Metal oxides and hydroxides as corrosion inhibitor pigments for a chromate-free corrosion resistant epoxy primer
View Patent ↗A corrosion resistant epoxy primer comprises a epoxy resin, a curing agent, and a non-chromate containing corrosion-inhibiting pigment.
1. An epoxy corrosion resistant primer comprising:
an epoxy resin;
a curing agent; and
a non-chromate containing corrosion inhibiting pigment;
wherein the non-chromate corrosion inhibiting pigment comprises extender pigments and a non-chromate corrosion inhibiting additive, wherein the non-chromate corrosion inhibiting additive comprises (1) an oxide of at least one of Mo and Ce, and (2) a hydroxide of at least one of Mo and Ce, wherein the ratio of Ce to Mo in the non-chromate containing corrosion inhibiting pigment is between 0.5:1 to 2.5:1.
2. A primer according to claim 1 wherein the epoxy resin is selected from the group consisting of a non-volatile dispersion of diglycidyl ether bisphenol A modified epoxies having weight per epoxide (WPE) value between 450-700 and viscosity between 12000-19000 cps.
3. A primer according to claim 2 wherein said epoxy is present in an amount of between 5 to 50 wt. % with respect to the final primer composition.
4. A primer according to claim 2 wherein said epoxy is present in an amount of between 15 to 30 wt. % with respect to the final primer composition.
5. A primer according to claim 2 wherein the curing agent is selected from the group consisting of: waterborne or water-reducible modified amine having an amine value between 300-450, and waterborne or water-reducible polyamidoamine adduct having an amine value between 300-450.
6. A primer according to claim 5 wherein the curing agent further includes a hydrophobic curing agent for enhanced water and corrosion resistance.
7. A primer according to claim 5 wherein said curing agent is present in an amount of between 2 to 20 wt. % with respect to the final primer composition.
8. A primer according to claim 5 wherein said curing agent is present in an amount of between 5 to 15 wt. % with respect to the final primer composition.
9. A primer according to claim 1 wherein the non-chromate corrosion inhibiting additive comprises a mixture of molytrioxide and ceric hydroxide.
10. A primer according to claim 1 wherein the non-chromate corrosion inhibiting additive is present in an amount of between 10 to 50 wt. % with respect to the total non-chromate containing corrosion inhibiting pigment.
11. A primer according to claim 1 wherein the non-chromate corrosion inhibiting additive is present in an amount of between 20 to 45 wt. % with respect to the total non-chromate containing corrosion inhibiting pigment.
12. A primer according to claim 1 wherein the non-chromate corrosion inhibiting pigment is present in an amount of between 25 to 60 wt. % with respect to the final primer composition.
13. A primer according to claim 1 wherein the non-chromate corrosion inhibiting pigment is present in an amount of between 40 to 55 wt. % with respect to the final primer composition.
14. A primer according to claim 1 , wherein the ratio of Ce to Mo in the non-chromate containing corrosion inhibiting pigment is between 0.6:1 to 1.5:1.