Fluorocarbon resin super-hydrophobic coating and preparation method thereof

Abstract

The invention provides a method for preparing a fluorocarbon resin super-hydrophobic coating, and relates to the field of coatings. The preparation method comprises the following steps: adding nano silicon dioxide into a mixture of ethanol and water, stirring, and carrying out ultrasonic dispersion to obtain a dispersion liquid; dropwise adding a silane coupling agent into the dispersion liquid, ultrasonically dispersing uniformly, heating and stirring in a water bath, cooling to room temperature, centrifuging, washing a solid with absolute ethyl alcohol, and drying to obtain nano silicon dioxide powder; s2, mixing the nano silicon dioxide powder prepared in the step S1 with an N-methyl pyrrolidone solution of PVDF, and uniformly stirring to obtain coating slurry; and taking an absolute ethyl alcohol solution of epoxy resin as a primer, spraying the primer on the cement surface, curing, spraying the coating slurry, and curing to obtain the coating. The super-hydrophobic coating plays a role in protecting and strengthening the cement matrix, and the mechanical strength of the surface of the cement matrix is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a fluorocarbon resin super-hydrophobic coating and a preparation method thereof. BACKGROUND

[0002] Cement is a common civil engineering material, which has high coagulation strength, good plasticity, strong adaptability and low cost, and is widely used in roads, bridges and houses. However, the cement in the building is exposed to the natural environment and is eroded by rain for a long time. When the weather is cold in winter, the water remaining on the surface of the cement will freeze, which not only brings inconvenience to the user, but also causes damage to the cement structure, thereby affecting the durability of the building. In addition, dust often adheres to the surface of the building during use, which will affect the aesthetics of the building if not cleaned in time. SUMMARY

[0003] The present application aims to solve the problems of cement material surface icing in winter, erosion by rain, self-cleaning of surface dust and insufficient mechanical properties and wear resistance of ordinary hydrophobic coating.

[0004] The method for preparing the fluorocarbon resin super-hydrophobic coating of the present application is carried out according to the following steps:

[0005] S1 modified filler: nano-silica is added to a mixture of ethanol and water, stirred, ultrasonically dispersed to obtain a dispersion liquid; silane coupling agent is added dropwise to the dispersion liquid, ultrasonically dispersed uniformly, then heated in a water bath and stirred, cooled to room temperature, centrifuged, the solid is washed with anhydrous ethanol and dried to obtain nano-silica powder;

[0006] S2 coating slurry preparation: the nano-silica powder prepared in step S1 is mixed with N-methyl pyrrolidone solution of PVDF, stirred uniformly to obtain a coating slurry;

[0007] S3 coating preparation: anhydrous ethanol solution of epoxy resin is used as a primer, the primer is sprayed onto the surface of the cement, after curing, the coating slurry is sprayed, and then cured to obtain the coating.

[0008] In some embodiments of the present application, in the step S1, the silane coupling agent is KH570, and the mass ratio of the nano-silica to KH570 is 10:1.

[0009] In some embodiments of the present application, in the step S1, the sum of the mass of the nano-silica and the silane coupling agent: the sum of the mass of ethanol and water = 1:15; the volume ratio of ethanol to water is 5:1.

[0010] In some embodiments of the present application, in the step S1, the power of ultrasonic dispersion is 60 KHz, and the dispersion time is 10-15 min.

[0011] In some embodiments of the present application, in the step S1, the temperature of the water bath heating stirring is 70 DEG C, the heating time is 5h, and the stirring speed is 350r / min.

[0012] In some embodiments of the present application, in the step S1, the temperature of the drying is 80 DEG C, and the drying time is 8-10h.

[0013] In some embodiments of the present application, in the step S3, the primer comprises epoxy resin, diethylene triamine and anhydrous ethanol, and the mass ratio of the three is 1:0.1:2.

[0014] In some embodiments of the present application, in the step S3, the curing temperature of the primer is 20-25 DEG C, and the curing time is 2-3h; the curing temperature of the coating paste is 70-80 DEG C, and the curing time is 1-2h.

[0015] In another aspect, the present application provides a fluorocarbon resin super-hydrophobic coating prepared by the above method.

