A hydrophobic corrosion protective coating and a method of making the same

Abstract

The application discloses a kind of hydrophobic anticorrosive coating and preparation method thereof, belong to anticorrosive coating preparation technical field.The above-mentioned method includes: step 1: preparation of nanometer silicon dioxide;Step 2: kaolin powder, acrylic resin, nanometer silicon dioxide are added to ethyl acetate, after ultrasonic dispersion, magnetic stirring is carried out at room temperature, and pre-solidification mixed solution is obtained;The mass ratio of the kaolin powder, acrylic resin, nanometer silicon dioxide is 1:0.66:0.05;Step 3: pre-solidification mixed solution is drop-coated on substrate, and solidification is carried out, to obtain hydrophobic anticorrosive coating.The application selects kaolin and acrylic resin to prepare film, and specific particle size kaolin can reduce the pore of film as far as possible, then the added modified nanometer silicon dioxide is further filled in the pore, so that the prepared coating has better hydrophobic anticorrosive effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anticorrosive coating preparation, in particular to a hydrophobic anticorrosive coating and a preparation method thereof. BACKGROUND

[0002] The adverse effects of metal corrosion on ecology and economy have driven the research on the development of anticorrosive coatings, and the engineering super-hydrophobic nano-structured coating is a promising application technology for self-cleaning and corrosion prevention. The working principle of the hydrophobic anticorrosive coating lies in the isolation of the metal substrate from liquid corrosion media such as water and the extension of the propagation path of the liquid corrosion media. However, the super-hydrophilic surface in air is generally super-gas-repellent; on the contrary, the super-hydrophobic surface in air is super-gas-attractive. Therefore, the hydrophobic anticorrosive coating will have higher gas-attractive performance than ordinary coatings during operation, making another corrosion medium O2 more easily contact with the metal substrate, and thus possibly accelerating the corrosion process. Therefore, it is necessary to explore the scientific problem of the relationship between the hydrophobicity of the coating surface and the corrosion resistance.

[0003] Common anticorrosive coatings mainly include epoxy resin coatings, polyurethane resin coatings, and acrylic resin coatings. Among them, the acrylic resin anticorrosive coating has good weather resistance, gloss retention, high gloss, and decoration, and also has good temperature resistance (can resist 160℃), fast drying speed, and can be cured normally at 0℃, once film forming thickness, and less construction passes. There are also related patents in the prior art to prepare super-hydrophobic acrylic resin, for example, CN102417773A discloses a super-hydrophobic acrylic resin coating, which is composed of nanoparticles, acrylic resin, mixed solvent, and heptadecafluorotrimethoxysilane. The coating prepared has a water droplet contact angle of 150-160°. CN111269628A discloses a super-hydrophobic anti-pollution flash coating capable of being applied by electricity and a preparation method thereof. The raw material composition of the coating comprises modified nano-silicon dioxide, modified low-surface-energy resin, dispersant, defoamer, leveling agent, and electrically chargeable solvent. The modified nano-silicon dioxide is made from the following raw materials by weight: trifluoropropylmethylcyclotrisiloxane, 1H, 1H, 2H, 2H-perfluorooctyltrichlorosilane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, trifluoromethyltrimethylsilane, nano-silicon dioxide powder, and electrically chargeable solvent. The coating prepared by the invention has super-hydrophobic, super-self-cleaning, and anti-pollution capabilities. However, neither of the above two patents discloses whether it has anticorrosive performance.

[0004] CN118995011A discloses a kind of high-temperature-resistant super-hydrophobic long-acting anticorrosive coating and its preparation method, surface modification is carried out on nanoparticles using γ-methacryloxypropyl trimethoxysilane, and modified nanoparticles are obtained;Surface modification is carried out on nanometer silicon dioxide using vinyl trimethoxysilane, and super-hydrophobic silicon dioxide is obtained;Modified nanoparticles, super-hydrophobic silicon dioxide and methyl methacrylate are polymerized, and then grafted onto phenolic epoxy resin through ring-opening reaction to obtain modified epoxy vinyl resin;Modified epoxy vinyl resin and curing agent are mixed uniformly, sprayed onto the surface of metal substrate, and high-temperature-resistant super-hydrophobic long-acting anticorrosive coating is obtained after curing.The invention not only improves the crosslinking degree, heat resistance, shielding property and toughness of epoxy vinyl resin, but also improves the hydrophobicity of the coating, so that the coating has long-acting anticorrosive property.However, the film-forming material of the anticorrosive coating is epoxy resin, and the anticorrosive property of acrylic resin as the film-forming material is not disclosed.

[0005] CN116410638A uses dodecafluoroheptyl propyl trimethoxysilane as a catalyst, and the silicon hydroxyl produced by hydrolysis of methacryloxypropyl trimethoxysilane reacts with the hydroxyl on the surface of nanometer silicon dioxide, and then further fluorination reaction occurs with perfluorooctyl ethyl trichlorosilane, introducing a large number of hydrophobic fluorinated groups and alkyl long chains on the surface of nanometer silicon dioxide to prepare modified silicon dioxide filler;Modified fluorinated silicon dioxide filler and talc powder of different mesh are added to acrylic resin to prepare a pressure-resistant, wear-resistant hydrophobic anticorrosive coating.However, its anticorrosive property needs to be further improved. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a kind of hydrophobic anticorrosive coating and its preparation method;The present application selects kaolin and acrylic resin to prepare a film, and the specific particle size of kaolin can reduce the porosity of the film as much as possible, and then the added modified nanometer silicon dioxide further fills the pores, so that the prepared coating has better anticorrosive effect.

[0007] To solve the above technical problems, the technical scheme of the present application is as follows:

[0008] In one aspect, the present application provides a method for preparing a hydrophobic anticorrosive coating, comprising:

[0009] Step 1: Preparation of nanometer silicon dioxide;

[0010] Step 2: Kaolin powder, acrylic resin and nanometer silicon dioxide are added to ethyl acetate, ultrasonic dispersion is carried out, and then magnetic stirring is carried out at room temperature to obtain a pre-cured mixed solution;The mass ratio of kaolin powder, acrylic resin and nanometer silicon dioxide is 1:0.66:0.05;

[0011] Step 3: drop the pre-cured mixture on the substrate, and cure to obtain the hydrophobic anticorrosive coating.

[0012] Further, in step 2, the particle size of the kaolin powder is 1-10 μm, preferably, the kaolin powder is a mixture of particle sizes of 1-4 μm and 5-8 μm at a mass ratio of 1:2.5.

[0013] Preferably, the molecular weight of the acrylic resin is 10000-50000. The volume ratio of ethyl acetate to the mass of the acrylic resin is 5 mL:1 g.

[0014] Further, in step 2, the ultrasonic dispersion is performed for 30-60 min, and the magnetic stirring is performed for 1-4 h.

[0015] In step 2, the substrate is a Q235 steel electrode sheet or a glass sheet; and the drop coating amount of the pre-cured mixture is 0.5-2 mL / cm 2 . The curing is normal temperature curing, and the time is 12-24 h.

[0016] Preferably, the preparation method of the nano-silica is as follows: a volume ratio of 1:1 of anhydrous ethanol solution and ammonia water is dispersed in a beaker; the above solution is placed in magnetic stirring for 0.5 h; then 2 ml of tetraethoxysilane (TEOS) is added dropwise into the continuously stirred mixed solution, and the stirring is continuously performed for 4 h; then the solution is centrifuged at 5000 r / min -1 for 30 min, the supernatant is removed, the solid is suction filtered, and the solid is washed with ethanol for 2-5 times to obtain nano-silica.

