The experiment was conducted according to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", and the results are shown in Table 2 below.

[0095] Table 2: Comparison of Corrosion Resistance Performance

[0096]

[0097]

[0098] Experiments showed that rust and bubbles appeared in blank example 300h, as did in examples 12 and 8. The reason was that the lack of amino grafting resulted in extremely poor adhesion, easy peeling of the coating, and rapid penetration of salt spray into the substrate.

[0099] Example 11 showed rust and bubbles after 500 hours. Without corrosion inhibitor protection, the coating relied solely on physical barriers, and corrosion occurred rapidly.

[0100] Example 9 showed rust and bubbles after 600 hours. The lack of hydrophobic SiO2 led to easy adsorption of moisture on the coating surface. While the microcapsules of the corrosion inhibitor partially compensated for this, corrosion resistance decreased. Example 10 showed rust and bubbles after 300 hours. Unmodified SiO2 was unevenly dispersed, and the coating contained micropores, exacerbating corrosion. Salt spray rapidly eroded the substrate through these defects. Hydrophobic nano-SiO2 further improved corrosion resistance by reducing surface energy and decreasing moisture adsorption.

[0101] In Example 6, rust and bubbles appeared after 600 hours. Ordinary corrosion inhibitors were unevenly dispersed and had limited protective effects, but amino grafting enhanced adhesion and delayed corrosion.

[0102] Examples 4, 5, and 7 showed no rust or blistering after 1000 hours. The corrosion inhibitor microcapsules continuously released benzotriazole, providing long-lasting protection and effectively inhibiting substrate corrosion. Combined with hydrophobic SiO2 and amino grafting, the coating was dense and defect-free. The microcapsules, through the slow release of corrosion inhibitors, suppressed electrochemical corrosion over a long period, with the best effect, especially when synergistic with amino grafting components.

[0103] Example 16: Self-cleaning performance

[0104] The contact angle was tested, and the test results are shown in Table 3 below.

[0105] Table 3: Comparison of contact angles:

[0106] Example Static contact angle (°) Dynamic contact angle (roll-off angle) Example 4 155 ≤5 Example 5 152 ≤7 Example 6 120 25 Example 7 156 ≤5 Example 8 105 30 Example 9 110 35 Example 115 28 Example 150 ≤8 Example 110 28 Blank example 95 40

[0107] Superhydrophobic nano-SiO2, after being modified with perfluorooctyltrichlorosilane, has a surface covered with low-surface-energy perfluorinated chains, which significantly improves the hydrophobicity of the coating (as in Examples 4, 5, 7, and 11). The high static contact angle (>150°) accompanied by a low roll-off angle (≤5°) allows water droplets to roll off the surface quickly, carrying away contaminants.

[0108] In the blank example (contact angle 95°), due to the hydrophilic surface, water droplets are difficult to roll off, and contaminants easily adhere. Unmodified nano-SiO2 (Examples 9 and 10) lacks perfluorinated groups, resulting in a small contact angle and decreased self-cleaning performance.

[0109] Amino-grafted fluoropolymer polyether-modified polysiloxanes (Examples 4 and 7): Hydrogen bonds are formed between the amino groups and the CF bonds of PVDF, enhancing interfacial bonding. Simultaneously, hydrophobic SiO2 is uniformly dispersed, forming a dense hydrophobic layer, achieving synergistic enhancement. Examples 8 and 12 lack amino grafting, resulting in higher surface energy and affecting cleaning performance. In Example 6, uneven dispersion of the corrosion inhibitor negatively impacts surface adhesion.

[0110] Example 17:

[0111] (1) Polyvinylidene fluoride was dissolved in supercritical CO2 solvent to form a homogeneous resin solution; the temperature of supercritical CO2 was 50℃, the pressure was 15MPa, the dissolution time was 2 hours, and the concentration of polyvinylidene fluoride was 50wt%.

[0112] (2) Add amino-grafted fluorinated polyether modified polysiloxane, hydrophobic nano silica, and benzotriazole corrosion inhibitor microcapsules in sequence, and disperse by ultrasonication; ultrasonic dispersion time is 30 minutes; frequency is 40 kHz.

[0113] The composition includes 50 wt% polyvinylidene fluoride, 8 wt% amino-grafted fluorinated polyether modified polysiloxane, 5 wt% hydrophobic nano-silica, and 1 wt% benzotriazole corrosion inhibitor microcapsules.

