| 摘要 |
<p>A layer of a photopolymerizable mixture for the production of relief plates and printing plates contain (a) one or more photopolymerizable olefinically unsaturated compounds, (b) one or more photoinitiators which, on exposure, initiate rapid photopolymerization in the layer, and (c) a combination, which on exposure does not initiate any appreciable photopolymerization in the layer and comprises (c1) a soluble acridinium, phenothiazinium, phenoxazinium or phenazinium dye and (c2) a mild reducing agent for the dye (c1). The layer gives an improved relief image (greater shadow well depths) in the production of relief plates, and is also advantageous in the production of gravure printing plates. On exposure, it undergoes a color change which facilitates evaluation of the exposed layers before development.</p> |
