| 摘要 |
PROBLEM TO BE SOLVED: To provide a plate making method of a lithographic printing plate by which the solubility of a nonpicture part with an alkali developer is improved, dissolving resistance of the picture part is maintained, and excellent development stability against damages can be obtd. SOLUTION: The plate making method includes a process to expose a lithographic printing master plate to IR laser light and a process to develop the plate with an alkali developer containing a nonionic surfactant, preferably polyoxyalkylene-based nonionic surfactant. The lithographic printing master plate has a photosensitive layer formed by applying a positive photosensitive compsn. for an IR laser on a supporting body. The photosensitive compsn. contains (A) an alkali-soluble polymer compd., (B) a compd. which decrease the solubility of the polymer compd. by dissolving compatibly soluble with the alkali-soluble polymer compd. to with an alkali soln. and which decreases its effect to decrease the solubility by heating, and (C) a compd. which absorbs light to generate heat. |
