Electrodepositable coating composition having improved crater control
The present invention is directed towards an electrodepositable coating composition comprising a polyfarnesene polymer and an ionic salt group-containing film-forming polymer. Also disclosed are methods of coating a substrate using the electrodepositable coating composition, coatings derived from the electrodepositable coating composition, and substrates coated with the coatings derived from the electrodepositable coating composition.
1. An electrodepositable coating composition comprising:
a polyfarnesene polymer; and
an ionic salt group-containing film-forming polymer.
2. The electrodepositable coating composition of claim 1 , wherein the polyfarnesene polymer comprises the residue of trans-β-farnesene.
3. The electrodepositable coating composition of claim 1 , wherein the polyfarnesene polymer further comprises the residue of α-farnesene, cis-β-farnesene, or any combination thereof.
4. The electrodepositable coating composition of claim 1 , wherein the polyfarnesene polymer further comprises the residue of butadiene, isoprene, styrene, a sesquiterpene, or any combination thereof.
5. The electrodepositable coating composition of claim 1 , wherein the polyfarnesene polymer has a number average molecular weight of 500 g/mol to 10,000 g/mol.
6. The electrodepositable coating composition of claim 1 , wherein the polyfarnesene polymer is present in the electrodepositable coating composition in an amount of 0.1% to 10% by weight based on the total weight of the resin blend solids.
7. The electrodepositable coating composition of claim 1 , the polyfarnesene polymer is incorporated into the electrodepositable coating composition as a reaction product comprising the residue of the polyfarnesene polymer.
8. The electrodepositable coating composition of claim 7 , wherein the polyfarnesene polymer comprises a functional group that is reacted with a compound to form the reaction product.
9. The electrodepositable coating composition of claim 1 , wherein the polyfarnesene polymer comprises an amino functional group, a thiol functional group, an epoxide functional group, an amide functional group, a carbamate functional group, a carboxylic acid group, a phosphorous acid group, a sulfonic acid group, or any combination thereof.
10. The electrodepositable coating composition of claim 1 , wherein the polyfarnesene polymer comprises at least one hydroxyl functional group.
11. The electrodepositable coating composition of claim 10 , wherein the polyfarnesene polymer has a theoretical hydroxyl group equivalent weight of 100 to 10,000 g/equivalent.
12. The electrodepositable coating composition of claim 10 , wherein the polyfarnesene polymer has a hydroxyl weight of 0.1 to 2.0 meq/g.
13. The electrodepositable coating composition of claim 1 , further comprising a polybutadiene polyol, a polybutylene oxide polymer, a polyetheramine adduct, a polyamine-dialdehyde adduct, an epoxy microgel, an acrylic microgel, an acrylic polymer, or any combination thereof.
14. The electrodepositable coating composition of claim 1 , wherein the ionic salt group-containing film-forming polymer comprises functional groups and the electrodepositable coating composition further comprises a curing agent that is reactive with the functional groups of the film-forming polymer.
15. The electrodepositable coating composition of claim 14 , wherein the curing agent comprises a blocked polyisocyanate.
16. The electrodepositable coating composition of claim 15 , wherein the blocked polyisocyanate is at least partially blocked with the polyfarnesene polymer as a blocking agent.
17. The electrodepositable coating composition of claim 1 , wherein the electrodepositable coating composition is substantially free of tin.
18. A method of coating a substrate comprising electrophoretically applying a coating deposited from the electrodepositable coating composition of claim 1 to at least a portion of the substrate.