To make a surface stain-proofing by forming a surface layer having structure in which a hydrophilic part in which photocatalytic oxide particles are exposed to outside air and a water repellent part in which a water repellent fluororesin is exposed to outside are dispersed microscopically on the surface of a backing.
A surface layer having structure in which hydrophilic part in which the excitation of electrons in a valence electron band occurs during the radiation of light having greater energy than the energy gap between the conductivity band and the valence electron band of a crystal, and photocatalytic oxide particles which can form a positive hole with a conductive electron is exposed to outside air and a water repellent part, exposed part in which a water repellent fluororesin is exposed to outside air are dispersed microscopically on the surface of a backing of a building material for an outer wall. A coating composition which contains photocatalytic oxide fine particles and a water repellent fluororesin as indispensable components and to which a solvent, a croslinking agent, and a surfactant are further added is applied by spray coating etc., fixed, and a surface layer in formed.
HAYAKAWA MAKOTO