[0017] Alternatively, preferably, the preparation method of the nano-silica is as follows:

[0018] ① anhydrous ethanol solution and ammonia water are mixed, and then the above mixed solution is stirred and mixed uniformly to obtain a mixed solution;

[0019] The volume ratio of the ethanol solution to the ammonia water is 1:1; the volume fraction of ethanol in the ethanol solution is 90%, and the mass fraction of NH3·H2O in the ammonia water is 25%-28%;

[0020] ② a silane modifier is added to the above mixed solution, and the mixture is stirred uniformly;

[0021] The silane modifier is dimethyldiethoxysilane, vinyltrimethoxysilane and γ-aminopropyltriethoxysilane at a mass ratio of 1:1.5:2; and the volume ratio of the mass of the silane modifier to the volume of the mixed solution in ① is 0.5-0.8 g:100 mL;

[0022] III. Under stirring, tetraethoxysilane is added drop by drop into the mixed solution of II, and stirring is continued for 2-6 hours; the volume ratio of tetraethoxysilane to the mixed solution of I is 1:50-100;

[0023] IV. Then, fluorine-containing modifier is added and stirred uniformly; the fluorine-containing modifier is hexafluorobutyl methacrylate and 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane with a mass ratio of 1:0.8; the mass ratio of the fluorine-containing modifier to the silane modifier is 1:0.4-0.6;

[0024] V. Then, centrifugal separation is performed to obtain solid product, the solid product is washed with anhydrous ethanol for 2-5 times, and then dried and ground to obtain nano-silica.

[0025] In another aspect, the application also provides a hydrophobic corrosion-resistant coating prepared by the above method.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] In the application, the nano-silica is modified and cooperates with kaolin to be well dispersed in the acrylic resin with a specific molecular weight; the synergistic effect of the three can effectively fill the gaps on the surface of the coating, and then more corrosion medium is blocked outside the surface of the coating, which improves the barrier property and corrosion resistance of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 (a) is the IR graph of the purchased nano-silica nanoparticles, and (b) is the IR graph of the nano-silica prepared in Example 1 of the application;

[0029] Figure 2 (a)-(b) are the SEM graphs of the nano-silica prepared in Example 1 of the application, and (c)-(d) are the TEM graphs of the nano-silica prepared in Example 1 of the application;

[0030] Figure 3 (a) is the SEM graph of Comparative Example 1, (b) is the SEM graph of Example 1, (c) is the SEM graph of Comparative Example 2, (d) is the SEM graph of Comparative Example 3, (e) is the SEM graph of Comparative Example 4, (f) is the SEM graph of Comparative Example 5, and (g) is the SEM graph of Comparative Example 6, wherein the inserted picture is the contact angle picture of the coating to water;

[0031] Figure 4(a) is the impedance result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 1 day, (b) is the impedance result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 3 days, (c) is the impedance result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 7 days;

[0032] Figure 5 (a) is the impedance result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 1 day, (b) is the impedance result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 3 days, (c) is the impedance result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 7 days;

[0033] Figure 6 (a) is the Bode result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 1 day, (b) is the Bode result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 3 days, (c) is the Bode result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 7 days;

[0034] Figure 7 (a) is the Bode result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 1 day, (b) is the Bode result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 3 days, (c) is the Bode result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 7 days. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and advantages to be solved by the present application more clear, the following will be described in detail with reference to the drawings and specific examples.

[0036] In the present application, the materials and reagents used are commercially available if not otherwise specified. Among them, the volume fraction of ethanol in the ethanol solution is 90%, and the mass fraction of NH3·H2O in the ammonia water is 28%.

[0037] The present application provides a kind of hydrophobic anticorrosive coating and preparation method thereof, and specific implementation is as follows.

[0038] Example 1

[0039] A method for preparing a hydrophobic corrosion-resistant coating layer, comprising:

[0040] Step 1: Preparation of nano-silica:

[0041] Anhydrous ethanol (50 ml) and ammonia solution (50 ml) were dispersed in a 250 mL beaker. The above mixed solution was placed in magnetic stirring for 0.5 h, so that the solution did not appear to be layered. 2 ml of tetraethoxysilane (TEOS) was added dropwise to the continuously stirred mixed solution, and flocculation appeared in the solution, and the stirring was continued for 4 h so that the silica spherical particles were no longer produced. Centrifugation was performed using a 5000 r / min high-speed centrifuge (30 min), the supernatant was removed, the solid was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns), the residual anhydrous ethanol and ammonia water were removed, and ethanol was used for washing twice, to obtain self-made silica nanoparticles; -1

[0042] Step 2: 1.0 g of kaolin powder, 0.66 g of acrylic resin AR (Guangzhou Changhao Trading Co., Ltd. (formerly Guangzhou Xianghao Chemical Co., Ltd.) SGR-7120 (molecular weight 13000)), and 0.05 g of nano-silica were added to ethyl acetate, ultrasonically dispersed for 30 min, and then magnetically stirred for 4 h, and then magnetically stirred at room temperature to obtain a pre-solidification mixed solution; the kaolin powder was a mixture with a mass ratio of 1:2.5 and particle sizes of 1-4 μm and 5-8 μm, respectively;

[0043] Step 3: The pre-solidification mixed solution was drop-coated on a Q235 steel electrode sheet, and the drop-coating amount was 2 mL / cm 2 , and the coating layer was cured at room temperature for 24 h to obtain a hydrophobic corrosion-resistant coating layer, denoted as CK 1.0 SO 0.05 AR (x represents the content of kaolin, and y represents the content of modified silica).

[0044] To further illustrate the beneficial effects of the present application, the following comparative examples are constructed.

[0045] Comparative Example 1

[0046] In this comparative example, the amount of nano-silica was 0 g, and the other conditions were the same as in Example 1, and the coating was denoted as CK 1.0 SO0AR.

[0047] Comparative Example 2

[0048] In this comparative example, the amount of nano-silica was 0.10 g, and the other conditions were the same as in Example 1, and the coating was denoted as CK 1.0 SO 0.10 AR.

[0049] ​Comparative Example 3

[0050] In this comparative example, the amount of kaolin powder was 0.17 g, and the other conditions were the same as in Example 1, and the coating obtained was designated CK 1.0 SO 0.17 AR.

[0051] Comparative Example 4

[0052] In this comparative example, the amount of kaolin powder was 0.20 g, and the other conditions were the same as in Example 1, and the coating obtained was designated CK 1.0 SO 0.20 AR.

[0053] Comparative Example 5

[0054] In this comparative example, the amount of kaolin powder was 0.25 g, and the other conditions were the same as in Example 1, and the coating obtained was designated CK 1.0 SO 0.25 AR.

[0055] Comparative Example 6

[0056] In this comparative example, the amount of kaolin powder was 0.30 g, and the other conditions were the same as in Example 1, and the coating obtained was designated CK 1.0 SO 0.30 AR.

[0057] The coatings obtained in the above examples and comparative examples were tested for performance, and the results are as follows.

[0058] In order to observe the difference between the self-made silica nanoparticles and the purchased silica nanoparticles, and whether the self-made silica nanoparticles were successfully added to the coating, infrared testing was used to characterize the particles and the super-hydrophobic coating. Figure 1 Figures (a) and (b) are infrared scanning spectra of the purchased nano-silica nanoparticles and the self-made silica nanoparticles, respectively. It can be clearly observed from the figures that the self-made silica nanoparticles have Si-O bond vibration peaks at 468 cm -1 and 800 cm -1 , and a Si-O-Si bond vibration peak at 1101 cm-1, which are smaller than those of the purchased nano-silica nanoparticles, but a Si-OH bond vibration peak at 943 cm-1 appears, which is not present in the purchased nano-silica nanoparticles, which proves that the hydroxyl groups on the periphery of the self-made silica particles have obviously increased, and are more prone to substitution reactions, and are modified into hydrophobic particles.

