| abstract |
To provide a plate making method comprising conducting UV exposure of an on-press developable lithographic printing plate precursor capable of undergoing image exposure with an infrared laser, through a lith film and conducting on-press development, wherein the printing durability and on-press development property are good, deposition of scum hardly occurs at the on-press development, and the vacuum adhesion property to a lith film is good. n A plate making method of a lithographic printing plate comprising (1) preparing a lithographic printing plate precursor capable of forming an image with a semiconductor laser emitting an infrared ray having a wavelength from 760 to 1,200 nm which comprises a support and an image-recording layer containing a cyanine dye, a diphenyl iodonium salt or triphenyl sulfonium salt which may have a substituent on the phenyl group, a radical polymerizable compound and a polymer fine particle having a polyoxyalkylene chain in its side chain in this order, (2) placing a lith film on the lithographic printing plate precursor and reducing pressure so that the lith film is closely adhered to the lithographic printing plate precursor, (3) conducting UV exposure, and (4) conducting on-press development. |