A super-hydrophilic anti-reflective anti-fog coating and preparation method thereof

Abstract

The present invention discloses a super-hydrophilic anti-reflective anti-fog coating and its preparation method. The coating is composed of dense hollow spherical particles of sulfonate-modified silica, which are electrostatically self-assembled layer by layer on an amino-modified substrate. The preparation method comprises the following steps: Step 1, preparing hollow spherical particles of mercapto-modified silica; Step 2, preparing hollow spherical particles of sulfonate-modified silica; Step 3, preparing an amino-modified substrate; Step 4, preparing an anti-fog coating; and Step 5, dip-coating the amino-modified substrate in the anti-fog coating. The coating of the present invention is highly hydrophilic, has strong adhesion to the substrate, and exhibits excellent anti-reflective properties.

Description

Technical Field

[0001] The present invention relates to the technical field of super-hydrophilic materials, in particular to a super-hydrophilic anti-reflection and anti-fog coating and a preparation method thereof. Background Art

[0002] Fogging is a common phenomenon in nature. It occurs when water vapor in the air condenses due to temperature differences, resulting in the formation of large numbers of small droplets. However, fogging on the surfaces of certain glass and polymer materials (such as silicate glass, quartz glass, polymethyl methacrylate, polyethylene, and polycarbonate) can reduce the substrate's light transmittance, affecting the user's aesthetics, hygiene, and safety.

[0003] Anti-fog materials are primarily categorized as superhydrophilic, superhydrophobic, and responsive materials. Superhydrophobic anti-fog surfaces require a certain tilt angle to allow droplets to slide off, and even when the air humidity is above a certain level, droplets will still condense. Responsive surfaces require a long time for water to penetrate the hydrophilic portion of the coating, and the coating's mechanical durability is also questionable. Therefore, current anti-fog materials focus on superhydrophilic polymer coatings, which absorb surrounding water molecules to form a quasi-continuous hydration layer on the substrate surface, significantly reducing light scattered by droplets and enhancing transmitted light. However, current superhydrophilic anti-fog coatings suffer from low hardness, poor abrasion resistance, short service life, susceptibility to contamination, and poor adhesion to the substrate. The development of long-lasting, durable, and anti-fog coatings has become a key research direction in this field. Materials used to prepare superhydrophilic materials are primarily organic, inorganic, and organic-inorganic hybrids. Organic-inorganic materials effectively combine the superhydrophilicity and flexibility of organic materials with the mechanical properties of inorganic materials, compensating for their respective shortcomings and offering significant potential for resolving the fogging problem. For example, inorganic SiO2 anti-fog coatings have strong hydrophilicity and wear resistance. However, due to the easy condensation of Si-OH into Si-O-Si and the easy adsorption of organic pollutants in the air by the hydroxyl groups on its surface, the hydrophilicity decreases, which in turn leads to a decline in anti-fog performance, that is, poor durability of the coating. However, if the surface of SiO2 is modified by organic-inorganic hybridization, replacing the hydroxyl groups on its surface with other hydrophilic groups (-COOH, -SO3H, -CONR2 / -CONHR, etc.), its anti-fog durability will be improved.

[0004] Make SiO The method for nanoparticle film forming has electrostatic self-assembly, sol-gel method, chemical vapor deposition and magnetron sputtering etc.Wherein chemical vapor deposition requires higher reaction temperature and comparatively complicated operating process, magnetron sputtering energy consumption is higher and can cause substrate to be heated, sol-gel method has longer preparation time usually, and the self-assembly process of sol causes the thickness and uniformity of film to be subject to some restrictions.Electrostatic self-assembly method is simple to operate, and by adjusting parameters such as nanoparticle concentration, electric charge, pH value, can realize the accurate control to the thickness, porosity and structure of film, thereby realize good particle attachment and interface bonding, higher bonding strength is provided.Therefore electrostatic self-assembly method has advantages such as simple to operate, controllable property is strong and good adhesion performance, makes it become a kind of conventional method to prepare SiO Nanoparticle film.The present invention promptly adopts electrostatic self-assembly method to make sulfonate modified SiO Nanoparticle self-assembles into super-hydrophilic anti-reflection anti-fog coating on glass substrate. Summary of the Invention

[0005] The purpose of the present invention is to address the shortcomings of the super-hydrophilic anti-fog coating in the prior art, such as water solubility, by combining the anti-fog performance of SiO2-based organic-inorganic hybrid materials and the advantages of the electrostatic self-assembly method. The present invention uses electrostatic action to adsorb hollow spherical particles composed of -SO3H-modified silica on an amino-modified positively charged glass substrate to form a super-hydrophilic anti-reflective anti-fog coating.

