Process for multicoat cathodic wet-on-wet painting of metallic conductive substrates

US4818356A · kind A · utility

Assignee

• Basf Lacke & Farben Aktiengesellschaft · DE

Inventors

• Michael Geist · Munster, DE
• Gunther Ott · Hachenburg, DE
• Georg Schon · Everswinkel, DE
• Arnold Dobbelstein · Cologne, DE
• Wolfgang Batzill · Munster, DE

Key dates

• Filing date: Sep 25, 1986
• Grant date: Apr 4, 1989
• Expiry date: Sep 25, 2006

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S524/901
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The invention relates to a process for coating an electrically conductive substrate, the said substrate being immersed in an aqueous bath based on a cationic synthetic resin binder which is at least in part neutralized with acids and contains amino and/or hydroxyl groups. The said bath contains a mixture of crosslinking agents as well as pigments, fillers, corrosion inhibitors, paint auxiliary substances, and, if appropriate, catalysts, as well as organic solvents in an amount of up to 15% by weight based on the total weight of the coating, the said substrate being cathodically connected. By the action of direct current, a film is deposited on the substrate, after which the said substrate is removed from the bath and the film is cured by stoving, the mixture of crosslinking agents comprising at least two crosslinking agents of different reactivities based on activated esters and/or polyisocyanates blocked by different blocking agents. The expression "different reactivities" means that the crosslinking reaction commences by heating to temperatures which are separated by at least 10.degree. C. and that crosslinking agent which is first to react is present in an amount of 15 to 60 mol…