| 摘要 |
PURPOSE:To prevent the ground stain of a lithographic printing plate and to improve the sensitivity of the image part by applying an aqueous soln. contg. a specified condensed resin to the printing plate after development and by burning the printing plate. CONSTITUTION:A photosensitive lithographic printing plate is imagewise exposed and developed. An aqueous soln. contg. a condensed resin is then applied to the printing plate. After the soln. is dried, the printing plate is burned. The condensed resin is prepd. by condensing aromatic sulfonic acid or a salt thereof such as sodium benzenesulfonate with aldehyde such as formaldehyde. By this method, desensitization after burning can be eliminated and a lithographic printing plate having superior printing resistance is obtd. The non-image part of the printing plate is not stained and the image part has high sensitivity. |
