| 摘要 |
PROBLEM TO BE SOLVED: To provide a plate making method for planographic printing plate for IR laser improved in low image forming ability of a recording layer using a high molecular compd. soluble in an aq. alkali soln., not limited in handling place, less liable to the lowering of the developability after storage, and capable of a direct photomechanical process. SOLUTION: A planographic printing plate with a photosensitive layer formed on the hydrophilic substrate by coating with a positive type photosensitive compsn. for IR laser is exposed with IR laser and developed with an aq. alkali soln. The photosensitive compsn. contains a high molecular compd. (A) soluble in the aq. alkali soln. and having at least one function group selected from among phenolic hydroxyl, sulfonamido and active imido groups, a compd. (B) which lowers the alkali solubility of the compound A by compatibility with the compound A and reduces its solubility lowering action by heating, a compd. (C) which absorbs light and generates heat and a cyclic acid anhydride (D). One compd. having both the characteristics of the component B, C, e.g. a cyanine dye may be used in place of the component B, C. |
