Glass surface multifunctional coating structure and preparation method and application thereof

Abstract

The invention discloses a glass surface multifunctional coating structure as well as a preparation method and application thereof, and belongs to a functional inorganic thin film technology. The method specifically comprises the following steps: firstly, coating a glass substrate with hollow silicon dioxide nanosphere sol to form an initial coating; the acidified hard component sol and the acidified hydrophilic component sol are uniformly mixed, the hard component sol adopts aluminum oxide sol, zirconium dioxide sol or cerium dioxide sol, and the hydrophilic component sol adopts titanium dioxide sol, zinc oxide sol or tin dioxide sol; and coating the surface of the glass substrate containing the initial coating with the mixed sol, carrying out heat treatment annealing, and finally obtaining a compact and stable multifunctional composite coating structure on the surface of the glass. Through a porous framework and inorganic binding phase composite structure, high light transmittance, high mechanical strength and a self-cleaning function are synergistically realized, and the problem that the performances are difficult to balance in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the field of functional inorganic thin film technology, specifically relating to a multifunctional coating structure for glass surfaces, its preparation method, and its application. Background Technology

[0002] Photovoltaic modules are key devices that directly convert solar energy into electrical energy, but Fresnel reflection at their air / encapsulation glass interface causes some incident light loss. To reduce surface reflection and improve transmittance, anti-reflection coatings are typically constructed on the glass surface, including subwavelength textured surfaces, single-layer or multi-layer dielectric films, etc.

[0003] Among them, silica antireflective coatings prepared based on sol-gel technology have been widely used in industry due to their simple process, low cost, and excellent optical performance. The low refractive index of this type of coating is mainly achieved by introducing nanoscale pores. Currently, methods for preparing porous silica films have been developed, including randomly stacked solid nanoparticles, disordered mesoporous network structures, and hollow silica nanosphere systems. In particular, the closed-pore structure inside the hollow silica spheres effectively inhibits the permeation of water vapor and pollutants through capillary action, contributing to improved environmental stability of the coating.

[0004] However, the introduction of porous structures often weakens the mechanical strength of the coating. The interactions between nanoparticles and between nanoparticles and the substrate are primarily van der Waals forces, making the coating susceptible to detachment under friction or impact. Unsealed pores within the porous framework allow moisture and contaminants to penetrate, leading to deterioration of the coating's optical performance and shortened lifespan. On the other hand, photovoltaic modules operating outdoors over long periods inevitably suffer from the accumulation of dust, sand, and other contaminants, resulting in decreased light transmittance of the encapsulation glass and reduced module power generation efficiency. Traditional methods relying on manual or mechanical cleaning are not only costly to maintain, but the friction during cleaning can also further damage the surface anti-reflective coating. Therefore, how to construct a multifunctional coating on the glass surface that combines high transmittance, mechanical robustness, and self-cleaning properties is a significant technological challenge.

[0005] To address the insufficient mechanical strength of porous silica antireflective coatings, existing technologies often introduce organic binders or construct organic-inorganic hybrid systems. For example, patent application CN117625033A discloses a hardening antireflective coating solution, which uses hollow silica nanospheres, magnesium fluoride sol, and polymers such as polyurethane acrylate resin and polyvinyl butyral to prepare the coating via ultraviolet light curing. While this method can increase the pencil hardness of the coating to 3H, the organic polymer components it relies on are prone to aging, yellowing, or degradation under long-term outdoor ultraviolet light, high temperature, and high humidity conditions, leading to deterioration of coating performance, limited lifespan, and failure to impart anti-fouling and self-cleaning functions to the coating. To impart self-cleaning properties to the coating, porous silica is typically combined with components possessing ultraviolet photoinduced superhydrophilic properties. For example, Fang et al. used dip coating to embed nano-TiO2 into hollow silica nanosphere coatings and then heat-treated them to obtain good anti-reflective and self-cleaning effects. However, the coating had poor wear resistance, and the average light transmittance decreased by 0.77% after 80 rubs under a 5 N load.

