Dyed trivalent chromium conversion coatings and methods of using same

• US 10,533,254 B2
• Filed: 01/31/2018
• Issued: 01/14/2020
• Est. Priority Date: 02/01/2017
• Status: Active Grant

• Current Assignee: CHEMEON Surface Technology, LLC
• Original Assignee: CHEMEON Surface Technology, LLC
• Inventors: Westre, Sjon, Clarke, Taylor James, Cruson, Jake
• Primary Examiner(s): Zheng, Lois L
• Application Number:
  US15/885,528
• Publication Number:
  US 20180216234A1
• Time in Patent Office: 713 Days
• CPC Class Codes: C09D 5/00 Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced electrically insulating plastics, resins or waxes H01B3/30; Filling pastes
• CPC Class Codes: C09D 5/08 Anti-corrosive paints
• CPC Class Codes: C23C 22/08 Orthophosphates
• CPC Class Codes: C23C 22/34 containing fluorides or complex fluorides
• CPC Class Codes: C23C 2222/10 Use of solutions containing trivalent chromium but free of hexavalent chromium

Abstract

An aqueous conversion coating solution comprises a trivalent chromium compound, a zirconate compound, and a dye compound. The trivalent chromium compound can comprise trivalent chromium compounds such as trivalent chromium sulfate. The dye compound can comprise an azo dye, a chromium complex dye, an anthraquinoid dye, and/or a methine dye. The zirconate compound can comprise alkali metal hexafluorozirconate compounds. The conversion coating solution can comprise a phosphorous compound such as an organic amino-phosphonic acid compound. The conversion coating solution can be formed by mixing a dye additive containing the dye with a trivalent chromium conversion coating solution that does not contain a dye. The conversion coating solution can be used to treat metal substrates comprising aluminum, magnesium, and/or zinc.

Claims

1. A trivalent chromium conversion coating solution comprising:

approximately 0.1 g/liter to approximately 20 g/liter of a trivalent chromium compound;

approximately 0.2 g/liter to approximately 20 g/liter of a zirconate compound; and

approximately 0.01 wt % to approximately 2 wt % of mordant dye, the mordant dye comprising a chromium complex azo dye or a triphenylmethane dye;

wherein the conversion coating solution is an aqueous solution and has a pH of at least 2.5; and

wherein the trivalent chromium conversion coating solution is capable of satisfying the corrosion resistance requirement of MIL-DTL-81706B Class 1A.

2. The trivalent chromium conversion coating solution of claim 1 wherein the trivalent chromium compound comprises trivalent chromium sulfate.

3. The trivalent chromium conversion coating solution of claim 1 comprising approximately 0.2 g/liter to approximately 10 g/liter of the trivalent chromium compound.

4. The trivalent chromium conversion coating solution of claim 1 wherein the zirconate compound comprises an alkali metal hexafluorozirconate compound.

5. The trivalent chromium conversion coating solution of claim 1 comprising approximately 0.5 g/liter to approximately 18 g/liter of the zirconate compound.

6. The trivalent chromium conversion coating solution of claim 1 wherein the mordant dye comprises a mix of chromium complex azo dyes.

7. The trivalent chromium conversion coating solution of claim 1 comprising approximately 0.02 wt % to approximately 1 wt % of the mordant dye.

8. The trivalent chromium conversion coating solution of claim 1 comprising a phosphorous compound.

9. The trivalent chromium conversion coating solution of claim 1 comprising 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, and/or benzotriazole.

10. The trivalent chromium conversion coating solution of claim 1 wherein the trivalent chromium conversion coating solution has a pH of approximately 3 to approximately 4.5.

11. A method comprising treating an aluminum substrate with the conversion coating solution of claim 1.

27. The trivalent chromium conversion coating solution of claim 1 wherein the trivalent chromium conversion coating solution is capable of satisfying the corrosion resistance requirement of MIL-DTL-5541F Type II Class 1A.