[0016] The super-hydrophobic coating prepared by the present application not only has ice resistance, weather resistance, corrosion resistance, but also has good physical and chemical stability and excellent mechanical properties. Moreover, the adaptability with different primers is studied, which effectively improves the combination of the coating and cement, and has a wide application prospect in civil engineering.

[0017] The present application has the following advantages:

[0018] The nano-SiO2 has good ultraviolet shielding property and stability, and the polyvinylidene fluoride has excellent mechanical property, high temperature resistance and chemical stability. In the present application, the nano-SiO2 is used as a filler, and the filler is modified by KH570, which solves the problems of icing in winter, erosion by rain, self-cleaning of surface dust and insufficient mechanical property and wear resistance of ordinary hydrophobic coating on the surface of cement material. The cement-based material can realize self-cleaning while having the functions of deicing and moisture-proof. The PVDF is used as a solvent, which has excellent mechanical property, so that the prepared coating has good hardness and strength. Moreover, the coating and the solvent have strong chemical stability, so that the prepared coating has good corrosion resistance. Meanwhile, the surface cement is reinforced, which can effectively prolong the service life of the cement. Moreover, the appropriate primer can effectively ensure the combination of the super-hydrophobic coating and the cement matrix, and further improve the durability of the cement. The super-hydrophobic coating has excellent mechanical property, weather resistance and chemical stability while having good hydrophobicity, which can protect the surface of the cement from erosion by water and damage by ice and frost. The spraying method can effectively make the coating uniformly adhere to the surface of the cement, which is fast and efficient, and the operation is also very simple. Therefore, the prepared super-hydrophobic coating has better durability and hydrophobicity compared with the traditional coating. Attached Figure Description

[0019] Figure 1 Figure (a) shows photographs of a specimen with a PVDF-12% SiO2 ratio and its contact angle, with a contact angle of 154°; and a specimen with a PVDF-9% SiO2 ratio and its contact angle of 155°.

[0020] Figure 2 These are photos of a tape peeling experiment.

[0021] Figure 3 Photographs showing the changes in contact angle during a sandpaper friction experiment;

[0022] Figure 4 Photographs of specimens used in pencil scratch experiments; the coating hardness grade is 6H.

[0023] Figure 5 Figure (a) shows the comparison photos of the specimen with a 4% PVDF-12% SiO2 ratio before and after soaking in H2SO4 solution with pH=1 for 48 hours; Figure (b) shows the comparison photos of the specimen with a 4% PVDF-12% SiO2 ratio before and after soaking in H2SO4 solution with pH=4 for 48 hours; Figure (c) shows the comparison photos of the specimen with a 4% PVDF-12% SiO2 ratio before and after soaking in NaOH solution with pH=11 for 48 hours; Figure (d) shows the comparison photos of the specimen with a 4% PVDF-12% SiO2 ratio before and after soaking in NaOH solution with pH=14 for 48 hours; Figure (e) shows the comparison photos of the specimen with a 4% PVDF-12% SiO2 ratio before and after soaking in 3.5% NaCl solution for 48 hours.

[0024] Figure 6 These are comparison photos before and after 10 hours of salt spray testing; the composition of specimen one is 4% PVDF-12% SiO2, and the composition of specimen two is 5% PVDF-9% SiO2.

[0025] Figure 7 The images are from a delayed icing experiment: (a) an image of bare copper icing; (b) an image of superhydrophobic coating with parameters of 4% PVDF-12% SiO2 icing; (c) an image of superhydrophobic coating with parameters of 5% PVDF-9% SiO2 icing; (d) an image of bare copper melting; (e) an image of superhydrophobic coating with parameters of 4% PVDF-12% SiO2 melting; and (f) an image of superhydrophobic coating with parameters of 5% PVDF-9% SiO2 icing. Detailed Implementation

[0026] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not indicated in the embodiments, conventional conditions or conditions suggested by manufacturers are adopted. If manufacturers of reagents or instruments are not indicated, all are conventional products that can be purchased in the market.

