| 摘要 |
PURPOSE: To obtain an original plate as a direct plate making material having such image reproducibility and printing resistance as to withstand practical use by successively laminating a non-silver salt photosensitive layer, an ink- repellent layer and a silver salt photo-sensitive layer on a substrate. CONSTITUTION: A silver salt photosensitive layer is formed on an ordinary original plate of a waterless planographic printing plate obtd. by successively laminating a non-silver salt photosensitive layer and an ink-repellent layer on a substrate to obtain the objective original plate excellent in image reproducibility and printing resistance. The silver salt photosensitive layer is not especially limited if it contains a silver salt which becomes blackened silver by exposure to make the layer opaque but the layer is composed essentially of a silver halide emulsion and a sensitizer. The pref. average particle diameter of the silver halide is 0.01-5μm. It is preferable that the grain size of the silver halide particles is varied, strain is applied to the grains or the particles are subjected to sulfur sensitization, reduction sensitization or chemical sensitization with a noble metallic salt so as to impart proper sensitivity. |
