Deep color, heat-reflective, superhydrophobic and anti-soiling coatings with waterborne silicone emulsion

Abstract

Recently, deep colored inorganic pigments with high infrared reflectance have attracted much attention for using in the building coating field because of their ability to reflect solar heat radiation and reduce the temperature of the roofs and outside walls. However, pollutants that are present in the air require the coatings to possess self-cleaning and anti-soiling properties. In this work, black infrared-reflective pigments, fluorinated acrylic resin emulsion and a small number of SiO2 nanoparticles were mixed in silicon resin emulsion, and the resulting mixture was coated on an aluminum plate. After drying, black coatings with high infrared reflectance, superhydrophobic (SH) and obvious anti-soiling properties were created. Between wavelengths of 1250–2500 nm, the infrared-reflectivity of the prepared cool coating is higher than that of the white SiO2 coatings. Under the radiation of a 275-Watt infrared lamp positioned at a height of 40 cm, the surface temperature of the cool coating is 30 °C lower than that of the carbon black coating (90 °C), and only 5–10 °C higher than that of the white SiO2 coating. Furthermore, the heat-reflective coating exhibited stable SH properties to both rain and UV irradiation, which allow for the coating to possess self-cleaning ability and retain its heat-reflective properties over a long period of time.