CN108774447B - Preparation method of carbon-silver microsphere/epoxy resin super-hydrophobic coating - Google Patents

Abstract

The invention belongs to the technical field of preparation of super-hydrophobic materials, and particularly relates to a preparation method of a carbon-silver microsphere/epoxy resin super-hydrophobic coating. The method comprises the steps of preparation of flower-shaped carbon-silver microspheres, low surface energy modification, combination of super-hydrophobic powder and a substrate and the like. The finishing angle of various substrates coated with the super-hydrophobic powder to water is more than 150 degrees, and the rolling angle is less than 10 degrees. Moreover, the combined super-hydrophobic substrate has strong abrasion resistance, self-cleaning property, stain resistance, high temperature resistance and chemical stability. Meanwhile, the surface of the composite material can be repaired by screening, spraying or dip coating again even if the surface is damaged forcibly. The preparation method disclosed by the invention is simple in preparation process, easy in raw material obtaining, non-toxic, environment-friendly, low in cost, strong in stability, suitable for large-area preparation and application, and suitable for the fields of industrial pipeline transportation with extremely severe working environment, the preparation of an oil-water separation metal net and the like.

Description

A kind of preparation method of carbon-silver microsphere/epoxy resin superhydrophobic coating

technical field

The invention belongs to the technical field of preparation of super-hydrophobic coatings, in particular to a preparation method of carbon-silver microspheres/epoxy resin super-hydrophobic coatings, which can be prepared with strong wear resistance, self-cleaning, anti-fouling and chemical stability Sexual superhydrophobic coating.

Background technique

Superhydrophobic phenomena exist widely in nature, such as the surface of lotus leaves, butterfly wings, and water strider legs. A superhydrophobic surface generally refers to a surface with an end angle of the material surface to water greater than 150° and a rolling angle less than 10°. Superhydrophobic surfaces have many unique and excellent properties: hydrophobicity, self-cleaning, anti-corrosion, anti-icing, anti-fog and other properties, which make them have great application prospects in many fields.

The superhydrophobic powder has better preservation, transportation and selectivity, and can be combined with various daily necessities or instruments through different methods. It can act on the surface of automobiles, airplanes, spacecraft, and high-rise buildings. When water falls on the surface, it can be quickly drained away, and a large amount of dust on the surface can be taken away, reducing cleaning times, reducing cleaning costs and avoiding high-altitude operations. On the other hand, because this powder is black and has high thermal stability, this powder can be coated on panels such as solar energy, which can absorb a lot of heat absorption, and can also protect the surface from acid rain, etc. It can also be quickly drained to prevent rain, fog and dew from freezing on the surface in winter and affect its work.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of carbon-silver microsphere/epoxy resin superhydrophobic coating, and to provide a simple, convenient, universal, and large-area preparation method of superhydrophobic coating. Superhydrophobicity has problems such as high production cost, weak mechanical strength, strong substrate dependence, and single preparation method. The superhydrophobic powder samples with three-dimensional hierarchical structure can be directly sieved onto various substrates with double-sided tape or epoxy adhesive. The modified surface has very stable hydrophobicity, the end angle to water is greater than 150°, the rolling angle is less than 10°, and has strong mechanical properties, chemical properties, thermal stability, self-cleaning and anti-fouling properties.

In order to realize the above-mentioned purpose of the invention, the present invention adopts the following technical solutions to be realized:

1. A method for preparing a carbon-silver microsphere/epoxy resin superhydrophobic coating, the steps of which are as follows:

Preparation of flower-shaped carbon-silver microspheres: the silver-containing compound is added to a mixed solution of water and ethanol, stirred to form a transparent solution, then ammonia water is added dropwise to the transparent solution to adjust the pH, and then an aqueous solution of dopamine is added dropwise, and magnetic stirring , after the reaction is completed, the dopamine/silver polymer is formed by suction filtration and continuous washing with ethanol and deionized water, followed by freeze-drying; finally, it is calcined in a muffle furnace and washed with ethanol to obtain flower-shaped carbon- silver microspheres;

B low surface energy modification: disperse the flower-shaped carbon-silver microspheres prepared in step A in a n-hexane mixed hexane solution containing a fluorine modifier, stir magnetically, and then filter, wash with n-hexane, and dry to obtain a modified superhydrophobic powder;

Preparation of C superhydrophobic coating surface: First, dissolve epoxy resin and curing agent into N, N-dimethylformamide, then add polyvinylidene fluoride-hexafluoropropylene copolymer particles, and stir vigorously to obtain a mixed solution , soak the cleaned substrate in the mixed solution for 5-10 min, take it out and dry it at room temperature for 3-5 min, then evenly sprinkle the superhydrophobic powder prepared in step B on the surface of the substrate, bake it Once dry, a superhydrophobic coating can be formed.

