| 摘要 |
PROBLEM TO BE SOLVED: To obtain a planographic printing plate showing improved workability under a safe light without decreasing photographic characteristics and printing property by incorporating an org. pigment having no more than two sulfonate groups or carboxyl groups. SOLUTION: This planographic printing plate is produced by successively applying at least a base coating layer, a silver halide emulsion layer and a physical development nuclei layer on a base body and contains an org. pigment which contains no more than two sulfonate groups or carboxyl groups. Such a water-insoluble pigment is used that consists of an org. matter having no more than two sulfonate groups or carboxyl groups as water-insoluble groups and is hardly soluble with water. Thereby, the pigment exists in a particle state in the photographic layer. As for a preferable org. pigment, a pigment having an azo dye structure is used. The size of the pigment is preferably about 0.05μm as the primary particle and the particles are dispersed in water by using a dispersant such as a nonion surfactant. |
