| 摘要 |
PROBLEM TO BE SOLVED: To provide a supporting body for lithographic printing plate, having no appearance defect, such as the variety of lines or the like, and excellent in the uniformity of pits. SOLUTION: A supporting body for lithographic printing plate is obtained by treating the surface of an aluminum alloy plate by a surface treatment process including an alkaline etching treatment and an electrochemical surface roughening treatment. A variety, defined in a formula (1) with respect to the containing amount of Fe, Si, Mn, Mg and Sn in the surface layer unit at the depth of 1 μm from the surface of the aluminum alloy plate is not more than 50% with respect to respective elements. Variety (%) = (maximum value -minimum value)/average value × 100(%) (1) Here; the maximum value, the minimum value and the average value are determined based on the data of containing amount of 8 pieces of elements excluding the maximum and the minimum values from the data of containing amount of 10 pieces of elements. |
