| 摘要 |
PURPOSE:To prevent the occurrence of spots by forming a thin Al2O3 layer having a specified thickness on a Al support, laying a photosensitive nonsilver layer and a photosensitive layer contg. silver halide on the thin layer in succession, and adding a specified amount of a mercapto compound to at least one of the photosensitive layers. CONSTITUTION:The surface of an Al plate is anodically oxdized to form an Al2O3 film having >=1g/cm<2>, and on the film a photosensitive nonsilver layer contg. a mercapto compound represented by formula I, II, III or IV [where M is H or an alkali metallic atom, A is (substituted) aryl, R is H or (substituted) alkyl, Z is atoms required to complete an aromatic ring which may have a substituent, Y is a divalent hetero atom, P is -SM, NH2, alkylamino, SR or OR] as well as a diazide compound and a photosensitive layer contg. silver halide are laid in succession to obtain a PS plate. Thus, a superior lithographic plate causing no spots in the plate making process is obtd. |
