A coating solution and an antireflective film

Abstract

This invention relates to the field of optical functional thin film technology, and discloses a coating solution and an antireflective film. The coating solution comprises, by volume, the following components: 1-3 parts of a hollow silica nanoparticle dispersion with a solid content of 15-25%; 3-5 parts of silica sol; 1-3 parts of a film-forming aid; and 8-12 parts of an aqueous solution of an organic temporary binder with a solid content of 0.05-0.2%. In this invention, by combining the hollow particle framework responsible for optical performance with the silica sol binder responsible for mechanical strength, and supplementing it with process control components such as the organic temporary binder and film-forming aid, an antireflective film that maintains a low refractive index while possessing good mechanical strength, adhesion, and durability can be prepared. The effective refractive index of the antireflective film can be controlled between 1.20 and 1.35 by adjusting the formulation ratio, achieving a good match with the refractive indices of air and the optical substrate. The antireflective film of this invention maintains a low refractive index and broadband antireflective performance while also possessing good mechanical strength, adhesion, and environmental stability.

Description

Technical Field

[0001] This invention relates to the field of optical functional thin film technology, and more particularly to a coating solution and an antireflective film. Background Technology

[0002] Anti-reflective coatings, also known as anti-reflective films, are functional thin films coated on the surface of optical components. Their function is to suppress surface reflection through the interference effect of light, thereby significantly improving light transmission efficiency. This technology has been widely used in many fields such as display panels, photovoltaic glass, camera lenses, and museum display cases, becoming a key means of improving the performance of optical systems.

[0003] Currently, the mainstream preparation technologies for antireflective membranes are mainly divided into two categories: One type is the traditional multilayer dielectric film technology, which typically uses materials such as magnesium fluoride, silicon dioxide, and titanium dioxide, and achieves optical interference effects by stacking them layer by layer through a vacuum coating process. Although this method can achieve excellent anti-reflection performance, it relies on high-cost vacuum equipment, has a complex process, and is difficult to achieve uniform coating on large-area or curved substrates, which limits its application in large-scale industrialization.

[0004] Another type is the sol-gel method, which is solution-based and uses low-temperature film formation. It boasts advantages such as simple processing, low cost, and suitability for large-area and curved surface coating, making it a research hotspot in recent years. To achieve broadband antireflection, the effective refractive index is often controlled by introducing nanopores into the film, with common approaches including template methods and phase separation methods. However, these methods generally suffer from a problem: increasing porosity can effectively reduce the refractive index and enhance the antireflection effect, but it often leads to a loose film structure, decreased abrasion resistance, and reduced adhesion; conversely, if high strength and durability are desired, porosity is limited, the refractive index increases, and the antireflection band narrows, making it difficult to achieve a balance between performance and cost.

[0005] Therefore, how to maintain low refractive index and broadband antireflection properties while endowing antireflection films with excellent mechanical strength, adhesion and environmental stability has become a technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0006] This invention provides a coating liquid and an antireflection film to solve at least one of the problems existing in the prior art of antireflection films, so as to ensure that the antireflection film has excellent mechanical strength, good adhesion and environmental stability while maintaining low refractive index and wide-band antireflection performance.

[0007] This invention provides a coating solution, comprising the following components by volume: A dispersion of hollow silica nanoparticles with a solid content of 15-25%, 1-3 parts; Silica sol, 3-5 parts; Film-forming aid, 1-3 parts; An aqueous solution of an organic temporary adhesive with a solid content of 0.05-0.2%, 8-12 parts.

[0008] According to the coating solution provided by the present invention, the solid content of the hollow silica nanoparticle dispersion is 20%.

[0009] According to the coating solution provided by the present invention, the particle size of the hollow silica nanoparticles in the hollow silica nanoparticle dispersion is 20~100nm.

[0010] According to the coating solution provided by the present invention, the equivalent concentration of silica in the silica sol is 1~10wt%.

[0011] According to the coating solution provided by the present invention, the equivalent concentration of silica in the silica sol is 5 wt%.

[0012] According to the coating solution provided by the present invention, the silica sol is selected from one of tetraethyl orthosilicate, methyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, sodium silicate, and fumed silica hydrolysate.

[0013] The coating solution provided by the present invention further includes: a main solvent, 1 to 3 parts; wherein the boiling point of the main solvent is lower than the boiling point of the film-forming aid.

[0014] In the coating solution provided by the present invention, the film-forming aid is an alcohol ether solvent with a boiling point higher than 100°C.

[0015] According to the coating solution provided by the present invention, the organic temporary adhesive in the aqueous solution of the organic temporary adhesive is selected from at least one of polyvinyl alcohol, polyvinylpyrrolidone, hydroxypropyl methylcellulose, polyethylene oxide, and polyethylene glycol.

