To provide a plate making method in which a lithographic printing original plate having high sensitivity and excellent suitability to safelight is developed with an aqueous developer of pH 2.0-10.0, and a lithographic printing original plate for use in the method.
In the method for making a lithographic printing plate, the lithographic printing original plate having a photosensitive layer containing (A) a specific sensitizing dye, (B) an initiator compound, (C) a polymerizable compound and (D) a hydrophobic binder polymer having an acid number of ≤0.3 meq/g and a protective layer in this order is exposed with laser light of 350-450 nm, and the plate surface is rubbed with a rubbing member in the presence of a developer of pH 2-10 using an automatic processing machine equipped with the rubbing member to remove the protective layer and the photosensitive layer of an unexposed portion. The lithographic printing original plate for use in the method is also provided.
COPYRIGHT: (C)2007,JPO&INPIT
Hironori Honda
Toshimitsu Ichikawa
Takeshi Takamatsu
Kiyozumi Yazawa
Next Patent: METHOD FOR MAKING LITHOGRAPHIC PRINTING PLATE, AND LITHOGRAPHIC PRINTING ORIGINAL PLATE