[0006] Another object of the present invention is to provide a method for preparing the super-hydrophilic anti-reflective anti-fog coating.

[0007] The technical solution adopted to achieve the purpose of the present invention is:

[0008] A super-hydrophilic anti-reflective anti-fog coating is composed of hollow spherical particles composed of dense sulfonate-modified silicon dioxide. The coating is self-assembled on an amino-modified substrate through layer-by-layer electrostatic self-assembly.

[0009] In the above technical solution, the coating has a thickness of 100 to 450 nm, and the particle size of the hollow spherical particles composed of the sulfonate-modified silica is 30 to 200 nm.

[0010] In the above technical solution, the material of the substrate is silicate glass, quartz glass, polymethyl methacrylate, polyethylene, or polycarbonate.

[0011] Another aspect of the present invention provides a method for preparing a super-hydrophilic anti-reflective anti-fog coating, comprising the following steps:

[0012] Step 1: stirring and dissolving a template polyacrylic acid aqueous solution in ammonia water at room temperature, adding anhydrous ethanol, and then adding a mixed solution of tetraethyl orthosilicate and 3-mercaptopropyltriethoxysilane to obtain a reaction solution, continuing to stir for 24 to 48 hours, so that the template polyacrylic acid is wrapped by the mercapto-modified silica to form spherical particles, centrifuging to remove the template polyacrylic acid located at the center of the spherical particles and pouring out the supernatant, drying to remove the solvent, and obtaining hollow spherical particles a composed of mercapto-modified silica, wherein the mass ratio of the polyacrylic acid aqueous solution, ammonia water, anhydrous ethanol, tetraethyl orthosilicate and 3-mercaptopropyltriethoxysilane is 0.36 to 1.2:16 to 30:300 to 480:0.4 to 2.5:0 to 2.25; preferably, the concentration of polyacrylic acid in the polyacrylic acid aqueous solution is 30%, and the concentration of the ammonia water is 30%;

[0013] Step 2: Adding hollow spherical particles a composed of mercapto-modified silica to deionized water, adding H2O2 solution after ultrasonic dispersion and stirring at room temperature for 3 to 6 hours, and drying the solution to obtain hollow spherical particles b composed of sulfonate-modified silica, wherein the mass ratio of the hollow spherical particles a composed of mercapto-modified silica, deionized water and H2O2 solution is 0.1 to 1.0:4 to 40:1 to 25; preferably, the concentration of the H2O2 solution is 30%;

[0014] Step 3: hydrolyzing 3-aminopropyltriethoxysilane in an ethanol aqueous solution at room temperature for 12 to 24 hours to obtain a solution c, and immersing the cleaned substrate in the solution c for 12 to 18 hours to obtain an amino-modified substrate, wherein the mass ratio of the 3-aminopropyltriethoxysilane, anhydrous ethanol, and deionized water is 3 to 15:2 to 14:0.35 to 1.8;

[0015] Step 4: dispersing the hollow spherical particles b composed of the sulfonate-modified silica obtained in step 2 in anhydrous ethanol, and adding solution c to prepare an anti-fog coating d, wherein the mass ratio of the hollow spherical particles b composed of the sulfonate-modified silica, anhydrous ethanol, and solution c is 0.005-0.9:2.5-180:0.001-0.4;

[0016] Step 5: Take the amino-modified substrate obtained in step 3 and dip it in the anti-fog coating d obtained in step 4, so that the hollow spherical particles composed of sulfonate-modified silica are electrostatically self-assembled layer by layer on the amino-modified substrate. Take out the modified substrate after dipping and dry it to obtain a super hydrophilic anti-reflective anti-fog coating.

[0017] In the above technical solution, in step 1, the average molecular weight of the polyacrylic acid is 3000 to 5000.

[0018] In the above technical solution, in step 1, the mass ratio of polyacrylic acid aqueous solution, ammonia water, anhydrous ethanol, tetraethyl orthosilicate and 3-mercaptopropyltriethoxysilane is 0.36-0.4:16-18:316-360:0.6-1.2:1.2-2.0.

