| 摘要 |
PROBLEM TO BE SOLVED: To provide a positive type original plate of a planographic printing plate adaptable to an IR laser for direct plate making, excellent in latitude in image formation by development, having high sensitivity and capable of suppressing abration in laser scanning exposure. SOLUTION: The positive type original plate is obtained by disposing a positive type recording layer containing a novolak resin and a photothermal conversion material and having solubility in an alkaline aqueous solution increased by exposure with infrared laser light on a support and the amount of a component having a weight average molecular weight of <=1,000 contained in the novolak resin is <=15 wt.% of the total amount of the novolak resin. |
