Process for sealing anodized aluminum

US4939001A · kind A · utility

Assignee

• Henkel Kommanditgesellschaft auf Aktien · DE

Inventors

• Dieter Brodalla · Düsseldorf, DE
• Winfried Kirchhoff · Düsseldorf, DE
• Willi Wuest · Ratingen, DE
• Helmut Blum · Goldkronach, DE
• Wolfgang Riedel · Neuenbürg, DE

Key dates

• Filing date: Jun 14, 1989
• Grant date: Jul 3, 1990
• Expiry date: Jun 14, 2009

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25D11/246
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

In the process of sealing decorative anodized aluminum oxide coatings in hot aqueous solutions, superior results are obtained when the sealing solutions contain 1-phosphonopropane-1,2,3-tricarboxylic acid, 1,1-diphosphonopropane-2,3-dicarboxylic acid, and/or alkali metal and/or alkanolamine salts of these acids. The presence of these acids or their salts prevents the formation of bloom and allows shorter sealing times with equivalent quality, and the addition of as little as 1 ppm of aluminum ions to such solutions also prevents iridescence.