[0027] The embodiments of the present application provide a fluorocarbon resin super-hydrophobic coating and a preparation method thereof, which comprises the following steps:

[0028] S1 modified filler: nano-silica is added into a mixture of ethanol and water, stirred, ultrasonically dispersed to obtain a dispersion liquid; a silane coupling agent is added dropwise into the dispersion liquid, ultrasonically dispersed uniformly, then heated in a water bath and stirred, cooled to room temperature, centrifuged, washed with anhydrous ethanol, dried to obtain nano-silica powder; wherein the silane coupling agent is KH570, and the mass ratio of the nano-silica to the KH570 is 10:1. The sum of the mass of the nano-silica and the silane coupling agent: the sum of the mass of the ethanol and the water = 1:15; the volume ratio of the ethanol to the water is 5:1. The power of ultrasonic dispersion is 60 KHz, and the dispersion time is 10-15 min. The temperature of the water bath heating and stirring is 70℃, the heating time is 5 h, and the stirring speed is 350 r / min. The drying temperature is 80℃, and the drying time is 8-10 h.

[0029] S2 preparation of coating slurry: the nano-silica powder prepared in step S1 is mixed with an N-methyl pyrrolidone solution of PVDF, stirred uniformly to obtain a coating slurry;

[0030] S3 preparation of coating: an anhydrous ethanol solution of epoxy resin is used as a primer, the primer is sprayed onto the surface of cement, after curing, the coating slurry is sprayed, and after curing, the coating is obtained. The primer comprises epoxy resin, diethylene triamine and anhydrous ethanol, and the mass ratio of the three is 1:0.1:2. The curing temperature of the primer is 20-25℃, and the curing time is 2-3 h; the curing temperature of the coating slurry is 70-80℃, and the curing time is 1-2 h.

[0031] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to specific embodiments.

[0032] Embodiment 1

[0033] The present embodiment is a method for preparing a fluorocarbon resin super-hydrophobic coating, which is specifically carried out according to the following steps:

[0034] S1 modified filler:

[0035] A mixture solution of deionized water and absolute ethanol with a volume ratio of 5:1 was stirred uniformly and poured into a beaker, 3 g of nano-silica was added into the beaker, and after stirring and ultrasonic dispersion for 15 min, the nano-silica was uniformly dispersed in the mixed solution to obtain a dispersion liquid. Then 15 wt.% of KH570 (γ-methacryloxypropyltrimethoxysilane) was added dropwise into the nano-silica dispersion liquid, and ultrasonic dispersion (60 kHz) was performed for 10 min to make it uniformly dispersed. Then the beaker was placed in a water bath at 70°C and heated and stirred for 5 h at a speed of 350 r / min. After the heating was completed, the beaker was cooled to room temperature, and a centrifuge was used for centrifugation (10000 RPM, 1 h), and then the supernatant was poured out and then washed with absolute ethanol to remove unreacted KH570. The speed of the centrifuge was set to 10000 r / min, and finally the super-hydrophobic nano-silica powder was obtained after drying in an oven at 80°C for 8 h.

[0036] The mass ratio of the nano-SiO2 and KH570 is 10:1;

[0037] The mass ratio of the sum of the nano-SiO2 and KH570 to ethanol and deionized water is 1:15;

[0038] S2 coating slurry preparation: the modified filler prepared in step S1 was quickly stirred in a N-methyl pyrrolidone solution of PVDF for 10 min at a stirring speed of 500 rpm to form a uniformly dispersed coating slurry system. The concentration of PVDF was 1%-5%, and the concentration of SiO2 was 3%, 6%, 9%, 12%, and 15% respectively, and 25 groups of samples were obtained through cross test. Through contact angle test, sandpaper rubbing experiment, pencil scratching experiment, and adhesion experiment, two groups of samples with parameters of 4% PVDF-12% SiO2 and 5% PVDF-9% SiO2 were further selected. The prepared sample coating was uniform and the surface no longer peeled off.

