Electrodeposition system
An electrocoat system for electrodeposition is described. The system includes an inorganic bismuth-containing compound or a mixture of inorganic and organic bismuth-containing compounds. The system demonstrates a high degree of crosslinking and produces a cured coating with optimal crosslinking and corrosion resistance.
1. A composition for electrodeposition, comprising:
an electrodeposition resin component; optionally, a crosslinking component;
optionally, an acid component; and
at least an inorganic bismuth salt of a metal oxyanion bismuth-containing compound comprising bismuth aluminate.
2. The composition of claim 1 , wherein the at least one inorganic bismuth-containing compound is a compound substantially insoluble in water at a pH of about 4 to 6 and a temperature of about 37° C.
3. The composition of claim 1 , wherein the composition includes a combination of the at least one inorganic bismuth-containing compound and an organic bismuth-containing compound comprising bismuth citrate.
4. The composition of claim 1 , further comprising:
about 40 to 95 percent by weight of the electrodeposition resin component based on the total weight of resin solids in the composition;
about 10 to 60 percent by weight of the blocked polyisocyanate component based on the total weight of resin solids in the composition;
and
about 0.5 to 10 percent by weight of the at least one inorganic bismuth-containing compound based on the total weight of resin solids in the composition.
5. A method of making a coated article by electrodeposition of a film of the composition of claim 1 .
6. The method of claim 5 , wherein the film has an average thickness of 10 to 25 pm.
7. A cationic electrodeposition bath comprising the composition of claim 1 .
8. The composition of claim 1 , wherein a coating formed from the composition is corrosion resistant.
9. The composition of claim 1 , wherein a coating formed from the composition demonstrates less than 3 mm creep from scribe according to ASTM D1654-08, wherein the coating is applied to a pretreated cold-rolled steel substrate.
10. The composition of claim 1 , wherein a coating formed from the composition demonstrates solvent resistance of at least 30 double rubs according to ASTM D5402-15.
11. A method, comprising:
combining an electrodeposition resin component including at least one crosslinkable functional group with a blocked isocyanate component;
an aliphatic carboxylic acid component; and
at least an inorganic bismuth salt of a metal oxyanion bismuth-containing compound comprising bismuth aluminate.
12. A method for electrodeposition, comprising:
providing an emulsion including a cationizable electrodeposition resin component and a blocked polyisocyanate crosslinker component; providing a pigment paste including a dispersion resin, pigment, and an inorganic bismuth salt of a metal oxyanion bismuth-containing compound comprising bismuth aluminate.