| 摘要 |
PROBLEM TO BE SOLVED: To provide a photomechanical process for a planographic printing plate using an alkali developing solution of a relatively low pH favorable to the environment and safety, giving a non-image area stably having good developability and free of stain in printing, ensuring superior contrast between image and non-image areas, little damage to the image area in development and high image strength, not causing printing trouble such as blinding in printing and capable of imparting superior age stability and high printing resistance. SOLUTION: A photosensitive planographic printing plate having a middle layer containing a compound having a phosphonic acid group or its salt on an aluminum base and a photosensitive layer of a photopolymerizable composition on the middle layer is imagewise exposed and developed with a developing solution containing an inorganic alkali agent and a nonionic surfactant having a polyoxyalkylene ether group and having pH 10.5-12.7 and 3-30 mS/cm electric conductivity. |
