Process and aqueous compositions for treating metal surfaces

US4761189A · kind A · utility

Assignee

• Gerhard Collardin GmbH · DE

Inventors

• Raschad Mady · Frechen, DE
• Christian Ries · Kalchreuth, DE
• Roland Morlock · Bergheim, DE

Key dates

• Filing date: May 20, 1987
• Grant date: Aug 2, 1988
• Expiry date: May 20, 2007

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C2222/10
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The invention relates to a process for treating metal surfaces, preferably of aluminum, aluminum alloys and steel, for the subsequent application of organic coating compositions. The metal surfaces are wetted with an aqueous bath solution containing chromium(III)ions, fluoride ions and an organic film former which is soluble or homogeneously dispersible in water, after which the solution applied is dried and converted by heating into a water-insoluble film. The bath solution preferably contains the following constituents and approximate quantities thereof: 0.5 to 10 g/l of chromium(III)ions, 0.55 to 11 g/l of fluoride ions, 0.6 to 12.5 g/l of phosphate ions, and 0.15 to 5.0 g/l of organic film former. The organic film former preferably used is a polymer containing free carboxyl groups, more preferably a homopolymer and/or copolymer of acrylic and/or methacrylic acid.