ANODIC OXIDATION AND SILICATE TREATMENTS OF ROUGHENED ALUMINIUM

摘要

The process for manufacturing materials, in the form of sheets, foils or webs, comprised of chemically, mechanically and/or electrochemically roughened and anodically oxidized aluminum or an aluminum alloy, which process is performed with a hydrophilizing post-treatment step. In this post-treatment step, a supported aluminum oxide layer is treated with an aqueous alkali metal silicate solution which also contains alkaline earth metal ions. Treatment of the aluminum oxide layer is accomplished by means of an immersion or electrochemically. Electrochemical roughening is performed in an aqueous solution containing nitric acid. Materials prepared by this process are particularly useful as supports for offset printing plates, showing an improved resistance to alkali and a reduced tendency to adsorb dyestuff.