PURPOSE: To obtain a lithographic plate without using a lith film by carrying out scanning image exposure using a PS plate formed by applying an under coat contg. a photosensitive resin to an Al plate having a surface Al2O3 layer and covering the coat with a photosensitive layer.
CONSTITUTION: The surface of an Al layer on a support is anodically oxidized to form an Al2O3 layer, and this layer is coated with a soln. contg. a photosensitive resin such as polyester or polyamide phenolaldehyde and a photocrosslinkable, photopolymerizable or photodecomposable compound such as benzo- or naphthoquinone- 1,2-diazido-5-sulfonic acid ester to form an under coat, which is then covered with a photosensitive resin layer contg. photosensitive silver halide. Image signals are converted into photosignals to subject the photosensitive layer to direct scanning image exposure, and the exposed layer is developed to obtain a silver image. This image as a mask is transferred onto the under coat. Thus, a stain-free lithographic plate with high sensitivity, high printing resistance and superior resolving power is obtained with low output laser.
SHIBA EISUKE
KASHIWARA AKIRA
MORI KEIJI
