Process for electrochemically modifying electrochemically roughened aluminum support materials and the use of these materials in the manufacture of offset printing plates

US4482444A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Werner Frass · Wiesbaden, DE
• Dieter Mohr · Appenheim, DE

Key dates

• Filing date: Jun 16, 1983
• Grant date: Nov 13, 1984
• Expiry date: Jun 16, 2003

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S204/08
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

This invention pertains to a process for electrochemically modifying electrochemically roughened aluminum or aluminum alloy-based support materials for printing plates. An aluminum or aluminum alloy-based support material is electrochemically roughened using alternating current in an electrolyte containing at least one from the group consisting of hydrochloric acid and nitric acid. Subsequently, at least one surface of the material is treated in an aqueous electrolyte, with the roughened material being made the cathode. The cathodic treatment results in removal of material from the surface in the order of from 0.1 to 10 g/m.sup.2, and is carried out in an aqueous electrolyte which has a pH value in the range from 3 to 11 and includes at least one water-soluble salt in a concentration ranging from 5 g/l up to the saturation limit thereof. The cathodic treatment is appropriately conducted using direct current at a current density from 3 to 100 A/dm.sup.2, at a temperature from 15.degree. to 90.degree. C., and for a duration from 5 to 90 seconds. The removal of material is optionally followed by an anodic oxidation of the support material and a hydrophilizing post-treatment of the oxi…