Non-chromate conversion coating treatment for metals
View Patent ↗Chromate-free treatments and compositions, for applying a conversion or passivation coating to zinc coated metal surfaces. The compositions comprise a polyamidoamine/epihalohydrin polymer or cationic polyamine/epihalohydrin polymer component, fluoacid, H 3 PO 4 , and a film forming polymer latex component. The requisite metal surfaces are contacted by the compositions and dried. Rinsing is optional.
1. A method of forming a conversion or passivation coating on a metal surface comprising contacting said metal surface with an acidic aqueous treatment composition having a pH of about 2 to about 6, said composition comprising: about 0.01 to 80 wt % of (a) (i) polyamidoamine/epihalohydrin resin or (ii) cationic polyamine/epihalohydrin copolymer, about 0.01-30 wt % (b) fluoacid of a Group IVB metal, about 0.01-30 wt % of (c) phosphoric acid, about 0.05-10 wt % of (d) an aminosilane compound and about 0.01-30 wt % of (e) a film forming latex.
2. A method as recited in claim 1 wherein said metal surface is a zinc coated metal surface.
3. A method as recited in claim 1 wherein said metal surface is galvanized steel.
4. A method as recited in claim 1 wherein said metal surface is aluminum.
5. The method as recited in claim 1 wherein said treatment composition is chromate free.
6. The method as recited in claim 1 wherein said fluoacid (b) is H 2 ZrF 6 .
7. The method as recited in claim 1 wherein said fluoacid (b) is H 2 TiF 6 .
8. Method as recited in claim 1 wherein (a) is present in an amount of 0.01-30 wt %; (b) is present in an amount of 0.01-10 wt %; (c) is present in an amount of 0.01-10 wt %; (d) is present in an amount of 0.05-10 wt % and (e) is present in an amount of 0.01-25 wt %.
9. A method as recited in claim 1 wherein said polyamidoamine/epihalohydrin resin is present and comprises a cross-linked polyazetidinium polymer.
10. The method as recited in claim 9 wherein said latex film forming component comprises a vinyl chloride or vinyl ester/acrylate.
11. A method as recited in claim 1 wherein said cationic polyamine/epihalohydrin copolymer is present.
12. The method as recited in claim 11 wherein said latex film forming component comprises a vinyl chloride or vinyl ester/acrylate.
13. A method of treating a galvanized metal surface to form a conversion or passivation coating of greater than 1 mg per square foot on said surface, said method comprising contacting said galvanized metal surface with an acidic aqueous treatment composition having a pH of about 2 to about 6, said treatment composition comprising a latex film forming component present in an amount of 0.01-30 wt %, a (i) polyamidoamine/epihalohydrin polymer or (ii) cationic polyamine/epihalohydrin polymer present in an amount of 0.01-80 wt %, fluoacid of a Group IVB metal present in an amount of 0.01-30 wt %, phosphoric acid, and aminosilane present in an amount of 0.05-10 wt %, said method comprising drying said metal surface after said contact thereof with said treatment composition.
14. Method as recited in claim 13 wherein said latex emulsion comprises vinyl chloride.
15. Method as recited in claim 13 wherein said latex comprises vinyl ester/acrylate.
16. Method as recited in claim 13 wherein polyamine/epihalohydrin polymer is present and wherein said latex component comprises vinyl ester/acrylate.
17. Method as recited in claim 13 wherein said polyamidoamine/epihalohydrin polymer is present and is a cross-linkable polyazetidinium polymer.
18. Method as recited in claim 13 wherein said cationic polyamine/epihalohydrin copolymer is present.
19. Method as recited in claim 13 , said latex film forming component being present in an amount of 0.01-25 wt %, said (i) polyamidoamine/epihalohydrin polymer or (ii) cationic polyamine/epihalohydrin polymer being present in an amount of 0.10-30 wt %, said fluoacid being present in an amount of 0.01-10 wt %, said phosphoric acid being present in an amount of 0.1-10 wt % and said aminosilane being present in an amount of 0.05-10 wt %.