[0016] In another aspect, the present invention provides an antireflection film, wherein the antireflection film is prepared using the coating solution described in any one of the above claims.

[0017] This invention provides a coating solution that combines a hollow particle framework responsible for optical performance with a silica sol binder responsible for mechanical strength, and supplements it with process control components such as organic temporary binders and film-forming aids. This allows for the preparation of an antireflective film that maintains a low refractive index (high light transmittance) while possessing good mechanical strength, adhesion, and durability. The effective refractive index of the antireflective film can be adjusted between 1.20 and 1.35 by controlling the formulation ratio, achieving a good match with the refractive index of air and optical substrates (such as glass). Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 The graph shows the transmittance curves of blank glass, the antireflection film of Example 1, and the antireflection film of Comparative Example 1. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] A specific embodiment of the first aspect of the present invention provides a coating solution. The coating solution comprises the following components by volume: 1-3 parts of a hollow silica nanoparticle dispersion with a solid content of 15-25%; 3-5 parts of silica sol; 1-3 parts of a film-forming aid; and 8-12 parts of an aqueous solution of an organic temporary binder with a solid content of 0.05-0.2%.

[0022] Hollow silica nanoparticles consist of air inside (refractive index approximately 1.0) and a silica shell (refractive index approximately 1.45). This core-shell structure results in an effective refractive index significantly lower than that of solid silica particles. The hollow structure of the silica nanoparticles themselves provides primary pores, while the gaps formed by the accumulation of particles during film formation constitute secondary pores. This multi-level nanoporous structure is fundamental to reducing the effective refractive index of the film and achieving broadband antireflection. These hollow silica nanoparticles also form the main framework of the antireflection film, providing a basic framework for the subsequent filling and bonding of other components.

[0023] Silica sol contains a large number of silanol groups (-Si-OH). During film formation, this sol further condenses to form a three-dimensional -Si-O-Si- network structure. This network fills the gaps between the hollow silica particles, acting as a welder to firmly bond the dispersed hollow silica nanoparticles together. This ensures that the antireflective membrane has high hardness and good adhesion, resolving the technical contradiction of high porosity leading to low strength in traditional antireflective membranes.

[0024] In its liquid state, the organic temporary binder can adsorb onto the surface of hollow silica nanoparticles, preventing them from agglomerating in the coating solution and ensuring uniform dispersion. Simultaneously, it increases the viscosity of the coating solution, improving leveling properties during the coating process and contributing to the formation of a uniformly thick wet film. In the early stages of film formation, the organic temporary binder also acts as a temporary adhesive, helping to maintain the structural stability of the wet film.

[0025] Film-forming aids are typically high-boiling-point solvents (such as ethylene glycol methyl ether). Their presence slows down the evaporation rate of the entire solvent system. This slower evaporation rate provides a longer leveling time for the wet film, helping to eliminate defects such as streaks and pinholes that may occur during the coating process.

[0026] In this embodiment, hollow silica nanoparticles serve as a "skeleton," pre-constructing a low-refractive-index porous structure to ensure broadband antireflection performance. Silica sol acts as a "strong binder," filling and "welding" this skeleton to form a dense inorganic network, providing high hardness and strong adhesion lacking in traditional porous membranes. This synergy between the rigid skeleton and strong adhesion makes the film both "transparent" and "rigid." During film formation, the film-forming aid ensures the macroscopic uniformity of the film layer by controlling the evaporation process. Simultaneously, the organic temporary binder aqueous solution ensures the uniform dispersion of nanoparticles at the microscopic level and adjusts the viscosity to suit the coating process; together, they ensure a smooth transition from liquid to high-quality solid film.

[0027] This embodiment combines a hollow particle framework responsible for optical performance with a silica sol binder responsible for mechanical strength, and supplements it with process control components such as organic temporary binders and film-forming aids. This allows for the preparation of an antireflective film that maintains a low refractive index (high light transmittance) while possessing good mechanical strength, adhesion, and durability. Furthermore, the effective refractive index of the antireflective film can be controlled between 1.20 and 1.35 through formulation ratios, achieving a good match with the refractive indices of air and optical substrates (such as glass).

[0028] It should be noted that the solid content of the hollow silica nanoparticle dispersion can be flexibly varied within the range of 15% to 25% according to actual needs. Using a higher solid content (e.g., 25%) increases the proportion of low-refractive-index units in the film-forming component, thereby further reducing the effective refractive index of the film and achieving a better anti-reflection effect. Conversely, using a lower solid content (e.g., 15%) means a higher relative proportion of the binder (silica sol), which helps to form a denser adhesive network, thus giving the film stronger mechanical hardness and adhesion. For example, this solid content can be selected from 15%, 20%, and 25%.

