Fluorosilane modified PVDF coating and preparation method thereof

Abstract

The invention belongs to the technical field of PVDF (Polyvinylidene Fluoride) coatings, and particularly relates to a fluorosilane modified PVDF coating and a preparation method thereof. The PVDF coating is prepared from the following raw materials in parts by weight: 50 to 60 parts of polyvinylidene fluoride, 8 to 10 parts of amino-grafted fluoro polyether modified polysiloxane or / and 5 to 8 parts of tridecafluorooctyltrimethoxysilane, 5 to 10 parts of hydrophobic nano silicon dioxide and 1 to 2 parts of corrosion inhibitor. Through a fluorosilane modification technology and a scientific formula design, the defects that a traditional PVDF coating is weak in adhesive force, single in function and insufficient in corrosion resistance are overcome, and the coating reaches the industry leading level in the aspects of adhesive force (5B grade), self-cleaning performance (the contact angle is larger than 150 degrees) and corrosion resistance (no failure occurs in salt mist for 1000 hours); the coating is suitable for long-acting protection requirements in severe environments such as buildings, automobiles and industrial equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of PVDF coatings, and in particular relates to a fluorosilane-modified PVDF coating and a preparation method thereof. Background Art

[0002] Polyvinylidene fluoride (PVDF) is a high-performance fluoropolymer with the chemical formula -(CH2-CF2)-n-, formed by the polymerization of vinylidene fluoride monomers. This material combines the excellent corrosion resistance and high-temperature resistance of fluoroplastics with the easy processing properties of thermoplastics. Polyvinylidene fluoride coatings are high-performance fluorocarbon coatings, primarily based on PVDF resin. 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 have problems such as insufficient adhesion, single function and poor synergy in complex scenarios, which restrict their application in high-end harsh environments. Specifically, it manifests itself in the following aspects: (1) Insufficient coating adhesion: Due to its non-polar molecular structure, PVDF has 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 of traditional PVDF coatings in practical applications. (2) Traditional coatings often focus on a certain performance, such as corrosion resistance or weather resistance, while ignoring the balance and synergy of other properties, such as self-cleaning efficiency. (3) PVDF coatings are prone to performance degradation in harsh environments and have weak corrosion resistance, resulting in a shortened coating life. Summary of the Invention

[0004] In view of the shortcomings of the above-mentioned traditional PVDF coating in the prior art, such as weak adhesion, single function and insufficient corrosion resistance, the present invention provides a fluorosilane-modified PVDF coating and a preparation method thereof.

[0005] To achieve the above object, on the one hand, 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 fluorine-based polyether modified polysiloxane or / and 5-8 parts of tridecafluorooctyltrimethoxysilane, 5-10 parts of hydrophobic nano-silica,

[0008] 1-2 parts of corrosion inhibitor.

[0009] As a further improvement of this solution, the preparation method of the amino-grafted fluorine-based polyether modified polysiloxane is as follows.

[0010] (1) Fluoropolyether modified polysiloxane pretreatment

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

[0012] (2) Hydrolysis of silane coupling agent

[0013] 3-aminopropyltrimethoxysilane is mixed with deionized water, and 0.5-1 wt% acetic acid is added to catalyze hydrolysis; the reaction temperature is 25-30° C., 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 fluorinated polyether-modified polysiloxane solution obtained in step (1) is mixed with the hydrolyzed solution obtained in step (2), and 0.1-0.3 wt% of acetic acid, based on the total weight of the system, is added to carry out the reaction. The reaction temperature is 70-80°C, the stirring speed is 400-500 rpm, and the reaction time is 6-8 hours. The entire process is protected by nitrogen. The molar ratio of the fluorinated polyether-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 of this solution is the preparation method of hydrophobic nano-silica as follows:

[0018] The gas-phase nano-SiO2 and perfluorooctyltrichlorosilane are mixed in ethanol at a molar ratio of 1:1.5-2, the pH is adjusted to 2.0-5.0, the mixture is stirred for reaction, and then centrifugally dried to obtain hydrophobic SiO2.

