Zirconium pretreatment compositions containing a rare earth metal, associated methods for treating metal substrates, and related coated metal substrates

Patent metadata

Field	Value
Publication number	US-10017861-B2
Application number	US-201113197075-A
Country	US
Kind code	B2
Filing date	Aug 3, 2011
Priority date	Aug 3, 2011
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

Disclosed are methods for treating metal substrates that include contacting the substrate with a pretreatment composition comprising a rare earth metal and a zirconyl compound. The present invention also relates to coated substrates produced thereby and further to substrates additionally coated with an electrophoretically applied coating composition.

First claim

We claim:

1. A pretreatment composition for treating a metal substrate comprising: (a) a soluble rare earth metal; (b) a zirconyl compound; and (c) an electropositive metal, wherein the pretreatment composition contains no free fluoride, wherein the pretreatment composition is free of phosphate ions, wherein a ratio of zirconium from said zirconyl compound to said rare earth metal in the pretreatment composition is 200/1 and 1/1, and wherein upon contact with the metal substrate, the pretreatment composition reacts with and chemically alters a surface of the metal substrate and binds to the surface of the metal substrate to form a protective layer.

2. The pretreatment composition of claim 1 , wherein said zirconyl compound (b) comprises zirconyl nitrate, zirconyl acetate, zirconyl carbonate, protonated zirconium basic carbonate, zirconyl sulfate, zirconyl chloride, zirconyl iodide, zirconyl bromide or a mixture thereof.

3. The pretreatment composition of claim 1 further comprising: (d) a group IVB and/or group VB metal.

4. The pretreatment composition of claim 3 , wherein the amount of metal from said zirconyl compound and from said group IVB and/or group VB metal in the pretreatment composition comprises from 10 ppm to 5000 ppm.

5. The pretreatment composition of claim 1 , wherein said rare earth metal (a) comprises yttrium, praseodymium, cerium, or mixtures thereof.

6. The pretreatment composition of claim 1 , wherein a source of said rare earth metal (a) comprises a rare earth metal compound.

7. The pretreatment composition of claim 6 , wherein said rare earth metal compound comprises a compound of yttrium, cerium, praseodymium, or a mixture thereof.

8. The pretreatment composition of claim 1 , wherein the amount of zirconium from said zirconyl compound in the pretreatment composition comprises from 10 ppm to 5000 ppm.

9. The pretreatment composition of claim 1 , wherein said electropositive metal is more electropositive than the metal substrate.

10. The pretreatment composition of claim 1 , wherein the pretreatment composition is substantially free of heavy metal phosphate.

11. The pretreatment composition of claim 1 , wherein the pretreatment composition is completely free of heavy metal phosphate.

12. A method for treating a metal substrate comprising:
(a) contacting the metal substrate with a pretreatment composition comprising a soluble rare earth metal, a zirconyl compound, and an electropositive metal,
wherein the pretreatment composition contains no free fluoride,
wherein the pretreatment composition is free of phosphate ions,
wherein a ratio of zirconium from said zirconyl compound to said rare earth metal in the pretreatment composition is 200/1 and 1/1, and
wherein upon contact with the metal substrate, the pretreatment composition reacts with and chemically alters a surface of the metal substrate and binds to the surface of the metal substrate to form a protective layer.

13. The method according to claim 12 , wherein said pretreatment composition is contacted to the metal substrate without the prior application of an electropositive metal.

14. The method of claim 12 , wherein said pretreatment composition further comprises a group IVB and/or group VB metal.

15. The method of claim 12 further comprising electrophoretically depositing a coating composition onto the metal substrate after step (a).

Assignees

• Silvernail Nathan J
• Mcmillen Mark W
• Cheng Shan
• Ppg Ind Ohio Inc

Inventors

• Silvernail Nathan J
• Mcmillen Mark W
• Cheng Shan

Classifications

• C23C22/50 Primary

  Treatment of iron or alloys based thereon · CPC title

• C23C22/83

  Chemical after-treatment · CPC title

• C23C22/53

  Treatment of zinc or alloys based thereon · CPC title

• C23C22/56

  Treatment of aluminium or alloys based thereon · CPC title

• C25D13/20

  Pretreatment · CPC title