[0059] The TEOS molecules undergo hydrolysis under the catalysis of ammonia hydroxide, converting the TEOS groups into Si-OH groups, and the adjacent Si-OH groups undergo polycondensation reactions, thereby inducing the self-assembly of the Si-OH-covered nano-silica particles. Figure 2The scanning electron microscope and the perspective electron microscope are used to generate the nanometer silica particle ball. By observing the morphology of the silica particle size, it is found that the generated nanometer silica particles are uniformly distributed, the particle size is about 450±50nm, and the average nanometer silica particle size is 470nm.

[0060] In order to study the surface characteristics of different hydrophobic coatings and the wettability of the hydrophobic coating, scanning electron microscope and hydrophobic angle test are used to characterize the coating. The results are shown in Figure 3 (a), (b), (c), (d), (e), (f) and (g) are respectively 0g, 0.05g, 0.10g, 0.17g, 0.20g, 0.25g and 0.30g. From Figure 3 It can be seen that (a), (b), (c), (d), (e), (f) and (g) respectively show the scanning electron microscope images with hydrophobic angle of 125°, 130°, 135°, 140°, 145°, 150° and 156°. From Figure 3 (a), (b), it can be seen that when the hydrophobic angle increases from 125° to 135°, with the increase of the coating particles, the particles will block the pores in the coating, and it is speculated that the ability of the coating to block the water molecules and oxygen molecules in the air will also increase. From Figure 3 (c), (d), when the contact angle of the coating is greater than 135°, the particles gradually accumulate to form an accumulation structure with the gradual increase of the particles, which increases the probability of the substrate contacting with the water molecules and oxygen molecules in the air, and when the contact angle reaches 140°, the accumulation structure forms the most macropores, the probability of the substrate contacting with the water molecules and oxygen molecules in the air is the largest, and the corrosion resistance of the coating should be the worst; Figure 3 (e), (f), (g), when the contact angle increases from 145° to 156°, with the increase of the hydrophobic angle of the coating, the number of pores formed by the accumulation structure is almost the same, and the size of the pores shows a slightly decreasing trend, it is speculated that the corrosion resistance of the coating is almost the same, showing a slightly rising trend. In order to verify this result, electrochemical workstation is used to represent the corrosion resistance of each coating, so as to represent the change trend of the probability of the substrate contacting with the water molecules and oxygen molecules in the air.

[0061] In order to measure the corrosion resistance of different hydrophobic coatings, electrochemical test is carried out on Q235 steel electrode sheet coated with different hydrophobic coatings, and the impedance test results are shown in Figures 4-5 .

[0062] Figure 4(a) is the impedance result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 1 day, (b) is the impedance result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 3 days, (c) is the impedance result of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 when immersed in 3.5wt% NaCl solution for 7 days, and the specific data are shown in Table 1.

[0063] Table 1

[0064]

[0065] The hydrophobic angle of the hydrophobic coating of Comparative Example 1, Example 1, Comparative Example 2, Comparative Example 3 is 125°-140°, and from Table 1, when immersed in 3.5wt% NaCl solution for 1 day, CK 1.0 SO 0.05 The AR coating has the largest radius of the impedance circle, and the impedance radius is about 3.80×10 6 Ω·cm 2 , which is almost one to two orders of magnitude larger than the impedance radius of other hydrophobic coatings, CK 1.0 SO0AR coating has an impedance radius of 3.30×10 5 Ω·cm 2 , which is almost the same as the impedance radius of CK 1.0 SO 0.10 AR coating 2.88×10 5 Ω·cm 2 , which is more than one order of magnitude larger than the impedance radius of CK 1.0 SO 0.17 AR coating 2.36×10 4 Ω·cm 2 . This indicates that for the coating with a hydrophobic angle of 125°-140°, when immersed in 3.5wt% NaCl solution for 1 day, the corrosion resistance shows a trend of first increasing and then decreasing, and the coating with a hydrophobic angle of 130° has the best corrosion resistance. When immersed in 3.5wt% NaCl solution for 3 days, CK 1.0 SO 0.05 The AR coating has the largest radius of the impedance circle, and the impedance radius is 2.86×10 6 Ω·cm 2 , CK 1.0 SO0AR coating has an impedance radius of 2.41×10 5 Ω·cm 2 , which is greater than the impedance radius of CK 1.0 SO 0.10 AR coating 1.98×10 5 Ω·cm 2, are greater than CK 1.0 SO 0.17 AR coating has an impedance radius of 1.63 x 10 4 Ω·cm 2 It is proved that the anticorrosion ability of the coating with a hydrophobic angle of 125°-140° is consistent with the rule when immersed in 3.5wt% NaCl solution for 1 day and 3 days. After being immersed in 3.5wt% NaCl solution for 7 days, CK 1.0 SO 0.05 AR coating has an impedance radius of 1.42 x 10 6 Ω·cm 2 , which is one to two orders of magnitude higher than other coatings. CK 1.0 SO0AR coating has an impedance radius of 1.76 x 10 5 Ω·cm 2 , which is greater than CK 1.0 SO 0.10 AR coating has an impedance radius of 1.51 x 10 5 Ω·cm 2 , which is higher than CK 1.0 SO 0.17 AR coating has an impedance radius of 1.17 x 10 4 Ω·cm 2 , which is one order of magnitude. It is proved that the anticorrosion ability of the coating with a hydrophobic angle of 125°-140° is consistent with the rule when immersed in 3.5wt% NaCl solution for 1 day and 3 days. After being immersed in 3.5wt% NaCl solution for 7 days, CK

[0066] Figure 5 Impedance results of the hydrophobic coatings of (a) Comparative Example 4, (f) Comparative Example 5 and (g) Comparative Example 6 when immersed in 3.5wt% NaCl solution for 1 day, (b) Comparative Example 4, (f) Comparative Example 5 and (g) Comparative Example 6 when immersed in 3.5wt% NaCl solution for 3 days, (c) Comparative Example 4, (f) Comparative Example 5 and (g) Comparative Example 6 when immersed in 3.5wt% NaCl solution for 7 days, see Table 2 for specific data.

[0067] Table 2

[0068]

[0069] For the coating with a hydrophobic angle of 145°-156°, CK 1.0 SO 0.30 AR coating has the largest impedance ring with an impedance radius of 1.03 x 10 5 Ω·cm 2 , which is greater than CK1.0 SO 0.25 AR coating has the largest impedance radius of 6.54 x 10 4 Ω·cm 2 , which is greater than that of CK 1.0 SO 0.20 AR coating has the largest impedance radius of 5.81 x 10 4 Ω·cm 2 . This shows that for the coating with a hydrophobic angle of 145°-156°, the corrosion resistance tends to increase when immersed in 3.5wt% NaCl solution for 1 day, but the corrosion resistance is weaker than that of the coating with a hydrophobic angle of 130°. When immersed in 3.5wt% NaCl solution for 3 days, CK 1.0 SO 0.30 AR coating has the largest impedance radius of 8.81 x 10 4 Ω·cm 2 , which is greater than that of CK 1.0 SO 0.25 AR coating has the largest impedance radius of 6.16 x 10 4 Ω·cm 2 , which is greater than that of CK 1.0 SO 0.20 AR coating has the largest impedance radius of 5.38 x 10 4 Ω·cm 2 , which is consistent with the corrosion rule of 1-day immersion. When immersed in 3.5wt% NaCl solution for 7 days, CK 1.0 SO 0.30 AR coating has the largest impedance radius of 7.57 x 10 4 Ω·cm 2 , which is greater than that of CK 1.0 SO 0.25 AR coating has the largest impedance radius of 4.89 x 10 4 Ω·cm 2 , which is greater than that of CK 1.0 SO 0.20 AR coating has the largest impedance radius of 2.55 x 10 4 Ω·cm 2 , which is consistent with the rules of 1-day and 3-day immersion.

