| 摘要 |
PROBLEM TO BE SOLVED: To retain a heat sensitive layer of a printing element portion and to obtain good image reproducibility by incorporating a compound capable of being decomposed by an operation of at least irradiating the sensitive layer with a laser beam and a novolac resin in the sensitive layer in an original plate for a direct lithographic printing plate having at least the sensitive layer and an ink repellent layer on a substrate. SOLUTION: An original plate for a direct writing waterless lithographic printing plate which can be directly engraved by a laser beam and printed without using dampening water comprises at least a heat sensitive layer and an ink repellent layer on a substrate. In this case, the sensitive layer contains a compound capable of being decomposed by irradiating the layer with a laser beam, and a novolac resin. As the compound capable of being decomposed by irradiating with the beam, (1) a compound does not absorb the beam but is decomposed by an operation of another compound for absorbing the beam, and (2) the compound itself absorbs the beam and decomposed. As the compound (1), an ammonium nitrate, a potassium nitrate, a sodium nitrate or the like can be used. |