[0006] In summary, constructing antireflective coatings faces two main contradictions: First, there is an inherent conflict between material properties. Low-refractive-index porous structures are beneficial for antireflection but often sacrifice mechanical strength; while high hardness and self-cleaning functions often rely on high-refractive-index dense metal oxides (such as TiO2 and Al2O3), which introduce optical losses and impair the coating's antireflective effect. Second, achieving synergy among these properties cannot be accomplished through simple physical mixing. Directly mixing sols with different functions often leads to unfavorable agglomeration, sedimentation, or phase separation between components, not only destroying the integrity of the porous structure but also potentially causing high-refractive-index components to clog pores or exhibit non-uniform distribution in the coating. Therefore, precise material design and controllable preparation processes are necessary to achieve a uniform and robust composite of reinforcing components and self-cleaning components while maintaining the low refractive index and structural stability of the porous framework. Summary of the Invention

[0007] The purpose of this invention is to solve the problem that existing technologies cannot simultaneously balance the anti-reflection, mechanical properties and self-cleaning properties of coatings, and to provide a multifunctional coating structure for glass surfaces, its preparation method and application.

[0008] The specific technical solution adopted in this invention is as follows:

[0009] In a first aspect, the present invention provides a method for preparing a multifunctional coating structure on a glass surface, the specific steps of which are as follows:

[0010] S1: Coating hollow silica nanosphere sol onto a clean glass substrate to form an initial coating;

[0011] S2: Mix the acidified hard component sol and hydrophilic component sol evenly to obtain a mixed sol; the hard component sol is alumina sol, zirconium dioxide sol or cerium dioxide sol, and the pH value is controlled at 3~5; the hydrophilic component sol is titanium dioxide sol, zinc oxide sol or tin dioxide sol, and the pH value is controlled at 2~4.

[0012] S3: The mixed sol is coated onto the glass substrate surface containing the initial coating obtained in step S1, and heat-treated and annealed to obtain a dense and stable multifunctional composite coating structure on the glass surface.

[0013] Preferably, the hollow silica nanosphere sol in step S1 is prepared by a template method or a microemulsion method; the particle size of the hollow silica nanospheres is 20~100 nanometers.

[0014] Preferably, the coating process in steps S1 and S3 is performed by one of dip coating, spin coating, spray coating, roll coating or screen printing.

[0015] Preferably, the total concentration of metal ions in the hard component sol of the mixed sol is 0.1~1 M, and the total concentration of metal ions in the hydrophilic component sol is 0.01~0.5 M.

[0016] Preferably, both the hard component sol and the hydrophilic component sol in step S2 are prepared by the sol-gel method; the precursor of the hard component sol is at least one of aluminum sec-butoxide, aluminum isopropoxide, and aluminum nitrate; the precursor of the hydrophilic component sol is at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, and titanium tetrachloride.

[0017] Furthermore, the aluminum ion concentration in the hard component sol of the mixed sol is 0.1~0.3 M.

[0018] Furthermore, the concentration of titanium ions in the hydrophilic component of the mixed sol is 0.01~0.1 M.

[0019] Preferably, the heat treatment in step S3 is performed using a tube furnace or a muffle furnace; the heat treatment temperature is 500~560℃, and the heat treatment time is 1~3 h.

[0020] In a second aspect, the present invention provides a multifunctional coating structure for a glass surface prepared by the preparation method described in the first aspect.

[0021] Thirdly, the present invention provides an application of the multifunctional coating structure on the glass surface described in the second aspect, which is used in photovoltaic glass, building energy-saving glass, displays, and windows of automotive photovoltaic and solar thermal systems.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) This invention creatively employs a composite structure of hollow silica nanosphere framework and functional oxide binder phase, which synergistically optimizes the antireflection performance, mechanical strength and self-cleaning function of a single inorganic coating. This single-layer structure avoids the interlayer interface matching problem and process complexity problem existing in traditional multilayer film systems, and effectively overcomes the problem of balancing these properties in the prior art.

