Preparation method of liquid-impregnation-resistant super-hydrophobic coating with ant nest structure

Abstract

The invention relates to a preparation method of a liquid-impregnation-resistant super-hydrophobic coating with an ant nest structure, which comprises the following steps of: adding tetraethoxysilane serving as a precursor for synthesizing silicon dioxide into a solution consisting of silicon dioxide sol and nano-scale silicon dioxide particles, and synthesizing silicon dioxide particles with a wide particle size distribution range by utilizing the dynamic difference of silicon dioxide nucleation and growth; meanwhile, high-concentration molecular-level fluorinated modified silicon dioxide particles are prepared through in-situ fluorination modification in the silicon dioxide nucleation and growth process and serve as a raw material for coating construction, and fluorocarbon resin serves as a binder to construct a'ant nest 'structure coating. The coating is of an ant nest structure with multiple through holes and the negative curvature hole inner surface, the liquid impregnation resistance time of the coating is prolonged by wrapping large-volume air, the stress concentration of the coating can be reduced through the negative curvature inner surface, and the mechanical stability of the coating is improved; the liquid impregnation resistance duration of the coating in typical liquids such as water, acid, alkali and salt exceeds 1000 hours.

Description

Technical Field

[0001] The present invention belongs to the technical field of super-hydrophobic coatings, and relates to a preparation technology of a super-hydrophobic coating for the inner wall of a sewage pipe for nuclear waste liquid or the like, specifically a preparation method of a super-hydrophobic coating with an "ant nest" structure that is resistant to liquid immersion. Background Art

[0002] Superhydrophobic coatings, with their unique ability to repel a wide range of liquids, hold great promise for applications in a wide range of fields, including nuclear power, aerospace, automotive, medical, and textiles. Currently, superhydrophobic coatings are prepared using various techniques, primarily optimizing them by reducing the surface energy of the coating material and constructing a superhydrophobic structure. Surface energy reduction techniques often involve modifying the coating with low-surface-energy materials, which are often expensive, environmentally polluting, and, more importantly, have poor service durability. Optimizing coating structure involves constructing a synergistic micro / nanostructure known as a "lotus leaf." While these techniques can yield superhydrophobic coatings, their resistance to liquid immersion is limited to only 300–500 hours (the duration during which the coating maintains a liquid contact angle greater than 150° and a rolling angle less than 10°). This is directly related to the volume of air entrained in the coating and the time it takes for this volume to vanish. Micromachining of structurally and compositionally stable superhydrophobic structures onto the surface of a substrate metal has been shown to achieve excellent superhydrophobic durability. However, this micromachining strategy significantly increases the coating's cost and is unsuitable for large-scale industrial production. Summary of the Invention

[0003] The present invention provides a method for preparing a super-hydrophobic coating that is resistant to long-term liquid immersion. This method uses simple traditional spraying technology to construct an "ant nest" structure super-hydrophobic coating on the surface of any substrate material. The coating has an ultra-long duration of maintaining liquid super-hydrophobic properties under typical liquid immersion conditions such as water, acid, alkali and salt.

[0004] The technical solution of the present invention is:

[0005] A method for preparing a liquid-immersion-resistant super-hydrophobic coating with an "ant nest" structure, comprising the following steps:

[0006] (1) Preparation of in situ fluorinated silica particles

[0007] Silica sol and silica nanoparticles were added simultaneously to a mixture of anhydrous ethanol, ammonia, and deionized water. The amount of silica nanoparticles added was the same as that of the silica sol. The volume percentages of anhydrous ethanol, ammonia, and deionized water were (5-15):(0.5-2):(1-3), and the mass ratio of silica sol to deionized water was 0.4:1.

[0008] The obtained mixture was ultrasonically stirred, and 75 vol.% of tetraethyl orthosilicate and 12.5 vol.% of a fluorinated silane coupling agent were added to deionized water. The mixture was stirred at 30°C for 24 hours and then centrifuged to obtain a silica particle precipitate. The silica particle precipitate was washed and purified with anhydrous ethanol, dried at 80°C, and ground to obtain in situ fluorinated modified silica particles.

[0009] (2) Preparation of liquid-immersion-resistant superhydrophobic coatings

[0010] The above-mentioned in-situ fluorinated modified silica particles are mixed with fluorocarbon resin and butyl acetate according to the configuration.

[0011] The mixture was ultrasonically stirred, 10 wt.% of fluorocarbon resin isocyanate was added, and the mixture was stirred thoroughly to obtain a liquid immersion-resistant superhydrophobic coating; wherein the weight percentages of in situ fluorinated modified silica particles, fluorocarbon resin, and butyl acetate were (2-6):(4-8):(50-56).

[0012] (3) Spraying to obtain the "ant nest" structure

[0013] The liquid-impregnation-resistant super-hydrophobic coating obtained in step (2) is sprayed, and the sprayed coating is horizontally placed in a vacuum drying oven at 80° C. and dried for 24 hours to obtain an “ant nest” structure.

