Patent ID: 8927197
Filing Date: 2015-01-06
Classification: B41C,C09B,G03F

Abstract:
1. A method for providing a lithographic printing plate comprising: imagewise exposing a negative-working lithographic printing plate precursor comprising a negative-working imageable layer to infrared radiation to provide an imaged precursor comprising exposed and non-exposed regions in the negative-working imageable layer, and processing the imaged precursor on-press to remove the negative-working imageable Layer in the non-exposed regions with a lithographic printing ink, fountain solution, or both a lithographic printing ink and fountain solution, wherein the negative-working lithographic printing plate precursor comprises a substrate and the negative-working imageable layer disposed on the substrate, the negative-working imageable layer comprising an infrared radiation absorber, a compound to provide free radicals upon exposure to infrared radiation in the presence of the infrared radiation absorber, a free radical polymerizable compound, and optionally a polymer binder, wherein the infrared radiation absorber is a cyanine dye represented by Formula (1a): wherein Z1 and Z2 independently represent S, O, NR R1 and R2 independently represent hydrogen or a substituted or unsubstituted alkyl group, R3 and R4 are independently hydrogen or substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, or substituted or unsubstituted cycloalkyl groups, Ar1 and Ar2 are independently aromatic hydrocarbon groups that can have one or more substituents X1 and X2 that independently represent hydrogen, a substituted or unsubstituted alkyl group, —COOR R R Y represents O or S.