| 摘要 |
PROBLEM TO BE SOLVED: To produce a printing plate of high quality by a simple method by forming a photosensitive layer and a thermosensitive layer on a supporting body in such a manner that the thermosensitive layer is opaque for the light for which the photosensitive layer has spectral sensitivity, that the thermosensitive layer becomes transparent when exposed to laser light, and that the thermosensitive layer is soluble or swellable in a water-based medium. SOLUTION: This element has a photosensitive layer and a thermosensitive layer on a supporting body having a hydrophilic surface. The thermosensitive layer is opaque for the light for which the photosensitive layer has spectral sensitivity and becomes transparent when exposed to laser light. Moreover, the thermosensitive layer is soluble or swellable in a water-based medium. By using the thermosensitive layer which is soluble or swellable in a water-based alkali medium, a lithographic plate can be obtd. from this image forming element by only one step of development with a general developer soln. The thermosensitive layer used contains an IR pigment dispersed in a binder. A preferable IR pigment is carbon black. As for the binder, any water-soluble or water-swellable binder can be used. |