[0019] The particle size of the gas-phase nano-SiO2 is 20-50 nm, the reaction temperature is 50-70° C., the reaction time is 4-6 hours, and the mass volume ratio (g:ml) of the gas-phase nano-SiO2 to ethanol is 1:3-5.

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

[0021] (2) adding amino-grafted fluorine-based polyether modified polysiloxane and / or tridecafluorooctyltrimethoxysilane, hydrophobic nano-silica, benzotriazole or benzotriazole corrosion inhibitor microcapsules in sequence, and ultrasonically dispersing;

[0022] The mass fraction of polyvinylidene fluoride is 50-60wt%, the mass fraction of amino-grafted fluorine-based polyether modified polysiloxane and tridecafluorooctyltrimethoxysilane is 8-10wt%, the mass fraction of hydrophobic nano-silica is 5-10wt%, and the mass fraction of benzotriazole or benzotriazole corrosion inhibitor microcapsules is 1-2wt%.

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

[0024] The beneficial effects of the present invention are:

[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 new 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 the amino-grafted fluorinated polyether modified polysiloxane and the CF bonds in the PVDF molecular chain form a strong interfacial bond through hydrogen bonding, effectively overcoming the problem of insufficient adhesion of traditional PVDF coatings due to their non-polar structure. Adhesion tests all reached the highest level (5B level). The uniform dispersion of hydrophobic nano-SiO2 further optimized the microstructure of the coating, reduced defects, and enhanced the bonding strength between the coating and the substrate. In addition, by providing tridecafluorooctyltrimethoxysilane modification, the synergistic effect with other raw materials also improved adhesion, which broadened the application prospects.

[0027] (3) After hydrophobic nanosilica is modified with perfluorooctyltrichlorosilane, its surface is covered with perfluoro chains with low surface energy. The amino-grafted components enhance the coating density and reduce micropores, further synergistically improving the hydrophobic effect. The coating obtained by the present invention forms a superhydrophobic surface with a contact angle greater than 150°, causing water droplets to roll off quickly (rolling angle ≤ 5°), achieving a self-cleaning function.

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

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

[0030] (6) The method of the present invention uses supercritical CO2 solvent to dissolve PVDF, combined with ultrasonic dispersion technology to ensure that the components are evenly dispersed and avoid the influence of traditional solvent residues on performance. DETAILED DESCRIPTION

[0031] To help those skilled in the art better understand the technical solutions of the present invention, the following clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0032] The raw materials used in the following examples of the present invention are all commercially available. Polyvinylidene fluoride (HSV900) was supplied by Guangzhou Hongcheng Plastics Co., Ltd. Fluoropolyether-modified polysiloxane (MDH) was supplied by Hubei Maidehao Biotechnology Co., Ltd. Fumed nano-SiO2 was sourced from Shandong Kasong New Materials Co., Ltd. Perfluorooctyltrichlorosilane (CAS No. 78560-45-9) was used.

[0033] Example 1:

[0034] Preparation of amino-grafted fluorinated polyether modified polysiloxane:

[0035] (1) Fluoropolyether modified polysiloxane pretreatment

[0036] The fluorine-based polyether-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. The mixture was stirred until the polysiloxane was completely dissolved.

[0037] (2) Hydrolysis of silane coupling agent

[0038] 3-Aminopropyltrimethoxysilane was mixed with deionized water in 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] Fluoropolyether-modified polysiloxane and 3-aminopropyltrimethoxysilane were mixed in a 1:1 molar ratio, and 0.1 wt% acetic acid was added to the mixture. The reaction was carried out at a temperature of 70°C, a stirring speed of 400 rpm, and a reaction time of 6 hours. Nitrogen was used throughout the reaction.

