BUILDING EXTERIOR WALL, BUILDING EXTERIOR WALL STRUCTURE ELEMENT AND BUILDING EXTERIOR WALL COATING MATERIAL

摘要

PROBLEM TO BE SOLVED: To prevent the so-called 'water-repellent contamination' occurring in an exterior wall of a building by a silicone sealing compound for a joint. SOLUTION: The surface of a building material forming a building exterior wall is coated with a transparent layer containing a semiconductor photocatalyst. The photocatalyst is excited by sunlight, and the surface of a photocatalyst-containing layer becomes hydrophilic to have a contact angle of the surface consequent upon water of lower tan 10 deg.. Even when molecules of an unhardened silicone precursor, isolated from a sealing compound of a joint are diffused with rain-water, they do not adhered to the surface of the building material around the joint. Soot and dirt adhered to the surface is washed away, and the surface is self-cleaned.