| abstract |
A planographic printing plate precursor includes a substrate and an image recording layer provided thereon, the image recording layer being capable of recording through exposure to an infrared ray and containing at least (A) an infrared absorbing agent, (B) a polymerization initiator comprising an onium salt formed by an onium cation and a carboxylic acid anion, where the carboxylic acid anion has an acid group, a hetero atom and an aromatic group, (C) a polymerizable compound and (D) a binder polymer. The planographic printing plate precursor is exposed imagewise with an infrared laser. Then, printing is carried out using the exposed planographic printing plate precursor, which is set in a printer without being subjected to any developing process, by feeding an oil based ink and an aqueous component onto the planographic printing plate precursor. Unexposed areas of the planographic printing plate precursor are removed during the printing process. |