MANUFACTURE OF PLANOGRAPHIC PRINTING PLATE

摘要

PROBLEM TO BE SOLVED: To obtain an image having high resolving power within a bright room and to exclude the generation of a waste soln. by heating a hydrophilic layer of a part where an image is formed by layer beam to expose the hydrophobic surface of a planographic printing base plate support. SOLUTION: A planographic printing base plate (e) is formed by covering the upper and rear surfaces of the paper base 11 of a support 1 with a hydrophobic resin 12 and providing a hydrophilic layer 3 on one hydrophobic resin layer as an upper layer. This planographic printing base plate (a) is irradiated with laser beam in a desired imagewise state. Herein, the hydraphilic layer 3 of the part irradiated with laser beam is thermally melted and/or decomposed and the resin 12 is exposed to complete plate making. Thereafter, when the planographic printing plate is mounted on a planographic printing press, the part where the hydrophobic resin 12 is exposed receives ink and the remaining hydrophilic layer 3 receives water to enable printing. An amt. of the hydrophilic polymer constituting the hydrophilic layer may be 0.5-10g/m<2> per one layer.