[0029] It should be noted that the solid content of the organic temporary binder aqueous solution can be flexibly varied within the range of 0.05% to 0.2% depending on the actual needs. When a specific coating process is required or the stability of the coating solution needs to be enhanced, a higher solid content (such as 0.2%) can be used, which can increase the viscosity of the coating solution, improve leveling, and prevent particle sedimentation. Conversely, when pursuing a thinner film or using processes such as spraying, a lower solid content (such as 0.05%) can be selected to obtain lower application viscosity and better spreadability. This flexible formulation adjustment capability allows the coating solution to balance optical and mechanical properties and can be widely matched with different substrates and production processes. For example, the solid content can be selected as 0.05%, 0.1%, or 0.2%.

[0030] It should be noted that a hollow silica nanoparticle dispersion with a solid content of 15-25% refers to a dispersion in which the mass concentration of hollow silica nanoparticles is 15-25%. A hollow silica nanoparticle dispersion is a colloidal system formed by stably and uniformly dispersing nanoparticles with an internal cavity and a silica outer shell in a liquid medium (such as water or ethanol).

[0031] For example, the hollow silica nanoparticle dispersion is a mixture of hollow silica nanoparticles and ethanol. In other words, the hollow silica nanoparticle dispersion is obtained by dispersing hollow silica nanoparticles in ethanol.

[0032] It should be noted that an aqueous solution of organic temporary adhesive with a solid content of 0.05~0.2% means that the mass concentration of organic temporary adhesive in the aqueous solution is 0.05~0.2%.

[0033] For example, an aqueous solution of organic temporary adhesive is a mixture of organic temporary adhesive and water; in other words, an aqueous solution of organic temporary adhesive is obtained by mixing organic temporary adhesive with water.

[0034] Optionally, the hollow silica nanoparticles in the dispersion have a particle size of 20–100 nm. Controlling the particle size within this range (20–100 nm) ensures that the size is much smaller than the wavelength of visible light (400–800 nm), preventing Rayleigh scattering and ensuring that the film maintains high transparency and clarity while achieving a low refractive index, without exhibiting a hazy appearance due to the presence of particles. Alternatively, using hollow silica nanoparticles with a particle size greater than 20 nm can reduce costs while still maintaining a low refractive index.

[0035] Optionally, the film-forming aid is an alcohol ether solvent with a boiling point above 100℃. A higher boiling point slows down the overall evaporation rate of the coating solution after coating, thus providing a longer leveling time for the wet film. This helps reduce the risk of defects such as streaks and pinholes during coating, allowing the hollow silica nanoparticles and silica sol components to be fully aligned. Simultaneously, the alcohol ether solvent's molecular structure contains both ether bonds and hydroxyl groups, exhibiting excellent amphiphilicity. This allows it to act as a bridge to improve the compatibility between components of different polarities in the coating solution, preventing system delamination and ensuring the uniformity of the final composite film.

[0036] Preferably, the alcohol ether solvent is selected from at least one of ethylene glycol methyl ether, ethylene glycol monobutyl ether, ethylene glycol monopropyl ether, ethylene glycol phenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monohexyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, and dipropylene glycol methyl ether. This series of solvents provides a wide range of boiling points and solubility options, allowing the drying characteristics of the coating solution to be controlled according to specific coating processes (such as dip coating, spin coating, etc.) and environmental conditions, thereby achieving better film quality and repeatability in different production scenarios.

[0037] Optionally, the organic temporary binder is selected from at least one of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC), polyethylene oxide (PEO), and polyethylene glycol (PEG). These organic polymers, acting as temporary binders, play a stabilizing and rheological control role in the coating solution. Their long-chain structures can adsorb onto the surface of hollow silica nanoparticles, forming steric hindrance and preventing the agglomeration of hollow silica nanoparticles during storage and coating, thereby ensuring the uniformity and stability of the coating solution and reducing the risk of optical scattering points in the film. Simultaneously, these polymers can also increase the viscosity of the coating solution, optimize the leveling performance during coating, and contribute to the formation of a uniform wet film. In the early stages of film formation, they can also provide temporary adhesion, maintaining the stability of the porous structure before the inorganic network is fully formed.

[0038] Preferably, the degree of polymerization of polyvinyl alcohol (PVA) is 200 to 2000. The molecular weight of polyvinylpyrrolidone (PVP) is in the range of 2000 to 54000.

[0039] Optionally, the silica sol is selected from one of tetraethyl orthosilicate, methyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, sodium silicate, and fumed silica hydrolysate. In other words, the silica sol is prepared using at least one of tetraethyl orthosilicate, methyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, sodium silicate, and fumed silica as a precursor.

