| abstract |
A negative planographic printing plate precursor for heat-modenexposure systems, which has, on a support, a photosensitive layerncontaining: (A) a light-to-heat conversion agent; (B) a polymerizablenunsaturated group-having compound; and (C) an onium salt having ancounter anion with a valency of at least 2. The precursor is capable ofnbeing exposed with an IR laser for image formation thereon. The oniumnsalt may be, for example, a diazonium salt, iodonium salt or sulfoniumnsalt. The counter anion has at least two anionic sites which may be thensame or different, and the anionic structure is preferably divalent tonhexavalent. |