Lithographic printing process

摘要

A lithographic printing process which comprises the steps of: imagewise exposing to infrared light a presensitized lithographic plate which comprises a hydrophilic support and a removable image-forming layer containing an infrared absorbing agent having the absorption maximum within an infrared region and a dye precursor having substantially no absorption within a visible region to change the dye precursor to a visible dye having an absorption within a visible region within the exposed area, and to make the image-forming layer irremovable within the exposed area; removing the image-forming layer within the unexposed area of the lithographic plate mounted on a cylinder of a printing press; and then printing an image with the lithographic plate mounted on the cylinder of the printing press. The other processes are also disclosed.