Hoechst Aktiengesellschaft

Reiner Beutel

Ulrich Simon

Gerhard Sprintschnik

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 two hydrophilizing post-treatment steps. In post-treatment step (a) a supported aluminum oxide layer is treated with an aqueous alkali metal silicate solution which optionally contains alkaline earth metal ions, and in step (b) the aluminum oxide layer is separately treated with an aqueous solution containing at least one organic polymer comprised of vinylphosphonic acid and/or vinylmethylphosphinic acid monomers, such as polyvinylphosphonic acid. Treatment of the aluminum oxide layer is accomplished by means of immersion and/or electrochemically. 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.

Process for a two-stage hydrophilizing post-treatment of aluminum oxide

A process for manufacturing materials in the form of sheets, foils or webs comprising chemically, mechanically and/or electrochemically roughened and anodically oxidized aluminum or one of its alloys, wherein the resultant aluminum oxide layers are post-treated with an aqueous solution containing phosphoroxo anions, is performed such that a post-treatment of the aluminum oxide layers is effected by immersion in an aqueous solution containing hexametaphosphate anion. In a preferred embodiment, the aqueous solution is adjusted to a pH of 1 to 5 by addition of an acid. The resulting materials, which have reduced adsorption properties, are preferably employed as support materials for offset printing plates.

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Weisbaden, Germany

Reiner Beutel