| 摘要 |
PURPOSE:To obtain a supporter for lithographic plate, having excellent resistances to wearing and alkalies and free of staining to film, by subjecting a roughened aluminum plate to an anodic oxidation treatment in which a current having a positive electricity quantity/negative electricity quantity ratio =1 or less under a specific condition. CONSTITUTION:The surface of an aluminum plate is roughened in order to raise the adhesion between a humectant layer and the overlying photosensitive material layer, and then subjected to an anodic oxidation treatment under the condition that anodic oxidation is made with a current density of 5A/dm<2> or more in an electrolyte of 80g/1 or less of sulfuric acid in such a way that the ratio of the negative electricity quantity to the positive electricity quantity is 1 or less. The photo-sensitive lithographic plate is exposed to light source containing active light, e.g., carbon arc lamp, xenon lamp, etc., for development to obtain a lithographic plate. |
