Patent ID: 7449282

Claim:
A lithographic printing plate precursor comprising a photosensitive layer comprising: (A) a fluorescent brightening agent which is a compound capable of absorbing light at a wavelength of 350 to 450 nm and emitting the absorbed light energy as fluorescence having a wavelength of 400 to 500 nm, said fluorescent brightening agent having a skeleton of the following structure, with the proviso that the skeleton may have one or more substituents: (B) a hexaarylbiimidazole activator compound being capable of inducing a chemical change by an interaction with light absorption of the fluorescent brightening agent to produce at least one of a radical, an acid and a base; (C) a compound being capable of undergoing a reaction by an effect of at least one of a radical, an acid and a base to irreversibly change in its physical or chemical properties; and (D) a polyurethane resin binder, wherein the polyurethane resin binder is synthesized from at least following compounds (i), (ii), (iii) and (iv): (i) a diisocyanate compound; (ii) a diol compound having at least one carboxyl group; (iii) a diol compound having a logP value of less than 0; and (iv) a diol compound having a logP value of 0 or more, with the proviso that each of the diol compound (iii) and the diol compound (iv) does not have a carboxyl group.