Patent ID: 6024858
Filing Date: 2000-02-15
Classification: B41N,C25F,Y10S

Abstract:
A method of producing an aluminum support for a planographic printing plate which comprises,(1) etching a surface of an aluminum plate chemically in an acidic or alkaline aqueous solution,(2) roughening the surface of the aluminum plate electrochemically in an acidic aqueous solution by applying DC voltage to form honeycomb pits having an average diameter from 0.5 to 10 .mu.m with a density of 10,000 to 100,000 pits/mm.sup.2 and to leave plateau portions without honeycomb pits or with honeycomb pits having an average diameter of less than 0.5 .mu.m at a rate from 15 to 60% of the surface,(3) etching the surface of the aluminum plate chemically in an acidic or alkaline aqueous solution to render the plateau portions less than 10% of the surface,(4) roughening the surface of the aluminum plate electrochemically in an acidic aqueous solution using direct current or alternating current to form honeycomb pits having an average diameter from 0.1 to 2 .mu.m,(5) etching the surface of the aluminum plate chemically in an acidic or alkaline aqueous solution, and(6) anodizing or anodizing and rendering hydrophilic the surface of the aluminum plate in an acidic aqueous solution.