Sodium water glass-based anti-reflection film and preparation method thereof

Abstract

The invention belongs to the technical field of optical thin films, and discloses a sodium water glass-based anti-reflection film and a preparation method thereof, and the preparation method comprises the following steps: 1) diluting sodium water glass, dropwise adding hydrochloric acid to adjust the pH value, stirring for reaction, and standing for aging to obtain aqueous silicon dioxide sol; (2) immersing the substrate into the water-based silicon dioxide sol, and pulling the substrate out of the water-based silicon dioxide sol to form a silicon oxide wet film on the surface of the substrate; 3) naturally drying the wet silicon oxide film in the air, cleaning with water, and drying by nitrogen flow to obtain a silicon oxide film; and 4) heating the silicon oxide film and carrying out heat treatment to obtain the sodium water glass-based anti-reflection film. The water-based silicon dioxide sol is prepared by taking sodium water glass as a precursor, water as a solvent and hydrochloric acid as a catalyst, so that the anti-reflection film is further prepared, and compared with an anti-reflection film prepared by an organic system, the cost and the environmental pollution can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of optical films, and in particular relates to a sodium water glass-based anti-reflection film and a preparation method thereof. Background Art

[0002] Anti-reflection film, also known as anti-reflection film, is applied to the surface of optical components to reduce the reflection of light on the surface of the optical components, increase the transmittance of light, and thus improve the working efficiency of the optical components in a specific band. At present, the material for preparing anti-reflection film is mainly silicon dioxide, and the preparation method is mainly sol-gel method, which has the advantages of simple operation, low cost, and industrial large-scale production.

[0003] However, the precursor reagents and solvents used in the preparation of silica anti-reflection film by the sol-gel method are mainly organic reagents. Due to the toxicity and volatility of organic matter, as well as the subsequent treatment process, a large amount of CO2 will be produced, which will cause certain pollution to the environment and aggravate the greenhouse effect. Therefore, it is necessary to explore a safer, less polluting, easy-to-operate and low-cost method for preparing anti-reflection film. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a sodium water glass-based anti-reflection film and a preparation method thereof in view of the shortcomings of the prior art. The method uses sodium water glass as a precursor, water as a solvent, and hydrochloric acid as a catalyst to prepare an aqueous silica sol and then prepare the anti-reflection film. Compared with the preparation of the anti-reflection film by an organic system, the method can reduce the cost and the pollution to the environment.

[0005] In order to solve the technical problem proposed by the present invention, the present invention provides a method for preparing a sodium water glass-based anti-reflection film, comprising the following steps:

[0006] 1) diluting sodium water glass, adding hydrochloric acid to adjust the pH value, stirring the reaction and then standing for aging to obtain an aqueous silica sol;

[0007] 2) immersing the substrate in an aqueous silica sol, and then pulling it out from the aqueous silica sol to form a silicon oxide wet film on the surface of the substrate;

[0008] 3) After the wet silicon oxide film is naturally dried in the air, it is washed with water and then dried with a nitrogen flow to obtain a silicon oxide film;

[0009] 4) The silicon oxide film is subjected to heat treatment by increasing the temperature to obtain a sodium water glass-based anti-reflection film.

[0010] In the above solution, the modulus of the sodium water glass is 2.3-3.8.

[0011] In the above scheme, after the sodium water glass is diluted, the concentration of sodium silicate therein is 2-5wt%.

[0012] In the above scheme, the concentration of the hydrochloric acid is 1-6 mol / L.

[0013] In the above scheme, the pH value is adjusted to 9-11.

[0014] In the above scheme, the stirring rate is 400-600r / min, and the stirring reaction time is 3-10h.

[0015] In the above scheme, the static aging time is 1-7 days.

[0016] In the above scheme, the substrate is immersed in the aqueous silica sol at a speed of 60-100 mm / min, maintained for 60-90 seconds after being completely immersed, and then pulled out of the aqueous silica sol at a speed of 60-100 mm / min.

[0017] In the above scheme, the natural drying time is 10-20 minutes.

[0018] In the above scheme, the time of washing with water is 20-60s.

[0019] In the above scheme, the drying time of the nitrogen flow is 5-30s.

[0020] In the above scheme, the heat treatment temperature is 300-550°C, and the heat treatment time is 0.5-4h.

[0021] Preferably, the heat treatment temperature is 400-500° C., and the heat treatment time is 0.5-2 h.

[0022] The invention also provides a sodium water glass-based anti-reflection film, which is prepared by the above method.

[0023] In the above scheme, the sodium water glass-based anti-reflection film has a thickness of 55-160 nm, a porosity of 8-51%, and a refractive index of 1.25-1.43.