[0040] For example, silica sol is obtained by hydrolyzing tetraethyl orthosilicate in an alcohol-water system containing an acidic catalyst. Preferably, the acidic catalyst includes at least one of hydrochloric acid, nitric acid, and acetic acid. By preparing silica oligomers rich in active silanol groups (-Si-OH) through hydrolysis of tetraethyl orthosilicate in an acidic alcohol-water system, the stability of the sol and its high reactivity during subsequent film formation are ensured. During film curing, these oligomers further condense to form a continuous, dense three-dimensional -Si-O-Si- network structure. This network fills the gaps in the hollow silica particle skeleton, firmly "welding" the originally loosely packed nanoparticles together, giving the porous film excellent cohesion. Simultaneously, the silanol groups on its surface can undergo dehydration condensation reactions with the hydroxyl groups on the surface of optical substrates (such as glass) to form stable chemical bonds. This results in a final film with strong adhesion (up to grade 0) and a pencil hardness of over 3H, solving the problem of poor mechanical properties in traditional porous membranes.

[0041] Optionally, the equivalent concentration of silica in the silica sol is 1–10 wt%. Here, wt% refers to the mass percentage. Using a lower concentration (e.g., close to 1%) allows for sufficient bonding without overfilling the pores between particles, thus preserving the porosity of the film and achieving a lower refractive index and higher light transmittance. Conversely, using a higher concentration (e.g., close to 10%) results in a denser and more robust bonding network, thereby improving the film's hardness and adhesion to meet more stringent durability requirements. Therefore, by adjusting the mass concentration within this range, a balance can be achieved between optical performance and mechanical strength according to specific application needs.

[0042] It should be noted that the equivalent concentration of silica in the silica sol can be flexibly adjusted within the range of 1wt% to 10wt% according to actual needs. For example, the equivalent concentration can be selected as one of 1wt%, 5wt%, or 10wt%.

[0043] It should be noted that the equivalent concentration of silica in silica sol of 1~10wt% means that the mass percentage is calculated as 1% to 10% based on the mass of silica that can be generated after the complete hydrolysis and condensation of all silicon sources (such as tetraethyl orthosilicate) in the sol.

[0044] In some embodiments of the present invention, the coating solution further includes 1-3 parts by volume of a main solvent; wherein the boiling point of the main solvent is lower than that of the film-forming aid. In other words, the coating solution includes the following components by volume: 1-3 parts of a hollow silica nanoparticle dispersion with a solid content of 15-25%; 1-3 parts of a main solvent; 3-5 parts of silica sol; 1-3 parts of a film-forming aid; and 8-12 parts of an aqueous solution of an organic temporary binder with a solid content of 0.05-0.2%.

[0045] The primary solvent, as the main solvent, plays a crucial role in dissolving or dispersing all solid and liquid components to form a homogeneous, stable liquid system with a suitable application viscosity, which is a prerequisite for successful coating application. The primary solvent and film-forming aids together constitute the solvent system. The primary solvent ensures the compatibility of the components, while the film-forming aids ensure the macroscopic uniformity of the film layer by controlling the evaporation process. Simultaneously, the aqueous solution of the organic temporary binder ensures the uniform dispersion of nanoparticles at the microscopic level and adjusts the viscosity to suit the coating process. Together, these three elements ensure a smooth transition from liquid to a high-quality solid film.

[0046] Optionally, the main solvent is selected from at least one of water, lower alcohol solvents, alcohol ether solvents, ketone solvents, ester solvents, and glycol ether esters; wherein, the lower alcohol solvent is selected from at least one of ethanol, ethylene glycol, propylene glycol, n-propanol, n-butanol, and isopropanol; the alcohol ether solvent is selected from at least one of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol methyl ether, and propylene glycol ethyl ether; the ketone solvent is selected from acetone or methyl ethyl ketone; the ester solvent is selected from ethyl acetate or ethyl lactate; and the glycol ether ester is selected from propylene glycol methyl ether acetate.

[0047] A specific embodiment of the second aspect of the present invention provides a method for preparing a coating solution. The method for preparing the coating solution includes: S1. Under stirring conditions, the main solvent is slowly added to the hollow silica nanoparticle dispersion with a solid content of 15-25% and mixed evenly to obtain pre-dispersion A; wherein, the main solvent is 1-3 parts and the hollow silica nanoparticle dispersion with a solid content of 15-25% is 1-3 parts.

[0048] S2. Mix silica sol with a high-boiling-point film-forming aid and stir until homogeneous to obtain mixture B; wherein, silica sol is 3-5 parts and film-forming aid is 1-3 parts.

[0049] S3. While stirring continuously, add mixture B dropwise to predispersant A at a rate of 1~3 mL / min. After the addition is complete, continue stirring to obtain mixture C.

[0050] S4. Under vigorous stirring, add an aqueous solution of organic temporary binder with a solid content of 0.05~0.2% to the mixture C at a rate of 1~3 mL / min. After the addition is complete, continue stirring to obtain a uniform, semi-transparent, slightly opalescent coating solution.

