Method for electrodeposition of self-crosslinking cationic compositions
AssigneePPG Industries, Inc.
InventorsRobert D. Jerabek, Joseph R. Marchetti
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Abstract
It has been found that aqueous coating compositions comprising a resin containing capped or blocked isocyanate groups, quaternary onium salt groups and, optionally, free epoxy groups may be electrodeposited on a cathode to produce coatings having highly desirable properties.
Claims16
A method of electrocoating an electrically-conductive surface serving as a cathode comprising passing an electric current between said cathode and an anode in electrical contact with an aqueous electrodepositable composition, wherein said electrodepositable composition comprises an aqueous dispersion of:
- A. a quaternary onium salt group-containing resin comprising the reaction product of:
- 1. an epoxy group-containing reaction product of an epoxy group-containing organic material and a semi-capped organic polyisocyanate;
- and
- 2. a reactant selected from the group consisting of an amine acid salt, a sulfide-acid mixture, and a phosphine-acid mixture, said reactant reacted with said epoxy group-containing reaction product in an amount and at a temperature sufficient to provide a quaternary onium salt-containing, water-dispersible resin;
- said quaternary onium group salt-containing resin (A) containing hydroxyl groups and capped isocyanate groups, said capped isocyanate groups stable at room temperature but reactive with hydroxyl groups at elevated temperatures;
- and
- B. a catalytic amount of a catalyst for urethane formation.
A method of electrocoating an electrically-conductive surface serving as a cathode comprising passing an electric current between said cathode and an anode in electrical contact with an aqueous electrodepositable composition, wherein said electrodepositable composition comprises an aqueous dispersion of:
- a quaternary onium salt group-containing resin comprising the reaction product of:
- 1. an epoxy group-containing reaction product of an epoxy group-containing organic material and a semi-capped organic polyisocyanate;
- and
- 2. a reactant selected from the group consisting of an amine acid salt, a sulfide-acid mixture, and a phosphine-acid mixture, said reactant reacted with said epoxy group-containing reaction product in an amount and at a temperature sufficient to provide a quaternary onium salt-containing, water-dispersible resin;
- said quaternary onium group salt-containing resin containing hydroxyl groups and capped isocyanate groups, said capped isocyanate groups stable at room temperature but reactive with hydroxyl groups at elevated temperatures.
Dependencies are inferred from the claim text.