Flachdruckplatte und Verfahren zur Herstellung eines Trägers dafür

摘要

A planographic printing plate in which a design pattern is realized in a part of the back surface of a support for the planographic printing plate without any adverse influence on a photosensitive resin layer on the front surface thereof. After an aluminum support with a thickness of 0.24 mm is cleaned by degreasing and etching, an electrolytic aqueous solution is prepared to contain the nitric acid concentration of 10 g/l and the aluminum ion concentration of 7 g/l. In an electrolytic treatment cell 5, the back surface of the aluminum support is arranged so as to be faced to an electrode. A 1 mm-thick masking plate formed of an insulating material punched to provided openings with arbitrary shapes is brought into close contact with the back surface of the aluminum support so that the back surface of the aluminum support is covered with the masking plate. A carbon plate with a thickness of 50 mm is used as the electrode. Further, the electrolytic aqueous solution is supplied from a blowout nozzle toward the masking plate at a flow rate of 50 m/min. The electrode and the aluminum support are connected to an electric source through a cable so that the aluminum support 7 was partially roughened electrochemically.