Henkel Kommanditgesellschaft Auf Aktien

Loert De Riese-Meyer

Juergen Lindener

Christine Schroeder

Rudolf Zauns-Huber

Dieter Brodalla

Volker Sander

Willi Wuest

Hans-Josef Beaujean

Peter Kuhm

Willi Buchmeier

Juergen Foell

Jens Bode

Joerg Sander

Jochen Hieber

Method for electrolytic coloring of aluminum surfaces using alternating

The invention concerns a method of preparing preferably highly concentrated aluminum triformate solutions containing alkali metals and/or alkaline earth metals, by the neutralization of an alkaline aluminate solution containing alkali metals and/or alkaline earth metals by adding formic acid, and subsequently heating the solid precipitated to give a clear, stable aluminum triformate solution. The invention also concerns highly concentrated aluminum triformate solutions containing alkali metals and/or alkaline earth metals and the use of such solutions to impregnate textiles, in disinfectant and cleaning agents, as a coagulant for paints, or as a setting agent in leather processing.

Process for the production of an aluminum triformate solution containing

Dilutable aluminum triformate tanning agents in the form of highly

Manufactured tin(II) sulfate granules for electrolytic coloring with

Substituted diphenols, phenyl ethers containing two oxygen atoms attached to a benzene nucleus, and naphthols are more practically effective than previously known additives in stabilizing tin (II) salts, in electrolyte solutions useful for coloring anodized aluminum by electrolysis therein, against oxidation to tin(IV) by reaction with ambient oxygen. Preferred additives include 2-tert-butyl-1,4-dihydroxybenzene, methylhydroquinone, trimethylhydroquinone, 4-hydroxynaphthalene-2,7-disulfonic acid, and p-hydroxyanisole. If p-toluenesulfonic acid or napthalene sulfonic acid are also used in the electrolyte, the throwing power can be greatly improved.

Process for dyeing anodized aluminum

Undesirable greenish tinges that normally result when coloring anodized aluminum by AC electrolysis in solutions of silver salts can be avoided by adding to the electrolytes an appropriate amount of p-toluenesulfonic acid and/or its salts. The coloring solution may also contain (i) sulfuric acid, (ii) alkali metal, ammonium and/or alkaline earth metal salts of sulfuric acid and/or (iii) alkali metal, ammonium and/or alkaline earth metal acetates.

Process for coloring anodized aluminum by AC electrolysis

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Duesseldorf, Germany

Loert De Riese-Meyer