[0070] The results of Bode test for different hydrophobic coatings are shown in Figure 6 , Figure 7 . Figure 6Fig. 1 is a graph showing the Bode results of the hydrophobic coatings of Comparative Example 1, Example 1, Comparative Example 2, and Comparative Example 3 when immersed in a 3.5 wt% NaCl solution for 1 day, Fig. 2 is a graph showing the Bode results of the hydrophobic coatings of Comparative Example 1, Example 1, Comparative Example 2, and Comparative Example 3 when immersed in a 3.5 wt% NaCl solution for 3 days, and Fig. 3 is a graph showing the Bode results of the hydrophobic coatings of Comparative Example 1, Example 1, Comparative Example 2, and Comparative Example 3 when immersed in a 3.5 wt% NaCl solution for 7 days.

[0071] For the coatings with a hydrophobic angle of 125°-140°, the corrosion resistance increased first and then decreased when immersed in a 3.5 wt% NaCl solution for 1 day, and the coating with a hydrophobic angle of 130° had the best corrosion resistance, which was consistent with the impedance graph. 1.0 SO 0.05 The AR coating had the largest Bode modulus at f = 0.1 Hz, about 3.75 x 10 6 Ω·cm 2 , which was one to two orders of magnitude larger than the other hydrophobic coatings, and the CK 1.0 SO 5 The modulus value of the AR coating was 3.20 x 10 2 Ω·cm 1.0 , which was larger than the CK 0.10 SO 5 The modulus value of the AR coating was 2.70 x 10 2， Ω·cm 1.0 , which was larger than the CK 0.10 SO 4 The modulus value of the AR coating was 2.20 x 10 2 Ω·cm 1.0 This indicated that for the coatings with a hydrophobic angle of 125°-140°, the corrosion resistance increased first and then decreased when immersed in a 3.5 wt% NaCl solution for 1 day, and the coating with a hydrophobic angle of 130° had the best corrosion resistance, which was consistent with the impedance graph. 0.05 SO 6 The AR coating had the largest modulus value, about 2.70 x 10 2 Ω·cm 1.0 , which was larger than the CK 5 SO 2 The modulus value of the AR coating was 2.40 x 10 1.0 Ω·cm 0.10 , which was larger than the CK 5 SO 2 The modulus value of the AR coating was 1.85 x 10 1.0 Ω·cm 0.17 , which was almost the same as the CK 4 SO 2The corrosion rule is consistent with that of 1 day immersion. When immersed in 3.5wt% NaCl solution for 7 days, CK 1.0 SO 0.05 The AR coating has the maximum modulus value of 1.40x10 6 Ω·cm 2 The corrosion rule is consistent with that of 1 day immersion. When immersed in 3.5wt% NaCl solution for 7 days, CK 1.0 SO0The modulus value of the AR coating is 1.75x10 5 Ω·cm 2 The corrosion rule is consistent with that of 1 day immersion. When immersed in 3.5wt% NaCl solution for 7 days, CK 1.0 SO 0.10 The modulus value of the AR coating is 1.45x10 5 Ω·cm 2 The corrosion rule is consistent with that of 1 day immersion. When immersed in 3.5wt% NaCl solution for 7 days, CK 1.0 SO 0.17 The modulus value of the AR coating is 1.14x10 4 Ω·cm 2 The corrosion rule is consistent with that of 1 day and 3 days immersion, and is consistent with the EIS corrosion rule.

[0072] Figure 7 (a) is the Bode result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 1 day, (b) is the Bode result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 3 days, (c) is the Bode result of the hydrophobic coating of Comparative Example 4, Comparative Example 5 and Comparative Example 6 when immersed in 3.5wt% NaCl solution for 7 days;

[0073] For the coating with a hydrophobic angle of 145°-156°, when immersed in 3.5wt% NaCl solution for 1 day, CK 1.0 SO 0.30 The AR coating has the maximum Bode modulus value at f=0.1Hz, about 1.30x10 5 Ω·cm 2 The corrosion rule is consistent with that of 1 day immersion. When immersed in 3.5wt% NaCl solution for 7 days, CK 1.0 SO 0.25 The modulus value of the AR coating is 8.80x10 4 Ω·cm 2 The corrosion rule is consistent with that of 1 day and 3 days immersion, and is consistent with the EIS corrosion rule. 1.0 SO 0.20 The modulus value of the AR coating is 8.02x104Ω·cm2. This indicates that for the coating with a hydrophobic angle of 145°-156°, when immersed in 3.5wt% NaCl solution for 1 day, the corrosion resistance shows an upward trend, which is consistent with the impedance diagram rule. When immersed in 3.5wt% NaCl solution for 3 days, CK 1.0 SO 0.30 The AR coating has the maximum Bode modulus value, about 1.17x10 5Ω·cm 2 greater than CK 1.0 SO 0.25 The modulus value of the AR coating is 7.80 x 10 4 Ω·cm 2 greater than CK 1.0 SO 0.20 The modulus value of the AR coating is 7.42 x 10 4 Ω·cm 2 consistent with the corrosion rule of soaking for 1 day. When soaked in 3.5 wt% NaCl solution for 7 days, CK 1.0 SO 0.30 The AR coating has the largest Bode modulus value, about 1.01 x 10 5 Ω·cm 2 greater than CK 1.0 SO 0.25 The modulus value of the AR coating is 6.05 x 10 4 Ω·cm 2 greater than CK 1.0 SO 0.20 The modulus value of the AR coating is 3.82 x 10 4 Ω·cm 2 consistent with the corrosion rule of soaking for 1 day, 3 days and impedance.

[0074] To further illustrate the beneficial effects of the present application, the inventors also designed the following comparative examples.

[0075] Comparative Example 7

[0076] In this comparative example, the amount of acrylic resin is 0.5 g, and the other conditions are the same as in Example 1.

[0077] Comparative Example 8

[0078] In this comparative example, the amount of acrylic resin is 1 g, and the other conditions are the same as in Example 1.

[0079] Comparative Example 9

[0080] In this comparative example, the amount of kaolin is 0.5 g, and the other conditions are the same as in Example 1.

[0081] Comparative Example 10

[0082] In this comparative example, the amount of kaolin is 1.2 g, and the other conditions are the same as in Example 1.

[0083] Comparative Example 11

[0084] In this comparative example, the particle size of kaolin is 500-800 nm, and the other conditions are the same as in Example 1.

[0085] Comparative Example 12

[0086] In the present comparative example, the particle size of the kaolin is 1-4 μm, and the other conditions are the same as in Example 1.

[0087] Comparative Example 13

[0088] In the present comparative example, the particle size of the kaolin is 5-8 μm, and the other conditions are the same as in Example 1.

[0089] Comparative Example 14

[0090] In the present comparative example, the kaolin powder is a mixture of particle sizes of 1-4 μm and 5-8 μm at a mass ratio of 1:1, and the other conditions are the same as in Example 1.

[0091] Comparative Example 15

[0092] In the present comparative example, the kaolin powder is a mixture of particle sizes of 1-4 μm and 5-8 μm at a mass ratio of 1:3, and the other conditions are the same as in Example 1.

[0093] The performance of the coating prepared in the above comparative examples and the hydrophobic coating prepared in Example 1 is compared, and the results are shown in Tables 3-4.

[0094] Table 3

[0095]

[0096] As shown in Table 3, adjusting the amount of acrylic resin and kaolin can cause the contact angle to change, and adjusting the particle size and proportion of kaolin can also cause the contact angle to change.

