Method of Developing a Lithographic Printing Plate Including Post Treatment

摘要

A method for producing a lithographic plate from a negative working, radiation imageable plate having an oleophilic resin coating that reacts to radiation by cross linking and is non-ionically adhered to a hydrophilic substrate. The steps include imagewise radiation exposing the coating to produce an imaged plate having partially reacted image areas at an initial double bond conversion rate including unreacted coating material, and completely unreacted nonimage areas; developing the plate by removing only the unreacted, nonimage areas from the substrate while retaining unreacted material in the image areas; and subjecting the upper surface of the plate to blanket post treatment energy, which further reacts the retained unreacted material in the image areas to increase the initial double bond conversion rate, producing a lithographic printing plate with enhanced durability.

主权项

1. A method for pre-press production of a lithographic printing plate from a negative working, radiation imageable plate having an oleophilic resin coating material containing active ingredients that participate in cross-linking reactions to radiation and is non-ionically adhered to a hydrophilic substrate, comprising the steps of:
(a) imagewise radiation exposing the coating to produce an imaged plate having image areas with partially reacted resin material at an initial double bond conversion per cent and nonimage areas of resin material that are completely unreacted; (b) without preheating, developing the plate with brushes in an aqueous solution to remove only the unreacted, nonimage areas from the substrate while retaining unreacted material in the image areas; and (c) blanket exposing the developed plate to an external source of energy which further reacts the retained unreacted material in the image areas, thereby increasing the initial double bond conversion by at least about 5 per cent.