[0051] A specific embodiment of the third aspect of the present invention provides an antireflection film. This antireflection film is prepared using the coating solution described in any of the above embodiments.

[0052] The antireflective film in this embodiment is a silica film with a nanocomposite porous structure. The antireflective film has a pencil hardness of 3H or higher, a cross-cut adhesion rating of 0, and excellent abrasion resistance. As a silica-based organic composite film, it possesses good weather resistance, UV aging resistance, and chemical stability. This film has a low effective refractive index in the visible light region, increasing the light transmittance of the glass substrate by 3-5%, while also exhibiting high hardness, strong adhesion, and excellent durability.

[0053] In some embodiments, the method for preparing the antireflective membrane includes the following steps: S10. Using one of the dip-coating method, spin coating method or meniscus coating method, the coating liquid of any of the above embodiments is coated onto the surface of the optical substrate to form a wet film. S20. Level the optical substrate coated with the wet film at room temperature while it is horizontal and stationary. S30. Place the leveled optical substrate horizontally and cure at room temperature to form an antireflective film on the surface of the optical substrate.

[0054] The preparation method of this embodiment does not require complex vacuum equipment, the process is simple and low cost, it can be cured at room temperature, and it is suitable for antireflection treatment of large-area optical components. The film thickness can also be controlled by adjusting the coating process parameters (such as lifting speed and spin coating speed). For example, the thickness of the antireflection film can be controlled in the range of 80~150nm by adjusting the coating process parameters.

[0055] It should be noted that before S10, the process also includes cleaning the optical substrate and drying it with nitrogen gas to ensure the cleanliness of the optical substrate.

[0056] Example 1 1. The coating solution is prepared by the following steps: Take 300 mL of hollow silica nanoparticle ethanol dispersion with a solid content of 20% (particle size of about 50 nm) and place it in a beaker. Slowly add 300 mL of anhydrous ethanol under magnetic stirring and stir for 10 minutes to obtain pre-dispersion A.

[0057] Take 500 mL of silica sol (equivalent silica concentration of about 2.5 wt%) prepared by acidic hydrolysis of TEOS (tetraethyl orthosilicate) and mix it with 300 mL of ethylene glycol methyl ether. Stir for 5 minutes to obtain mixture B.

[0058] While stirring, mixture B was added dropwise to predispersant A at a rate of about 2 mL / min. After the addition was complete, stirring was continued for 20 minutes to obtain mixture C.

[0059] Prepare a 0.1% PVP (polyvinylpyrrolidone) aqueous solution (average molecular weight 50,000). Under vigorous stirring, slowly add 1200 mL of this PVP aqueous solution to mixture C. After the addition is complete, continue stirring for 40 minutes to obtain a uniform, semi-transparent, slightly opalescent coating solution. Seal and let stand for 12 hours before use.

[0060] 2. The antireflective membrane is prepared using the following steps: Ordinary glass slides were ultrasonically cleaned in sequence with dish soap, deionized water, acetone, and ethanol, and then dried with nitrogen.

[0061] The immersion-lift method is used. The glass slide is vertically immersed into the coating solution at a speed of 200 mm / min. After standing for 10 seconds, it is lifted out of the liquid surface at a uniform speed of 100 mm / min.

[0062] The pulled-out glass slide was left to level horizontally for 2 minutes in a dust-free environment at room temperature, and then cured at room temperature for 24 hours, successfully preparing an antireflective film on the glass slide.

[0063] Example 2 Compared to Example 1, Example 2 adjusted the proportions of the components in the coating solution as follows: 225 mL of hollow silica nanoparticle dispersion, 275 mL of ethanol, 500 mL of silica sol, 225 mL of ethylene glycol methyl ether, and 1000 mL of a 0.08% PVP aqueous solution. The preparation methods for the coating solution and the antireflective film were the same as in Example 1.

[0064] The antireflection film of Example 2 was tested using a UV-Vis spectrophotometer. The transmittance of the antireflection film of Example 2 reached 95% at 550 nm, indicating that applying the antireflection film of Example 2 to blank glass can increase the transmittance by approximately 3%. The pencil hardness of the antireflection film of Example 2 is 3H, and its adhesion in the cross-cut adhesion test is grade 0. After rubbing with a soft cloth bearing a weight of 500g 100 times, the transmittance change is less than 0.1%. The antireflection film of Example 2 was aged in an environment with a temperature of 85°C and a humidity of 85% for 600 hours, and then exposed to ultraviolet (UV) radiation for 400 hours; its optical properties and adhesion showed no significant degradation.

[0065] Example 3 Compared to Example 1, Example 3 adjusted the proportions of the components in the coating solution as follows: 275 mL of hollow silica nanoparticle dispersion, 225 mL of ethanol, 400 mL of acidic silica sol, 275 mL of ethylene glycol methyl ether, and 1100 mL of a 0.12% PVP aqueous solution. The preparation methods for both the coating solution and the antireflective film were the same as in Example 1.

