| 摘要 |
PURPOSE:To stably print with clear image quality, by treating at least one side of an aluminum or aluminum alloy plate to obtain a graining with a center line average roughness of 0.3-1.3mum and a maximum waviness of not more than 4.0mum. CONSTITUTION:The surface of an aluminum or aluminum alloy plate is roughened by mechanical graining by, for example, a method wherein an abrasive/water slurry is blasted against the surface. Then, the roughened surface is chemically treated by bringing it into contact with an aqueous solution of an acid or a base to obtain the base for a planographic plate. The base has a graining with a center line average roughness Ra of 0.1-1.3mum, and a maximum waviness (WCM) of the graining as measured from a filtered waviness curve with a high cut-off value of 0.08mm and a basic length of 2.5mm is not more than 4.0mum. Accordingly, a stable affinity for ink can be displayed even when imaged parts are abraded during printing. |