[0024] (2) In the coating preparation method provided by the present invention, a porous structure with low refractive index is first constructed by the hollow silica nanosphere skeleton; then, a mixed sol composed of hard components and hydrophilic components serves as a functional oxide binder phase, which fully fills the pores of the hollow silica nanospheres at the nanoscale and strengthens the interfacial bonding. Among them, the hard components significantly improve the mechanical strength of the coating, so that the pencil hardness of the coating can reach above 4H, and the light transmittance can remain basically unchanged after repeated friction with non-woven fabric, which meets the mechanical durability requirements of outdoor applications such as photovoltaic modules. At the same time, the hydrophilic components (such as TiO2) can significantly reduce the water contact angle of the coating surface under ultraviolet light irradiation, which promotes the formation of a uniform thin water film on the surface. This water film can float and carry away the dust, particles and organic pollutants attached to the coating, while weakening the surface electrostatic adsorption, achieving long-term effective self-cleaning and significantly reducing daily maintenance costs.

[0025] (3) The coating preparation method provided by the present invention has a high degree of controllability. By adjusting the particle size and hollowness of the hollow silica nanospheres, the thickness of the coating, and the proportion of each component in the functional oxide mixed sol, the optical performance, mechanical performance and hydrophilicity can be flexibly optimized and balanced, thereby adapting to the performance requirements of different application scenarios, such as achieving customized goals such as high light transmittance priority or high wear resistance priority. Attached Figure Description

[0026] Figure 1 A schematic diagram of the multifunctional coating structure on the glass surface provided by the present invention;

[0027] Figure 2 A scanning electron microscope image of the multifunctional coating structure prepared in Example 1;

[0028] Figure 3 This is a comparison diagram of the light transmittance before and after applying the multifunctional coating to the structure in Example 1;

[0029] Figure 4 The image shows a comparison of the light transmittance of the multifunctional coating structure prepared in Example 1 before and after friction.

[0030] Figure 5 The image shows the hardness test results of the multifunctional coating structure prepared in Example 1;

[0031] Figure 6 The image shows the contact angle test results of the multifunctional coating structure prepared in Example 1. Detailed Implementation

[0032] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0033] The schematic diagram of the multifunctional coating structure provided by this invention is shown below. Figure 1 As shown, a composite coating with high light transmittance, excellent mechanical strength, and self-cleaning function is constructed on the surface of a glass substrate 1 as the supporting substrate. This coating mainly consists of two parts: a porous framework structure formed by tightly packed hollow silica nanospheres 2, and a mixed sol containing hard and hydrophilic components that fills and coats the voids between the hollow silica nanospheres 2 and their surfaces. Finally, after heat treatment, a stable oxide binder phase is formed, resulting in a dense single-layer functional coating. This invention can effectively control the final refractive index, mechanical strength, and surface hydrophilicity of the coating by adjusting the particle size and hollowness of the hollow silica nanospheres 2 and the composition and concentration of the mixed sol 3.

[0034] Example 1

[0035] This embodiment provides a method for preparing a multifunctional coating structure on a glass surface, the specific steps of which are as follows:

[0036] (1) Pretreatment of glass substrate

[0037] The glass substrate was sequentially immersed in deionized water and anhydrous ethanol, and ultrasonically cleaned for 10 minutes each time to thoroughly remove surface contaminants. After cleaning, it was dried in a clean oven for later use.

[0038] (2) Preparation of hollow silica nanosphere sol

[0039] Accurately weigh 0.4 g of polyacrylic acid and dissolve it in 10 mL of concentrated ammonia water, stirring until completely dissolved to obtain a clear solution A. While continuously stirring, add solution A dropwise to 200 mL of anhydrous ethanol. After the addition is complete, continue stirring for 20 minutes to obtain a uniformly dispersed mixed solution B. Subsequently, slowly add 2 mL of tetraethyl orthosilicate in portions to solution B over 30 minutes. After the addition is complete, continue stirring at room temperature for 6–8 hours to allow the tetraethyl orthosilicate to fully hydrolyze and condense. Finally, allow the sol to age at room temperature for 48 hours to obtain a stable hollow silica nanosphere sol, wherein the hollow silica nanosphere particle size is 40–60 nm.

