| 摘要 |
PURPOSE:To obtain a printing plate of high resolving power by forming latent images electrostatic-photographically by the use of a photosensitive material having a positive type photosensitive layer and a photoconductive insulation layer on a conductive substrate having a hydrophilic surface then developing the same by the use of a liquid developer and further exposing the same and removing the photosensitive layer having no developed images. CONSTITUTION:A positive type photosensitive layer 2 contg. o-quinone diazide compound, a depolymerized type photosensitive resin or the like alone or an alkali soluble resin (novolak type phenol-formaldehyde resin, polyamide, etc.) together with a binder is provided on a conductive substrate 3 of an Al plate or the like having a hydrophilic-treated surface. A lithographic printing plate forming a photoconductive insulation layer 1 on the layer 2 by using a photoconductive material and an alkali soluble binder is made. Such printing plate is corona charge 4, is exposed 5 with images 6, is developed 7 with a liquid developer contg. opaque toner particles 7, and is reexposed 8, after which the parts having no developer 7 are removed by using an alkaline soln., whereby the printing plate of high resolving power is obtained. It is equally well to use a photosensitive plate formed with the layer 1' contained with a photoconductor and a photosensitive material on the same layer on the substrate 3. |