Preferably, the silver-containing compound in step A is silver nitrate. The silver ions in silver nitrate can well chelate with the phthalophene groups in dopamine to affect the surface morphology of carbon particles and increase the surface area.

Preferably, the concentration that described step A silver nitrate is added to the mixed solution of water and ethanol is 0.06～0.08 mol/L, and the volume ratio of ethanol and water in the mixed solution of described step A water and ethanol is 1/3～1 /2.

Because ethanol and water can be completely fused, it can prevent to a certain extent that when ammonia water is added dropwise, hydroxide ions react with silver ions in silver nitrate to form precipitates.

Preferably, the concentration that the described step A silver nitrate is added to the mixed solution of water and ethanol is 0.06～0.08 mol/L, and the volume ratio of ethanol and water in the mixed solution of described step A water and ethanol is 1:2-3 . An appropriate concentration of dopamine aqueous solution can ensure that the silver ions in the silver nitrate are completely chelated with the phthalodifen group in the dopamine, and prevent the formation of carbon/silver microspheres with a relatively smooth surface due to insufficient silver nitrate concentration.

Preferably, in the step A, the ammonia water is adjusted to pH 8-9, the magnetic stirring temperature in the step A is 15-30° C., and the stirring time is 10-12 h. A slightly alkaline environment with a pH of 8~9 is more conducive to the chelation reaction, and prolonging the reaction time as much as possible can make the reaction more thorough and generate more carbon/silver microspheres.

Preferably, in the step A, the dopamine/silver polymer is formed by suction filtration and continuous washing with ethanol and deionized water, followed by freezing in a refrigerator of -20~25°C for 20~24 h to make it completely dry; finally, 450 After calcining in a sealed muffle furnace at ~500 °C for 2~3 h, and washing with ethanol, flower-like carbon-silver microspheres can be obtained. Low-temperature freeze-drying can control the surface morphology, which is beneficial to the formation of flower-like structures; high-temperature calcination at 450-500 °C can convert dopamine/silver polymers without certain morphology into flower-like carbon-silver microspheres.

Preferably, the fluorine-containing modifier in the step B is perfluorooctyltriethoxysilane, and the volume concentration of the perfluorooctyltriethoxysilane in the n-hexane mixed solution is 0.5% to 1%. Appropriately increasing the concentration of perfluorooctyltriethoxysilane can shorten the modification time, and can also make the fluorine-containing modifier self-assemble on the surface of carbon/silver microspheres, and bond with the surface more firmly.

Preferably, in step C, the volume ratio of epoxy resin, curing agent, and N,N-dimethylformamide is 3:1:40~50, and the mass concentration of the polyvinylidene fluoride-hexafluoropropylene copolymer is : 0.02~0.03 g/mL. Because epoxy resin is a hydrophilic substance, and polyvinylidene fluoride-hexafluoropropylene copolymer is a hydrophobic substance, adding a certain concentration of polyvinylidene fluoride-hexafluoropropylene copolymer here can increase the hydrophobicity of the adhesive. , but also can increase the bond strength of the coating.

Preferably, the substrate comprises glass or cotton cloth or stainless steel mesh or paper or aluminum sheet or others. The choice of different substrate materials here is to prove that this coating can be universally applied to various substrate materials, and it has good universality.

Preferably, in the step C, the superhydrophobic powder prepared in the step B can also be directly bonded to the surface of the substrate through double-sided tape or sprayed liquid glue, and the superhydrophobic coating can be formed after drying. To demonstrate the strong suitability of this coating here, it can be applied to different substrates by a simple bonding method.

Beneficial effects of the present invention:

1. The process is simple, the raw materials are readily available, and the cost is low;

2. The prepared flower-like carbon-silver microspheres have a particle size of about 1 μm and a flower-like hierarchical structure. After being modified by a fluorine-containing repair agent, they have stable superhydrophobicity;

3. This superhydrophobic powder is not affected by the surface morphology and performance of the substrate, and has strong universality. The superhydrophobic powder has substrate independence and is suitable for various substrates;

4. The surface of the prepared material has super-hydrophobicity, self-cleaning and anti-fouling properties, the end angle of water is greater than 150°, and the rolling angle is less than 10°;

5. High mechanical strength, strong adhesion and long service life. The coating was placed on 400# sandpaper under 200g gravity. Even after 200 friction cycles (10cm forward and 10cm back as one cycle), the surface still had strong superhydrophobicity. In addition, the coating was placed in the natural environment (wind, sun and rain) for 6 months, and the coating still had strong superhydrophobicity.

