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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.

Autodeposition coatings are thin, highly corrosion resistant organic coatings that deposit paint by reaction with the metal surface. The coating deposits only on metallic surfaces, thus allowing coating of just the metal portion of metal-plastic or metal-rubber assemblies. Because it is a chemical reaction with the metal surface, it is possible to evenly paint the inside of tubular and boxed sections, which is where corrosion typically starts. The overall autodeposition process includes cleaning, water rinse, coat, reaction rinse, and cure. The use of a reaction rinse after the autodeposition coating application allows unique properties to be introduced to the coating before curing. This presentation will briefly review the general chemistry of autodeposition. Next it will focus on commercial automotive applications of several newly developed autodeposition coatings. The corrosion performance and physical characteristics of both black and gray epoxy-acrylic coatings will be presented.

Autodeposition coatings are thin, highly corrosion resistant organic coatings that are deposited in a chemical reaction with a metal surface. Because the autodeposition process deposits a coating only on metallic surfaces, coating of just the metal portion of metal-plastic or metal-rubber assemblies is possible. The overall autodeposition process includes stages of clean, water rinse, coat, reaction rinse, and cure. The use of a reaction rinse after the autodeposition stage is unique among coating processes and allows new properties to be introduced to the coating before curing. This paper will briefly review the general chemistry of autodeposition, and then focus on how corrosion performance and physical characteristics of a recently developed epoxy-acrylic autodeposition coating are designed into the product and how the autodeposition process controls these properties. The role of the organic polymer and the reaction rinse in all the properties will be discussed.