Patent ID: 10126654

Abstract:
Provided is a method of producing a planographic printing plate, including: subjecting a planographic printing plate precursor, which has a support and a positive-working image recording layer, to image-wise exposure; and developing it using an alkaline aqueous solution which contains a specific compound and has a pH of from 8.5 to 10.8, in this order. The recording layer has: a lower layer containing a water-insoluble and alkali-soluble resin and an infrared ray absorbing agent; and an upper layer containing a water-insoluble and alkali-soluble polyurethane resin and a polyorganosiloxane. The specific compound is a nonionic or anionic surfactant, or at least one compound represented by Formula (1) or (2), wherein R11, R12, and R13 each represent an alkyl group; R14 represents an alkylene group; and R15 represents a single bond or a divalent linking group containing a hetero atom; and R21, R22, and R23 each represent an alkyl group.