Abstract: A positive-working lithographic printing plate precursor is disclosed which comprises on a support having a hydrophilic surface or which is provided with a hydrophilic layer a heat and/or light-sensitive coating including an infrared absorbing agent, said heat and/or light-sensitive coating comprising a first layer comprising a binder including a monomeric unit including a sulfonamide group; characterized in that the binder further comprises a monomeric unit including a phosphonic acid group or a salt thereof, and that the monomeric unit comprising the phosphonic acid group is present in an amount comprised between 2 mol % and 15 mol %.

Abstract: A lithographic printing plate precursor comprising a support having a hydrophilic surface or which is provided with a hydrophilic layer, and a coating thereon, said coating comprising an IR absorbing agent and a polyvinylacetal binder, said polyvinylacetal comprising an acetal group having an acetal carbon atom substituted by a phenolic group, a naphtol group or an antracenol group, a second recurring unit comprising an acetal group having an acetal carbon atom substituted by an alkyl group having a hydrocarbon chain containing 1, 2 or 3 carbon atoms, and a third recurring unit comprising an acetal group having an acetal carbon atom substituted by an alkyl group having a hydrocarbon chain containing 1, 2 or 3 carbon atoms wherein the alkyl group of the acetal group of the third recurring unit is different from the alkyl group of the acetal group of the second recurring unit. The precursor exhibits an improved sensitivity on exposure and the stability against daylight exposure is further improved.

Abstract: 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, (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, characterized in that said first polymer is an alkaline soluble polymer comprising a first sulfonamide containing monomeric unit having a specified structure according to formula I or formula II and a second amide containing monomeric unit having a specified structure according to formula III. The printing plates show an improved chemical resistance of the coating and a reduced undercutting of the image forming parts of the coating.

Abstract: A positive-working lithographic printing plate precursor is disclosed which comprises on a support having a hydrophilic surface or which is provided with a hydrophilic layer a heat and/or light-sensitive coating including an infrared absorbing agent, said heat and/or light-sensitive coating comprising a first layer comprising a binder including a monomeric unit including a sulfonamide group; characterized in that the binder further comprises a monomeric unit including a phosphonic acid group or a salt thereof, and that the monomeric unit comprising the phosphonic acid group is present in an amount comprised between 2 mol % and 15 mol %.

Abstract: 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, (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, characterised in that said first polymer is an alkaline soluble polymer comprising a first sulfonamide containing monomeric unit having a specified structure according to formula I or formula II and a second amide containing monomeric unit having a specified structure according to formula III. The printing plates show an improved chemical resistance of the coating and a reduced undercutting of the image forming parts of the coating.