To prevent oil stains from sticking to a building material by forming a coated film containing an oil-repellent substance and a photocatalyst particles on the surface of a base material so that both oil-repellent substance and photocatalyst particles are exposed on the coated film and a part of the catalyst particles are exposed so as to come into contact with the outside air.
The surface of a base material 1 is covered with a resin 2 containing an oil-repellent substance of alkyl groups and fluoroalkyl groups. A part of photocatalyst particles 3 such as titanium oxide or zinc oxide or the like is exposed out of the resin 2 containing an oil-repellent substance to form a smooth coated film. Further, the surface of the base material 1 is covered with a binder 4 such as phthalic acid resin, chlorinated rubber resin, epoxy resin, etc., so that a coated film which is covered with a portion where a part of the photocatalyst particles 3 is exposed out of the binder 4 and a part where the oil-repellent substance 2 is exposed out of the binder 4, is formed on the surface of the binder 4. Accordingly, oily stains are hard to stick to the building material and further, stuck oily stains can be easily wiped out and remaining oil film which has not been yet wiped out is also easy to wipe out.
MORIKAWA TOMOAKI
NAKANISHI YOSHIYUKI
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