[0040] (3) Preparation of hard component sol

[0041] Weigh 12 g of aluminum sec-butoxide and add it to 120 mL of isopropanol. Stir the mixture at room temperature for 1 hour using a constant-temperature magnetic stirrer until it is completely dissolved, yielding a clear solution. Then, while stirring, slowly add 8 mL of ethyl acetoacetate to the solution, continuing stirring for 6 hours after the addition is complete. Next, add a pre-mixed water-alcohol solution of 4 mL of deionized water and 20 mL of isopropanol, and continue stirring at room temperature for 24 hours. Then, allow the mixture to stand and age for 72 hours to complete the hydrolysis and aging process of the sol, obtaining alumina sol.

[0042] Finally, concentrated nitric acid was added dropwise to the aged alumina sol to adjust the pH value of the sol to between 3 and 5, resulting in a stable and transparent alumina sol with an aluminum ion concentration of 0.3 M.

[0043] (4) Preparation of hydrophilic component sol

[0044] Measure 120 mL of anhydrous ethanol and 2 mL of deionized water and mix thoroughly. Add 0.5 mL of concentrated nitric acid to the mixture and stir for 10 minutes to ensure complete mixing. Then, while stirring continuously, slowly add 6 mL of tetrabutyl titanate. After the addition is complete, continue stirring at room temperature for at least 6 hours to obtain a homogeneous, clear, and transparent titanium dioxide sol (pH 2-4) with a titanium ion concentration of 0.12 M.

[0045] (5) Initial coating preparation

[0046] The pretreated glass substrate was vertically immersed in the hollow silica nanosphere sol for 10 seconds. Subsequently, the glass substrate was uniformly pulled out of the liquid surface at a speed of 2000 μm / s, thus obtaining an initial coating composed of hollow silica nanospheres on the glass surface.

[0047] (6) Preparation of composite coating

[0048] The acidified alumina sol and titanium dioxide sol were mixed, and a certain volume of isopropanol was added for dilution to ensure that the total concentration of aluminum ions in the mixed sol was 0.2 M and the total concentration of titanium ions was 0.01 M. The mixed sol was ultrasonically treated for 15 minutes to ensure uniform mixing, thus obtaining an aluminum-titanium mixed sol.

[0049] Using an dip-pull method, a glass substrate coated with the initial coating is vertically immersed in the aforementioned aluminum-titanium mixed sol. After immersion for 10 seconds, the substrate is uniformly pulled out of the liquid surface at a speed of 1000 μm / s. The glass coated with the composite coating is placed in a tube furnace and held at 550°C for 2 hours, then cooled to room temperature with the furnace. Through this heat treatment process, a dense single-layer multifunctional coating is finally formed on the glass surface.

[0050] Next, the performance of the multifunctional coating structure on the glass surface prepared in this embodiment will be tested:

[0051] (1) Scanning electron microscopy test

[0052] The results are as follows Figure 2 As shown, the coating uses hollow silica nanospheres with closed-pore structure as the basic framework. The nanopores formed by their accumulation are fully filled and coated by the subsequently introduced Al2O3-TiO2 mixed sol, forming a dense and uniform inorganic composite structure with a coating thickness of about 121 nanometers.

[0053] (2) Ultraviolet-Visible-NearInfrared Spectroscopy Test

[0054] UV-Vis-NIR spectroscopy was performed on both the pretreated glass substrate and the glass substrate with a multifunctional coating. The results are as follows: Figure 3 As shown, the glass substrate has a maximum transmittance of only 91% before coating, while after coating, the maximum transmittance can reach 96.03%, and there is a significant improvement in the spectral range of 400~1100 nm.

