A transparent anti-fog self-cleaning coating and a method for preparing the same

Abstract

The application discloses a kind of transparent anti-fog self-cleaning coating and preparation method thereof, specifically as follows: (1) a certain mass of tetrabutyl titanate, concentrated hydrochloric acid, silane coupling agent is dissolved in organic solvent, stir for a proper time, and is recorded as reaction liquid 1; (2) a certain mass of acrylamide, polyvinyl alcohol, aminated polysilsesquioxane, ammonium persulfate, N, N-methylene bisacrylamide is dissolved in water, stir uniformly, and is recorded as reaction liquid 2; (3) reaction liquid 1 is spin-coated on clean glass sheet, dried and taken out, spin-coat reaction liquid 2, continue to dry, obtain transparent anti-fog frost coating with persistent anti-fog performance.The application has simple preparation process, and the prepared coating has excellent anti-fog performance, anti-frost performance, anti-fouling performance, transmittance and stability, which solves the problem that anti-fouling coating is limited in application scenarios such as photovoltaic glass and front windshield, which have demand for transparency.

Description

Technical Field

[0001] This invention belongs to the field of novel polymer functional materials and polymer coatings, specifically relating to a transparent anti-fog self-cleaning coating and its preparation method. Background Technology

[0002] Condensation occurs when water vapor condenses on the surface of a material due to changes in ambient temperature, forming droplets with varying radii of curvature. This condensation scatters and diffuses incident light, reducing the material's light transmittance. There is significant demand for condensation in transparent materials such as automotive windshields, eyeglass lenses, bathroom glass, solar panels, and greenhouse plastic films.

[0003] Currently, the two most commonly used anti-fogging methods are: one is based on thermodynamic principles, which reduces the temperature difference by heating the solid surface to prevent steam condensation and thus prevent fog formation. While this method achieves the anti-fogging effect, its practicality is greatly limited, as the heating device is too complex to install and too expensive, hindering large-scale application. The other method, which alters the surface properties of the substrate (chemical composition and roughness) or changes the wetting state of water droplets on the material surface by applying a suitable coating, is more favored. Based on wettability, it can be divided into two states: one is when the water contact angle on the substrate surface approaches 0 (superhydrophilic state), water will spread into a uniform water film, reducing light scattering and thus preventing fog formation. As the water droplets diffuse on the surface, more and more transmitted light passes through the substrate surface, increasing light transmittance. The other method is to hydrophobize the material surface (water contact angle greater than 90°), increasing the contact angle of the water droplets, causing them to roll off under their own gravity, achieving the anti-fogging effect. However, many hydrophobic systems contain components such as fluorine, which not only pollute the environment but also result in poor adhesion and low strength between the material and the substrate. Therefore, research on hydrophilic antifog coatings has greater potential. This application has advantages such as ease of operation, low price, lower cost, economic applicability, and good antifog effect, while also possessing certain wear resistance and self-healing properties. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a transparent anti-fog self-cleaning coating. The coating prepared by spin coating has the advantages of high transparency, excellent anti-fog and anti-frost performance and stability. It solves the problems of complex operation process, poor mechanical properties, low light transmittance and easy aging in the preparation of hydrophilic anti-fog surface. The prepared anti-fog film is environmentally friendly and non-toxic.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a transparent anti-fog self-cleaning coating includes the following steps: (1) Preparation of spin coating solution 1 Weigh out a certain mass of tetrabutyl titanate, concentrated hydrochloric acid, and silane coupling agent, dissolve them in an organic solvent, stir for an appropriate time, and record this as reaction solution 1; (2) Prepare spin coating solution 2 Weigh out a certain mass of acrylamide, polyvinyl alcohol, amino-modified polysilsesquioxane, ammonium persulfate, and N,N-methylenebisacrylamide, dissolve them in water, stir well, and record this as reaction solution 2. (3) Spin coating and drying Spin-coat reaction solution 1 onto a clean glass slide, dry and remove it, spin-coat reaction solution 2, and continue drying to obtain a transparent anti-fog and anti-frost coating with durable anti-fog properties.

[0006] In the mixed solution 1 described in step (1), the mass of tetrabutyl titanate is 15-25 g, the mass of concentrated hydrochloric acid is 1-5 g, and the mass of silane coupling agent is 1-5 g.

