Water-based two-component coating compositions
View Patent ↗A water-based coating compositions including: at least one cross-linkable water-reducible binder having acid functional groups and functional groups with active hydrogen, at least one polyisocyanate cross-linking agent with free isocyanate groups, and water and optionally at least one organic solvent. The acid functional groups of the at least one water-reducible binder are at least partly neutralized with at least one neutralizing agent, the neutralizing agent including a monoamine having a secondary amino group attached to a tertiary carbon atom. The monoamine is preferably a reaction product of at least one monoamine having a primary amino group attached to a tertiary carbon atom and a mono-epoxide, or a reaction product of at least one monoamine having a primary amino group attached to a tertiary carbon atom and a mono-unsaturated compound.
1. A water-based coating composition comprising:
at least one cross-linkable water-reducible binder having acid functional groups and functional groups with active hydrogen,
at least one polyisocyanate cross-linking agent with free isocyanate groups, and
water,
wherein the acid functional groups of the at least one cross-linkable water-reducible binder are at least partly neutralized with at least one neutralizing agent, the neutralizing agent comprising a monoamine having a secondary amino group attached to a tertiary carbon atom.
2. The water-based coating composition of claim 1 , wherein the monoamine having a secondary amino group attached to a tertiary carbon atom is a reaction product of at least one monoamine having a primary amino group attached to a tertiary carbon atom and a mono-unsaturated compound.
3. The water-based coating composition of claim 2 , wherein the monoamine having a primary amino group attached to a tertiary carbon atom has a number average molecular weight of about 73 to about 1000.
4. The water-based coating composition of claim 2 , wherein said monoamine having a primary amino group attached to a tertiary carbon atom is tert-butylamine.
5. The water-based coating composition of claim 2 , wherein the mono-unsaturated compound comprises acrylates, methacrylates, maleates, fumarates and/or itaconates.
6. The water-based coating composition of claim 1 , wherein the monoamine having a secondary amino group attached to a tertiary carbon atom is a reaction product of at least one monoamine having a primary amino group attached to a tertiary carbon atom and a mono-epoxide compound.
7. The water-based coating composition of claim 6 , wherein the mono-epoxide compound has 2 to 33 carbon atoms.
8. The water-based coating composition of claim 1 , wherein the neutralizing agent comprises 2-(tert-butylamino) ethanol.
9. The water-based coating composition of claim 1 , wherein the functional groups with active hydrogen are hydroxyl groups.
10. The water-based coating composition of claim 1 , wherein the at least one cross-linkable water-reducible binder has an acid value of about 10 to about 150 mg KOH/g.
11. The water-based coating composition of claim 1 , wherein the acid groups of the at least one water-reducible binder are neutralized with said neutralizing agent according to a neutralization degree of about 60 to about 140%.
12. The water-based coating composition of claim 1 , wherein the water-based coating composition is a clear coat coating composition.
13. The water-based coating composition of claim 1 further comprising at least one organic solvent.
14. A method for producing an automotive coating, the method comprising;
applying onto a substrate a water-based coating composition comprising:
at least one cross-linkable water-reducible binder having acid functional groups and functional groups with active hydrogen,
at least one polyisocyanate cross-linking agent with free isocyanate groups, and
water, wherein the acid functional groups of the at least one cross-linkable water-reducible binder are at least partly neutralized with at least one neutralizing agent, the neutralizing agent comprising a monoamine having a secondary amino group attached to a tertiary carbon atom; and
curing the water-based coating composition.
15. The method of claim 14 wherein the water-based coating composition further comprises an organic solvent, and wherein the method further comprises flashing off the water-based coating composition to remove at least a portion of the water and the organic solvent.
16. The method of claim 14 wherein curing the water-based coating composition comprises baking or irradiating with IR radiation.
17. The method of claim 14 wherein the substrate is a color-imparting and/or special effect-imparting pre-dried base coat layer.
18. The method of claim 14 wherein the substrate is an uncoated metal or plastic substrate.
19. An aqueous binder dispersion comprising at least one water-reducible binder having acid functional groups and functional groups with active hydrogen, wherein said acid functional groups of the at least one water-reducible binder are at least partly neutralized with a neutralizing agent, the neutralizing agent comprising a monoamine having a secondary amino group attached to a tertiary carbon atom.
20. The aqueous binder dispersion of claim 19 , wherein the monoamine having a monoamine having a secondary amino group attached to a tertiary carbon atom is a reaction product of at least one monoamine having a primary amino group attached to a tertiary carbon atom and a mono-unsaturated compound and/or a reaction product of at least one monoamine having a primary amino group attached to a tertiary carbon atom and a mono-epoxide compound.