Anti-reflection film, also known as anti-reflection film, is mainly used to reduce the reflected light on the surface of the material and increase the transmitted light. It is a coating film with a wide range of applications and has been widely used in daily life, electronics, industry, astronomy, military. And other fields. The traditional cleaning method is to use surfactant cleaning, which not only aggravates environmental pollution, but also needs to be repeated, which requires a lot of manpower, financial resources and material resources. Therefore, in recent years, research and development of self-cleaning anti-reflection films have received great attention, and preparation of anti-reflection films having self-cleaning characteristics and high efficiency has become a demand for technological development.
Introduction to the principle. (1) Principle of anti-reflection, in order to reduce the reflected light and increase the transmitted light, a film layer with a suitable thickness and refractive index can be plated on the surface of the substrate, and the anti-reflection effect is mainly achieved by destructive interference, mainly by using a film. The resulting interference effect eliminates reflected light and increases the transmittance of light. (2) Self-cleaning principle, in terms of hydrophilicity, the contact angle of water droplets on the surface of the material tends to zero. When the water contacts the material, it rapidly spreads on the surface to form a uniform water film, which can be removed by the gravity drop of the water film. Staining, so as to achieve self-cleaning effect; in terms of hydrophobicity, the principle is based on the "Lotus effect", the self-cleaning effect of the lotus leaf is the fine structure composed of the air layer, the nipple and the wax layer on the surface. The rough fine structure can increase the contact angle of water droplets on the surface of the material, making the water droplets roll off easily, and the water droplets will take away dust and contaminants when rolling on the surface of the material, thereby achieving self-cleaning effect.
A common material for self-cleaning anti-reflection films. (1) Titanium dioxide is widely used as a material for self-cleaning anti-reflection film due to its photocatalytic, photo-super-hydrophilic and low cost, especially the development of nano-scale powders and films, so that the application of TiO2 has been obtained. Promotion. However, due to the large size of the TiO2 film, the refractive index is relatively high, generally between 2.2 and 2.7, which increases the reflectivity of the transparent substrate surface. Therefore, scientific researchers use different processes to reduce the refractive index of the TiO2 film. In the year, Wang Jianwu and others used the sol-gel method to prepare the SiO2/TiO2 double-layer anti-reflection film, which has a high transmittance in the visible light range of 97.2%, and the contact angle of the film after ultraviolet light irradiation is close to 0°. Has a good self-cleaning property. (2) Silica, which has excellent properties such as low refractive index (refractive index of about 1.3), low-cost electrical properties, high chemical stability, acid and alkali corrosion resistance, is currently widely studied, and is also widely used for reversal. One of the membranes. Nowadays, many scientists are exploring and constructing SiO2 anti-reflection film with "leaf effect". Wei-Lun Min et al. have prepared ordered micro-convex silica hexagonal particle array structure by spin coating and etching. It enhances the transmittance of visible light on the surface of the material, and controls the contact angle by controlling the etching time to make it self-cleaning.
Research progress in self-cleaning anti-reflection film. In the research work of self-cleaning anti-reflection film, many high-quality scientific research workers have made outstanding contributions and made certain achievements. In 2013, the literature used laminate technology (LBL) to prepare a wide-wavelength anti-reflection and ultra-double-difference film composed of nanoparticles, hollow nanospheres and nanosheets on a glass substrate. Although scientific researchers have taken various measures to construct anti-reflection films with self-cleaning properties, most of the research knowledge is limited to the research stage of the laboratory and is not suitable for large-scale production. Therefore, for the actual There are still great opportunities and challenges in the production and application: first, the mechanicality is poor; secondly, the cost is high and the scale is small. Most of the preparation processes with self-cleaning properties reported today involve complex processes, harsher preparation environments, expensive reagents and equipment, etc., are costly, and are only suitable for smaller substrates or specific substrate materials. , the scale is small.
The trend of self-cleaning anti-reflection film. Such limited durability and high cost can hinder the application and development of such anti-reflective films with self-cleaning properties. In the future, the following research directions will attract more researchers' attention: 1Using the current advanced analytical tools and tools and theoretical calculation levels, more exploration reveals the relationship between film composition, structure, surface characteristics and film mechanism. Construction; 2 construction of high-strength and durable self-cleaning anti-reflection film surface structure is still the focus of research work, of course, environmental factors should also be taken into account; 3 new materials and advanced coating technology applications can also Broaden the application of self-cleaning anti-reflection film.