[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 fluorine-based polyether-modified polysiloxane, and when compounded with polyvinylidene fluoride (PVDF), the interfacial bonding strength can be significantly improved through the hydrogen bonding effect of -NH2 and CF bonds.

[0044] Example 2:

[0045] Preparation of amino-grafted fluorinated polyether modified polysiloxane:

[0046] (1) Fluoropolyether modified polysiloxane pretreatment

[0047] The fluorine-based polyether-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. The mixture was stirred until completely dissolved.

[0048] (2) Hydrolysis of silane coupling agent

[0049] 3-Aminopropyltrimethoxysilane was mixed with deionized water in 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] Fluoropolyether-modified polysiloxane and 3-aminopropyltrimethoxysilane were mixed in a molar ratio of 1:1.2, and 0.3 wt% acetic acid was added to the mixture. The reaction was carried out at 80°C, stirring at 500 rpm, and for 8 hours, with nitrogen 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 are the products of Example 1 used in the examples.

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

[0056] The gas-phase nano-SiO2 and perfluorooctyltrichlorosilane are mixed in ethanol at a molar ratio of 1:1.5-2, and the pH is adjusted to 2.0-5.0 with acetic acid. After stirring for reaction, the mixture is centrifuged and dried to obtain hydrophobic SiO2.

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

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

[0059] In the following example, using this parameter, gas-phase nano-SiO2 (particle size 20-50nm) 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 centrifugal drying, hydrophobic SiO2 was obtained, and the contact angle was measured to be 155°.

[0060] Example 4:

[0061] Preparation of fluorosilane-modified PVDF coating:

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

[0063] Add amino-grafted fluorinated polyether-modified polysiloxane, hydrophobic nano-silica, and benzotriazole corrosion inhibitor microcapsules in sequence, stirring and ultrasonically dispersing for 30 minutes at a frequency of 50 kHz. The mass fraction of polyvinylidene fluoride is 55wt%, the mass fraction of amino-grafted fluorinated polyether-modified polysiloxane is 9wt%, the mass fraction of hydrophobic nano-silica is 7wt%, and the mass fraction of benzotriazole corrosion inhibitor microcapsules is 1.5wt%.

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

[0065] Sodium benzotriazole (BTA·Na) and ZIF-8 were mixed in 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 are added in sequence, stirred, and ultrasonically dispersed for 30 minutes at a frequency of 50 kHz. The mass fraction of polyvinylidene fluoride is 55wt%, the mass fraction of tridecafluorooctyltrimethoxysilane is 9wt%, the mass fraction of hydrophobic nano-silica is 7wt%, and the mass fraction of benzotriazole corrosion inhibitor microcapsules is 1.5wt%.

[0068] Example 6:

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

[0070] Example 7:

[0071] The difference from Example 4 is that amino-grafted fluorine-based polyether modified polysiloxane, tridecafluorooctyltrimethoxysilane, hydrophobic nano-silica, and benzotriazole corrosion inhibitor microcapsules are added in sequence and ultrasonically dispersed;

[0072] The mass fraction of polyvinylidene fluoride is 55wt%, the mass fractions of amino-grafted fluorine-based polyether modified polysiloxane and tridecafluorooctyltrimethoxysilane are 4.5wt% respectively, the mass fraction of hydrophobic nano-silica is 7wt%, and the mass fraction of benzotriazole or benzotriazole corrosion inhibitor microcapsules is 1.5wt%.

[0073] Example 8:

[0074] The difference from Example 4 is that the amino-grafted fluorine-based polyether-modified polysiloxane is not added.

[0075] Example 9:

[0076] The difference from Example 4 is that no hydrophobic nano-silica is added.

[0077] Example 10:

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

[0079] Example 11:

[0080] The difference from Example 4 is that no corrosion inhibitor is added.

[0081] Example 12:

[0082] The difference from Example 4 is that the amino-grafted fluorine-based polyether-modified polysiloxane is replaced by fluorine-based polyether-modified polysiloxane.