[0066] The antireflection film of Example 3 was tested using a UV-Vis spectrophotometer. The transmittance of the antireflection film of Example 3 reached 95.6% at 550 nm, indicating that applying the antireflection film of Example 3 to blank glass can increase the transmittance by approximately 3.6%. The pencil hardness of the antireflection film of Example 3 is 3H, and its adhesion in the cross-cut adhesion test is grade 0. After rubbing with a soft cloth bearing a weight of 500g 100 times, the transmittance change is less than 0.1%. The antireflection film of Example 3 was aged in an environment with a temperature of 85°C and a humidity of 85% for 500 hours, and then exposed to ultraviolet (UV) radiation for 400 hours; its optical properties and adhesion showed no significant degradation.

[0067] Example 4 Take 100 mL of hollow silica nanoparticle ethanol dispersion with a solid content of 15% (particle size of about 20 nm) and place it in a beaker. Slowly add 100 mL of anhydrous isopropanol under magnetic stirring and stir for 15 minutes to obtain pre-dispersion A.

[0068] Take 300 mL of silica sol (equivalent silica concentration of about 1 wt%) prepared by acidic hydrolysis of TEOS (tetraethyl orthosilicate) and mix it with 100 mL of ethylene glycol monopropyl ether. Stir for 10 minutes to obtain mixture B.

[0069] While stirring, mixture B was added dropwise to predispersant A at a rate of about 1 mL / min. After the addition was complete, stirring was continued for 20 minutes to obtain mixture C.

[0070] Prepare a PVP aqueous solution with a solid content of 0.05%. Under vigorous stirring, slowly add 800 mL of this PVP aqueous solution to mixture C. After the addition is complete, continue stirring for 50 minutes to obtain a uniform, semi-transparent, slightly opalescent coating solution. Seal and let stand for 18 hours before use.

[0071] 2. The antireflective membrane is prepared using the following steps: Ordinary glass slides were ultrasonically cleaned in sequence with dish soap, deionized water, acetone, and ethanol, and then dried with nitrogen.

[0072] The immersion-lift method is used. The glass slide is vertically immersed into the coating solution at a speed of 150 mm / min. After standing for 10 seconds, it is lifted out of the liquid surface at a uniform speed of 80 mm / min.

[0073] The pulled-out glass slide was left to level horizontally for 5 minutes in a dust-free environment at room temperature, and then cured at room temperature for 24 hours, successfully preparing an antireflective film on the glass slide.

[0074] The antireflection film of Example 4 was tested using a UV-Vis spectrophotometer. The transmittance of the antireflection film of Example 4 reached 96.3% at 550 nm, indicating that applying the antireflection film of Example 4 to blank glass can increase the transmittance by approximately 4.3%. The pencil hardness of the antireflection film of Example 4 is 4H, and its adhesion in the cross-cut adhesion test is grade 0. After rubbing with a soft cloth bearing a weight of 500g 100 times, the transmittance change is less than 0.1%. The antireflection film of Example 4 was aged in an environment with a temperature of 85°C and a humidity of 85% for 600 hours, and then exposed to ultraviolet (UV) radiation for 400 hours; its optical properties and adhesion showed no significant degradation.

[0075] Example 5 Take 200 mL of hollow silica nanoparticle ethanol dispersion with a solid content of 18% (particle size of about 40 nm) and place it in a beaker. Slowly add 300 mL of anhydrous isopropanol under magnetic stirring and stir for 20 minutes to obtain pre-dispersion A.

[0076] Take 400 mL of silica sol (equivalent silica concentration of about 5 wt%) prepared by acidic hydrolysis of TEOS (tetraethyl orthosilicate) and mix it with 200 mL of diethylene glycol monoethyl ether. Stir for 10 minutes to obtain mixture B.

[0077] While stirring, mixture B was added dropwise to predispersant A at a rate of about 3 mL / min. After the addition was complete, stirring was continued for 20 minutes to obtain mixture C.

[0078] Prepare an HPMC aqueous solution with a solid content of 0.1%. Under vigorous stirring, slowly add 1000 mL of the HPMC aqueous solution to mixture C. After the addition is complete, continue stirring for 50 minutes to obtain a uniform, semi-transparent, slightly opalescent coating solution. Seal and let stand for 15 hours before use.

[0079] 2. The antireflective membrane is prepared using the following steps: Ordinary glass slides were ultrasonically cleaned in sequence with dish soap, deionized water, acetone, and ethanol, and then dried with nitrogen.

[0080] The immersion-lift method is used. The glass slide is vertically immersed into the coating solution at a speed of 100 mm / min. After standing for 5 seconds, it is lifted out of the liquid surface at a uniform speed of 50 mm / min.

