Patent ID: 6541183
Filing Date: 2003-04-01
Classification: B41C,G03F,Y10S

Abstract:
A method of imaging a lithographic plate, comprising in order:(a) providing a lithographic plate comprising on a substrate a semisolid radiation-sensitive layer capable of hardening upon exposure to a laser selected from the group consisting of infrared laser, visible laser, and ultraviolet laser; said radiation-sensitive layer exhibiting an affinity or aversion substantially opposite to the affinity or aversion of said substrate to at least one printing liquid selected from the group consisting of ink and an adhesive fluid for ink; wherein said substrate has a roughened surface comprising, at least, peaks and valleys, and said radiation-sensitive layer is substantially conformally coated on the roughened substrate surface so that the surface of said radiation-sensitive layer has peaks and valleys substantially corresponding to the major peaks and valleys of the substrate microscopic surface; and said substrate has an average surface roughness Ra of 0.2 to 2.0 microns, said radiation-sensitive layer has an average coverage of 0.1 to 2.0 g/m2, and the average height of the valleys on the radiation-sensitive layer surface is at least 0.1 microns below the average height of the peaks on the radiation-sensitive layer surface; and (b) imagewise exposing the plate with said laser according to digital imaging information to cause hardening of the radiation-sensitive layer in the exposed areas.