12. A trivalent chromium conversion coating solution comprising:

approximately 0.1 g/liter to approximately 20 g/liter of a trivalent chromium sulfate;

approximately 0.2 g/liter to approximately 20 g/liter of an alkali metal hexafluorozirconate compound; and

approximately 0.01 wt % to approximately 2 wt % of mordant dye, the mordant dye comprising a chromium complex azo dye or a triphenylmethane dye;

wherein the conversion coating solution is an aqueous solution and has a pH of at least 2.5; and

wherein the trivalent chromium conversion coating solution is capable of satisfying the corrosion resistance requirement of MIL-DTL-81706B Class 1A.

13. The trivalent chromium conversion coating solution of claim 12 wherein the trivalent chromium conversion coating solution has a pH of approximately 3 to approximately 4.5.

14. The trivalent chromium conversion coating solution of claim 12 comprising:

approximately 0.2 g/liter to approximately 10 g/liter of the trivalent chromium sulfate;

approximately 0.5 g/liter to approximately 18 g/liter of the alkali metal hexafluorozirconate compound; and

a pH of approximately 3.5 to approximately 4.

15. The trivalent chromium conversion coating solution of claim 12 wherein the mordant dye comprises a mix of chromium complex azo dyes.

16. The trivalent chromium conversion coating solution of claim 12 comprising approximately 0.02 wt % to approximately 1 wt % of the mordant dye.

17. The trivalent chromium conversion coating solution of claim 12 comprising an organic amino-phosphonic acid compound.

18. The trivalent chromium conversion coating solution of claim 12 comprising 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, and/or benzotriazole.

28. The trivalent chromium conversion coating solution of claim 12 wherein the trivalent chromium conversion coating solution is capable of satisfying the corrosion resistance requirement of MIL-DTL-5541F Type II Class 1A.

19. A dye additive for a trivalent chromium conversion coating solution, the dye additive comprising:

water; and

mordant dye comprising a chromium complex azo dye or a triphenylmethane dye;

wherein the dye additive is an aqueous solution and has a pH of at least 2.5; and

wherein the dye additive is capable of producing a solution that satisfies the corrosion resistance requirement of MIL-DTL-81706B Class 1A when added to a trivalent chromium conversion coating solution.

20. The dye additive of claim 19 comprising a trivalent chromium compound.

21. The dye additive of claim 19 comprising a corrosion inhibitor compound.

22. The dye additive of claim 19 comprising a trivalent chromium compound and a corrosion inhibitor.

23. The dye additive of claim 22 wherein the corrosion inhibitor comprises 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, and/or benzotriazole.

24. A method comprising:

mixing the dye additive of claim 19 with a trivalent chromium conversion coating solution to form a mixed solution having a pH of at least 2.5;

wherein the trivalent chromium conversion coating solution comprises a trivalent chromium compound and a zirconate compound; and

wherein the mixed solution is capable of satisfying the corrosion resistance requirement of MIL-DTL-81706B Class 1A.

25. The method of claim 24 comprising applying the mixed solution to a metal surface to form a trivalent chromium conversion coating on the metal surface.

26. The trivalent chromium conversion coating solution of claim 19 wherein the mordant dye comprises a mix of chromium complex azo dyes.

29. The dye additive of claim 19 wherein the dye additive is capable of producing a solution that satisfies the corrosion resistance requirement of MIL-DTL-5541F Type II Class 1A when added to the trivalent chromium conversion coating solution.

30. The method of claim 24 wherein the mixed solution is capable of satisfying the corrosion resistance requirement of MIL-DTL-5541F Type II Class 1A.

31. An aluminum substrate comprising:

an aluminum surface;

a trivalent chromium conversion coating on the aluminum surface, the trivalent chromium conversion coating including mordant dye, the mordant dye comprising a chromium complex azo dye or a triphenylmethane dye;

wherein the trivalent chromium conversion coating satisfies the corrosion resistance requirement of MIL-DTL-81706B Class 1A.

32. The aluminum substrate of claim 31 wherein the trivalent chromium conversion coating satisfies the corrosion resistance requirement of MIL-DTL-5541F Type II Class 1A.

33. The aluminum substrate of claim 31 wherein the mordant dye comprises a mix of chromium complex azo dyes.