| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coating material which forms a light shielding film excellent in strength, light transmittance, etc., when applied to the surface of a lamp and fired by incorporating polycrystalline silica, manganese doped iron oxide and a silica-base powdery glass. SOLUTION: The coating material contains polycrystalline silica, manganese doped iron oxide preferably represented by the formula (Fe1-xMnx)2O3, (where 0.05<x<0.4) and a silica-base powdery glass preferably having a compsn. consisting of two or more selected from silica, boron oxide and alumina and 600-1,400 deg.C softening point. The solid constituents contained in the coating material preferably include 5-20 wt.% silica-base powdery glass and the solid constituents except the powdery glass are preferably 20-80 wt.% polycrystalline silica and 80-20 wt.% manganese doped iron oxide. The objective light shielding film formed on a lamp using the coating material does not cause peeling, cracking, discoloration, etc., even by exposure to >=700 deg.C for >=200 hr during lighting.
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