| 摘要 |
PURPOSE:To obtain a planographic plate having excellent hydrophilic property, water retention and high durability in printing and being less liable to generate contamination of non-image parts, by a method wherein an electric current having an asymmetrical alternating wave form is impressed on an aluminum plate in an aqueous solution containing nitric acid and a specified amount of a chloride to electrolytically roughen the surface of the aluminum plate. CONSTITUTION:An electric current having an asymmetrical alternating wave form is impressed on the aluminum plate in an aqueous solution containing nitric acid and a chloride in an amount of 0.25-0.5pts.wt. per 1pt.wt. of nitric acid, thereby electrolytically roughening the surface of the aluminum plate. The electrolyte solution must contain small but effective amounts of nitric acid and the chloride in combination as active electrolytes. The chloride is preferably aluminum chloride, ammonium chloride, magnesium chloride, zinc chloride or the like. Accordingly, a uniform grain with a high surface roughness can be obtained, and a planographic plate can be obtained which has high water retention, hydrophilic property and durability in printing, and is less liable to generate contamination of non-image parts. |
