Patent ID: 6495310
Filing Date: 2002-12-17
Classification: B41C,B41M,B41N,G03F,Y10S

Abstract:
A method of lithographically printing images on a receiving medium, comprising in order:(a) providing a lithographic printing plate comprising: (i) a substrate with roughened surface comprising, at least, peaks and valleys; (ii) a photosensitive layer capable of hardening or solubilization upon exposure to an actinic radiation and 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 abhesive fluid for ink, the non-hardened or solubilized areas of said photosensitive layer being soluble or dispersible in ink (for waterless plate) or in ink and/or fountain solution (for wet plate); and (iii) an ink and/or fountain solution soluble or dispersible overcoat; wherein said photosensitive layer is substantially conformally coated on the substrate surface and said overcoat is substantially conformally coated on the photosensitive layer surface, so that the surface of said overcoat has peaks and valleys substantially corresponding to the major peaks and valleys of the substrate microscopic surface and the average height of the valleys on the overcoat surface is at least 0.1 microns below the average height of the peaks of the overcoat surface; (b) imagewise exposing the plate with the actinic radiation to cause hardening or solubilization of the exposed areas; and (c) contacting said exposed plate with ink (for waterless plate), or with ink and/or fountain solution (for wet plate) on a printing press to remove the overcoat and the non-hardened or solubilized areas of the photosensitive layer, and to lithographically print images from said plate to the receiving medium.