PHOTOSENSITIVE PLANOGRAPHIC PRINTING PLATE

摘要

PURPOSE:To obtain the photosensitive phanographic printing plate which is lessened in after-colors and has high printing resistance by setting the concn. of the dyes in photosensitive layers lower in at least the region near the surface of the photosensitive layers on the side near a base than in the other regions of the photosensitive layers. CONSTITUTION:A positive type photosensitive compsn. layer which contain the dyes and is made soluble in a developer by exposing is provided on an aluminum sheet subjected to a surface roughening treatment then to anodic oxidation. The dyes are so icorporated into the photosensitive layers that the concn. thereof is lower in at least the region near the surface of the photosensitive layers on the side near the base than in the other regions of the photosensitive layers. The photosensitive planographic printing plate which is decreased in the after-colors of non-image parts when subjected to development processing and has the excellent printing resistance is obtd. in this way.