[0007] In step (2), the mass of acrylamide in the mixed solution 2 is 1-5 g, the mass of polyvinyl alcohol is 0-1 g, the mass of aminated polysilsesquioxane is 0-1 g, the mass of ammonium persulfate is 0-1 mg, and the mass of N,N-methylenebisacrylamide is 0-1 mg.

[0008] The beneficial effects of this invention are as follows: (1) The preparation process adopts spin coating technology, which involves coating the pre-prepared precursor solution into a film and then drying it. The operation is simple and convenient, with no excess waste generated, making it green and environmentally friendly. It overcomes the problems of complex preparation procedures, long time consumption, and large environmental pollution of many traditional processes.

[0009] (2) The prepared coating has anti-frost and self-cleaning properties. The coating remains intact after being frozen for 24 hours under extremely cold conditions (-20℃) and still has anti-fog effect after being taken out. The coating contaminated with oil can be quickly restored to cleanliness after being soaked in water.

[0010] (3) The prepared coating has long-term stability. After being subjected to tests such as impact of sand and gravel, 100 times of sandpaper abrasion, 60 times of tape adhesion, ultraviolet aging, and high temperature exposure, it has shown excellent anti-fog performance. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1The images show the anti-fog effect (a) and anti-frost effect (b) of the anti-fog coating of the present invention. Figure 2 This demonstrates the anti-fog coating and blank glass of the present invention in terms of icing delay performance at -10 ℃. Figure 3 The following images illustrate the underwater oil contact angle (a) of the anti-fog coating of the present invention with blank glass, the self-cleaning performance process (b), and the cleaning results (c). Figure 4 The diagram shows a sandpaper friction test of the anti-fog coating of the present invention (a), a graph showing the relationship between the number of sandpaper friction cycles and the change in contact angle (b), and an optical anti-fog image of the coating after 80 cycles. Figure 5 The diagram shows a sandblasting test of the anti-fog coating of the present invention (a) and a comparison of transmittance before and after sandblasting (b). The inset shows a comparison of the anti-fog performance before and after sandblasting. Figure 6 To enhance the UV protection effect of the anti-fog coating of the present invention, it was applied to PE film (a), PET (b), and glass (c). Detailed Implementation

[0012] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0013] Example 1 Step 1: Prepare spin coating solution 1 The glass slide was placed in a beaker and sonicated for 10 min in anhydrous ethanol and deionized water, then dried in a 60 ℃ oven and cooled for later use. 18 g of tetrabutyl titanate, 1.7 g of concentrated hydrochloric acid, and 3 g of γ-methacryloyloxypropyltrimethoxysilane were weighed and dissolved in 20 mL of n-butanol. After stirring evenly, this solution was recorded as reaction solution 1. Step 2: Prepare spin coating solution 2 Weigh 0.75 g acrylamide, 0.25 g polyvinyl alcohol, 0.1 g amino-modified polysilsesquioxane, 1.2 mg ammonium persulfate, and 6.5 mg N,N-methylenebisacrylamide and dissolve them in 30 mL of water. Stir well and record as reaction solution 2. Step 3: Spin coating and drying The prepared glass slide was treated with oxygen plasma for 1 min. Then, reaction solution 1 was spin-coated onto the oxygen plasma-treated glass slide. After drying at 40 °C for 10 min, reaction solution 2 was spin-coated. The spin-coating speed was 1000 r / min for 12 s. The slide was then placed in an oven at 80 °C for 5 min to dry.

[0014] Example 2 Step 1: Prepare spin coating solution 1 The glass slide was placed in a beaker and sonicated for 10 min in anhydrous ethanol and deionized water, then dried in a 60 ℃ oven and cooled for later use. 20 g of tetrabutyl titanate, 2.7 g of concentrated hydrochloric acid, and 4 g of γ-methacryloyloxypropyltrimethoxysilane were weighed and dissolved in 22 mL of n-butanol. After stirring evenly, this solution was recorded as reaction solution 1. Step 2: Prepare spin coating solution 2 Weigh 1.24 g acrylamide, 1.50 g polyvinyl alcohol, 0.2 g amino-modified polysilsesquioxane, 2.2 mg ammonium persulfate, and 7.6 mg N,N-methylenebisacrylamide and dissolve them in 30 mL of water. Stir well and record this as reaction solution 2. Step 3: Spin coating and drying The prepared glass slide was treated with oxygen plasma for 3 min. Then, reaction solution 1 was spin-coated onto the oxygen plasma-treated glass slide. After drying at 60 °C for 20 min, reaction solution 2 was spin-coated. The spin-coating speed was 1200 r / min for 13 s. The slide was then placed in an oven at 80 °C for 5 min to dry.