[0097] The impedance results of the coating prepared in Comparative Examples 7-15 when immersed in a 3.5 wt% NaCl solution for 1 day, 3 days and 7 days are shown in Table 4.

[0098] Table 4

[0099]

[0100] As shown in Table 4, reducing or increasing the amount of acrylic ester and kaolin or adjusting the particle size of kaolin can reduce the impedance radius of the corrosion-resistant coating by two orders of magnitude. This may be due to the fact that the increase in the contact angle causes the coating to absorb air and form an air layer, the coating has more pores, increasing the probability of contact between the corrosion medium and the substrate, thereby reducing the corrosion resistance of the coating, and reducing the impedance radius of the corrosion-resistant coating by two orders of magnitude.

[0101] The preparation method of nano-silicon dioxide is also optimized, and the specific implementation is as follows.

[0102] Example 2

[0103] A method for preparing a hydrophobic corrosion-resistant coating comprises:

[0104] Step 1: Preparation of nano-silica:

[0105] ① Anhydrous ethanol (50 ml) and ammonia solution (50 ml) were dispersed in a 250 mL beaker. The above mixture was placed in magnetic stirring for 0.5 h, so that the solution did not appear to be stratified;

[0106] ② 0.6 g of silane modifier was added to the above mixture, and stirred uniformly; wherein the silane modifier was dimethyldiethoxysilane, vinyltrimethoxysilane and γ-aminopropyl triethoxysilane in a mass ratio of 1:1.5:2;

[0107] ③ 2 mL of tetraethoxysilane was added dropwise to the mixture of ② under stirring, and the stirring was continued for 4 h;

[0108] ④ Then 1.0 g of fluorine-containing modifier was added and stirred uniformly; the fluorine-containing modifier was hexafluorobutyl methacrylate and 1H, 1H, 2H, 2H- perfluorodecyl triethoxysilane in a mass ratio of 1:0.8;

[0109] ⑤ Then centrifuged with a 5000 r / min high-speed centrifuge (30 min), the supernatant was removed, the solid component was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns), and the solid product was obtained. The solid product was washed with anhydrous ethanol for 3 times, then dried in a 60 degree Celsius oven, ground through a 5000 mesh sieve, and nano-silica was obtained; -1

[0110] Step 2: 1.0 g of kaolin powder, 0.66 g of acrylic resin AR (Guangzhou Changhao Trading Co., Ltd. (formerly Guangzhou Xianghao Chemical Co., Ltd.) SGR-7120 (molecular weight 13000)), and 0.05 g of nano-silica were added to ethyl acetate, ultrasonically dispersed for 30 min, then magnetically stirred for 4 h, and then magnetically stirred at room temperature to obtain a pre-solidification mixture; the kaolin powder was a mixture of particle sizes of 1-4 μm and 5-8 μm in a mass ratio of 1:2.5;

[0111] Step 3: The pre-solidification mixture was drop-coated on a Q235 steel electrode sheet, the drop-coating amount was 2 mL / cm 2 , and the temperature was cured at room temperature for 24 h to obtain a hydrophobic corrosion-resistant coating.

[0112] Example 3

[0113] In this example, the acrylic resin was Japan Mitsubishi BR-113 (molecular weight 30000), and the other conditions were the same as in Example 2.

[0114] Example 4

[0115] ​In this example, the acrylic resin is Mitsubishi BR-116 (molecular weight 45000) from Japan, and the other conditions are the same as in Example 2.

[0116] Example 5

[0117] A method for preparing a hydrophobic anticorrosive coating layer, comprising:

[0118] Step 1: Preparation of modified nano-silica:

[0119] ① Anhydrous ethanol (50 ml) and ammonia solution (50 ml) were dispersed in a 250 mL beaker. The above mixture was placed in magnetic stirring for 0.5 h to prevent the solution from separating;

[0120] ② 0.5 g of silane modifier was added to the above mixture and stirred uniformly; the silane modifier was dimethyldiethoxysilane, vinyltrimethoxysilane and γ-aminopropyltriethoxysilane in a mass ratio of 1:1.5:2;

[0121] ③ 1 mL of tetraethoxysilane was added dropwise to the mixture of ② under stirring, and the stirring was continued for 2 h; the volume ratio of tetraethoxysilane to the mixture in ① was 1:50-100;

[0122] ④ Then 1.0 g of fluorine-containing modifier was added and stirred uniformly; the fluorine-containing modifier was hexafluorobutyl methacrylate and 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane in a mass ratio of 1:0.8;

[0123] ⑤ Then centrifuged at 5000 r / min for 30 min using a high-speed centrifuge, removed the supernatant, and the solid component was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns), to obtain a solid product. The solid product was washed with anhydrous ethanol for 3 times, then dried in an oven at 60 degrees Celsius, and ground through a 5000 mesh sieve to obtain modified nano-silica; -1

[0124] Step 2: 1.0 g of kaolin powder, 0.66 g of acrylic resin AR (BR-113 (molecular weight 30000) from Guangzhou Changhao Trading Co., Ltd. (formerly Guangzhou Xianghao Chemical Co., Ltd.)), and 0.05 g of modified nano-silica were added to ethyl acetate and ultrasonically dispersed for 40 min, then magnetically stirred for 2 h, and then magnetically stirred at room temperature to obtain a pre-solidification mixture; the kaolin powder was a mixture of particle sizes of 1-4 μm and 5-8 μm in a mass ratio of 1:2.5;

[0125] Step 3: The pre-solidification mixture was drop-coated on a Q235 steel electrode sheet at a drop-coating amount of 1 mL / cm 2 , and cured at room temperature for 18 h to obtain a hydrophobic anticorrosive coating layer. ​

[0126] Example 6

[0127] A method for preparing a hydrophobic anticorrosive coating layer, comprising:

[0128] Step 1: Preparation of modified nano-silica:

[0129] ① Anhydrous ethanol (50 ml) and ammonia solution (50 ml) were dispersed in a 250 mL beaker. The above mixture solution was placed in magnetic stirring for 0.5 h to prevent the solution from stratifying;

[0130] ② 0.8 g of silane modifier was added to the above mixture solution and stirred uniformly; wherein the silane modifier was dimethyldiethoxysilane, vinyltrimethoxysilane and γ-aminopropyltriethoxysilane in a mass ratio of 1:1.5:2;

[0131] ③ 2 mL of tetraethoxysilane was added dropwise to the mixture solution of ② under stirring, and the stirring was continued for 6 h; the volume ratio of tetraethoxysilane to the mixture solution in ① was 1:50-100;

[0132] ④ Then 1.6 g of fluorine-containing modifier was added and stirred uniformly; the fluorine-containing modifier was hexafluorobutyl methacrylate and 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane in a mass ratio of 1:0.8;

[0133] ⑤ Then centrifuged at 5000 r / min for 30 min using a high-speed centrifuge, removed the supernatant, and the solid component was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns) to obtain a solid product. The solid product was washed with anhydrous ethanol for 5 times, then dried in an oven at 60 degrees Celsius, and ground through a 5000 mesh sieve to obtain modified nano-silica; -1

[0134] Step 2: 1.0 g of kaolin powder, 0.66 g of acrylic resin AR (Guangzhou Changhao Trading Co., Ltd. (formerly Guangzhou Xianghao Chemical Co., Ltd.) BR-113 (molecular weight 30000)), and 0.05 g of modified nano-silica were added to ethyl acetate and ultrasonically dispersed for 60 min, magnetically stirred for 1 h, and then magnetically stirred at room temperature to obtain a pre-cured mixed solution; the kaolin powder was a mixture of particle sizes of 1-4 μm and 5-8 μm in a mass ratio of 1:2.5;

[0135] Step 3: The pre-cured mixed solution was drop-coated on a Q235 steel electrode sheet at a drop-coating amount of 0.5 mL / cm 2 , and cured at room temperature for 12 h to obtain a hydrophobic anticorrosive coating layer.