6. Has strong chemical stability and thermal stability.

Description of drawings:

Fig. 1: Scanning electron microscope image of flower-shaped superhydrophobic carbon-silver microsphere particles obtained in Example 1;

Figure 2: End angle and rolling angle of the flower-shaped superhydrophobic carbon-silver microsphere coating obtained in Example 1;

Fig. 3: Hydrophobic diagram after friction of the flower-shaped superhydrophobic carbon-silver microsphere coating obtained in Example 2;

Fig. 4: hydrophobicity change diagram after acid-base immersion of the flower-shaped superhydrophobic carbon-silver microsphere coating obtained in Example 2;

Figure 5: Thermal decomposition curve of the flower-shaped superhydrophobic carbon-silver microsphere coating obtained in Example 3;

Figure 6: Oil-water separation diagram of the flower-like superhydrophobic carbon-silver microsphere coating obtained in Example 4.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with examples.

Example 1

(1) Preparation of flower-shaped carbon-silver microsphere particles:

Dissolve 1.25 g of silver nitrate in a mixed solution of 80 mL of water and 40 mL of ethanol, and then add a certain amount of ammonia water (0.02 M) dropwise to it under magnetic stirring to adjust the pH to about 8.5. 50 mL of 20 mg/mL dopamine hydrochloride solution was added dropwise to the system, and the reaction was continued for 12 h. After the reaction, suction-filtered and placed in a -25 ℃ refrigerator for 24 h. Then, it was calcined at 450 °C for 3 h in a sealed muffle furnace to obtain a black powdery product, thus completing the preparation of flower-like carbon-silver microspheres.

(2) Low surface energy modification:

The carbon-silver microsphere powder product prepared in step A was added to 50 ml of 0.5% perfluorooctyltriethoxysilane n-hexane solution, and stirred to disperse. After 20 min of reaction, a modified white powder was obtained by centrifugation, washing with n-hexane and drying. Finally, the modified powder samples were dried in an oven at 80 °C for 2 h to obtain superhydrophobic powders. The scanning electron microscope picture of the obtained modified carbon-silver microsphere particles is shown in FIG. 1 .

(3) Coating preparation:

Dissolve 4 mL of epoxy resin and curing agent (3:1 by volume) in 40 mL of N,N-dimethylformamide, and add 1 g of polyvinylidene fluoride-hexafluoropropylene copolymer with continuous stirring , so that it is completely dissolved; after soaking the cleaned substrate in the above solution for 10 minutes, take it out and dry it in the air for 3 minutes, then sprinkle the above powder evenly on the surface, and after drying, you can get different super Hydrophobic sample. Pictures of the water end angle and roll angle of the resulting coating are shown in Figure 2. It can be seen from Figure 1 that a large number of carbon-silver microspheres with a diameter of 1-5 μm are distributed on the surface of the coating, and the nano-scale wrinkles on the surface of the microspheres are distributed on the surface of the microspheres like petals. The contact angle of the coating is 157±0.75° and the rolling angle is 4.5±0.5° as measured by Fig. 2 .

Example 2:

(1) Preparation of flower-like carbon-silver microsphere particles:

Dissolve 1.25 g of silver nitrate in a mixed solution of 80 mL of water and 40 mL of ethanol, and then add a certain amount of ammonia water (0.02 M) dropwise to it under magnetic stirring to adjust the pH to about 8.5. 50 mL of 20 mg/mL dopamine hydrochloride solution was added dropwise to the system, and the reaction was continued for 12 h. After the reaction, suction-filtered and placed in a -25 ℃ refrigerator for 24 h. Then, it was calcined at 450 °C for 3 h in a sealed muffle furnace to obtain a black powdery product, thus completing the preparation of flower-like carbon-silver microspheres.

(2) Low surface energy modification:

The carbon-silver microsphere powder product prepared in step A was added to 50 ml of 0.5% perfluorooctyltriethoxysilane n-hexane solution, and stirred to disperse. After 20 min of reaction, a modified white powder was obtained by centrifugation, washing with n-hexane and drying. Finally, the modified powder samples were dried in an oven at 80 °C for 2 h to obtain superhydrophobic powders.

