| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing method for a positive original plate for a planographic printing plate for an IR laser for direct plate making free of corrosion of an image area and a spotty residual film in a non-image area and capable of direct plate making particularly from a digital signal of a computer or the like. SOLUTION: In the developing method, an original plate for a planographic printing plate obtained by disposing at least two positive recording layers containing a water-insoluble and alkali-soluble resin and an IR absorbent and having solubility in an alkaline aqueous solution increased by exposure with an IR laser on a surface-roughened hydrophilic support is processed with an aqueous alkaline developing solution at >=2,000 mm/min conveyance speed. Preferably the lower layer of the positive recording layers has higher alkali solubility than the upper layer. |