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

[0025] 1) The present invention uses cheap and readily available sodium water glass as a precursor, water as a solvent, and hydrochloric acid as a catalyst to prepare an aqueous silica sol, and then deposits the aqueous silica sol on a substrate by a pulling method to prepare an anti-reflection film; the method can adjust the porosity of the anti-reflection film by adjusting the amount of hydrochloric acid added, effectively reduce the refractive index of the anti-reflection film, and improve the transmittance of the optical element; in order to avoid the negative impact of sodium salt in the aqueous silica sol on the performance, the silicon oxide film can be washed with water to remove the sodium salt, and there is no need to separate the sodium salt by precipitation of an organic solvent during the preparation of the aqueous silica sol, and then the water on the surface of the film is blown dry with a nitrogen gas flow, thereby reducing contact with air and avoiding OH in the film- The reaction with CO2 in the air reduces the performance of the film; thus, the excellent performance of the anti-reflection film is guaranteed without using organic reagents.

[0026] 2) The preparation process of the present invention is simple and easy to operate. Compared with the organic system, it has lower cost and reduces CO2 emissions, delays the greenhouse effect, is environmentally friendly, green and less polluting, is conducive to large-scale industrial application, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope surface morphology image of the sodium water glass-based anti-reflection film of Example 1.

[0028] Figure 2 It is the transmittance spectrum of the sodium water glass based anti-reflection film of Example 1.

[0029] Figure 3 This is a scanning electron microscope surface morphology image of the sodium water glass-based anti-reflection film of Example 2.

[0030] Figure 4 It is the transmittance spectrum of the sodium water glass based anti-reflection film of Example 2. DETAILED DESCRIPTION

[0031] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] A method for preparing a sodium water glass-based anti-reflection film comprises the following steps:

[0034] 1) diluting sodium silicate with a modulus of 3.6 with deionized water to a sodium silicate concentration of 2 wt %, adding 1 mol / L hydrochloric acid to adjust the pH value to 9.4, stirring the mixture at a rate of 600 r / min for 6 h, and then standing and aging the mixture for 6 d to obtain an aqueous silica sol;

[0035] 2) immersing the glass substrate in the aqueous silica sol at a speed of 100 mm / min, maintaining it for 90 seconds after being completely immersed, and then pulling it out of the aqueous silica sol at a speed of 100 mm / min to form a silicon oxide wet film on the surface of the substrate;

[0036] 3) The wet silicon oxide film was dried naturally in air for 15 min, washed with water for 20 s, and then dried in nitrogen flow for 15 s to obtain a silicon oxide film;

[0037] 4) The silicon oxide film is placed in a muffle furnace and heat treated at 500° C. for 0.5 h to obtain a sodium water glass-based anti-reflection film.

[0038] from Figure 1 It can be seen that the film prepared by the present invention has good surface uniformity and high porosity, the porosity is 51%, and the film thickness is 108.1nm; Figure 2 It can be seen that within 380-1100nm, the average transmittance of the uncoated glass substrate is 88.4%, and the average transmittance of the coated glass substrate can reach 91.91%, an increase of 3.51%; under this parameter, the refractive index of the anti-reflection film is 1.25.

[0039] Example 2

[0040] A method for preparing a sodium water glass-based anti-reflection film comprises the following steps:

[0041] 1) diluting sodium silicate with a modulus of 3.6 with deionized water to a sodium silicate concentration of 2 wt%, adding 2 mol / L hydrochloric acid to adjust the pH value to 9.8, stirring the mixture at a rate of 500 r / min for 8 h, and then aging the mixture for 7 days to obtain an aqueous silica sol;

[0042] 2) immersing the glass substrate in the aqueous silica sol at a speed of 100 mm / min, maintaining the glass substrate for 60 seconds after being completely immersed, and then pulling it out of the aqueous silica sol at a speed of 100 mm / min to form a silicon oxide wet film on the surface of the substrate;

[0043] 3) The wet silicon oxide film was dried naturally in air for 10 min, washed with water for 30 s, and then dried with nitrogen flow for 10 s to obtain a silicon oxide film;

[0044] 4) The silicon oxide film is placed in a muffle furnace and heat treated at 500° C. for 0.5 h to obtain a sodium water glass-based anti-reflection film.

[0045] from Figure 3 It can be seen that the film prepared by the present invention has good surface uniformity and high porosity, the porosity is 39%, and the film thickness is 54.8nm; Figure 4 It can be seen that within the range of 380-1100nm, the average transmittance of the uncoated glass substrate is 88.4%, and the average transmittance of the coated glass substrate can reach 91.4%, an increase of 3.0%; under this parameter, the refractive index of the anti-reflection film is 1.3.

