Photographic Methods Based on Dye-Sensitized Photopolymerization.

Dye-sensitized photopolymerization involves the use of a vinyl monomer, photo- reducible dye, and a mild reducing agent. Exposure to visible light reduces the dye to its leuco form, which reacts with ambient oxygen to form a redox catalyst system. Free radicals generated in this oxidation-reduction reaction initiate the vinyl polymerization. Image-wise exposure of viscous liquid layers or dry binder coatings of the above catalyst-monomer systems yield photopolymer images. Possible uses of such photopolymerizable layers in the graphic arts include the following: Photoresists, three- dimensional master models, printing plates, and copying processes. Several methods of making photopolymer images visible have been investigated, e.g., selective dyeing, dye imbibition, formation of light-scattering polymers, and selective control of chemical color reactions.