To provide a method of making a lithographic printing plate which achieves development with an aqueous developer solution of 2.0 to 10.0 in pH, and also has superior sensitivity and developability, a fast developing speed, and superior printing durability.
The method of making the lithographic printing plate is characterized in that after an original plate of the lithographic printing plate having a photosensitive layer containing (A) sensitizing coloring matter, (B) a polymerization initiator, (C) a polymerizable compound, (D) a binder, and (E) a phosphonium compound and a protection layer on a base in this order is exposed to an image using a laser, the protection layer and the photosensitive layer of an unexposed portion are removed at the same time using a developing solution containing a hydrophilic polymer.
OHASHI HIDEKAZU
ARITOMI TAKASHI
Kiyozumi Yazawa