Negative-working lithographic printing plate precursors and use

摘要

A negative-working lithographic printing plate precursor comprises a negative-working radiation-sensitive imageable layer and an outermost layer comprising a vinyl alcohol copolymer comprising at least one unit of each of the (a), (b), and (c) recurring units, in any order, defined in the disclosure. The (c) recurring units are present in the vinyl alcohol copolymer in an amount of at least 0.5 mol %, based on the total recurring units. These precursors can be used to prepare lithographic printing plates either on-press or off-press after imaging using near-UV, visible, or infrared radiation.

主权项

1. A method for providing a lithographic printing plate, comprising:
imagewise exposing a negative-working lithographic printing plate precursor that comprises a substrate, a negative-working radiation-sensitive imageable layer, and an aqueous solution soluble outermost layer to imaging radiation to provide exposed regions and non-exposed regions in the negative-working radiation-sensitive imageable layer, and removing the aqueous solution soluble outermost layer and the non-exposed regions of the negative-working radiation-sensitive imageable layer,
wherein the negative-working radiation-sensitive imageable layer comprises a free radically polymerizable compound, a radiation absorber, a compound to generate free radicals upon irradiation, and a polymeric binder, andthe aqueous solution soluble outermost layer comprising a first vinyl alcohol copolymer comprising at least one unit of each of the following (a), (b), and (c) recurring units, in any order: wherein R, R′, and R″ are independently hydrogen or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, R1 is hydrogen or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, R2 represents a single connecting bond or a substituted or unsubstituted alkylene or cycloalkylene group, wherein the (c) recurring units are present in an amount of at least 0.5 mol %, based on the total recurring units in the first vinyl alcohol copolymer.