[0014] When spraying, the process used is: spray gun diameter 0.3~1.0 mm, spraying air pressure 0.5~1.0 MPa, and spraying distance 10~60 cm.

[0015] The beneficial effects of the present invention are:

[0016] The present invention can construct a super-hydrophobic coating resistant to liquid immersion on the surface of any substrate material; the coating material is a highly concentrated, in-situ fluorinated silicon dioxide at the molecular level, and the negative curvature inner surface structure reduces the stress concentration of the coating, thereby improving the mechanical stability of the coating and extending the time the coating maintains low surface energy. It has excellent high temperature resistance and UV radiation resistance. The modified silicon dioxide used to construct the coating has a wide particle size distribution range, so that the constructed coating has an "ant nest" structure with porous penetration and negative curvature pore inner surface, thereby entraining a large volume of air, improving the coating's resistance to liquid immersion, and the immersion time in typical liquids exceeds 1000 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Scanning electron microscope images of the (a) surface and (b) cross-section of the liquid-immersion-resistant superhydrophobic coating with an “ant nest” structure.

[0018] Figure 2Comparison of Fourier transform infrared spectra of the superhydrophobic coating for liquid immersion resistance of "ant nest" structure and silica particles used for building coating before and after in situ fluorination modification.

[0019] Figure 3 The relationship curves of the contact angle and rolling angle of the "ant nest" structure liquid immersion-resistant superhydrophobic coating in four typical liquids (a), (b), (c) and (d) as the immersion time increases.

[0020] Figure 4 Ultrasonic performance test results of the liquid-immersion-resistant superhydrophobic coating of the "ant nest" structure after (a) high temperature and (b) ultraviolet irradiation. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention are described in detail below in conjunction with the technical solutions and drawings.

[0022] Example 1

[0023] Preparation of a liquid-immersion-resistant super-hydrophobic coating with an "ant nest" structure, the specific process is as follows:

[0024] (1) Preparation of in-situ fluorinated silica particles. A silica sol (40% by weight of deionized water) and an equal amount of silica nanoparticles were added to a mixture of anhydrous ethanol, ammonia, and deionized water in a volume ratio of 20:1:2. After stirring and ultrasonic dispersion, tetraethyl orthosilicate (75% by weight of deionized water) and perfluorodecyltriethoxysilane (12.5%) were added. The mixture was stirred at 30°C for 24 hours and the silica precipitate was centrifuged. After washing and purification with anhydrous ethanol, the mixture was vacuum-dried at 80°C and ground to obtain in-situ fluorinated silica particles with a wide particle size distribution.

[0025] (2) Preparation of coating spray slurry. The modified silica particles were mixed with fluorocarbon resin and butyl acetate in a mass ratio of 2:3:50. After stirring and ultrasonic dispersion treatment, isocyanate with a mass fraction of 10% of the fluorocarbon resin was added and stirred thoroughly to obtain a spray slurry.

[0026] (3) Spraying and curing of the coating. A titanium alloy plate was selected as the coating substrate, and the slurry was sprayed onto the substrate surface using a 0.5 mm diameter spray gun. The spraying process was as follows: the spraying pressure was 0.8 MPa and the spraying distance was 20 cm. The sprayed coating was placed horizontally in a vacuum drying oven at 80°C for 24 hours to obtain a super-hydrophobic coating with an "ant nest" structure that was resistant to liquid immersion.

[0027] Figure 1Scanning electron micrographs of (a) the surface and (b) the cross-section of a liquid-immersion-resistant superhydrophobic coating with an "ant's nest" structure. The coating exhibits an "ant's nest" structure with porous, through-holes and negatively curvature pore walls.

[0028] Figure 2 Comparison of Fourier transform infrared spectra of the "ant nest" structure liquid immersion resistant super hydrophobic coating and the silica particles used for the construction coating before and after in situ fluorination modification. It can be seen that compared with the silica particles without in situ fluorination modification, the silica particles modified by in situ fluorination and the prepared "ant nest" structure liquid immersion resistant super hydrophobic coating have a higher FTIR value at 3425 cm -1 The -OH stretching vibration peaks at both ends disappeared, and the -CF2 bond peaks (656 and 704 cm -1 ) and -CF3 bonds (1148 and 1210 cm -1 ), indicating that the in-situ fluorinated silica particles were successfully grafted with perfluorodecyltriethoxysilane, achieving high-concentration fluorination modification at the silica molecular level.

[0029] Figure 3 The following curves show the relationship between the contact angle and rolling angle of the "ant nest" structure superhydrophobic coating immersed in four typical liquids (a), (b), (c), and (d) as a function of immersion time. As can be seen, the coating maintains its superphobic properties (liquid contact angle and rolling angle greater than 150° and less than 10°, respectively) for 1128 hours, 1128 hours, 1080 hours, and 1008 hours, respectively. The "ant nest" structure superhydrophobic coating prepared by the present invention is significantly more resistant to liquid immersion than existing superhydrophobic coatings.

