Composition and process for activating metal surfaces prior to zinc phosphating and process for making said composition

US4957568A · kind A · utility

Assignee

• Henkel Kommanditgesellschaft auf Aktien · DE

Inventors

• Helmut Endres · Zusmarshausen, DE
• Peter Christophliemk · Düsseldorf, DE
• Karl-Dieter Brands · Goldkronach, DE
• Wolf-Achim Roland · Solingen, DE
• Joerg Riesop · Niederzier, DE

Key dates

• Filing date: Apr 28, 1989
• Grant date: Sep 18, 1990
• Expiry date: Apr 28, 2009

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C22/80
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Activation of metal surfaces prior to phosphating can be improved by using aqueous dispersions of polymeric titanium(IV) phosphates in which at least 95% by weight of the polymeric particles have a particle diameter of less than 200 nm. This low particle diameter is attained by adding a titanium(IV)-complexing agent before or during an otherwise conventional reaction between a titanium(IV) compound, acid or phosphate, and water. The complexing agent is used in an amount of less than the stoichiometric amount, based on the titanium(IV) content. The best complexing agents are poly(aldehydocarboxylic acids), 1,1-diphosphonic acids, and/or the alkali metal salts of these types of acids.