[0081] The pulled-out glass slide was left to level horizontally for 2 minutes in a dust-free environment at room temperature, and then cured at room temperature for 24 hours, successfully preparing an antireflective film on the glass slide.

[0082] The antireflection film of Example 5 was tested using a UV-Vis spectrophotometer. The transmittance of the antireflection film of Example 5 reached 95.8% at 550 nm, indicating that applying the antireflection film of Example 5 to blank glass can increase the transmittance by approximately 3.8%. The pencil hardness of the antireflection film of Example 5 is 3H, and its adhesion in the cross-cut adhesion test is grade 0. After rubbing with a soft cloth bearing a weight of 500g 100 times, the transmittance change is less than 0.1%. The antireflection film of Example 5 was aged in an environment with a temperature of 85°C and a humidity of 85% for 550 hours, and then exposed to ultraviolet (UV) radiation for 300 hours; its optical properties and adhesion showed no significant degradation.

[0083] Example 6 Take 300 mL of hollow silica nanoparticle ethanol dispersion with a solid content of 25% (particle size of about 100 nm) and place it in a beaker. Slowly add 300 mL of anhydrous ethanol under magnetic stirring and stir for 20 minutes to obtain pre-dispersion A.

[0084] Take 500 mL of silica sol (equivalent silica concentration of about 10 wt%) prepared by acidic hydrolysis of TEOS (tetraethyl orthosilicate) and mix it with 300 mL of propylene glycol monobutyl ether. Stir for 10 minutes to obtain mixture B.

[0085] While stirring, mixture B was added dropwise to predispersant A at a rate of approximately 1.5 mL / min. After the addition was complete, stirring was continued for 20 minutes to obtain mixture C.

[0086] Prepare a PEO aqueous solution with a solid content of 0.2%. Under vigorous stirring, slowly add 1200 mL of this PEO aqueous solution to mixture C. After the addition is complete, continue stirring for 50 minutes to obtain a uniform, semi-transparent, slightly opalescent coating solution. Seal and let stand for 12 hours before use.

[0087] 2. The antireflective membrane is prepared using the following steps: Ordinary glass slides were ultrasonically cleaned in sequence with dish soap, deionized water, acetone, and ethanol, and then dried with nitrogen.

[0088] The immersion-lift method is used. The glass slide is vertically immersed into the coating solution at a speed of 300 mm / min. After standing for 20 seconds, it is lifted out of the liquid surface at a speed of 200 mm / min.

[0089] The pulled-out glass slide was left to level horizontally for 5 minutes in a dust-free environment at room temperature, and then cured at room temperature for 24 hours, successfully preparing an antireflective film on the glass slide.

[0090] The antireflection film of Example 6 was tested using a UV-Vis spectrophotometer. The transmittance of the antireflection film of Example 6 reached 96.1% at 550 nm, indicating that applying the antireflection film of Example 6 to blank glass can increase the transmittance by approximately 4.1%. The pencil hardness of the antireflection film of Example 6 is 4H, and its adhesion in the cross-cut adhesion test is grade 0. After rubbing with a soft cloth bearing a weight of 500g 100 times, the transmittance change is less than 0.1%. The antireflection film of Example 6 was aged in an environment with a temperature of 85°C and a humidity of 85% for 500 hours, and then exposed to ultraviolet (UV) radiation for 300 hours; its optical properties and adhesion showed no significant degradation.

[0091] Comparative Example 1 1. The coating solution is prepared by the following steps: Take 1200 mL of silica sol (equivalent silica concentration of about 2.5 wt%) prepared by acidic hydrolysis of TEOS (tetraethyl orthosilicate) and mix it with 300 mL of ethylene glycol methyl ether. Stir for 5 minutes to obtain mixture D. Prepare a 0.1% PVP (polyvinylpyrrolidone) aqueous solution (average molecular weight 50,000). Under vigorous stirring, slowly add 1200 mL of this PVP aqueous solution to mixture D. After the addition is complete, continue stirring for 120 minutes to obtain a uniform, semi-transparent, slightly opalescent coating solution. Seal and let stand for 12 hours before use.

[0092] 2. The antireflective membrane is prepared using the following steps: Ordinary glass slides were ultrasonically cleaned in sequence with dish soap, deionized water, acetone, and ethanol, and then dried with nitrogen.

[0093] The immersion-lift method is used. The glass slide is vertically immersed into the coating solution at a speed of 200 mm / min. After standing for 10 seconds, it is lifted out of the liquid surface at a uniform speed of 100 mm / min.

[0094] The pulled-out glass slide was left to level horizontally for 2 minutes in a dust-free environment at room temperature, and then cured at room temperature for 24 hours, successfully preparing an antireflective film on the glass slide.

