Processes and compositions for improving corrosion performance of zirconium oxide pretreated zinc surfaces

Patent metadata

Field	Value
Publication number	US-2017137947-A1
Application number	US-201715417837-A
Country	US
Kind code	A1
Filing date	Jan 27, 2017
Priority date	Feb 8, 2011
Publication date	May 18, 2017
Grant date	—

Abstract

A method of improving corrosion resistance of a metal substrate comprising a zinc surface coated with zirconium oxide conversion coating by, prior to conversion coating, contacting the zinc surface with a composition comprising:
a) iron(III) ions, b) a source of hydroxide ion; c) at least one complexing agent selected from organic compounds which have at least one functional group —COOX, wherein X represents either a H or an alkali and/or alkaline earth metal; d) 0.0 to about 4 g/l cobalt (II) ions; and optionally e) a source of silicate: wherein the composition has a pH of at least 10.

First claim

What is claimed is:

1 . A coated metal article coated according to a method comprising steps of:
1.) providing a metal substrate comprising at least one zinc or zinc alloy surface; 2.) contacting said one at least one zinc or zinc alloy surface with an alkaline pre-rinse composition comprising:
a) iron(III) ions,
b) a source of hydroxide ion;
c) at least one complexing agent selected from organic compounds which have at least one functional group —COOX, wherein X represents either a H or an alkali and/or alkaline earth metal;
d) 0.0 to about 4 g/l cobalt (II) ions; and
optionally
e) a source of silicate:
wherein the composition has a pH of at least 10;
3.) optionally rinsing said surface; 4.) applying to the metal substrate a zirconium-based metal pretreatment coating composition comprising zirconium, thereby forming a zirconium oxide coating on all surfaces of the metal substrate including said at least one zinc or zinc alloy surface resulting in a zirconium oxide conversion coated substrate; and 5.) optionally applying a paint to the metal pretreatment coated metal substrate.

2 . The coated metal article of claim 1 wherein contact time of step 2.) is from 2 to 60 seconds and the alkaline pre-rinse composition has a temperature of 85 to 125 degrees F.

3 . The coated metal article of claim 1 wherein the iron(III) ions are present in the alkaline pre-rinse composition in an amount of about 5 ppm to about 400 ppm; and the source of hydroxide ion is present in an amount of about 0.5 g/l to about 4.0 g/l.

4 . The coated metal article of claim 1 wherein the metal pretreatment coated metal substrate comprises iron on the at least one zinc or zinc alloy surface and/or in the zirconium oxide coating.

5 . The coated metal article of claim 1 wherein the cobalt (II) ions are present in the alkaline pre-rinse composition in an amount of 1 ppm up to the solubility limit of the cobalt (II) ions.

6 . The coated metal article of claim 5 wherein the metal pretreatment coated metal substrate comprises cobalt and iron on the at least one zinc or zinc alloy surface and/or in the zirconium oxide coating.

7 . The coated metal article of claim 1 wherein the alkaline pre-rinse composition is phosphate-free.

8 . The coated metal article of claim 1 wherein the zirconium-based metal pretreatment coating composition further comprises fluoride and a chelating agent.

9 . The coated metal article of claim 1 wherein the zirconium-based metal pretreatment coating composition comprises 50 to 300 ppm of dissolved Zr, 0 to 50 ppm of dissolved Cu, 0 to 100 ppm of SiO 2 , 150 to 2000 ppm of total Fluoride, 10 to 100 ppm of free Fluoride and optionally a chelating agent.

10 . A coated metal article comprising:
A) a steel substrate; B) a first layer comprising a zinc or zinc alloy metal surface deposited on the steel substrate; C) a phosphate-free second layer comprising iron, and optionally cobalt, deposited on said zinc or zinc alloy metal surface; D) a third layer comprising a zirconium oxide conversion coating; and E) a fourth layer comprising at least one paint applied to the zirconium oxide conversion coating;
wherein said coated metal article having a coating of the first, second, third and fourth layers has better resistance to cyclic corrosion than a comparative metal article coated with the first layer, the third layer and the paint in the absence of the second layer.

11 . The coated metal article of claim 10 wherein the fourth layer is an electrodeposition paint.

12 . The coated metal article of claim 10 further comprising at least one of a primer and a basecoat paint layer applied to the fourth layer.

13 . The coated metal article of claim 12 further comprising a clearcoat paint layer applied to the primer or basecoat paint layer.

14 . The coated metal article of claim 10 wherein said coating comprises iron on the at least one zinc or zinc alloy surface and/or in the zirconium oxide coating.

15 . The coated metal article of claim 10 wherein the coating comprises cobalt and iron on the at least one zinc or zinc alloy surface and/or in the zirconium oxide coating.

16 . The coated metal article of claim 10 wherein the first and second layers are phosphate-free.

17 . A coated metal article comprising:
A) a metal substrate comprising at least one zinc or zinc alloy surface; B) a phosphate-free layer comprising iron, and optionally cobalt, deposited on said zinc or zinc alloy metal surface; C) a zirconium oxide conversion coating layer deposited on B); and D) a paint applied to the zirconium oxide conversion coating layer;
wherein said coated metal article has better resistance to cyclic corrosion than a comparative metal article coated similarly coated in the absence of B).

18 . The coated metal article of claim 17 wherein the paint comprises one or more paint layers selected from an electrodeposition paint layer, a primer layer, a basecoat paint layer and a clearcoat paint layer.

19 . The coated metal article of claim 17 wherein the metal substrate further comprises at least one cold rolled steel surface.

20 . The coated metal article of claim 17 wherein the metal substrate is a hot dip galvanized or electro galvanized steel substrate.

Assignees

• Henkel Ag & Co Kgaa

Inventors

• Kapic Edis
• Goodreau Bruce H
• Bobadilla Alvaro
• Febbraro Michael

Classifications

• C23C22/80

  with solutions containing titanium or zirconium compounds · CPC title

• Y10T428/12611

  Oxide-containing component · CPC title

• C23F11/06 Primary

  in markedly alkaline liquids · CPC title

• C23C22/83

  Chemical after-treatment · CPC title

• C23C22/60

  using alkaline aqueous solutions with pH greater than 8 · CPC title