POSITIVE PHOTOSENSITIVE LITHOGRAPHIC PRINTING PLATE

摘要

PROBLEM TO BE SOLVED: To obtain a positive photosensitive lithographic printing plate having excellent contrast and enough film remaining rate in a printing area by roughening a base body and applying a positive photosensitive compsn. to form a film in a specified film thickness range. SOLUTION: This printing plate is obtd. by forming a positive photosensitive compsn. containing a photo-thermal convertible material and an alkali-soluble resin on a base body as the component of the printing plate in which difference in solubility with an alkaline developer is produced between an exposed part and an unexposed part due to main changes except for chemical change. The base body is preliminarily roughened. The positive photosensitive compsn. is applied to obtain 2 to 12 g/m<2> film thickness as a dry base, preferably 2.4 to 9.0 g/m<2> , and more preferably 2.7 to 7.0 g/m<2> .