Lithographic printing plate and treating liquids for such plate comprising a hydrophilic amphoteric block copolymer

摘要

A lithographic printing plate that works according to the silver salt diffusion transfer reversal process is disclosed. The lithographic properties of said plate can be improved by incorporating a hydrophilic amphoteric block copolymer, comprising a non-ionic block of acrylic units with pendant nitrile groups and an acrylamid(in)e block which comprises units with pendant basic and acidic groups. The hydrophilic amphoteric block copolymer is preferentially present in the image receiving layer of the lithographic printing plate. In an alternative embodiment, said block copolymer may be present in a treating solution used for processing said plate or applied onto said plate while printing. The hydrophilicity of the printing plate's surface is improved without deteriorating the ink-acceptance in the printing areas.