[0095] In other words, no hollow silica nanoparticles were added in Comparative Example 1.

[0096] Comparative Example 2 1. The coating solution is prepared by the following steps: Take 600 mL of hollow silica nanoparticle ethanol dispersion with a solid content of 20% (particle size of about 50 nm) and place it in a beaker. Slowly add 300 mL of anhydrous ethanol and 300 mL of ethylene glycol methyl ether under magnetic stirring. Stir for 20 minutes to obtain mixture E.

[0097] Prepare a 0.1% solids content PVP (polyvinylpyrrolidone) aqueous solution (average molecular weight 50,000). Under vigorous stirring, slowly add 1200 mL of this PVP aqueous solution to mixture E. After the addition is complete, continue stirring for 120 minutes to obtain a uniform, semi-transparent, slightly opalescent coating solution. Seal and let stand for 12 hours before use.

[0098] 2. The antireflective membrane is prepared using the following steps: Ordinary glass slides were ultrasonically cleaned in sequence with dish soap, deionized water, acetone, and ethanol, and then dried with nitrogen.

[0099] The immersion-lift method is used. The glass slide is vertically immersed into the coating solution at a speed of 200 mm / min. After standing for 10 seconds, it is lifted out of the liquid surface at a uniform speed of 100 mm / min.

[0100] The pulled-out glass slide is left to level horizontally for 2 minutes in a dust-free environment at room temperature. After curing at room temperature, a loose film is formed on the glass slide, and the film is prone to cracking and falling off.

[0101] Table 1. Components and proportions of the coating solutions in each embodiment and comparative example.

[0102] In Table 1, SiO2 represents silicon dioxide.

[0103] The antireflection membranes of Example 1 and Comparative Example 1 were tested using a UV-Vis spectrophotometer, and the results are as follows: Figure 1 As shown, the transmittance of the glass (i.e., blank glass) at 550 nm is 92%, while the antireflective film of Example 1 achieves a transmittance of 96.2% at 550 nm, indicating that applying the antireflective film of Example 1 to the blank glass can increase the transmittance by about 4%. The film of Comparative Example 1 has a high refractive index and limited antireflective effect, with a transmittance of only about 93.5% at 550 nm. The film of Comparative Example 2 is porous and easily cracks and peels off after curing at room temperature, failing to form a complete optical film.

[0104] The antireflective film of Example 1 has a pencil hardness of 4H and an adhesion rating of 0 in the cross-cut adhesion test. After rubbing with a soft cloth bearing a weight of 500g for 100 cycles, the light transmittance changes by less than 0.1%.

[0105] The antireflective film of Example 1 was aged for 500 hours in an environment with a temperature of 85°C and a humidity of 85%, and then exposed to ultraviolet (UV) light for 300 hours. Its optical properties and adhesion did not show significant degradation.

[0106] The test results above show that the antireflective film of Example 1 has ultra-low refractive index, ultra-high light transmittance, excellent mechanical strength and good durability. Moreover, the process is simple and the cost is low, which has broad prospects for industrial application.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coating solution, characterized in that, Based on volume parts, it includes the following components: A dispersion of hollow silica nanoparticles with a solid content of 15-25%, 1-3 parts; Silica sol, 3-5 parts; Film-forming aid, 1-3 parts; An aqueous solution of an organic temporary adhesive with a solid content of 0.05-0.2%, 8-12 parts.

2. The coating solution according to claim 1, characterized in that, The solid content of the hollow silica nanoparticle dispersion is 20%.

3. The coating solution according to claim 1, characterized in that, The hollow silica nanoparticles in the hollow silica nanoparticle dispersion have a particle size of 20~100nm.

4. The coating solution according to claim 1, characterized in that, The equivalent concentration of silica in the silica sol is 1~10wt%.

5. The coating solution according to claim 4, characterized in that, The equivalent concentration of silica in the silica sol is 5 wt%.

6. The coating solution according to claim 1, characterized in that, The silica sol is selected from one of tetraethyl orthosilicate, methyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, sodium silicate, and fumed silica hydrolysate.

7. The coating solution according to any one of claims 1 to 6, characterized in that, Also includes: Main solvent, 1-3 parts; wherein the boiling point of the main solvent is lower than the boiling point of the film-forming aid.

8. The coating solution according to any one of claims 1 to 6, characterized in that, The film-forming aid is an alcohol ether solvent with a boiling point higher than 100°C.

9. The coating solution according to any one of claims 1 to 6, characterized in that, The organic temporary adhesive in the aqueous solution is selected from at least one of polyvinyl alcohol, polyvinylpyrrolidone, hydroxypropyl methylcellulose, polyethylene oxide, and polyethylene glycol.

10. An antireflective membrane, characterized in that, The antireflective film is prepared using the coating solution described in any one of claims 1 to 9.

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