[0114] Example 18:

[0115] (1) Polyvinylidene fluoride was dissolved in supercritical CO2 solvent to form a homogeneous resin solution; the temperature of supercritical CO2 was 65℃, the pressure was 20MPa, the dissolution time was 3 hours, and the concentration of polyvinylidene fluoride was 60wt%.

[0116] (2) Add amino-grafted fluorinated polyether modified polysiloxane, hydrophobic nano silica, and benzotriazole corrosion inhibitor microcapsules in sequence, and disperse by ultrasonication; ultrasonic dispersion time is 30-60 minutes; frequency is 60kHz.

[0117] The composition includes 60 wt% polyvinylidene fluoride, 10 wt% amino-grafted fluorinated polyether modified polysiloxane, 10 wt% hydrophobic nano-silica, and 2 wt% benzotriazole corrosion inhibitor microcapsules.

[0118] Experiments show that the coatings of Examples 16 and 17 exhibited adhesion grade 5B, contact angle >150°, dynamic contact angle ≤5°, and no failure after 1000 hours of salt spray corrosion resistance, demonstrating the versatility of the coatings and methods.

[0119] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A fluorosilane-modified PVDF coating, characterized in that, Raw materials including the following weight fractions: 50-60 parts of polyvinylidene fluoride 8-10 parts of amino-grafted fluoropolyether modified polysiloxane 5-10 parts of hydrophobic nano-silica 1-2 parts corrosion inhibitor.

2. The fluorosilane-modified PVDF coating according to claim 1, characterized in that, The preparation method of the amino-grafted fluoropolyether modified polysiloxane is as follows: (1) Dissolve fluoropolyether-modified polysiloxane in toluene at a concentration of 20-30 wt% and stir until completely dissolved; (2) Mix 3-aminopropyltrimethoxysilane with deionized water, and add 0.5-1 wt% acetic acid to catalyze hydrolysis; (3) Mix the fluoropolyether modified polysiloxane solution obtained in step (1) with the hydrolysate obtained in step (2), and add 0.1-0.3 wt% acetic acid of the total system mass to carry out the reaction; The raw material molar ratio of fluorinated polyether modified polysiloxane in step (1) to 3-aminopropyltrimethoxysilane in step (2) is 1:1-1.

2.

3. The fluorosilane-modified PVDF coating according to claim 2, characterized in that: In step (1), the stirring temperature is 60-70℃, the stirring speed is 300-400 rpm, and the stirring time is 1-2 hours.

4. The fluorosilane-modified PVDF coating according to claim 2, characterized in that: In step (2), the reaction temperature is 25-30℃ and the time is 30-60 minutes. 3-Aminopropyltrimethoxysilane and deionized water are mixed at a volume ratio of 1:1-1.

2.

5. The fluorosilane-modified PVDF coating according to claim 2, characterized in that: In step (3), the reaction temperature is 70-80℃, the reaction time is 6-8 hours, and nitrogen gas is used for protection throughout the process.

6. The fluorosilane-modified PVDF coating according to claim 1, characterized in that: The corrosion inhibitor is benzotriazole or benzotriazole corrosion inhibitor microcapsules.

7. The fluorosilane-modified PVDF coating according to claim 1, characterized in that: The preparation method of hydrophobic nano-silica is as follows: Vaporized nano-SiO2 and perfluorooctyltrichlorosilane were mixed in ethanol at a molar ratio of 1:1.5-2, the pH was adjusted to 2.0-5.0, and after stirring and reacting, hydrophobic SiO2 was obtained by centrifugation and drying.

8. The fluorosilane-modified PVDF coating according to claim 7, characterized in that; The vapor-phase nano-SiO2 has a particle size of 20-50 nm, the reaction temperature is 50-70℃, the reaction time is 4-6 hours, and the mass-volume ratio (g:ml) of vapor-phase nano-SiO2 to ethanol is 1:3-5.

9. A method for preparing fluorosilane-modified PVDF coatings according to any one of claims 1-8: characterized in that: (1) Dissolve polyvinylidene fluoride in supercritical CO2 solvent to form a homogeneous resin solution; (2) Add amino-grafted fluorinated polyether modified polysiloxane, hydrophobic nano silica and corrosion inhibitor in sequence, and disperse by ultrasonication.

10. The method for preparing the fluorosilane-modified PVDF coating according to claim 9: characterized in that: In step (1), the temperature of the supercritical CO2 is 50-65℃, the pressure is 15-20 MPa, the dissolution time is 2-3 hours, and the concentration of polyvinylidene fluoride is 50-60 wt%.

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