| 摘要 |
PROBLEM TO BE SOLVED: To keep the water-repellent property of a surface and prevent the surface from getting dirty, by forming a surface layer containing photocatalyst particles, water-repellent silicone, and a substance preventing the water-repellent silicone from getting hydrophilic owing to the photoexcitation of the photocatalyst, on a base material surface. SOLUTION: A surface layer containing photocatalyst particles such as anatase type titanium oxide, zinc oxide, tin oxide, water-repellent silicone, a substance such as cobalt or cobalt compounds preventing the water-repellent silicone from getting hydrophilic owing to the photoexcitation of the photocatalyst, is formed on the base material surface of a building material for an external wall such as glazed tiles, non-glazed tiles, bricks. Cobalt alloy, cobalt oxide, etc., are favorable for cobalt compounds and the film thickness of the surface layer is favorably made 0.4μm or thinner. In this way, white turbidity resulting from diffuse reflection of light can be prevented and the surface layer becomes substantially transparent. And further, color development of the surface layer resulting from interference of light can be prevented by making the film thickness 0.2μm or thinner.
|
