Browse Publications Technical Papers 2010-01-0235

Co-Cure Process: Autodeposition Primer and Powder Topcoat 2010-01-0235

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.


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