[0055] (3) Friction test

[0056] A nonwoven fabric was used to conduct 200 reciprocating friction cycles on the multifunctional coated surface of the glass under a 5 N load, and the light transmittance curves before and after friction were compared. The results are as follows: Figure 4 As shown, the transmittance curves before and after friction are almost completely overlapping, indicating that the optical performance of the coating did not degrade after repeated friction, demonstrating excellent wear resistance.

[0057] (4) Pencil hardness test

[0058] According to the standard pencil hardness test method, a 4H hardness pencil was used to conduct a scratch test on the multifunctional coating on the glass surface. For example... Figure 5 The optical microscope image shown indicates that no obvious scratches were observed on the coating surface after being drawn with a 4H pencil, indicating that the pencil hardness of the coating reaches or exceeds 4H, and it has high surface hardness and scratch resistance.

[0059] (5) Contact angle test

[0060] After irradiating the coating with ultraviolet light for 45 minutes, the surface water contact angle was measured. The results are as follows: Figure 6 As shown, water droplets spread rapidly on the coating surface, and the measured water contact angle is as low as 5.2°, indicating that the coating has excellent photoinduced superhydrophilicity, which helps to remove surface contaminants through water film spreading and achieve self-cleaning function.

[0061] Example 2

[0062] Compared to Example 1, this example provides a method for preparing a multifunctional coating structure on a glass surface using different concentrations of titanium dioxide sol. The glass substrate pretreatment, hollow silica nanosphere sol preparation, hard component sol (alumina sol) preparation, and hydrophilic component sol (titanium dioxide sol) preparation are the same as in Example 1.

[0063] (1) Initial coating preparation

[0064] The pretreated glass substrate was vertically immersed in the hollow silica nanosphere sol for 10 seconds. Subsequently, the glass substrate was uniformly pulled out of the liquid surface at a speed of 2000 μm / s, thus obtaining an initial coating composed of hollow silica nanospheres on the glass surface.

[0065] (2) Preparation of composite coating

[0066] The acidified alumina sol and titanium dioxide sol were mixed, and a certain volume of isopropanol was added for dilution to ensure that the total concentration of aluminum ions in the mixed sol was 0.2 M and the total concentration of titanium ions was 0.03 M. The mixed sol was ultrasonically treated for 15 minutes to ensure uniform mixing, thus obtaining an aluminum-titanium mixed sol.

[0067] Using an dip-pull method, a glass substrate coated with the initial coating is vertically immersed in the aforementioned aluminum-titanium mixed sol. After immersion for 10 seconds, the substrate is uniformly pulled out of the liquid surface at a speed of 1000 μm / s. The glass coated with the composite coating is placed in a tube furnace and held at 550°C for 2 hours, then cooled to room temperature with the furnace. This heat treatment process ultimately forms a dense, single-layer, multifunctional coating on the glass surface.

[0068] The prepared product was tested, and the highest light transmittance of the coating was approximately 95%, which is lower than that of the coating prepared in Example 1. This is mainly due to the increased proportion of high-refractive-index titanium dioxide (TiO2) components, but it is still significantly higher than that of the glass substrate without the multifunctional coating. Furthermore, the coating maintains a pencil hardness of 4H, and its light transmittance curve remains unchanged after rubbing with nonwoven fabric under a 5 N load, demonstrating excellent mechanical strength. After 45 minutes of UV irradiation, the water contact angle on the coating surface significantly decreased to 2.1°, exhibiting a superior and faster photoinduced superhydrophilic response. This indicates that increasing the content of hydrophilic components can effectively enhance the surface self-cleaning ability of the coating.

[0069] Comparative Example 1

[0070] This comparative example provides a method for preparing a coating without adding titanium dioxide sol, wherein the glass substrate pretreatment, hollow silica nanosphere sol preparation, and hard component sol (alumina sol) preparation are the same as in Example 1.

