Patent ID: 8304166

Claim:
A heat-sensitive positive-working lithographic printing plate precursor comprising (1) a support having a hydrophilic surface or which is provided with a hydrophilic layer, and (2) a heat-sensitive coating comprising an underlayer on said support and thereon an upperlayer, an IR absorbing agent in at least one of said underlayer and upperlayer, a phenolic resin in said upperlayer, and a first polymer in said underlayer, wherein said first polymer is an alkaline soluble polymer comprising a first monomeric unit having a structure according to formula I or formula II and a second monomeric unit having a structure according to formula III, wherein * denotes the binding sites of the monomeric unit in the polymer backbone, each R 1 independently represents hydrogen or an alkyl group, Z represents oxygen or —NR 2 —, a and b independently are 0 or 1, R 2 represents hydrogen or an optionally substituted alkyl, alkenyl or alkynyl group, Ar 1 and Ar 2 are an aromatic group with the proviso that at least one of Ar 1 and Ar 2 is an optionally substituted heteroaromatic group, R 3 represents hydrogen or an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted aralkyl group or an optionally substituted alkaryl group, or an aryl group which is not substituted by a sulphonamide group or a heteroaryl group which is not substituted by a sulphonamide group, and Ar 3 is an aromatic group which is not substituted by a sulphonamide group.