[0030] Figure 4 Ultrasonic performance test results of the "ant nest" structure liquid-resistant superhydrophobic coating after (a) high temperature and (b) ultraviolet irradiation. The high-temperature resistance test results of the coating (a) show that after being heated at 400℃ for 3 hours, the coating can still maintain the super-hydrophobic properties of four typical liquids, indicating that the coating has excellent high-temperature resistance. The ultraviolet irradiation resistance test results of the coating (b) show that when the coating is subjected to an intensity of 186 W / cm 2 After 48 hours of ultraviolet radiation, it can still maintain superphobic properties to four typical liquids, indicating that the coating has excellent resistance to ultraviolet radiation.

Claims

1. A method for preparing a liquid-immersion-resistant super-hydrophobic coating with an "ant nest" structure, characterized by: (1) Preparation of in situ fluorinated silica particles Silica sol and silica nanoparticles are added simultaneously to a mixture of anhydrous ethanol, ammonia water and deionized water, wherein the amount of silica nanoparticles added is the same as that of the silica sol; The mixture was ultrasonically stirred, and then 75 vol.% of tetraethyl orthosilicate and 12.5 vol.% of a fluorinated silane coupling agent were added to deionized water. The mixture was stirred at 30°C for 24 hours and then centrifuged to obtain a silica particle precipitate. The mixture was washed and purified with anhydrous ethanol, dried at 80°C, and ground to obtain in-situ fluorinated modified silica particles. (2) Preparation of liquid-immersion-resistant superhydrophobic coatings The above-mentioned in-situ fluorinated modified silica particles are mixed with fluorocarbon resin and butyl acetate according to the configuration. The mixture was ultrasonically stirred, 10 wt.% of fluorocarbon resin isocyanate was added, and the mixture was stirred thoroughly to obtain a liquid immersion resistant super hydrophobic coating; (3) Spraying to obtain the "ant nest" structure The liquid-impregnation-resistant super-hydrophobic coating obtained in step (2) is sprayed, and the sprayed coating is horizontally placed in a vacuum drying oven at 80° C. and dried for 24 hours to obtain an "ant nest" structure.

2. The method for preparing a liquid-immersion-resistant super-hydrophobic coating having an "ant nest" structure according to claim 1, wherein: In step (1), the volume percentages of anhydrous ethanol, ammonia water, and deionized water are (5-15):(0.5-2):(1-3).

3. A method for preparing a liquid-immersion-resistant super-hydrophobic coating with an "ant nest" structure, characterized by: In step (1), the mass ratio of silica sol to deionized water is 0.4:

1.

4. A method for preparing a liquid-immersion-resistant super-hydrophobic coating with an "ant nest" structure, characterized by: In step (2), the weight percentages of the in-situ fluorinated modified silica particles, the fluorocarbon resin, and butyl acetate are (2-6):(4-8):(50-56).

5. A method for preparing a liquid-immersion-resistant super-hydrophobic coating with an "ant nest" structure, characterized by: In step (3), during spraying, the process adopted is: the spray gun caliber is 0.3~1.0 mm, the spraying air pressure is 0.5~1.0 MPa, and the spraying distance is 10~60 cm.

6. The method for preparing a liquid-immersion-resistant super-hydrophobic coating having an "ant nest" structure according to claim 1, wherein Here are the steps: (1) Preparation of in situ fluorinated silica particles; 40% of the mass of deionized water was added to a mixture of anhydrous ethanol, ammonia water and deionized water in a volume ratio of 20:1:

2. After stirring and ultrasonic dispersion, 75% of the mass of deionized water was added to tetraethyl orthosilicate and 12.5% ​​of perfluorodecyltriethoxysilane. The mixture was stirred at 30°C for 24 hours and then centrifuged to obtain the silica particle precipitate. After washing and purification with anhydrous ethanol, the mixture was dried in a vacuum oven at 80°C and ground to obtain in situ fluorinated silica particles with a wide particle size distribution range. (2) Preparation of coating spray slurry: The modified silica particles, fluorocarbon resin and butyl acetate are mixed in a ratio of 2:3:50 by mass, and after stirring and ultrasonic dispersion treatment, 10% by mass of isocyanate of fluorocarbon resin is added and stirred thoroughly to obtain a spray slurry; (3) Spraying and curing of the coating: A titanium alloy plate was selected as the coating substrate, and the slurry was sprayed on the surface of the substrate using a spray gun with a diameter of 0.5 mm. The spraying process was as follows: the spraying pressure was 0.8 MPa and the spraying distance was 20 cm. The sprayed coating was placed horizontally in a vacuum drying oven at 80 °C and dried for 24 hours to obtain a super-hydrophobic coating with an "ant nest" structure that was resistant to liquid immersion.

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