Preparation and properties of TiO2 photocatalytic self-cleaning coating material for glass

Abstract

The balance of light transmittance, durability and self-cleaning performance of the coating film is the main reason that hinders the wide application of photocatalytic self-cleaning coating on building exterior glass. In this article, TiO2 powder was prepared with different concentrations of tetrabutyl titanate, hydrochloric acid and ethanol; and following with compounded polyvinyl alcohol (PVA) and waterborne polyurethane as adhesives; the mixed composite coating was loaded on the glass surface by spraying method to obtain superhydrophilic glass with self-cleaning properties. The physical and chemical properties of TiO2 composite films were characterized and tested by diffraction, scanning electron microscopy, optical contact angle measuring instrument and photocatalytic testing system. The results showed that the X-ray diffractometer analysis of the powder obtained with different alcohol-ester ratios showed that the crystal synthesis was successful, and the grain size conformed to the nanometer standard. TiO2 dispersion with a concentration of 0.08 g/L, after 30 min of irradiation with an ultraviolet (UV) lamp, the methyl orange added dropwise in the solution can be completely degraded. With the increase of TiO2 concentration, the photocatalytic efficiency increased rapidly, the contact angle decreased, when the TiO2 concentration reached 0.3% and 3% binder compounding, the surface of the composite coating film was still smooth at the nanometer level, the visible light transmittance was between 86.95 and 88.89%, and the contact angle was reduced from the initial 46.49 to 14.89◦ after 2 h of UV illumination. After 5 repeated degradation experiments and outdoor 180-d standing test, the composite coating film has recyclability and good durability. Therefore, TiO2 composite coating prepared by this method has a wide application prospect in the daily cleaning and subsequent maintenance of building glass.