Photopolymerisable compsn. contg. dimeric nitroso cpd. - to inhibit thermal but not photo polymerisation of unsatd. cpd. by free radicals from light sensitive system

摘要

The compsn. contains 100 ppm to 2 wt % (0.1-10 wt %) nitroso cpd. e.g. nitrosocyclohexane, and 0.1-2.0 wt % organic light-sensitive system forming free radicals. The action of the nitroso cpd. depends on its dissociation into the monomer, which acts as inhibitor. Dissociation is slight (dissociation constant 10-2 to 10-10 in soln at 25 degrees C) but sufficient to prevent polymsn. during storage and handling at normal temp. and is higher temps. The dissociation rate is comparable with the polymerisation rate of the unsatd. cpd(s). at the working temp. The compsn is used for making presensitised lithographic printing plates, as photoresist for etched or plated printed circuits, for making colour pictures from colour print negatives, suitable for colour correction, or for copying by thermal transfer to a substrate.