[0071] (1) Initial coating preparation

[0072] The pretreated glass substrate was vertically immersed in the hollow silica nanosphere sol for 10 seconds. Subsequently, the glass substrate was uniformly pulled out of the liquid surface at a speed of 2000 μm / s, thus obtaining an initial coating composed of hollow silica nanospheres on the glass surface.

[0073] (2) Preparation of hard component coating

[0074] A certain volume of alumina sol was measured and diluted with a certain volume of isopropanol, resulting in a total aluminum ion concentration of 0.2 M in the sol. Using the dip-pull method, a glass substrate with the initial coating was vertically immersed in the alumina sol for 10 seconds, and then uniformly pulled out of the liquid surface at a speed of 1000 μm / s. The glass coated with the hard component was placed in a tube furnace and held at 550 °C for 2 hours, followed by furnace cooling to room temperature. This heat treatment process ultimately forms a dense single-layer coating on the glass surface.

[0075] The prepared product was tested, and the highest transmittance of the coating was 96.56%, which is higher than that of the TiO2-containing coating. Simultaneously, the coating maintained a pencil hardness of 4H, and its transmittance remained stable after friction under a 5 N load, proving that the main hard binder phase provided by alumina is sufficient to ensure the excellent mechanical properties of the coating. After irradiation with ultraviolet light for 45 minutes, the water contact angle of the control coating surface remained stable at around 30°, without exhibiting obvious superhydrophilic properties, demonstrating that the coating without titanium dioxide has poor hydrophilicity and poor self-cleaning ability.

[0076] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A method for preparing a multifunctional coating structure on a glass surface, characterized in that, The specific steps are as follows: S1: Coating hollow silica nanosphere sol onto a clean glass substrate to form an initial coating; S2: Mix the acidified hard component sol and hydrophilic component sol evenly to obtain a mixed sol; the hard component sol is alumina sol, zirconium dioxide sol or cerium dioxide sol, and the pH value is controlled at 3~5; the hydrophilic component sol is titanium dioxide sol, zinc oxide sol or tin dioxide sol, and the pH value is controlled at 2~4. S3: The mixed sol is coated onto the glass substrate surface containing the initial coating obtained in step S1, and then subjected to heat treatment annealing to obtain a multifunctional coating structure on the glass surface with a dense and stable composite coating.

2. The preparation method according to claim 1, characterized in that, The hollow silica nanosphere sol described in step S1 is prepared by template method or microemulsion method; the particle size of the hollow silica nanospheres is 20~100 nanometers.

3. The preparation method according to claim 1, characterized in that, The coating process described in steps S1 and S3 is performed by one of the following methods: dip coating, spin coating, spray coating, roll coating, or screen printing.

4. The preparation method according to claim 1, characterized in that, The total concentration of metal ions in the hard component sol of the mixed sol is 0.1~1 M, and the total concentration of metal ions in the hydrophilic component sol is 0.01~0.5 M.

5. The preparation method according to claim 1, characterized in that, Both the hard component sol and the hydrophilic component sol in step S2 are prepared by the sol-gel method; the precursor of the hard component sol is at least one of aluminum sec-butoxide, aluminum isopropoxide, and aluminum nitrate; the precursor of the hydrophilic component sol is at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, and titanium tetrachloride.

6. The preparation method according to claim 5, characterized in that, The aluminum ion concentration in the hard component sol of the mixed sol is 0.1~0.3 M.

7. The preparation method according to claim 5, characterized in that, The concentration of titanium ions in the hydrophilic component of the mixed sol is 0.01~0.1 M.

8. The preparation method according to claim 1, characterized in that, The heat treatment in step S3 uses a tube furnace or a muffle furnace; the heat treatment temperature is 500~560℃, and the heat treatment time is 1~3 h.

9. A multifunctional coating structure for a glass surface prepared by any one of the preparation methods described in claims 1 to 8.

10. An application of the multifunctional coating structure on a glass surface as described in claim 9, characterized in that, This multifunctional coating structure is used in photovoltaic glass, building energy-saving glass, displays, and windows for automotive photovoltaic and solar thermal systems.

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