Method of making a lithographic printing plate

摘要

A method of making a lithographic printing plate is disclosed which comprises the steps of : providing a positive or negative working heat-sensitive imaging element which comprises on a lithographic base having a hydrophilic surface : (i) a hydrophobic layer which comprises a polymer which is soluble in an aqueous alkaline solution, and (ii) a top layer which is sensitive to IR-radiation; exposing the imaging element with an IR-laser, thereby inducing a decreased or increased capacity of the top layer for being penetrated and/or solubilised by said aqueous alkaline solution; developing the exposed imaging element with said aqueous alkaline solution.