Preparation method for hydrophobic organic-modified silicate thin film with adjustable refractive index and silicate thin film

Abstract

The invention belongs to the technical field of chemical thin films, and particularly discloses a preparation method for a hydrophobic organic-modified silicate thin film with an adjustable refractive index. The method specifically comprises the following steps: (1) preparing an initial SiO2 sol coating solution, adding ethyl orthosilicate and absolute ethyl alcohol into the initial SiO2 sol coating solution, mixing and stirring the mixture, dropwise adding a mixed solution of the absolute ethyl alcohol, deionized water and ammonium hydroxide, and then stirring, standing and aging; (2) modifying the SiO2 sol coating solution through PMHS (Polymethyl Hydrogen Siloxane), namely, adding a certain amount of PMHS reagent into the aged stable SiO2 sol coating solution, adding a catalyst after stirring the solution uniformly, continuously performing sealed stirring and standing again after a reaction is completed; (3) preparing the hydrophobic thin film. The preparation method is easy to operate; the refractive index of the prepared thin film can be accurately controlled to change between 1.18 and 1.36; the thin film surface does not have a large amount of hydroxy residues; the hydrophobic thin film is directly formed; meanwhile, the service lifetime of the coating solution is greatly prolonged; the stability of the film solution is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of chemical film products, in particular to a hydrophobic organically modified silicate film with adjustable refractive index and a preparation method thereof. Background technique [0002] At present, anti-reflection film technology is widely used in solar cover glass, optical devices and other fields. By preparing a layer of anti-reflection film on the surface of glass (or other optical devices), the transmittance of the film can be greatly increased, and The wavelength band of transmitted light can be selected. [0003] In the prior art, it is generally required that the refractive index of the anti-reflection film used is lower than 1.25, and the conventional film material with the lowest known refractive index is a magnesium fluoride film with a refractive index of 1.35. [0004] At present, the following technical problems exist in the production process of anti-reflection film: [0005] 1. The refra...

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Problems solved by technology

[0006] 2. Existing reports can control the change of the refractive index of the film between 1.22-1.44 through the acid-base two-step catalysis method, but the report that can accurately control the change of the refractive index of the material between 1.18-1.36 has not yet been seen

[0007] 3. The alkaline SiO2 coating solution can be prepared by the sol-gel method. A large amount of hydroxyl groups will remain on the surface of the film prepared by the sol-gel method, which will greatly reduce the weather resistance of the film. The existing process usually adopts post-processing methods to eliminate These hydroxyl groups form a hydrophobic film, but this method increases the process and cost, which is not conducive to industrial production

[0008] 4. The silica particles in the alkaline coating solution will be connected together under the action of mutual collision and condensation reaction, so that the viscosity of the coating solution increases rapidly, which seriously affects the service life of the coating solution

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