Patent ID: 7754412
Filing Date: 2010-07-13
Classification: G03F

Abstract:
1. A process for making a flexographic printing plate comprising: (a) providing a photosensitive element comprising a support and a photopolymerizable elastomeric layer on the support, the photopolymerizable layer comprising a binder, at least one monomer, a photoinitiator, an onium salt and a leuco dye, wherein the onium salt is present in greater reactive amount than the leuco dye and the leuco dye is 0.1 to 0.3% by weight, based on the total weight of the components in the photopolymerizable layer; (b) imagewise exposing the photopolymerizable layer to actinic radiation forming polymerized portions and unpolymerized portions in the layer; (c) treating the element of (b) to remove the unpolymerized portions and form a relief surface having raised areas; and prior to treating step (c), backflash exposing the photopolymerizable layer through the support to actinic radiation to form a floor that contrasts in color with the raised areas of the relief surface.