POSITIVE PHOTOSENSITIVE COMPOSITION AND LITHOGRAPHIC PRINTING PLATE FORMED BY USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a lithographic printing plate superior in contrast and sufficient in the film endurance of image line parts by using a new positive photosensitive composition. SOLUTION: This positive photosensitive composition contains a constituent to be allowed to cause difference in solubility in an alkaline developing solution between exposed parts and unexposed parts mainly due to changes except chemical changes, and constituents causing such differences are embodied by (a) a substance convertible by light and heat and (b) an alkali-soluble resin, and the photosensitive film formed by using this composition needs to have a contact angle to water >=75 deg.C.