Process for the electrochemical roughening of aluminum for use as printing plate supports, in an aqueous mixed electrolyte

摘要

Disclosed is a process for electrochemically roughening aluminum or aluminum alloys for use as printing plate supports, in an aqueous mixed electrolyte solution containing hydrochloric acid (HCl) and, as an additional inorganic electrolyte, at least one compound selected from the group consisting of condensed phosphoric acids, amidosulfonic acid, and the water-soluble alkali metal salts and ammonium salts thereof. In particular, the solution contains from 0.5 to 10% by weight of HCl and from 0.05 to 5.0% by weight of the additional inorganic electrolyte (for example, diphosphoric acid or polyphosphoric acid). The support materials which are particularly uniformly roughened are employed in the production of offset-printing plates.