Electrophotographic process for the production of lithographic printing plates and light-sensitive materials for use therein

Claim 1

A process for producing a lithographic printing plate using a light-sensitive material comprising an electrically conductive support having a hydrophilic surface, and a positive working light-sensitive layer and a photoconductive insulative layer containing an alkali-soluble resin on the support, said process comprising the steps of: (A) forming an electrophotographic latent image on the photoconductive layer of the light-sensitive material; (B) developing the latent image with a liquid developer containing developer particles which are opaque to light having a wavelength to which the positive working light-sensitive layer is sensitive; (C) exposing to light the positive working light-sensitive layer through the developed image obtained in step (B); and (D) selectively removing with an alkali solution the area of the positive working light-sensitive layer not bearing the developed image together with areas corresponding to said areas of the positive working light-sensitive layer not bearing the developed image of the photoconductive layer; wherein: the positive working light-sensitive layer and the photoconductive insulative layer are provided on the support as a unit layer, or are individually provided in that order; and the photoconductive insulative layer is substantially chargable either positively or negatively, and contains said alkali-soluble resin in such an amount as to not inhibit the selective removal of the positive working light-sensitive layer in step (D).