[0019] In the above technical solution, in the step 2, the mass ratio of the hollow spherical particles a composed of the mercapto-modified silica, deionized water and H2O2 solution is 0.2-0.5:8-25:4-15.

[0020] In the above technical solution, in step three, the mass ratio of 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water is 6-9:6-10:0.67-0.9.

[0021] In the above technical solution, in step three, when the substrate is silicate glass or quartz glass, the substrate is placed in a muffle furnace and calcined at 450-600°C for 4-12 hours to obtain a cleaned substrate. When the substrate is polymethyl methacrylate, polyethylene, or polycarbonate, it is cleaned and dried with ethanol to obtain a cleaned substrate.

[0022] In the above technical solution, in step 4, the mass ratio of the hollow spherical particles b composed of sulfonate-modified silica, anhydrous ethanol and solution c is 0.01-0.6:5-150:0.005-0.2.

[0023] In the above technical solution, in step five, the dipping time is 6-18 hours.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Compared with the existing super-hydrophilic anti-fog coating, the super-hydrophilic anti-reflective anti-fog coating adds 3-aminopropyltriethoxysilane hydrolyzed solution during the reaction process, and self-assembles hollow spherical particles (negatively charged) composed of -SO3H-modified silica layer by layer on a positively charged amino-modified glass slide through electrostatic self-assembly.

[0026] 2. The hollow spherical particles composed of sulfonate-modified silica are evenly and densely distributed on the glass substrate, forming a uniform and dense rough structure. The coating has super hydrophilicity, and the hollow spherical particles have anti-reflection properties. Therefore, the present invention is a super hydrophilic anti-reflection anti-fog coating.

[0027] 3. The preparation method of the present invention is simple and easy to implement, while also providing excellent anti-fog effects. Specifically, the anti-fog coating's transmittance in the visible light range is approximately 4% higher than that of uncoated glass. Furthermore, the surface potential of the hollow spherical particles composed of sulfonate-functionalized silica is more negative than that of unmodified hollow spherical silica particles, resulting in stronger bonding with the substrate during electrostatic self-assembly, further enhancing the anti-fog capabilities of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1(a) shows the dynamic contact angle of the anti-fog coating in Example 1 and Example 4, Figure 1(b) shows the transmittance of the anti-fog coating in blank glass, Comparative Example 1, Example 1 and Example 4, Figure 1(c) shows the roughness of the anti-fog coating in blank glass, Example 1 and Example 5, Figure 1(d) shows the scanning electron microscope image of the anti-fog coating in Comparative Example 2, Example 1 and Example 2, and Figure 1(e) shows the anti-fog effect of blank glass, Example 1, Comparative Example 2, Example 2, Example 3 and Comparative Example 4 after being placed above a 100 ml beaker containing 40 ml of 60°C hot water for 2 minutes.

[0029] Figure 2 SEM images of the anti-fog coatings in Example 1, Example 3 and Comparative Example 4 and TEM images of the corresponding spherical particles are shown.

[0030] Figure 3 SEM images of the dip-coated amino-modified glass slides of the anti-fog coating in Example 1, Example 8, Example 9, Example 10 and Comparative Example 5 at different times are shown, and the thumbnails are cross-sectional SEM images corresponding to each example.

[0031] Figure 4(a) shows the Zeta potential diagram of the sulfonate-modified hollow silica particles in the anti-fog coatings of Example 1, Comparative Example 3, and Example 6 dispersed in ethanol, Figure 4(b) shows the binding force diagram of the anti-fog coatings of Example 1, Comparative Example 3, and Example 6 with the glass slide substrate, Figure 4(c) shows the water contact angle diagram of the anti-fog coatings of Example 1, Example 2, and Comparative Example 3 after exposure to air for corresponding periods of time, Figure 4(d) shows the anti-fog effect diagram of the anti-fog coatings of Example 1, Example 2, and Comparative Example 3 after exposure to air for 25 days, and Figure 4(e) shows the self-cleaning effect diagram of blank glass and Example 1. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] Example 1

[0034] A method for forming a super-hydrophilic anti-reflective anti-fog coating comprises the following steps:

