| 摘要 |
PROBLEM TO BE SOLVED: To provide a substrate for a lithographic printing plate which is constituted of an aluminum material or an aluminum alloy material and has the rear free of a fault called streaky unevenness and excellent in the quality of external appearance. SOLUTION: An aluminum sheet of which the standard deviation of the surface oxygen concentration in an aluminum surface expressed by the formula (1) is 15 or less, or an aluminum sheet of which the ratio between the oxygen concentration in the surface and the oxygen concentration in a part at 1 μm from a surface layer satisfies the condition of the formula (2), wherein the former is denoted by [O]s and the latter by [O]i, and of which the standard deviation of the surface oxygen concentration is 15 or less, is made to have a roughened surface and subjected to anodizing treatment. Standard deviation of surface oxygen concentration = Σ√(surface oxygen concentration n -surface average oxygen concentration)2/n...(1) [O]s/[O]i<=1.2...(2). |