[0015] Example 3 Step 1: Prepare spin coating solution 1 The glass slide was placed in a beaker and sonicated for 10 min in anhydrous ethanol and deionized water, then dried in a 60 ℃ oven and cooled for later use. 22 g of tetrabutyl titanate, 3.7 g of concentrated hydrochloric acid, and 5 g of γ-methacryloyloxypropyltrimethoxysilane were weighed and dissolved in 26 mL of n-butanol. After stirring evenly, this solution was recorded as reaction solution 1. Step 2: Prepare spin coating solution 2 Weigh 1.42 g acrylamide, 0.75 g polyvinyl alcohol, 0.3 g amino-modified polysilsesquioxane, 2.8 mg ammonium persulfate, and 8.9 mg N,N-methylenebisacrylamide and dissolve them in 30 mL of water. Stir well and record as reaction solution 2. Step 3: Spin coating and drying The prepared glass slide was treated with oxygen plasma for 5 min. Then, reaction solution 1 was spin-coated onto the oxygen plasma-treated glass slide. After drying at 80 °C for 30 min, reaction solution 2 was spin-coated. The spin-coating speed was 1500 r / min for 15 s. The slide was then placed in an oven at 80 °C for 5 min to dry.

[0016] Example 4 Step 1: Prepare spin coating solution 1 The glass slide was placed in a beaker and sonicated for 10 min in anhydrous ethanol and deionized water, then dried in a 60 ℃ oven and cooled for later use. 24 g of tetrabutyl titanate, 4.7 g of concentrated hydrochloric acid, and 6 g of γ-methacryloyloxypropyltrimethoxysilane were weighed and dissolved in 28 mL of n-butanol. After stirring evenly, this solution was recorded as reaction solution 1. Step 2: Prepare spin coating solution 2 Weigh 1.86 g acrylamide, 1.0 g polyvinyl alcohol, 0.4 g amino-modified polysilsesquioxane, 3.6 mg ammonium persulfate, and 0.12 g N,N-methylenebisacrylamide and dissolve them in 30 mL of water. Stir well and record as reaction solution 2. Step 3: Spin coating and drying The prepared glass slide was treated with oxygen plasma for 7 min. Then, reaction solution 1 was spin-coated onto the oxygen plasma-treated glass slide. After drying at 100 °C for 40 min, reaction solution 2 was spin-coated. The spin-coating speed was 1700 r / min for 20 s. Then, it was placed in an oven at 80 °C for 5 min to dry.

[0017] Example 5 Step 1: Prepare spin coating solution 1 The glass slide was placed in a beaker and sonicated for 10 min in anhydrous ethanol and deionized water, then dried in a 60 ℃ oven and cooled for later use. 26 g of tetrabutyl titanate, 5.7 g of concentrated hydrochloric acid, and 7 g of γ-methacryloyloxypropyltrimethoxysilane were weighed and dissolved in 30 mL of n-butanol. After stirring evenly, this solution was recorded as reaction solution 1. Step 2: Prepare spin coating solution 2 Weigh 3.52 g acrylamide, 1.25 g polyvinyl alcohol, 0.5 g amino-modified polysilsesquioxane, 4.2 mg ammonium persulfate, and 0.15 g N,N-methylenebisacrylamide and dissolve them in 30 mL of water. Stir well and record as reaction solution 2. Step 3: Spin coating and drying The prepared glass slide was treated with oxygen plasma for 13 min. Then, reaction solution 1 was spin-coated onto the oxygen plasma-treated glass slide. After drying at 120 °C for 50 min, reaction solution 2 was spin-coated. The spin-coating speed was 2000 r / min for 25 s. The slide was then placed in an oven at 80 °C for 5 min to dry.

