PREPARING LITHOGRAPHIC PRINTING PLATE

摘要

A method for preparing a lithographic printing plate is disclosed. The method involves providing a light-sensitive material comprised of an electroconductive support having a hydrophilic surface. The surface has provided thereon a light-sensitive layer and a photo-conductive insulating layer which may be provided in that order or combined in a single layer. The material is imagewise exposed and then subjected to electrophotographic processing to form an electrostatic latent image on the photoconductive insulating layer. After exposure the electrostatic latent image is developed with developer particles which are opaque to the light to which the light-sensitive layer is sensitive in the presence of an electrode facing the photoconductive insulating layer. The development is carried out while applying a bias voltage between the electrode and the light-sensitive layer so that residual charge on the non-latent image areas appears zero. The exposed or unexposed areas of the light sensitive layer are then removed together with the photoconductive insulating layer. The method provides a lithographic printing plate which has high resolution without a printing stain.