[0035] Step 1: 0.36g of polyacrylic acid (30%, average molecular weight 3000) solution was stirred and dissolved in 16g of ammonia water (25%) at room temperature, 316g of anhydrous ethanol was added, and then a mixed solution of 0.62g of tetraethyl orthosilicate and 1.86g of γ-mercaptopropyltriethoxysilane was added. After stirring for 24 hours, the polyacrylic acid was wrapped by the mercapto-modified silica to form spherical particles. The template polyacrylic acid located at the center of the spherical particles was removed by centrifugation and the supernatant was discarded. The solvent was dried to obtain hollow spherical particles a composed of mercapto-modified silica, wherein the mass ratio of polyacrylic acid, ammonia water, anhydrous ethanol, tetraethyl orthosilicate, and γ-mercaptopropyltriethoxysilane was 0.36:16:316:0.62:1.86;

[0036] Step 2: Add 0.2 g of mercapto-modified hollow spherical particles a to 8 g of deionized water, ultrasonically disperse, add 4 g of 30% H₂O₂ solution, and stir at room temperature for 3 hours to produce sulfonate-modified hollow spherical particles b. The mass ratio of mercapto-modified hollow spherical particles a, deionized water, and 30% H₂O₂ is 0.2:8:4.

[0037] Step 3: Hydrolyze 6 g of 3-aminopropyltriethoxysilane in 6 g of anhydrous ethanol and 0.67 g of deionized water at room temperature for 12 hours to obtain solution C. Immerse a clean glass slide calcined at 450°C for 12 hours in solution C for 12 hours to prepare an amino-modified glass slide. The mass ratio of 3-aminopropyltriethoxysilane, anhydrous ethanol, and deionized water is 6:6:0.67.

[0038] Step 4: Disperse 0.01 g of the hollow spherical particles b composed of the sulfonate-modified silica described in Step 2 in 5 g of anhydrous ethanol, and add 0.005 g of solution c to prepare an anti-fog coating d. The mass ratio of the hollow spherical particles b composed of the sulfonate-modified silica, anhydrous ethanol, and solution c is 0.01:5:0.005.

[0039] Step 5: Take the amino-modified glass slide prepared in step 3 and dip it in the anti-fog coating d for 10 hours, take out the modified glass slide after dipping, and dry it to obtain a super-hydrophilic anti-reflective anti-fog coating.

[0040] The dynamic contact angle of the prepared super-hydrophilic anti-reflective and anti-fog coating is shown in Figure 1(a), and the transmittance is 94% as shown in Figure 1(b). Compared with ordinary glass, it has a 4% anti-reflection rate, a roughness of Ra = 12nm, and the HSN-SO3H on the coating surface is uniform and dense as shown in Figure 1(d). The coated slide is placed on a 100ml beaker containing 40ml of 60℃ hot water. The coating does not fog within 2 minutes as shown in Figure 1(e); the particle size of the hollow spherical particles composed of the synthesized sulfonate-modified silica is about 50nm, as shown in Figure 1(e). Figure 2 As shown in (a); the Zeta potential of the hollow spherical particles composed of sulfonate-modified silica is -38 mV, as shown in Figure 4(a); therefore, the bonding force with the substrate (1.2 MPa) is higher than that of the hollow spherical particles composed of unmodified silica obtained in Comparative Example 3, as shown in Figure 4(b); the contact angle does not change much after exposure to air for 25 days, as shown in Figure 4(c); it still has anti-fog properties after exposure to air for 25 days, as shown in Figure 4(d); the coating has self-cleaning properties, as shown in Figure 4(e).

[0041] Comparative Example 1

[0042] Compared with Example 1, the method for forming the super hydrophilic anti-reflective anti-fog coating in Comparative Example 1 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Comparative Example 1, no polyacrylic acid is added when preparing the anti-fog coating in step 1, and the obtained spherical particles composed of sulfonate-modified silica are solid. The final electrostatic self-assembled particles are solid spherical particles composed of sulfonate-modified silica.

[0043] The transmittance of the super-hydrophilic anti-fog coating formed by the solid spherical particles of sulfonate-modified silica is 90.0%, as shown in FIG1( b ), which is not much different from that of the blank glass slide.

[0044] Comparative Example 2

[0045] Compared with Example 1, the method for forming the coating in Comparative Example 2 is basically the same as that in Example 1, the only difference is that in the coating preparation process of Comparative Example 2, solution c is not added when preparing the anti-fog coating in step 4.

