To provide a plate-making method for a planographic printing plate, which does not cause problems on cleanability and four-color registrability, in a printing mode wherein an original plate for the planographic printing plate, dispensing with dampening water, is formed in a roll shape and supplied into a plate cylinder of a printing machine, its printing surface is attached onto the plate cylinder so as to be positioned on a front side, its new surface is spooled so as to be positioned in a printing area on the plate cylinder, the plate cylinder is scanned imagewise with a laser, and printing is done after the removal of a silicone rubber layer of a laser irradiation part.
In the original plate for the planographic printing plate, dispensing with the dampening water, at least a photothermal conversion layer and the silicone rubber layer are sequentially laminated on a substrate. In this method, the planographic printing plate is made by performing treatment including: a process (a) wherein the plate is irradiated with the laser imagewise on the printing machine; and a process (b) wherein the silicone rubber layer of the laser irradiation part is removed by being rubbed with a cleaning member. A coefficient of dynamic friction between a surface of the silicone rubber layer and the cleaning member in cleaning is set to be in a range of 0.36-0.7.
NAKANO JUNJI
AOSHIMA KOJI
Hironori Honda
Toshimitsu Ichikawa
Takeshi Takamatsu
Yuriko Hamada