| 摘要 |
PURPOSE:To improve the strength and elasticity of a back coat surface by adding further a compd. having specific Mohs hardness to a system of a back coat layer contg. zinc sulfide and org. binder. CONSTITUTION:Zinc sulfide is white amorphous powder or crystal and is used for paint, etc. by mixing the same with particularly barium sulfide as a white pigment or is used as a phosphor. The grain size thereof is <=0.5mum, more particularly preferably <=0.2mum in terms of an electromagnetic conversion characteristic, surface characteristic, etc. The compds. having 5-7Mohs hardness is TiO2, SnO2, MgO, ZrO2, etc., among which TiO2 is more preferable. The TiO2 has an adequate reinforcing effect when incorporated into the back surface and is therefore best suited in terms of the crack of the back surface. The back coat layer having excellent repetitive durability and running property is thus obtd. The particle size of such compd. is not particularly limited but the compd. having usually <=0.5mum is used. The compd. having 0.2-0.5mum is more particularly preferable in terms of the surface characteristic.
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