[0046] The hollow spherical particles composed of sulfonate-functionalized silica have poor uniformity and density, as shown in Figure 1(d), and have no anti-fog performance, as shown in Figure 1(e).

[0047] Comparative Example 3

[0048] Compared to Example 1, the coating formation method of Comparative Example 3 was essentially the same as that of Example 1, with the only difference being that γ-mercaptopropyltriethoxysilane was not added during step 1 of the anti-fog coating preparation process. In other words, the resulting coating consisted of hollow spherical particles composed of unmodified silica.

[0049] The contact angle of the prepared coating increased to 17° after 10 days in air, as shown in Figure 4(c), and the anti-fog performance was lost, as shown in Figure 4(d).

[0050] Comparative Example 4

[0051] Compared with Example 1, the method for forming the super hydrophilic anti-reflective anti-fog coating in Comparative Example 4 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Comparative Example 4, the masses of polyacrylic acid, ammonia water, ethanol, tetraethyl orthosilicate, and γ-mercaptopropyltriethoxysilane in step 1 are 0.36 g, 16 g, 355 g, 0.1 g, and 2.8 g, respectively, and the mass ratio is 0.36:16:355:0.1:2.8.

[0052] The surface of the coating obtained is uneven, such as Figure 2 As shown in (f); the synthesized spherical particles no longer have a hollow structure, as shown in Figure 2 It does not have anti-fog performance, as shown in Figure 1(e).

[0053] Comparative Example 5

[0054] Compared with Example 1, the method for forming the coating in Comparative Example 5 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Comparative Example 5, the amino-modified glass slide in step 5 is dipped in the anti-fog coating d for 2 hours. The surface of the coating obtained is uneven and dense, and the reaction is insufficient (such as Figure 3 shown).

[0055] Example 2

[0056] Compared with Example 1, the method for forming the super hydrophilic anti-reflective anti-fog coating in Example 2 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Example 2, the molecular weight of the polyacrylic acid in step 1 is 5000.

[0057] The surface of the super-hydrophilic anti-fog coating composed of hollow spherical particles of sulfonate-modified silica is uniform and dense, as shown in Figure 1(d); it has anti-fog performance, as shown in Figure 1(e); and the contact angle does not change much after exposure to air for 25 days, as shown in Figure 4(c); and it still has anti-fog properties, as shown in Figure 4(d).

[0058] Example 3

[0059] Compared with Example 1, the method for forming the super hydrophilic anti-reflective anti-fog coating in Example 3 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Example 3, the masses of polyacrylic acid, ammonia water, ethanol, tetraethyl orthosilicate, and γ-mercaptopropyltriethoxysilane in step 1 are 1.2 g, 30 g, 360 g, 1.2 g, and 1.2 g, respectively, and the mass ratio is 0.4:18:360:1.2:1.2.

[0060] The hollow spherical particles of sulfonate-modified silica on the surface of the super-hydrophilic anti-reflective anti-fog coating are uniform and dense ( Figure 2 (e)), the particle size of the hollow spherical particles is about 100 nm ( Figure 2 (b)), and has anti-fog performance (Figure 1(e)).

[0061] Example 4

[0062] Compared with Example 1, the method for forming the super-hydrophilic anti-reflective anti-fog coating in Example 4 is basically the same as that in Example 1, except that, in the preparation process of the anti-fog coating in Example 4, the masses of polyacrylic acid, ammonia water, ethanol, tetraethyl orthosilicate, and γ-mercaptopropyltriethoxysilane in step 1 are 0.375 g, 17.5 g, 355 g, 0.62 g, and 1.86 g, respectively; and the mass ratios of the hollow spherical particles a composed of mercapto-modified silica, deionized water, and 30% H2O2 in step 2 are 0.5 g, 25 g, and 15 g.

[0063] The dynamic contact angle of the surface of the prepared super-hydrophilic anti-reflective anti-fog coating is shown in FIG1( a ). The light transmittance of the coating is 93.4%, which shows a certain anti-reflective effect.

[0064] Example 5

[0065] Compared with Example 1, the method for forming the super-hydrophilic anti-reflective anti-fog coating in Example 5 is basically the same as that in Example 1, except that, in the preparation process of the anti-fog coating in Example 5, the masses of polyacrylic acid, ammonia water, ethanol, tetraethyl orthosilicate, and γ-mercaptopropyltriethoxysilane in step 1 are 0.375 g, 17.5 g, 355 g, 0.62 g, and 1.86 g, respectively, and the masses of the hollow spherical particles a composed of mercapto-modified silica, deionized water, and 30% H2O2 in step 2 are 0.3 g, 10 g, and 6 g, respectively.

