| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative type original plate of a planographic printing plate capable of direct recording from digital data of a computer or the like with an IR laser, not requiring heating after imagewise exposure, excellent in sensitivity in recording and adaptable to a heat mode. SOLUTION: The original plate has a photosensitive layer containing (A) a photothermal converting agent, (B) a compound having a polymerizable unsaturated group and (C) an onium salt having a di- or higher valent anion as a counter ion and capable of recording with an IR laser on the base. The onium salt is, e.g. a diazonium salt, an iodonium salt or a sulfonium salt, the polyvalent anion is preferably a di- to hexavalent anion and the structures of anion parts may be the same or different. |