[0039] S3 coating preparation: an absolute ethanol solution of epoxy resin was used as a primer (the mass ratio of epoxy resin, diethylene triamine, and absolute ethanol was 1:0.1:2), and the primer was first sprayed onto the surface of the cement, and after curing, the coating slurry was sprayed, and after curing, a hydrophobic coating was obtained. The curing temperature of the primer was 20°C, and the curing time was 2 h; the curing temperature of the coating slurry was 80°C, and the curing time was 1 h. The adhesion grade and hardness of the coating were analyzed, the contact angle was tested, and the corrosion immersion experiment was performed to determine the influence of the primer on the performance of the coating.

[0040] Example 2

[0041] The difference from example 1 is that the N-methylpyrrolidone solution in step S2 is replaced by hexamethylphosphoric triamide, and the remaining raw materials and preparation methods are the same as those of example 1. The coating sample prepared in this example is relatively uniform, but peeling occurs on the surface.

[0042] Example 3

[0043] The difference from example 1 is that the primer in step S3 is replaced by epoxy resin, diethylene triamine and anhydrous ethanol in a mass ratio of 10:1:20. The remaining raw materials and preparation methods are the same as those of example 1. The coating sample prepared is relatively uniform, but peeling occurs on the surface.

[0044] Example 4

[0045] The difference from example 1 is that the curing temperature of the primer in step S3 is room temperature (20℃), and the curing time is changed to 6h. The others are the same as example 1. The surface of the sample prepared no longer peels off, but the coating is uneven.

[0046] Example 5

[0047] The difference from example 1 is that the spraying in step S3 is replaced by dipping. The others are the same as example 1. The coating sample prepared is uneven and the surface no longer peels off.

[0048] In summary, the super-hydrophobic coating prepared in the example of the present application not only has ice resistance, weather resistance, corrosion resistance, but also has good physical and chemical stability and excellent mechanical properties. At the same time, because the adaptability with different primers is studied, the combination of the coating and cement is effectively improved, which has a wide application prospect in civil engineering.

[0049] The above-described embodiments are part of the embodiments of the present application, not all embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

Claims

1. A method of making a fluorocarbon resin superhydrophobic coating, characterized in that The method comprises the following steps: S1: modifying the filler, adding nano-silica into a mixture of ethanol and water, stirring, ultrasonic dispersion to obtain a dispersion, adding silane coupling agent dropwise into the dispersion, ultrasonic dispersion, water bath heating and stirring, cooling to room temperature, centrifugation, anhydrous ethanol washing of the solid, drying to obtain nano-silica powder; S2: preparing the coating slurry, mixing the nano-silica powder prepared in step S1 with N-methylpyrrolidone solution of PVDF, stirring to obtain the coating slurry; S3: preparing the coating, using anhydrous ethanol solution of epoxy resin as the primer, spraying the primer onto the surface of the cement, solidifying, then spraying the coating slurry, and solidifying to obtain the coating.

2. The method for preparing fluorocarbon resin superhydrophobic coating according to claim 1, characterized in that, In the step S1, the silane coupling agent is KH570, and the mass ratio of the nano-silica to KH570 is 10:

1.

3. The method for preparing a fluorocarbon resin superhydrophobic coating according to claim 1, characterized in that, In the step S1, the sum of the mass of the nano-silica and the silane coupling agent: the sum of the mass of ethanol and water = 1:15, and the volume ratio of ethanol to water is 5:

1.

4. The method of claim 1, wherein the fluorocarbon resin superhydrophobic coating is prepared by the steps of: In the step S1, the power of ultrasonic dispersion is 60 KHz, and the dispersion time is 10-15 min.

5. The method of claim 1, wherein in the step S1, the temperature of water bath heating and stirring is 70℃, the heating time is 5 h, and the stirring speed is 350 r / min.

6. The method of claim 1, wherein in the step S1, the drying temperature is 80℃, and the drying time is 8-10 h.

7. The method of claim 1, wherein in the step S3, the primer comprises epoxy resin, diethylene triamine and anhydrous ethanol, and the mass ratio of the three is 1:0.1:

2.

8. The method of claim 1, wherein in the step S3, the curing temperature of the primer is 20-25℃, and the curing time is 2-3 h; the curing temperature of the coating slurry is 70-80℃, and the curing time is 1-2 h.

9. A fluorocarbon resin superhydrophobic coating characterized by, The coating prepared by the method of any one of claims 1-8.

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