[0066] The surface roughness of the obtained super-hydrophilic anti-reflective and anti-fog coating is Ra=4.69 nm ( FIG. 1( c )), which is slightly higher than that of the blank glass but lower than that of Example 1.

[0067] Example 6

[0068] The method for forming a super-hydrophilic anti-reflective anti-fog coating of the present invention comprises the following steps:

[0069] Step 1: 0.375g of polyacrylic acid (30%, average molecular weight 5000) solution was stirred and dissolved in 17.5g of ammonia water (25%) at room temperature, 355g of anhydrous ethanol was added, and then a mixed solution of 0.62g of tetraethyl orthosilicate and 1.86g of γ-mercaptopropyltriethoxysilane was added. After stirring for 24 hours, the polyacrylic acid was wrapped by the mercapto-modified silica to form spherical particles. The template polyacrylic acid located at the center of the spherical particles was removed by centrifugation and the supernatant was discarded. The solvent was dried to obtain hollow spherical particles a composed of mercapto-modified silica, wherein the ratio of polyacrylic acid, ammonia water, ethanol, tetraethyl orthosilicate, and γ-mercaptopropyltriethoxysilane was 0.375:17.5:355:0.62:1.86;

[0070] Step 2: Add 0.3 g of mercapto-modified hollow spherical particles a to 10 g of deionized water. After ultrasonic dispersion, add 6 g of a 30% H₂O₂ solution and stir at room temperature for 6 hours to produce sulfonate-modified hollow spherical particles b (negatively charged). The mass ratio of mercapto-modified hollow spherical particles a, deionized water, and 30% H₂O₂ is 0.3:10:6.

[0071] Step 3: Hydrolyze 7.5 g of 3-aminopropyltriethoxysilane in 8 g of anhydrous ethanol and 0.88 g of deionized water at room temperature for 12 hours to obtain solution C. Immerse a clean glass slide calcined in a muffle furnace at 450°C for 12 hours in solution C for 12 hours to prepare an amino-modified glass slide. The mass ratio of 3-aminopropyltriethoxysilane, anhydrous ethanol, and deionized water is 7.5:8:0.88.

[0072] Step 4: Disperse 0.6 g of the sulfonate-modified hollow silica particles b described in step 2 in 150 g of anhydrous ethanol, and add 0.2 g of solution c to prepare an anti-fog coating d. The mass ratio of sulfonate-modified hollow silica particles b, anhydrous ethanol, and solution c is 0.6:150:0.2.

[0073] Step 5: Take the amino-modified glass slide prepared in step 3 and dip it in the anti-fog coating d for 10 hours, take out the modified glass slide after dipping, and dry it to obtain a super-hydrophilic anti-reflective anti-fog coating.

[0074] The synthesized hollow spherical particles composed of sulfonate-modified silica have a Zeta potential of approximately -38.4 mV in ethanol (Figure 4(a)) and a binding force with the substrate of 1.1 MPa.

[0075] Example 7

[0076] The method for forming a super-hydrophilic anti-reflective anti-fog coating of the present invention comprises the following steps:

[0077] Step 1: 0.375g of polyacrylic acid (30%, average molecular weight 5000) solution was stirred and dissolved in 17.5g of ammonia water (25%) at room temperature, 355g of anhydrous ethanol was added, and then a mixed solution of 0.62g of tetraethyl orthosilicate and 1.86g of γ-mercaptopropyltriethoxysilane was added. After stirring for 24 hours, the polyacrylic acid coated with silica was removed by centrifugation and the supernatant was discarded. The precipitate was dried to obtain hollow spherical particles a composed of mercapto-modified silica. The mass ratio of polyacrylic acid, ammonia water, ethanol, tetraethyl orthosilicate, and γ-mercaptopropyltriethoxysilane was 0.375:17.5:355:0.62:1.86;

[0078] Step 2: 0.3 g of mercapto-modified hollow spherical particles a were added to 10 g of deionized water, and after ultrasonic dispersion, 6 g of 30% H2O2 solution was added and stirred at room temperature for 6 h to obtain sulfonate-modified hollow spherical particles b ( ). The mass ratio of the mercapto-modified hollow spherical particles a, deionized water, and 30% H2O2 was 0.3:10:6.