(3) Coating preparation:

Dissolve 4 mL of epoxy resin and curing agent (3:1 by volume) in 40 mL of N,N-dimethylformamide, and add 1 g of polyvinylidene fluoride-hexafluoropropylene copolymer with continuous stirring , so that it is completely dissolved; after soaking the cleaned substrate in the above solution for 10 minutes, take it out and dry it in the air for 3 minutes, then sprinkle the above powder evenly on the surface, and after drying, different superhydrophobic properties can be obtained. sample. The prepared poor post-hydrophobic coating has strong mechanical stability and chemical stability. Figure 3 shows the glass coating rubbed for 50 cycles (with a 400-grit sandpaper with a load of 200g and rubbed back and forth for 10cm for one round) and 200 rounds of hydrophobicity. photo. Figure 4 is a graph showing the change of the end angle of the glass layer immersed in an acid-base salt solution at different times. It can be seen from Figure 3 that even after 200 cycles of friction, the droplets can still maintain a spherical shape on the coating surface, and the contact angle is still greater than 150°. It can be seen from Fig. 4 that even if the coating is immersed in 2 M hydrochloric acid solution for 120 min, the contact angle is still greater than 150°; for alkaline solution and salt solution, the surface contact angle varies by 6° when the immersion time exceeds 180 min. This indicates that the coating has good chemical stability.

Example 3:

(1) Preparation of flower-like carbon-silver microsphere particles:

Dissolve 1.25 g of silver nitrate in a mixed solution of 80 mL of water and 40 mL of ethanol, and then add a certain amount of ammonia water (0.02 M) dropwise to it under magnetic stirring to adjust the pH to about 8.5. 50 mL of 20 mg/mL dopamine hydrochloride solution was added dropwise to the system, and the reaction was continued for 12 h. After the reaction, suction-filtered and placed in a -25 ℃ refrigerator for 24 h. Then, it was calcined at 450 °C for 3 h in a sealed muffle furnace to obtain a black powdery product, thus completing the preparation of flower-like carbon-silver microspheres.

(2) Low surface energy modification:

The carbon-silver microsphere powder product prepared in step A was added to 50 ml of a n-hexane solution of perfluorooctyltriethoxysilane with a concentration of 0.5%, and stirred to disperse. After 20 min of reaction, a modified white powder was obtained by centrifugation, washing with n-hexane and drying. Finally, the modified powder samples were dried in an oven at 80 °C for 2 h to obtain superhydrophobic powders.

(3) Coating preparation:

A double-sided tape was pasted on a clean glass substrate, and then the prepared superhydrophobic powder was sprinkled on the double-sided tape and dried at room temperature to obtain a superhydrophobic glass surface. The surface has high thermal stability. Figure 5 is its thermal decomposition curve. It can be seen from Figure 5 that the thermal decomposition temperature of the coating ranges from 200 to 582 °C. Even if the temperature is as high as 403 °C, the thermal decomposition amount is only 25%, which shows that the coating has strong thermal stability.

Example 4:

(1) Preparation of flower-like carbon-silver microsphere particles:

Dissolve 1.25 g of silver nitrate in a mixed solution of 80 mL of water and 40 mL of ethanol, and then add a certain amount of ammonia water (0.02 M) dropwise to it under magnetic stirring to adjust the pH to about 8.5. 50 mL of 20 mg/mL dopamine hydrochloride solution was added dropwise to the system, and the reaction was continued for 12 h. After the reaction, suction-filtered and placed in a -25 ℃ refrigerator for 24 h. Then, it was calcined at 450 °C for 3 h in a sealed muffle furnace to obtain a black powdery product, thus completing the preparation of flower-like carbon-silver microspheres.

(2) Low surface energy modification:

The carbon-silver microsphere powder product prepared in step A was added to 50 ml of 0.5% perfluorooctyltriethoxysilane n-hexane solution, and stirred to disperse. After 20 min of reaction, a modified white powder was obtained by centrifugation, washing with n-hexane and drying. Finally, the modified powder samples were dried in an oven at 80 °C for 2 h to obtain superhydrophobic powders.

