Autodeposition is an immersion, direct-to-metal coating process
that forms a paint film on metal surfaces by a chemical reaction
between an aqueous paint dispersion and the base metal. The
autodeposition process consists of cleaning, rinsing, organic
coating deposition, and a sealing rinse. Conventional
pretreatment/primer systems require full thermal cure prior to
topcoat application because of volatiles that must be lost during
cure. The latest autodeposition chemistry consists of an
epoxy-acrylic hybrid mini-emulsion. The chemical combination of a
flexible, high molecular weight acrylic with a hard, tough epoxy in
a semi-interpenetrating network provides a very low VOC (≤0.03
lb/gal) coating. Upon dehydration ~100°C, the autodeposited coating
provides a dry-to-handle, tack-free film with physical integrity. A
powder topcoat or sealer/adhesive can be applied to the dehydrated
autodeposited coating. Finally, both the primer and topcoat or
primer and sealer/-adhesive are chemically "Co-Cured" in
a single oven.
This paper describes the autodeposition chemistry, process
sequence, and deposition mechanism. It illustrates the innovative
modeling and design of the latest autodeposition chemistry that led
to the implementation of the "Co-Cure" process. Further,
it describes the "Co-Cure" process, showing its
performance, simplicity advantages, and demonstrates its
contribution to a sustainable, lean, and modular paint shop.