[0046] Example 3

[0047] 1) diluting sodium silicate with a modulus of 3.2 with deionized water to a sodium silicate concentration of 5 wt %, adding 6 mol / L hydrochloric acid to adjust the pH value to 10.6, stirring the mixture at a rate of 600 r / min for 10 h, and then standing and aging for 3 days to obtain an aqueous silica sol;

[0048] 2) immersing the glass substrate into the aqueous silica sol at a speed of 80 mm / min, maintaining the glass substrate completely immersed for 90 seconds, and then pulling it out of the aqueous silica sol at a speed of 80 mm / min to form a silicon oxide wet film on the surface of the substrate;

[0049] 3) The wet silicon oxide film was dried naturally in air for 20 min, washed with water for 60 s, and then dried in nitrogen flow for 30 s to obtain a silicon oxide film;

[0050] 4) The silicon oxide film is placed in a muffle furnace and heat treated at 450° C. for 2 h to obtain a sodium water glass-based anti-reflection film.

[0051] The film prepared by the present invention has a high porosity of 48% and a film thickness of 90.3nm; within 380-1100nm, the average transmittance of the uncoated glass substrate is 88.4%, and the average transmittance of the coated glass substrate can reach 91.42%, an increase of 3.02%; under this parameter, the refractive index of the anti-reflection film is 1.26.

[0052] Example 4

[0053] 1) diluting sodium silicate with a modulus of 3.2 with deionized water to a sodium silicate concentration of 5 wt %, adding 3 mol / L hydrochloric acid to adjust the pH value to 11, stirring the reaction at a rate of 550 r / min for 10 h, and then standing and aging for 5 days to obtain an aqueous silica sol;

[0054] 2) immersing the glass substrate in the aqueous silica sol at a speed of 100 mm / min, maintaining it for 60 seconds after being completely immersed, and then pulling it out of the aqueous silica sol at a speed of 80 mm / min to form a silicon oxide wet film on the surface of the substrate;

[0055] 3) The wet silicon oxide film was dried naturally in air for 30 min, washed with water for 40 s, and then dried with nitrogen flow for 20 s to obtain a silicon oxide film;

[0056] 4) The silicon oxide film is placed in a muffle furnace and heat treated at 450° C. for 2 h to obtain a sodium water glass-based anti-reflection film.

[0057] The film prepared by the present invention has a higher porosity of 35% and a film thickness of 60.4nm; within 380-1100nm, the average transmittance of the uncoated glass substrate is 88.4%, and the average transmittance of the coated glass substrate can reach 91.2%, an increase of 2.8%; under this parameter, the refractive index of the anti-reflection film is 1.32.

[0058] The above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A method for preparing a sodium water glass-based anti-reflection film, characterized in that: The following steps are involved: 1) diluting sodium water glass, adding hydrochloric acid to adjust the pH value, stirring the reaction and then standing for aging to obtain an aqueous silica sol; 2) immersing the substrate in an aqueous silica sol, and then pulling it out from the aqueous silica sol to form a silicon oxide wet film on the surface of the substrate; 3) After the wet silicon oxide film is naturally dried in the air, it is washed with water and then dried with a nitrogen flow to obtain a silicon oxide film; 4) The silicon oxide film is heated to perform heat treatment to obtain a sodium water glass-based anti-reflection film.

2. The method for preparing a sodium water glass-based anti-reflection film according to claim 1, characterized in that: The modulus of the sodium water glass is 2.3-3.8; after the sodium water glass is diluted, the sodium silicate concentration is 2-5wt%.

3. The method for preparing a sodium water glass-based anti-reflection film according to claim 1, characterized in that: The concentration of the hydrochloric acid is 1-6 mol / L; the pH value is adjusted to 9-11.

4. The method for preparing a sodium water glass-based anti-reflection film according to claim 1, characterized in that: The stirring rate is 400-600 r / min, and the stirring reaction time is 3-10 h.

5. The method for preparing a sodium water glass-based anti-reflection film according to claim 1, characterized in that: The static aging time is 1-7 days.

6. The method for preparing a sodium water glass-based anti-reflection film according to claim 1, characterized in that: The substrate is immersed in the aqueous silica sol at a speed of 60-100 mm / min, maintained for 60-90 seconds after being completely immersed, and then pulled out of the aqueous silica sol at a speed of 60-100 mm / min.

7. The method for preparing a sodium water glass-based anti-reflection film according to claim 1, characterized in that: The natural drying time is 10-20 minutes; the washing time with water is 20-60 seconds; and the nitrogen flow drying time is 5-30 seconds.

8. The method for preparing a sodium water glass-based anti-reflection film according to claim 1, characterized in that: The heat treatment temperature is 300-550° C., and the heat treatment time is 0.5-4 hours.

9. A sodium water glass-based anti-reflection film prepared by the method according to any one of claims 1 to 8.

10. The sodium water glass based anti-reflection film according to claim 9, characterized in that: The sodium water glass-based anti-reflection film has a thickness of 55-160 nm, a porosity of 8-51%, and a refractive index of 1.25-1.43.

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