Process for forming a lithographic printing plate by electrophotography

Abstract

A process for preparing a lithographic printing plate from an electrophotographic photosensitive material comprising a photoconductive insulating layer containing photoconductive zinc oxide and a thermoplastic insulating resin disposed on a waterproof support, said method comprising the steps of electrical charging, imagewise exposure, and development of the material in a wet developer having toner particles containing an oleophilic component dispersed in an insulating liquid carrier, thereby providing an oleophilic toner image, and heating the developed photosensitive material under such conditions that when an adhesive tape having a tackiness of 280 to 350 g/10 mm wide portion as measured by the 180.degree. peeling method of JIS C2107 (passed once between pressure rollers at 50 mm/sec) and which has been contact-bonded to the surface of said toner image-bearing photosensitive material by passage between a metal roll and a rubber roll pressed against said roll at a pressure of 6000 g/cm.sup.2, is peeled off said photosensitive material one minute after the contact-bonding at a peeling rate of 500 mm/min and an angle of 180 degrees, the toner image carried away by adhering to the tape is not more than 30 wt. % of the toner in the solid image area on which at least 0.03 mg/cm.sup.2 of the toner is deposited, and the cohesion of toner particles inside the toner layer against the peeling force is at least about 350 g/10 mm wide portion.