PURPOSE: To improve running durability and to decrease light transmittance by incorporating block pulverous powder of oxide formed by calcining a compd. contg. ≥2 kinds among Fe, Mn, Cu and Cr at a high temp.

CONSTITUTION: A back layer is formed of a paint which is prepd. by mixing and dispersing thoroughly black pulverous powder of oxide formed by calcining a compd. contg. ≥2 kinds among Fe, Mn, Cu and Cr, a binder and a dispersant, lubricating agent, etc. added in small amt. according to need and has a desired component ratio. A thermoplastic resin, thermosetting resin or reaction type resin alone or a mixed system composed thereof is used as the binder. Lecithin, higher fatty acid, higher fatty acid ester, silicone oil, fluorine oil, etc. are used as the additive such as dispersant, lubricating agent. The above-mentioned black inorg. pigment powder having 0.02W2μm grain size is preferably used. The ratio of the pigment powder to be added into the coated film is preferably 20W80pts. wt. by 100pts.wt. the coated film.