[0136] The hydrophobic anticorrosive coating layer prepared in the above example was tested for hydrophobicity and corrosion resistance, and the results are shown in Tables 5-6.​

[0137] Table 5

[0138] Sample No. Contact Angle / ° Example 2 156.23 Example 3 153.14 Example 4 151.42 Example 5 148.68 Example 6 144.73

[0139] From Table 5, it can be seen that the modification of nano-silica can effectively improve its contact angle with water.

[0140] The impedance results of the coating prepared in Example 2-6 when immersed in 3.5wt% NaCl solution for 1 day, 3 days and 7 days are shown in Table 6.

[0141] Table 6

[0142]

[0143] From Table 6, it can be seen that the modification of nano-silica can improve its corrosion resistance on the original basis, and the impedance radius is improved by 1-2 orders of magnitude. It is proved that the method of the present application successfully prepares a corrosion-resistant coating with good hydrophobicity and corrosion resistance.

[0144] To further illustrate the influence of the preparation of nano-silica on the coating, the following comparative examples are constructed.

[0145] Comparative Example 16

[0146] In this comparative example, the acrylic resin is Japan Mitsubishi BR-106 (molecular weight 60000), and the other conditions are the same as in Example 2.

[0147] Comparative Example 17

[0148] In this comparative example, the silane modifier is vinyl trimethoxysilane and γ-aminopropyl triethoxysilane with a mass ratio of 2.5:2, and the other conditions are the same as in Example 2.

[0149] Comparative Example 18

[0150] In this comparative example, the silane modifier is dimethyldiethoxysilane and γ-aminopropyl triethoxysilane with a mass ratio of 2.5:2, and the other conditions are the same as in Example 2.

[0151] Comparative Example 19

[0152] In this comparative example, the silane modifier is vinyl trimethoxysilane and γ-aminopropyl triethoxysilane with a mass ratio of 1.5:3, and the other conditions are the same as in Example 2.

[0153] Comparative Example 20

[0154] In this comparative example, the silane modifier is dimethyldiethoxysilane and γ-aminopropyl triethoxysilane with a mass ratio of 1:3.5, and the other conditions are the same as in Example 2.

[0155] Comparative Example 21

[0156] In this comparative example, the silane modifier is dimethyldiethoxysilane, vinyltrimethoxysilane and γ-aminopropyltriethoxysilane at a mass ratio of 1:1:1, and the other conditions are the same as in Example 2.

[0157] Comparative Example 22

[0158] In this comparative example, the silane modifier is dimethyldiethoxysilane, vinyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane at a mass ratio of 1:1:1, and the other conditions are the same as in Example 2.

[0159] Comparative Example 23

[0160] In this comparative example, the fluorine-containing modifier is hexafluorobutyl methacrylate, and the other conditions are the same as in Example 2.

[0161] Comparative Example 24

[0162] In this comparative example, the fluorine-containing modifier is 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and the other conditions are the same as in Example 2.

[0163] Comparative Example 25

[0164] In this comparative example, the fluorine-containing modifier is hexafluorobutyl methacrylate and 1H,1H,2H,2H-perfluorodecyltriethoxysilane at a mass ratio of 1:1, and the other conditions are the same as in Example 2.

[0165] Comparative Example 26

[0166] In this comparative example, the fluorine-containing modifier is hexafluorobutyl methacrylate and 1H,1H,2H,2H-perfluorodecyltriethoxysilane at a mass ratio of 0.8:1, and the other conditions are the same as in Example 2.

[0167] Comparative Example 27

[0168] In this comparative example, the fluorine-containing modifier is hexafluorobutyl methacrylate and 1H,1H,2H,2H-perfluorodecyltriethoxysilane at a mass ratio of 1:0.5, and the other conditions are the same as in Example 2.

[0169] Comparative Example 28

[0170] In this comparative example, the fluorine-containing modifier is dodecafluoroheptyl methacrylate and 1H,1H,2H,2H-perfluorodecyltriethoxysilane at a mass ratio of 1:0.8, and the other conditions are the same as in Example 2.

[0171] Comparative Example 29

[0172] A method for preparing a hydrophobic anticorrosive coating, comprising:

[0173] Step 1: Preparation and modification of nano-silica

[0174] Anhydrous ethanol (50 ml) and ammonia solution (50 ml) were dispersed in a 250 mL beaker. The above mixture solution was placed in magnetic stirring for 0.5 h, so that the solution did not appear to be stratified. 2 ml of tetraethoxysilane (TEOS) was added dropwise to the continuously stirred mixture solution, and flocculation appeared in the solution, and the stirring was continued for 4 h, so that the silica spherical particles were no longer produced. Centrifugation was performed using a 5000 r / min high-speed centrifuge (30 min), the supernatant was removed, the solid was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns), the residual anhydrous ethanol and ammonia water were removed, and ethanol was used for washing twice, to obtain self-made silica nanoparticles; -1 Centrifugation was performed using a 5000 r / min high-speed centrifuge (30 min), the supernatant was removed, the solid was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns), the residual anhydrous ethanol and ammonia water were removed, and ethanol was used for washing twice, to obtain self-made silica nanoparticles;

[0175] 1 g of nano-SiO2 particles was weighed and added to a flask containing 50 ml of ethanol and 1 ml of ammonia water, and it was placed in an ultrasonic cleaner for ultrasonic dispersion for 30 min, so that the SiO2 was uniformly dispersed, to obtain a nano-SiO2 / ethanol suspension. Subsequently, 2 ml of octadecyltrimethoxysilane was rapidly added dropwise under stirring, and the reaction was carried out for 4 h. After the completion of the modification reaction, the obtained liquid was separated by centrifugation at a speed of 5000 r for 30 min, and then washed twice with ethanol. The obtained solid was placed in a 60°C oven for drying for 12 h, and then fully ground, to obtain modified nano-SiO2 powder.

[0176] Step 2-3 was the same as in Example 2, to obtain an anticorrosive coating.

[0177] Comparative Example 30

[0178] A method for preparing a hydrophobic anticorrosive coating, comprising:

[0179] Step 1: Preparation and modification of nano-silica

[0180] Anhydrous ethanol (50 ml) and ammonia solution (50 ml) were dispersed in a 250 mL beaker. The above mixture solution was placed in magnetic stirring for 0.5 h, so that the solution did not appear to be stratified. 2 ml of tetraethoxysilane (TEOS) was added dropwise to the continuously stirred mixture solution, and flocculation appeared in the solution, and the stirring was continued for 4 h, so that the silica spherical particles were no longer produced. Centrifugation was performed using a 5000 r / min high-speed centrifuge (30 min), the supernatant was removed, the solid was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns), the residual anhydrous ethanol and ammonia water were removed, and ethanol was used for washing twice, to obtain self-made silica nanoparticles; -1 Centrifugation was performed using a 5000 r / min high-speed centrifuge (30 min), the supernatant was removed, the solid was suction filtered (the filter membrane was a PVC membrane with a pore size of 0.22 microns), the residual anhydrous ethanol and ammonia water were removed, and ethanol was used for washing twice, to obtain self-made silica nanoparticles;

[0181] Weigh 1 g of nano-SiO2 particles, add to a flask containing 50 ml of ethanol and add 1 ml of ammonia water, place in an ultrasonic cleaner and ultrasonically disperse for 30 min to make the SiO2 uniformly dispersed, to obtain a nano-SiO2 / ethanol suspension. Subsequently, under stirring conditions, rapidly add 2 ml of dimethyldiethoxysilane, vinyltrimethoxysilane and γ-aminopropyltriethoxysilane in a mass ratio of 1:1.5:2, then react for 4 h. After the modification reaction is complete, the obtained liquid is separated by centrifugation at a speed of 5000 r for 30 min, then washed twice with ethanol, and the obtained solid is placed in a 60°C oven to dry for 12 h, then ground thoroughly to obtain the modified nano-SiO2 powder.

