The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 12, 1991
Filed:
Jul. 19, 1989
Dieter Brodalla, Duesseldorf, DE;
Juergen Lindener, Duesseldorf, DE;
Loert de Riese-Meyer, Duesseldorf, DE;
Willi Wuest, Ratingen, DE;
Christine Schroeder, Duesseldorf, DE;
Willi Buchmeier, Duesseldorf, DE;
Juergen Foell, Duesseldorf, DE;
Henkel Kommanditgesellschaft auf Aktien, Duesseldorf, DE;
Abstract
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.