[0018] Comparative Example 1 (without spin coating solution 1) Step 1: Prepare spin coating solution 2 The glass slide was placed in a beaker and sonicated for 10 min in anhydrous ethanol and deionized water, then dried in a 60 ℃ oven and cooled for later use. 1.42 g acrylamide, 0.75 g polyvinyl alcohol, 0.3 g amino-modified polysilsesquioxane, 2.8 mg ammonium persulfate, and 8.9 mg N,N-methylenebisacrylamide were weighed and dissolved in 30 mL of water. The solution was stirred until homogeneous and recorded as reaction solution 2. Step 2: Spin coating and drying The prepared glass slide was treated with oxygen plasma for 5 min. Then, reaction solution 1 was spin-coated onto the oxygen plasma-treated glass slide. After drying at 80 °C for 30 min, reaction solution 2 was spin-coated. The spin-coating speed was 1500 r / min for 15 s. The slide was then placed in an oven at 80 °C for 5 min to dry.

[0019] Comparative Example 2 (Aminated polysilsesquioxane was not added to reaction solution 2) Step 1: Prepare spin coating solution 1 The glass slide was placed in a beaker and sonicated for 10 min in anhydrous ethanol and deionized water, then dried in a 60 ℃ oven and cooled for later use. 22 g of tetrabutyl titanate, 3.7 g of concentrated hydrochloric acid, and 5 g of γ-methacryloyloxypropyltrimethoxysilane were weighed and dissolved in 26 mL of n-butanol. After stirring evenly, this solution was recorded as reaction solution 1. Step 2: Prepare spin coating solution 2 Weigh 1.42 g acrylamide, 0.75 g polyvinyl alcohol, 2.8 mg ammonium persulfate, and 8.9 mg N,N-methylenebisacrylamide and dissolve them in 30 mL of water. Stir well and record this as reaction solution 2. Step 3: Spin coating and drying The prepared glass slide was treated with oxygen plasma for 5 min. Then, reaction solution 1 was spin-coated onto the oxygen plasma-treated glass slide. After drying at 80 °C for 30 min, reaction solution 2 was spin-coated. The spin-coating speed was 1500 r / min for 15 s. The slide was then placed in an oven at 80 °C for 5 min to dry.

[0020] Figure 1 Images (a) and (b) show the anti-fogging effect and anti-frost effect of the anti-fogging coating of the present invention. Figure 1 As shown in (a), after placing the prepared coating and blank glass at a height of 5 cm above a 250 mL beaker containing 60 °C for 10 s, it was observed that the coating did not fog up and the letters at the bottom of the beaker could be clearly observed, but the blank glass was blurry, indicating that the coating has excellent anti-fogging performance; Figure 1As shown in (b), after the prepared coating and glass were frozen in a -20 ℃ freezer for 24 h, they were quickly taken out and observed. It was found that the letters at the bottom of the sample were clear, but the letters at the bottom of the glass were blurred, indicating that the coating has excellent antifreeze and anti-frost properties.

[0021] Figure 2 To demonstrate the freezing delay performance of the anti-fog coating and blank glass of this invention at -10 °C, 4 μL water droplets were added to the coated sample and blank glass, respectively. The cooling stage was controlled to cool from 20 °C to -10 °C at a rate of -13 °C / min. The delay time was recorded as the time it took for the droplet to change from transparent to the start of crystallization. The entire freezing process was recorded using the video recording function of a contact angle measuring instrument. Figure 2 As shown, the freezing time of water droplets on the blank glass surface is 197 s, while the freezing time of water droplets on the coated sample surface is 245 s, indicating that the coating has excellent freezing delay performance.

[0022] Figure 3 The self-cleaning performance process (b) and post-cleaning images (c) are shown for the underwater oil contact angle (a) between the anti-fog coating of the present invention and blank glass; as shown. Figure 3 The underwater oil contact angle of the blank glass shown in (a) is 138.5°, while that of the coated sample is 145.2°, indicating that the coating has excellent underwater oleophobic properties. Figure 3 As shown in (b), the oil contamination affected both the sample and the blank glass. The oil on the glass slowly dripped down, while the oil on the sample slid off quickly. The sample extracted from the water showed... Figure 3 As shown in (c), the letters behind the sample are clearly visible, while a large amount of oil stains remain on the glass surface.

