| 摘要 |
PROBLEM TO BE SOLVED: To retard print summing at non-image part by an arrangement wherein a processing liquid contains a specified quantity of cathode ion compound after anodic oxidation and the absolute value of potential difference between an aluminum support and a processing tank is regulated to a specified level or below at the time of processing. SOLUTION: An aluminum support having dismatted and electrolytically roughened surface is etched in an alkaline aqueous solution and then neutralized by immersing into an acid of phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixture thereof. Subsequently, it is washed with water and subjected to anodic oxization. The processing liquid contains 10-5000ppm of cathode ion compound after anodic oxidation and the absolute value of potential difference between the aluminum support and a processing tank is regulated to 2V or below at the time of processing by connecting an insulating plate with the processing tank and earthing, for example. An aluminum support thus obtained is then sealed thus providing a hydrophilic layer. Finally, the support is coated with a photosensitive composition and dried to obtain a photosensitive lithographic printing plate. |