[0079] Step 3: Hydrolyze 7.5 g of 3-aminopropyltriethoxysilane in 8 g of anhydrous ethanol and 0.88 g of deionized water at room temperature for 12 hours to obtain solution C. Immerse a clean glass slide calcined in a muffle furnace at 450°C for 12 hours in solution C for 12 hours to prepare an amino-modified glass slide. The mass ratio of 3-aminopropyltriethoxysilane, anhydrous ethanol, and deionized water is 7.5:8:0.88.

[0080] Step 4: Disperse 0.2 g of the sulfonate-modified hollow silica particles b described in step 2 in 50 g of anhydrous ethanol, and add 0.1 g of solution c to prepare an anti-fog coating d. The mass ratio of sulfonate-modified hollow silica particles b, anhydrous ethanol, and solution c is 0.2:50:0.1.

[0081] Step 5: Take the amino-modified glass slide prepared in step 3 and dip it in the anti-fog coating d for 10 hours, take out the modified glass slide after dipping, and dry it to obtain a super-hydrophilic anti-reflective anti-fog coating.

[0082] The hollow silica particles modified by sulfonate groups on the surface of the prepared super hydrophilic anti-reflective anti-fog coating are uniform and dense, with a coating thickness of 220 nm ( Figure 3 ).

[0083] Example 8

[0084] Compared with Example 1, the method for forming the super hydrophilic anti-reflective anti-fog coating in Example 8 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Example 8, the amino-modified glass slide in step 5 is immersed in the anti-fog coating d for 6 hours.

[0085] The hollow silica particles modified with sulfonate groups on the surface of the prepared super-hydrophilic anti-reflective and anti-fog coating are uniform and dense, and the coating thickness is 103 nm.

[0086] Example 9

[0087] Compared with Example 1, the method for forming the super hydrophilic anti-reflective anti-fog coating in Example 9 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Example 9, the amino-modified glass slide in step 5 is dipped in the anti-fog coating d for 18 hours.

[0088] The hollow silica particles modified with sulfonate groups on the surface of the prepared super-hydrophilic anti-reflective and anti-fog coating are uniform and dense, and the coating thickness is 435 nm.

[0089] Example 10

[0090] Compared with Example 1, the method for forming the super hydrophilic anti-reflective anti-fog coating in Example 10 is basically the same as that in Example 1, the only difference is that in the preparation process of the anti-fog coating in Example 10, the amino-modified glass slide in step 5 is immersed in the anti-fog coating d for 24 hours.

[0091] The hollow silica particles modified by sulfonate groups on the surface of the prepared super hydrophilic anti-reflective and anti-fog coating are uniform and dense, with a coating thickness of 450 nm. The coating thickness no longer increases with time ( Figure 3 ).

[0092] The test methods used in the above examples and comparative examples are as follows:

[0093] (1) Anti-fog performance test: A 100ml beaker is filled with 40ml of 60℃ hot water. A glass slide with the coating is placed on the beaker. A photo is taken to observe whether the glass slide has an anti-fog effect within 2 minutes.

[0094] (2) Water resistance test: Immerse the coated glass slide in a beaker of water for 24 hours, and use the anti-fog performance test in (1) to observe whether it still has the anti-fog effect.

[0095] (3) Self-cleaning performance test: Take 5 ml of dodecane solution in a beaker, add 0.1 g of oil red dye, and then stir to mix evenly. Take 0.5 ml of the mixed solution and drop it on the coated glass slide, and then place it in a beaker containing deionized water. Observe whether the dyed oil droplets are completely separated from the glass slide. After removing the glass slide from the deionized water, take a photo to show the residual dodecane oil droplets.

[0096] (4) Substrate adhesion test: According to the “Standard Test Method for Determining the Peel Strength of Coatings Using a Portable Adhesion Tester”, the adhesion between the coating and the substrate was tested using a BGD 500 digital pull-off adhesion tester.

