A method for producing lithographic plates by using an imaging element sensitive to IR radiation or heat

摘要

According to the present invention there is provided a method for obtaining a negative working lithographic printing plate comprising the steps of: (a) image-wise or information-wise exposing to IR light or heat an imaging element comprising on a hydrophilic surface of a lithographic base an IR radiation or heat sensitive layer comprising a quinone diazide, a water insoluble, alkali soluble or swellable resin and an infrared absorber, b) overall exposing the imaging element with UV light after the image-wise or information-wise exposure of the imaging element to provide increased solubility in the image-wise or information-wise unexposed areas; (c) developing said image-wise or information wise and overall exposed imaging element with an aqueous alkaline developing solution in order to remove the image-wise or information-wise unexposed areas and thereby form a lithographic printing plate.