| 摘要 |
PURPOSE:To obtain a base for printing plate capable of giving a uniform roughened surface, showing favorable durability in printing and less liable to suffer contamination of non-image parts, by chemically etching an aluminum plate and electrochemically etching the plate. CONSTITUTION:An aluminum plate with a surface cleaned is chemically etched with an aqueous solution containing a mineral acid and an aluminum salt of a mineral acid. Hydrochloric acid is particularly preferable for use as a mineral acid, and aluminum chloride is particularly preferable for use as the salt. The chemical etching is so conducted as to obtain a center line surface roughness of 0.3-1.3 mum. Since smut is formed on the surface of the aluminum plate thus chemically etched, a desmutting treatment is performed. The plate is then electrochemically etched, in an acicid electrolytic liquid by using AC current. The acicid electrolytic liquid is preferably hydrochloric acid, sulfuric acid or a combination thereof. Since smut is formed on the surface of the plate thus electrochemically etched, the plate is washed with water and is desmutted. Where a planographic plate of a higher durability in printing is desired, the plate is further subjected to anodic oxidation. |
