Abstract:
Photopolymer printing plates having, on top of a photosensitive layer (a) attached to a base, a thin layer (b) of a suspension of finely crystalline conjugated diacetylene compounds in a binder, which compounds change color when photopolymerized. Such printing plates make possible the production of positive copies of a positive transparency by producing in layer (b) an image with areas which do not transmit light by exposure to light having a wavelength of less than 320 m Mu and optional fixing, and initiating photopolymerization in layer (a) by exposing it through the said image to light having a wavelength of from 320 to 450 m Mu and then washing out the unexposed areas of layer (a).
Abstract:
Photosensitive coating materials comprising polymers containing o-nitrocarbinol ester groups, particularly of polymers and copolymers of o-nitrocarbinol esters of ethylenically unsaturated carboxylic acids, which as a result of exposure become soluble in an alkaline solvent used as developer in which they were not soluble prior to exposure. Such materials are used in particular for coating lithographic printing plates and as photoresists.