(3) Preparation of superhydrophobic coatings:

A layer of liquid glue is sprayed on the clean PU sponge base material, and then the prepared superhydrophobic powder can be sprinkled on the glue-sprayed sponge base and dried at room temperature to obtain a superhydrophobic sponge. Due to the strong lipophilic and superhydrophobic properties of the sponge, it can be used for oil-water separation. It can be seen from Figure 6 that when the superhydrophobic sponge is inserted into water, it can be found that the sponge is not wetted; but when the sponge touches the dyed heavy oil (dichloroethane) at the bottom of the beaker, the oil is immediately completely absorbed by the sponge, indicating that the superhydrophobic sponge is completely absorbed by the sponge. The hydrophobic sponge has a good oil-water separation effect.

The above content is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be considered that the specific embodiments of the present invention are limited to this. Several simple substitutions can also be made, which should be regarded as belonging to the scope of patent protection of the present invention.

Claims (9)

1. A preparation method of a carbon-silver microsphere/epoxy resin super-hydrophobic coating comprises the following steps:

a, preparing flower-shaped carbon-silver microspheres: adding a silver-containing compound into a mixed solution of water and ethanol, stirring to form a transparent solution, then dropwise adding ammonia water into the transparent solution to adjust the pH value, then dropwise adding a dopamine aqueous solution, magnetically stirring, after the reaction is finished, carrying out suction filtration, continuously washing with ethanol and deionized water, and then carrying out freeze drying to form a dopamine/silver polymer; finally calcining in a muffle furnace, and cleaning with ethanol to obtain flower-shaped carbon-silver microspheres;

b, low surface energy modification: b, dispersing the flower-like carbon-silver microspheres prepared in the step A in a normal hexane solution containing a fluorine modifier, magnetically stirring, and then filtering, washing with normal hexane, and drying to obtain modified super-hydrophobic powder;

c, preparing the surface of the super-hydrophobic coating: firstly, dissolving epoxy resin and a curing agent into N, N-dimethylformamide, then adding polyvinylidene fluoride-hexafluoropropylene copolymer particles, violently stirring to obtain a mixed solution, soaking a cleaned substrate into the mixed solution for 5-10 min, taking out, drying at room temperature for 3-5 min, then uniformly scattering the super-hydrophobic powder prepared in the step B on the surface of the substrate, and drying to form a super-hydrophobic coating;

and C, epoxy resin, a curing agent and N, N-dimethylformamide in a volume ratio of 3: 1: 40-50, wherein the mass concentration of the polyvinylidene fluoride-hexafluoropropylene copolymer in the mixed solution is as follows: 0.02-0.03 g/mL.

2. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 1, wherein the method comprises the following steps: the silver-containing compound in the step A is silver nitrate.

3. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 2, characterized in that: the concentration of the silver nitrate added into the mixed solution of the water and the ethanol in the step A is 0.06-0.08 mol/L, and the volume ratio of the ethanol to the water in the mixed solution of the water and the ethanol in the step A is 1: 2-3.

4. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 2, characterized in that: the concentration of the dopamine aqueous solution in the step A is 15-25 mg/mL, and the volume ratio of the dopamine aqueous solution to the silver nitrate solution in the step A is 1/3-1/2.

5. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 1, wherein the method comprises the following steps: and (B) adjusting the pH value of the ammonia water in the step (A) to 8-9, wherein the magnetic stirring temperature in the step (A) is 15-30 ℃, and the stirring time is 10-12 h.

6. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 1, wherein the method comprises the following steps: step A, performing suction filtration, continuously washing with ethanol and deionized water, and then placing in a refrigerator at the temperature of-20-25 ℃ for freezing for 20-24 hours to completely dry the product to form a dopamine/silver polymer; and finally calcining the microspheres in a sealed muffle furnace at 450-500 ℃ for 2-3 h, and cleaning the microspheres with ethanol to obtain the flower-shaped carbon-silver microspheres.

7. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 1, wherein the method comprises the following steps: and the fluorine-containing modifier in the step B is perfluorooctyl triethoxysilane, and the volume concentration of the perfluorooctyl triethoxysilane in the normal hexane mixed solution is 0.5-1%.

8. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 1, wherein the method comprises the following steps: the substrate comprises glass or cotton cloth or stainless steel mesh or paper or aluminum sheet.

9. The method for preparing the carbon-silver microsphere/epoxy resin super-hydrophobic coating according to claim 1, wherein the method comprises the following steps: in the step C, the super-hydrophobic powder prepared in the step B can be directly adhered to the surface of the substrate through double-sided adhesive tape or sprayed liquid adhesive, and the super-hydrophobic coating can be formed after drying.

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