[0083] Example 13: Performance Test

[0084] The obtained coating was evenly applied to the substrate surface using an electrostatic spraying device, with the wet film thickness controlled at 80-100 μm. The product was first baked at 80°C for 1 hour and then annealed at 120°C for 2 hours.

[0085] The products of Examples 4-12 were tested separately, and a blank group (products with 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: Adhesion performance comparison

[0089]

[0090]

[0091] The above data demonstrates that Examples 4, 7, and 11 offer the best results. The amino groups hydrogen bond with the C-F bonds, enhancing interfacial bonding and the hydrophobic SiO2 improving uniformity, resulting in optimal adhesion. The absence of a corrosion inhibitor in Example 11 does not affect short-term adhesion, but may lead to long-term delamination. Combining Examples 8 and 12 reveals that the absence of amino groups prevents hydrogen bonding, resulting in 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 the amino-grafted fluoropolyether-modified polysiloxane. Example 6 shows poor corrosion inhibitor dispersibility, but has little effect on adhesion. Example 9 shows decreased hydrophobicity, leading to a decrease in adhesion. Example 10 shows that the unmodified SiO2 is unevenly dispersed and has many coating defects, resulting in a significant decrease in adhesion.

[0093] Example 15: Corrosion resistance

[0094] The experiment was conducted using GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test", and the results are shown in Table 2 below.

[0095] Table 2: Corrosion resistance performance comparison

[0096]

[0097]

[0098] The experiment showed that rust and bubbles appeared in the blank example after 300 hours, and also appeared in Example 12 and Example 8. The reason was that the adhesion was very poor due to the lack of amino grafting, the coating was easy to peel off, and the salt spray quickly penetrated into the substrate.

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

[0100] Example 9 showed rust and bubbles after 600 hours. This is due to the lack of hydrophobic SiO2, which makes the coating surface susceptible to water vapor adsorption. The corrosion inhibitor microcapsules partially compensated for this, but the corrosion resistance decreased. Example 10 showed rust and bubbles after 300 hours. The unmodified SiO2 was unevenly dispersed, and the coating had micropores, which aggravated corrosion. Salt spray quickly eroded the substrate through these defects. Hydrophobic nano-SiO2 reduces surface energy and reduces water vapor adsorption, further improving corrosion resistance.

[0101] Example 6 showed rust and bubbles after 600 hours. The ordinary corrosion inhibitor was unevenly dispersed and had limited protective effect. However, amino grafting enhanced adhesion and delayed corrosion.

[0102] Examples 4, 5, and 7 showed no signs of rust or bubbles after 1000 hours. The corrosion inhibitor microcapsules continuously released benzotriazole, providing long-lasting protection and effectively inhibiting substrate corrosion. Combined with the hydrophobic SiO2 and amino-grafted coatings, the coatings were dense and defect-free. The microcapsules' slow release of the corrosion inhibitor provided long-term electrochemical corrosion suppression, and the effect was particularly effective when combined with the amino-grafted component.

[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 Contact angle comparison:

[0106] Example Static contact angle (°) Dynamic contact angle (sliding 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, modified with perfluorooctyltrichlorosilane, is coated with low-surface-energy perfluoro chains, significantly enhancing the coating's hydrophobicity (as demonstrated in Examples 4, 5, 7, and 11). The high static contact angle (>150°) coupled with a low rolling angle (≤5°) allows water droplets to roll off the surface quickly, carrying away contaminants.

[0108] The blank (contact angle 95°) has a hydrophilic surface, making it difficult for water droplets to roll off and pollutants to adhere easily. The unmodified nano-SiO2 (Examples 9 and 10) has a small contact angle and a reduced self-cleaning performance due to the lack of perfluorinated groups.

