Corrosion resistant hybrid silanized epoxy ester resins, coatings and surface pre-treatment formulations
A self-healing coating composition for use on metals includes a polyurea, an epoxy ester unsaturated resin, a combination of amine terminated siloxane and epoxy terminated siloxane and an organoclay. The polyurea is a water-soluble, aromatic polyurea and likewise, the epoxy ester is a water-soluble, aromatic epoxy ester. The coating composition is formed in a non-volatile solvent, such as N-Methylpyrrolidone. It can be applied to a metal surface and cured at room temperature to form a coating that is resistant to corrosion. Further the coating self-heals in a manner similar to a chromate coating.
1. A coating formed from:
a water-soluble epoxy ester unsaturated resin;
a water-soluble polyurea;
an amine terminated siloxane and an epoxy terminated siloxane; and
a clay.
2. The coating composition claimed in claim 1 wherein said epoxy ester unsaturated resin is a water-soluble, aromatic epoxy ester.
3. The coating composition claimed in claim 2 wherein said epoxy ester unsaturated resin is formed from an aromatic epoxy and an unsaturated fatty acid.
4. The coating composition claimed in claim 3 wherein said fatty acid is a C15 to C18 fatty acid.
5. The coating composition claimed in claim 3 wherein said formulation includes from about 20% to about 50% by weight epoxy ester.
6. The coating composition claimed in claim 5 wherein said coating composition includes from 30-45% by weight epoxy ester.
7. The coating composition claimed in claim 1 wherein said polyurea is a water-soluble, aromatic polyurea.
8. The coating composition claimed in claim 7 wherein said polyurea has a molecular weight of 5,000 to about 20,000 weight avg MW.
9. The coating composition claimed in claim 7 wherein said polyurea has an intrinsic viscosity of 0.05 to about 0.21.
10. The coating composition claimed in claim 1 wherein said coating composition has a ratio by weight of polyester to polyurethane of 30 to 70, to 70 to 30.
11. The coating composition claimed in claim 1 wherein said clay is montmorillonite clay.
12. The coating composition claimed in claim 11 wherein said clay is treated with a quaternary ammonium compound.
13. The coating composition claimed in claim 12 wherein said clay is 15A cloisite.
14. The coating composition claimed in claim 11 wherein the coating compound comprises 0.1% to 5% clay.
15. The coating composition claimed in claim 14 comprising 0.5 to 2.5% clay by weight.
16. The coating composition claimed in claim 1 further comprising a non-volatile organic solvent.
17. The coating composition claimed in claim 16 wherein said non-volatile organic solvent comprises N-Methylpyrrolidone.
18. A metal surface selected from the group consisting of aluminum, aluminum alloys, iron, and steel coated with the composition of claim 1 .