| abstract |
The invention a method of producing a negative planographic printing plate of the invention including: exposing, to an infrared laser, a negative planographic printing plate precursor at least having a hydrophilic support, and on the hydrophilic support, a polymerizable recording layer including (A) an infrared absorber, (B) an onium salt, (C) a polymerizable compound having a urethane bond and a plurality of ethylenically unsaturated bonds, and (D) a polyurethane binder, and developing the precursor by using a developer which has a pH of from 11.5 to 12.8 and includes an alkali silicate and an anionic surfactant, the alkali silicate having an SiO 2 /M 2 O molar ratio of 0.75 to 4.0 wherein M represents an alkali metal or an ammonium group. |