LITHOGRAPHIC PLATE PRECURSOR

摘要

There is described a method of preparing a lithographic plate which comprises coating on a lithograhic support having a hydrophilic surface a layer of a radiation sensitive coating imaging the coating then acting on the plate whilst on the press with aqueous found solution to remove the unexposed areas of the coating to reveal the hydrophilic surface of the plate and to leave an ink receptive image, wherein the radiation sensitive coating comprises a diazo salt of formula (I), wherein R1 is an anion, R2 and R3 represent optional substitution, R4 is -N- or -S- and R5 is a group which after exposure of the plate renders the residue of the diazo salt oleophilic and fount solution insoluble.