DIRECT DRAWING ORIGINAL PLATE OF PLANOGRAPHIC PRINTING PLATE

摘要

PROBLEM TO BE SOLVED: To provide a negative type direct drawing original plate of a planographic printing plate having good image reproducibility and suitability to printing-out. SOLUTION: The direct drawing original plate has at least a heat sensitive layer, an ink-repellent layer and a protective film in this order on an aluminum substrate. When the original plate is irradiated with laser light and the ink- repellent layer in the irradiated part is removed, the objective printing plate is produced. The original plate further has a layer that changes its color when irradiated with the laser light on the surface of the protective film.