[0023] Figure 4 The diagram shows (a) of the sandpaper friction test of the anti-fog coating of the present invention, (b) the relationship between the number of sandpaper friction cycles and the change in contact angle, and an optical anti-fog image of the coating after 80 cycles; as shown. Figure 4 As shown in (a), 1500# sandpaper was fixed to the table with double-sided tape. Then, a 100 g weight was placed on top of the coated sample. The sample was pulled at a constant speed parallel to the table, allowing it to slide 5 cm on the sandpaper. After a certain number of cycles, the sample was removed to measure the contact angle and anti-fog performance. Each back-and-forth friction was counted as one cycle.

[0024] Figure 5 The diagram shows (a) of the sandblasting test of the anti-fog coating of the present invention and a comparison of transmittance before and after sandblasting (b). The inset shows a comparison of the anti-fog performance before and after sandblasting. Figure 5As shown in (a), the sample was fixed to the table with double-sided tape. 1500# sandpaper was placed on the coating, and a 100g weight was placed on top. The sandpaper was pulled at a constant speed parallel to the table, allowing it to completely rub the entire coating surface. After a certain number of cycles, the sample was removed to measure the contact angle and anti-fogging performance. Each back-and-forth friction was counted as one cycle. Figure 5 As shown in (b), Example 3 exhibits the smallest change in water contact angle, while Comparative Example 1 (without the intermediate layer) and Comparative Example 2 (without POSS-NH2) show significant changes in contact angle. This indicates that both provide excellent wear resistance. Figure 5 The anti-fogging performance test after 80 rubs in (c) shows that the coating remains intact, which also demonstrates that the coating has excellent wear resistance.

[0025] Figure 6 To enhance the UV protection effect of the anti-fog coating of this invention, it was applied to PE film (a), PET (b), and glass (c), respectively. Figure 6 As shown in (a), within the visible light wavelength range, there is no significant difference in transmittance between the PA, PAKT coating, and blank PE film. However, within the ultraviolet light wavelength range, the transmittance of the PAKT coating decreases significantly. The PA coating may be hindering the transmittance of the blank PE film, resulting in a slight overall decrease. This is mainly because the TiO2 in the underlying KT coating of the PAKT coating has a strong ultraviolet shielding ability, giving the coating excellent UV resistance. Similarly, similar properties are observed for PET and glass substrates, but the performance varies. Figure 6 (as shown in bc).

[0026] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A transparent anti-fog self-cleaning coating, characterized in that: The preparation method of the transparent anti-fog self-cleaning coating includes the following steps: (1) Weigh a certain mass of tetrabutyl titanate, concentrated hydrochloric acid, and silane coupling agent and dissolve them in an organic solvent. Stir for an appropriate time and record it as reaction solution 1. (2) Weigh a certain amount of acrylamide, polyvinyl alcohol, amino-modified polysilsesquioxane, ammonium persulfate, and N,N-methylenebisacrylamide, dissolve them in water, stir well, and record this as reaction solution 2. (3) Spin-coat reaction solution 1 onto a clean glass slide, dry and remove it, spin-coat reaction solution 2, continue drying, and obtain a transparent anti-fog and anti-frost coating with durable anti-fog properties.

2. The transparent anti-fog self-cleaning coating according to claim 1, characterized in that: In step (1), the mass of tetrabutyl titanate 1 is 15-25 g, the mass of concentrated hydrochloric acid is 1-5 g, and the mass of silane coupling agent is 1-5 g.

3. The transparent anti-fog self-cleaning coating according to claim 1, characterized in that: In step (2), the reaction solution 2 contains 1-5 g of acrylamide, 0-1 g of polyvinyl alcohol, 0-1 g of aminated polysilsesquioxane, 0-1 mg of ammonium persulfate, and 0-1 mg of N,N-methylenebisacrylamide.

4. The transparent anti-fog self-cleaning coating according to claim 1, characterized in that: The organic solvent mentioned in step (1) is any one of alkyl ketones and alkyl alcohols.

5. The transparent anti-fog self-cleaning coating according to claim 1, characterized in that: Step (3) The drying temperature range is 20-200 ℃.

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