[0097] The performance results of the coating samples in Examples 1 to 9 and Comparative Examples 1 to 5 are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A super hydrophilic anti-reflective anti-fog coating, characterized in that: The coating consists of dense hollow spherical particles of sulfonate-modified silica, which are electrostatically self-assembled layer by layer on an amino-modified substrate; The preparation method of the super hydrophilic anti-reflective anti-fog coating comprises the following steps: Step 1, stirring and dissolving a template polyacrylic acid aqueous solution in ammonia water at room temperature, adding anhydrous ethanol, and then adding a mixed solution of tetraethyl orthosilicate and 3-mercaptopropyltriethoxysilane to obtain a reaction solution, continuing to stir for 24 to 48 hours, the thiol-modified silica wraps the template polyacrylic acid to form spherical particles, centrifuging to remove the template polyacrylic acid located at the center of the spherical particles and pouring out the supernatant, drying to remove the solvent, and obtaining hollow spherical particles a composed of thiol-modified silica, wherein the mass ratio of the polyacrylic acid aqueous solution, ammonia water, anhydrous ethanol, tetraethyl orthosilicate and 3-mercaptopropyltriethoxysilane is 0.36 to 0.4:16 to 18:316 to 360:0.6 to 1.2:1.2 to 2.0; Step 2: adding hollow spherical particles a composed of mercapto-modified silica to deionized water, adding H2O2 solution after ultrasonic dispersion, stirring at room temperature for 3 to 6 hours, and drying the solution to obtain hollow spherical particles b composed of sulfonate-modified silica, wherein the mass ratio of the hollow spherical particles a composed of mercapto-modified silica, deionized water, and H2O2 solution is 0.1 to 1.0:4 to 40:1 to 25; Step 3: 3-aminopropyltriethoxysilane is hydrolyzed in anhydrous ethanol and deionized water at room temperature for 12 to 24 hours to obtain solution c, and the cleaned substrate is immersed in solution c for 12 to 18 hours to obtain an amino-modified substrate, wherein the mass ratio of the 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water is 3 to 15:2 to 14:0.35 to 1.8; Step 4: dispersing the hollow spherical particles b composed of the sulfonate-modified silica obtained in step 2 in anhydrous ethanol, and adding solution c to prepare an anti-fog coating d, wherein the mass ratio of the hollow spherical particles b composed of the sulfonate-modified silica, anhydrous ethanol, and solution c is 0.005-0.9:2.5-180:0.001-0.4; Step 5: Take the amino-modified substrate obtained in step 3 and dip it in the anti-fog coating d obtained in step 4, so that the hollow spherical particles composed of sulfonate-modified silica are electrostatically self-assembled layer by layer on the amino-modified substrate, take out the modified substrate after dipping, and dry it to obtain a super hydrophilic anti-reflective anti-fog coating, wherein the dipping time is 6-18 hours.

2. The super-hydrophilic anti-reflective anti-fog coating according to claim 1, wherein: The thickness of the coating is 100-450 nm, and the particle size of the hollow spherical particles composed of the sulfonate-modified silica is 30-200 nm.

3. The super-hydrophilic anti-reflective anti-fog coating according to claim 1, wherein: The substrate is made of silicate glass, quartz glass, polymethyl methacrylate, polyethylene or polycarbonate.

4. The super-hydrophilic anti-reflective anti-fog coating according to claim 1, wherein: In the step 1, the average molecular weight of the polyacrylic acid is 3000-5000.

5. The super-hydrophilic anti-reflective anti-fog coating according to claim 1, wherein: In the step 2, the mass ratio of the hollow spherical particles a composed of the mercapto-modified silica, deionized water and H2O2 solution is 0.2-0.5:8-25:4-15.

6. The super-hydrophilic anti-reflective anti-fog coating according to claim 1, wherein: In the step 3, the mass ratio of the 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water is 6-9:6-10:0.67-0.

9.

7. The super-hydrophilic anti-reflective anti-fog coating according to claim 1, wherein: In the step three, when the substrate is silicate glass or quartz glass, the substrate is placed in a muffle furnace and calcined at 450-600° C. for 4-12 hours to obtain a cleaned substrate. When the substrate is polymethyl methacrylate, polyethylene or polycarbonate, it is washed and dried with ethanol to obtain a cleaned substrate.

8. The super-hydrophilic anti-reflective anti-fog coating according to claim 1, wherein: In the step 4, the mass ratio of the hollow spherical particles b composed of the sulfonate-modified silica, anhydrous ethanol, and solution c is 0.01-0.6:5-150:0.005-0.2.

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