[0109] Amino-grafted fluorinated polyether modified polysiloxane (Examples 4 and 7): The amino group forms a hydrogen bond with the CF bond of PVDF to enhance the interface bonding. At the same time, the hydrophobic SiO2 is evenly dispersed to form a dense hydrophobic layer, achieving synergistic enhancement. Examples 8 and 12 do not have amino grafting, and the surface energy is high, which affects the cleaning effect. The uneven dispersion of the corrosion inhibitor in Example 6 affects the surface.

[0110] Example 17:

[0111] (1) Dissolving polyvinylidene fluoride in supercritical CO2 solvent to form a uniform resin solution; the supercritical CO2 temperature is 50°C, the pressure is 15 MPa, the dissolution time is 2 hours, and the polyvinylidene fluoride concentration is 50 wt%.

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

[0113] The mass fraction of polyvinylidene fluoride is 50wt%, the mass fraction of amino-grafted fluorine-based polyether modified polysiloxane is 8wt%, the mass fraction of hydrophobic nano-silica is 5wt%, and the mass fraction of benzotriazole corrosion inhibitor microcapsules is 1wt%.

[0114] Example 18:

[0115] (1) Dissolving polyvinylidene fluoride in supercritical CO2 solvent to form a uniform resin solution; the supercritical CO2 temperature is 65°C, the pressure is 20 MPa, the dissolution time is 3 hours, and the polyvinylidene fluoride concentration is 60 wt%.

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

[0117] The mass fraction of polyvinylidene fluoride is 60wt%, the mass fraction of amino-grafted fluorine-based polyether modified polysiloxane is 10wt%, the mass fraction of hydrophobic nano-silica is 10wt%, and the mass fraction of benzotriazole corrosion inhibitor microcapsules is 2wt%.

[0118] Experiments show that the coatings of Examples 16 and 17 have adhesion level 5B, contact angle > 150°, dynamic contact angle ≤ 5°, and corrosion resistance of 1000 hours in salt spray without failure, indicating the versatility of the coating and method.

[0119] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person skilled in the art who can easily conceive of changes or substitutions within the technical scope disclosed in the present invention shall be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A fluorosilane-modified PVDF coating, characterized in that: The following raw materials are included in weight fractions: 50-60 parts of polyvinylidene fluoride, 8-10 parts of amino-grafted fluorine-based polyether modified polysiloxane or / and 5-8 parts of tridecafluorooctyltrimethoxysilane, 5-10 parts of hydrophobic nano-silica, 1-2 parts of corrosion inhibitor.

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

2.

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

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

2.

5. The fluorosilane-modified PVDF coating according to claim 2, characterized in that: In the step (3), the reaction temperature is 70-80° C., the stirring speed is 400-500 rpm, the reaction time is 6-8 hours, and the whole process is protected by nitrogen.

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: The gas-phase nano-SiO2 and perfluorooctyltrichlorosilane are mixed in ethanol at a molar ratio of 1:1.5-2, the pH is adjusted to 2.0-5.0, the mixture is stirred for reaction, and then centrifugally dried to obtain hydrophobic SiO2.

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

9. A method for preparing a fluorosilane-modified PVDF coating according to any one of claims 1 to 8, characterized in that: (1) dissolving polyvinylidene fluoride in supercritical CO2 solvent to form a uniform resin solution; (2) adding amino-grafted fluorine-based polyether modified polysiloxane and / or tridecafluorooctyltrimethoxysilane, hydrophobic nano-silica, benzotriazole or benzotriazole corrosion inhibitor microcapsules in sequence, and ultrasonically dispersing; The mass fraction of polyvinylidene fluoride is 50-60wt%, the mass fraction of amino-grafted fluorine-based polyether modified polysiloxane and tridecafluorooctyltrimethoxysilane is 8-10wt%, the mass fraction of hydrophobic nano-silica is 5-10wt%, and the mass fraction of benzotriazole or benzotriazole corrosion inhibitor microcapsules is 1-2wt%.

10. The method for preparing the fluorosilane-modified PVDF coating according to claim 9, characterized in that: In the step (1), the temperature of the supercritical CO2 is 50-65°C, 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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