[0182] Step 2-3 is the same as in Example 2 to obtain an anticorrosive coating.

[0183] The properties of the coating prepared in the above comparative examples and the hydrophobic coating prepared in Example 2 are compared, and the results are shown in Tables 7-10.

[0184] Table 7

[0185]

[0186] As can be seen from Table 7, adjusting the molecular weight of the acrylic resin, the amount of silane modifier or fluorine-containing modifier has little effect on the hydrophobic properties of the prepared anticorrosive coating.

[0187] The impedance results of the coatings prepared in Comparative Examples 16-30 after immersion in a 3.5 wt% NaCl solution for 1 day are shown in Table 8.

[0188] Table 8

[0189] Sample No. Rs (Ω-cm 2 )]]> [C(Ω -1 • cm -2 • sn)] [Rp(Ω·cm 2 )]]> Comparative Example 16 1.39 x 10 4 ]]> 4.19 x 10 -9 ]] 3.64 x 10 6 ]] Comparative Example 17 1.45 x 10 4 ]]> 6.59 x 10 -9 ]] 2.82 x 10 6 ]] Comparative Example 18 1.24 x 10 4 ]] 4.38 x 10 -9 ]] 3.46 x 10 6 ]] Comparative Example 19 1.71 x 10 4 ]]> 7.19 x 10 -9 ]] 2.58 x 10 6 ]]> Comparative Example 20 1.79 x 10 4 ]] 7.63 x 10 -9 ]]> 2.34 x 10 6 ]]> Comparative Example 21 1.63 x 10 4 ]]> 1.01 x 10 -9 ]]> 5.63 x 10 6 ]]> Comparative Example 22 1.26 x 10 4 ]]> 8.13 x 10 -9 ]] 2.18 x 10 6 <!-- 14 -->]]> Comparative Example 23 1.96 x 10 4 ]] 8.53 x 10 -9 ]] 1.83 x 10 6 ]]> Comparative Example 24 1.52 x 10 4 ]]> 9.87 x 10 -10 ]] 5.84 x 10 6 ]] Comparative Example 25 1.31 x 10 4 ]]> 1.45 x 10 -9 ]]> 4.64 x 10 6 ]]> Comparative Example 26 1.89 x 10 4 ]]> 1.05 x 10 -9 ]]> 5.21 x 10 6 ]] Comparative Example 27 1.15 x 10 4 ]]> 6.38 x 10 -9 ]] 2.94 x 10 6 ]] Comparative Example 28 1.46 x 10 4 ]]> 5.73 x 10 -9 ]] 3.12 x 10 6 ]]> Comparative Example 29 1.85 x 10 4 ]]> 7.32 x 10 -9 ]] 3.14 x 10 6 ]]> Comparative Example 30 1.67 x 10 4 ]] 8.14 x 10 -9 ]] 2.33 x 10 6 ]]>

[0190] The impedance results of the coatings prepared in Comparative Examples 16-30 after immersion in a 3.5 wt% NaCl solution for 3 days are shown in Table 9.

[0191] Table 9

[0192] Sample No. Rs (Ω-cm 2 )]]> [C(Ω -1 • cm -2 • sn)] [Rp(Ω·cm 2 )]]> Comparative Example 16 1.31 x 10 4 ]]> 4.83 x 10 -8 ]]> 7.52 x 10 5 ]]> Comparative Example 17 1.25 x 10 4 ]]> 6.73 x 10 -8 ]] 6.51 x 10 5 ]]> Comparative Example 18 1.64 x 10 4 ]]> 4.96 x 10 -8 ]] 7.28 x 10 5 ]]> Comparative Example 19 1.81 x 10 4 ]]> 7.34 x 10 -8 ]] 6.23 x 10 5 ]]> Comparative Example 20 1.59 x 10 4 ]]> 7.84 x 10 -8 ]] 6.05 x 10 5 ]] Comparative Example 21 1.23 x 10 4 ]]> 2.46 x 10 -8 ]] 8.75 x 10 5 ]] Comparative Example 22 1.46 x 10 4 ]]> 8.47 x 10 -8 ]]> 5.97 x 10 5 ]]> Comparative Example 23 1.66 x 10 4 ]]> 8.96 x 10- 8 ]] 5.73 x 10 5 ]] Comparative Example 24 1.42 x 10 4 ]]> 2.17 x 10 -8 ]] 8.78 x 10 5 ]] Comparative Example 25 1.61 x 10 4 ]] 3.45 x 10 -8 ]] 8.32 x 10 5 ]] Comparative Example 26 1.19 x 10 4 ]] 2.64 x 10 -8 ]] 8.73 x 10 5 ]] Comparative Example 27 1.05 x 10 4 ]]> 6.54 x 10 -8 ]] 6.62 x 10 5 ]] Comparative Example 28 1.02 x 10 4 ]] 7.12 x 10 -8 ]] 6.88 x 10 5 ]] Comparative Example 29 1.62 x 10 4 ]] 9.38 x 10 -8 ]] 7.92 x 10 5 ]] Comparative Example 30 1.59 x 10 4 ]] 9.16 x 10 -8 ]] 7.18 x 10 5 ]]

[0193] The impedance results of the coatings prepared in Comparative Examples 16-30 after immersion in a 3.5 wt% NaCl solution for 7 days are shown in Table 10.

[0194] Table 10

[0195] Sample No. Rs (Ω-cm 2 )]]> [C(Ω -1 • cm -2 • sn)] [Rp(Ω·cm 2 )]]> Comparative Example 16 1.24 x 10 4 ]]> 7.46 x 10 -7 ]] 5.05 x 10 5 ]] Comparative Example 17 1.17 x 10 4 ]] 9.86 x 10 -7 ]] 3.63 x 10 5 ]] Comparative Example 18 1.23 x 10 4 ]]> 7.96 x 10 -7 ]] 4.95 x 10 5 ]] Comparative Example 19 1.32 x 10 4 ]] 9.36 x 10 -7 ]] 2.89 x 10 5 ]]> Comparative Example 20 1.27 x 10 4 ]] 9.84 x 10 -7 ]] 2.63 x 10 5 ]] Comparative Example 21 1.15 x 10 4 ]]> 5.56 x 10 -7 ]]> 5.51 x 10 5 ]]> Comparative Example 22 1.63 x 10 4 ]]> 1.07 x 10 -7 ]] 2.17 x 10 5 ]] Comparative Example 23 1.59 x 10 4 ]]> 1.26 x 10 -7 ]]> 1.24 x 10 5 ]]> Comparative Example 24 1.29 x 10 4 ]] 5.46 x 10 -7 ]] 5.53 x 10 5 ]] Comparative Example 25 1.38 x 10 4 ]]> 6.35 x 10 -7 ]] 5.32 x 10 5 <!-- 15 -->]]> Comparative Example 26 1.72 x 10 4 ]]> 5.64 x 10 -7 ]] 5.45 x 10 5 ]]> Comparative Example 27 1.56 x 10 4 ]]> 9.54 x 10 -7 ]] 3.89 x 10 5 ]] Comparative Example 28 1.23 x 10 4 ]]> 8.62 x 10 -7 ]] 2.88 x 10 5 ]] Comparative Example 29 1.38 x 10 4 ]] 8.15 x 10 -7 ]] 6.14 x 10 5 ]]> Comparative Example 30 1.25 x 10 4 ]]> 9.20 x 10 -7 ]] 5.97 x 10 5 ]]

[0196] As shown in Tables 8-10, when the molecular weight of the acrylic resin is large (Comparative Example 16), the impedance radius of the corrosion-resistant coating prepared is reduced by 1-2 orders of magnitude compared with Example 2, which is probably due to the fact that the voids and micro-cracks between the macromolecular acrylic resins are more, thus increasing the probability of corrosion substances contacting the substrate, and thus reducing the impedance radius of the coating.

