Composition for treating surface of metal, method for treating surface of metal using the composition, and coating film for treating surface of metal utilizing the composition and the method

Abstract

A process for metal surface treatment includes dipping a metallic material with a cleaned surface into a composition containing 5 to 30% by weight of a nonionic and / or cationic water-based resin, 100 to 1,000 ppm of trivalent Bi ions, and an aminopolycarboxylic acid at 0.5 to 10 times in molar concentration based on the Bi ions, then performing a first electrolysis using the metallic material as a cathode at a voltage of 0 to 15 V for 10 to 120 seconds, and performing a second electrolysis at a voltage of 50 to 300 V for 30 to 300 seconds, in which the performing the first electrolysis is prior to the performing the second electrolysis, and thereafter rising with water, and baking to deposit a film over the metallic material.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a Divisional of U.S. patent application Ser. No. 13 / 254,175, filed Sep. 1, 2011, which is a national stage application of PCT / JP2010 / 000965, filed Feb. 17, 2010, which claims priority of Japanese Patent Application No. 2009-048474, filed Mar. 2, 2009. This application claims the priorities and benefits of all these prior applications and incorporates the disclosures of these prior applications by reference in their entireties.BACKGROUND OF INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a composition for metal surface treatment capable of forming films capable of imparting excellent corrosion resistance in relation to metallic materials, in particular, metal formations having complex shapes through a single dipping step, a process for metal surface treatment using the same and a metal surface treatment film using the same.[0004]2. Background Art[0005]Traditionally, electrodeposition coati...

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Benefits of technology

[0039]The inventors have then confirmed that films obtained thereby can sufficiently improve not only the catalysis ability for curing a resin which Bi possesses but also the corrosion resistance of the basis metals by virtue of Bi existing at high concentrations on the basis metal surfaces, to successfully accomplish the present invention.

Problems solved by technology

Since desired corrosion resistance may not be obtained solely by electrodeposited films obtained by electrodeposition coating in many cases, however, surface treatment of chemical conversion type, such as zinc phosphate-based chemical conversion treatment has been typically applied in a stage prior to such electrodeposition coating.

However, sufficient rust resistance could not be obtained thereby and, therefore, surface treatment such as zinc phosphate-based chemical conversion treatment was essential.

However, the bismuth compounds in these patent references only act in place of chromium and / or lead compounds and, therefore, sufficient corrosion resistance may not be obtained without surface treatment such as zinc phosphate-based chemical conversion treatment.

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