Patent ID: 7560221

Claim:
A lithographic printing plate precursor comprising a) an untreated or pretreated substrate and b) a radiation-sensitive coating comprising (i) at least one polymeric binder soluble or swellable in aqueous alkaline developers; (ii) at least one free-radical polymerizable monomer and/or oligomer comprising at least one non-aromatic C—C double bond and at least one SH group in the molecule; and (iii) a radiation-sensitive initiator or initiator system for free-radical polymerization comprising as least one IR absorber capable of absorbing radiation in the wavelength of more than 750 to 1,200 nm and at least one coinitiator selected from polyhalogenalkyl-substituted compounds, onium compounds and mixtures of a polyhalogenalkyl-substituted compound and an onium compound, wherein component (ii) has the following formula (I): HS-Z-(Z 1 -CR 1a ═CR 1b R 1c ) c (I) wherein each R 1a , R 1b and R 1c is independently selected from H, C 1 -C 6 alkyl, C 2 -C 8 alkenyl, aryl, halogen, CN and COOR 1d , wherein R 1d is H, C 1 -C 18 alkyl, C 2 -C 8 alkenyl, C 2 -C 8 alkynyl or aryl; and Z is an aliphatic, heterocyclic or heteroaromatic spacer or a combination of two or more thereof, wherein Z can optionally comprise one or more additional SH groups and/or one or more additional non-aromatic C—C double bonds; and each Z 1 is independently selected from a single bond, wherein R 2a , R 2b and R 2c are independently selected from H, C 1 -C 6 alkyl and aryl, Z 2 is selected from a single bond, O, S and NR 2c , Z 3 is a single bond which is connected to Z, b is an integer from 1 to 10 and c is an integer from 1 to 3, wherein either: the component (ii) comprises two SH groups and one non-aromatic C—C double bond a molecule; or the component (ii) comprises one SH group and two or more non-aromatic C—C double bonds per molecule.