Patent ID: 6846615

Claim:
A method for making a lithographic printing plate, which comprises imagewise exposing a presensitized plate having a photopolymerizable layer on a substrate having a hydrophilic surface by scanning the plate with laser light having a wavelength of 450 nm or shorter, developing the exposed plate with a developer and further exposing the whole surface of the developed plate to light having a wavelength of 450 nm or shorter, wherein the lithographic printing plate is heated to a temperature ranging from 30° C. to 150° C. simultaneously with the exposure of the whole surface of the plate to light, and wherein the photopolymerizable layer comprises a sensitizing dye represented by the following general formula (1): wherein, A represents an optionally substituted aromatic ring or heterocyclic ring, X represents oxygen atom, sulfur atom or —N(R 3 )—, R 1 , R 2 and R 3 each independently represents hydrogen atom or monovalent nonmetallic atom group and A and R 1 , or R 2 and R 3 can be linked together to form an aliphatic or an aromatic ring.