[0197] The components and proportions of the silane modifier and the fluorine-containing modifier were adjusted (Comparative Examples 17-28), and the inventors found that the impedance radius of the corrosion-resistant coating prepared was reduced by 1-2 orders of magnitude compared with Example 2, which is probably due to the fact that different silane modifiers and fluorine-containing modifiers have different abilities to modify silica, and different components and proportions bring different effects to the modified silica, and the addition of the modifier can change the effect of the modified silica, thus greatly reducing the corrosion resistance.

[0198] On the basis of the modification of the nanosilica in Example 2, the inventors also adjusted the content of the acrylic resin, the content and particle size of the kaolin, and found that the impedance radius of the corrosion-resistant coating prepared was reduced by 2-4 orders of magnitude compared with Example 2, which proved that the corrosion resistance was greatly reduced.

[0199] The inventors detected the corrosion of the prepared hydrophobic corrosion-resistant coating in a simulated seawater environment to evaluate its corrosion resistance. The bare Q235 steel electrode sheet, the coatings prepared in Examples 1-6 and Comparative Examples 1-30 were immersed in 50 ml of 3.5wt% NaCl at room temperature and atmospheric pressure for accelerated corrosion test, and the changes in surface morphology were recorded. The inventors found that in the initial stage of 1 day of immersion, the surface of the bare electrode changed more obviously and a passivation film appeared, and it can be seen that the coatings of the examples and the comparative examples had a certain corrosion resistance to the substrate. However, after 1 week of immersion, the edges of Comparative Examples 1-15 had already appeared water bubbles, and the exposed parts appeared cracks and rust spots, and as the immersion time increased, the rust stains gradually spread to the center, and even after 2 weeks, the coating of Comparative Example 1-15 peeled off from the substrate, which meant that the substrate lost the protective layer and thus produced yellow porous Fe2O3 corrosion products. After 2 weeks of immersion, the edges of Examples 1 and Comparative Examples 16-30 also had slight water bubbles, and after 1 month of immersion, Examples 1 and Comparative Examples 16-30 had cracks and rust spots on the exposed parts, and some of them also peeled off; while the coating samples prepared in Examples 2-6 still performed very stably after 1 month of immersion, and no obvious rust spots and peeling occurred. This phenomenon is consistent with the electrochemical test results, which is attributed to the fact that the modified nanosilica can be well dispersed in the acrylic resin of a specific molecular weight in cooperation with the kaolin of a specific particle size, and the synergistic effect of the three can block more corrosion media outside the coating surface, which improves the barrier property and corrosion resistance of the coating.

[0200] The application also regulates the amount of kaolin and acrylic resin and the particle size of kaolin on the basis of modification of nanosilica, and it is found that the prepared coating has a certain corrosion resistance, but the impedance radius is reduced by 2-3 orders of magnitude compared with example 2, proving that the corrosion resistance is poor.

[0201] In summary, the application selects kaolin and acrylic resin to prepare a film, and the kaolin with a specific particle size can reduce the pores of the film as much as possible, and then the added modified nanosilica further fills the pores, so that the prepared coating has better hydrophobic corrosion resistance.

[0202] The above is the preferred embodiment of the application, and for those skilled in the art, some improvements and refinements without departing from the principles of the application should be considered within the protection scope of the application.

Claims

1. A process for the preparation of a hydrophobic corrosion protective coating, characterized in that, The application relates to a method for preparing a hydrophobic anticorrosive coating. Step 1: preparation of nano-silica; Step 2: adding kaolin powder, acrylic resin and nano-silica into ethyl acetate, ultrasonic dispersion, magnetic stirring at room temperature to obtain a pre-solidification mixed solution; the mass ratio of the kaolin powder, the acrylic resin and the nano-silica is 1:0.66:0.05; the kaolin powder is a mixture of particles with diameters of 1-4 mu m and 5-8 mu m at a mass ratio of 1:2.5; the molecular weight of the acrylic resin is 10000-50000; Step 3: drop coating the pre-solidification mixed solution on a substrate, solidification to obtain a hydrophobic anticorrosive coating.

2. The method for preparing a hydrophobic corrosion protective coating according to claim 1, characterized in that, The volume ratio of the ethyl acetate to the mass of the acrylic resin is 5:

1.

3. The method for preparing a hydrophobic corrosion protective coating according to claim 2, characterized in that, In step 2, the ultrasonic dispersion lasts for 30-60 min, and the magnetic stirring lasts for 1-4 h.

4. The method for preparing a hydrophobic corrosion protective coating according to claim 3, characterized in that, In step 3, the substrate is a Q235 steel electrode sheet or a glass sheet; the pre-solidification mixed solution drop coating amount is 0.5-2 mL / cm 2 .

5. The method for preparing a hydrophobic corrosion protective coating according to claim 4, characterized in that, In step 3, the solidification is normal temperature solidification, and the time is 12-24 h.

6. The method of claim 1, wherein the hydrophobic corrosion protective coating is prepared by, The preparation method of the nano-silica is as follows: a volume ratio of 1:1 anhydrous ethanol solution and ammonia water is dispersed in a beaker; the above solution is placed in magnetic stirring for 0.5 h; then 2 ml of tetraethoxysilane is added dropwise into the continuously stirred mixed solution, and the stirring is continued for 4 h; then 5000 r / min -1 centrifugation for 30 min, removal of supernatant, suction filtration of solid, and washing with ethanol for 2-5 times to obtain nano-silica.

7. The method of claim 1, wherein the hydrophobic corrosion protective coating is prepared by, The preparation method of the nano-silica is as follows: ① mixing anhydrous ethanol solution and ammonia water, stirring to obtain a mixed solution; The volume ratio of the ethanol solution to the ammonia water is 1:1; the volume fraction of ethanol in the ethanol solution is 90%, and the mass fraction of NH3·H2O in the ammonia water is 25%-28%; ② adding a silane modifier into the mixed solution, stirring to be uniform; The silane modifier is dimethyldiethoxysilane, vinyltrimethoxysilane and gamma-aminopropyltriethoxysilane at a mass ratio of 1:1.5:2; the volume ratio of the mass of the silane modifier to the mixed solution in ① is 0.5-0.8 g:100 mL; ③ under stirring, adding tetraethoxysilane drop by drop into the mixed solution in ②, and continuously stirring for 2-6 h; the volume ratio of the tetraethoxysilane to the mixed solution in ① is 1:50-100; ④ then adding a fluorine-containing modifier, stirring to be uniform; the fluorine-containing modifier is hexafluorobutyl methacrylate and 1H,1H,2H,2H-perfluorodecyltriethoxysilane at a mass ratio of 1:0.8; the mass ratio of the fluorine-containing modifier to the silane modifier is 1:0.4-0.6; ⑤ then centrifugal separation, washing the solid product with anhydrous ethanol for 2-5 times, then drying, grinding and sieving to obtain nano-silica.

8. The anticorrosive coating prepared by the method in any one of claims 1-7.

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