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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.

Over the past 60 years, chemical companies have been supplying automotive manufacturers state-of-the-art zinc phosphate conversion coatings which, when applied properly to a metal surface promote excellent paint adhesion and corrosion resistance. Phosphate conversion coatings have undergone many transformations over the years. Now some of their essential components and byproducts are being more tightly regulated under new environmental guidelines. The metal pretreatment industry is now challenged with the task to replace the traditional zinc phosphate coating with the next generation product. This paper will examine the advantages of a new generation conversion coating based on zirconium oxide. The performance and process cost savings will be discussed. This technology has been advancing over the past several years, and in 2007 several successful commercial line trials with this new conversion coating were conducted.

Surface pretreatments based on dilute hexafluorozirconic acid (FZ) solution were evaluated as replacements for the phosphating process before paint application. The behavior of a FZ coating was compared to those of a modified FZ (MFZ) coating and phosphating treatments. Results of electrochemical tests on painted cold rolled steel (CRS) samples with different conversion coatings show that the MFZ surface treatment in combination with various paints provides corrosion protection performance comparable to phosphate conversion coatings. AFM studies of MFZ coatings on CRS reveal that the coating surface exhibits small features tens of nm in size and clusters of these features that are on the scale of microns. Clusters have lower surface potentials (higher activity). Z-contrast TEM images of MFZ coatings show that the coating is about 20 nm thick, continuous and adherent to the substrate. Major components are Zr, Fe and O; the Fe amount decreases toward the coating surface.

Over the past 60 years chemical companies have been supplying automotive manufacturers a state-of-the-art zinc phosphate conversion coating, which when applied properly to a metal surface promotes excellent paint adhesion and corrosion resistance. Phosphate conversion coatings have undergone many transformations over the years, and now some of their essential components and byproducts are being more tightly restricted under new environmental guidelines. The metal pretreatment industry is now challenged with the task of replacing the traditional zinc phosphate coating with the next generation product. This paper examines the advantages of the new generation conversion coatings through performance milestones as well as process and environmental cost savings realized by this technology.

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.

A new epoxy-based Autophoretic® coating has been developed and trialed at a full-scale jobber coating line. Autophoretic coatings are a proprietary series of autodepositing coatings specifically for ferrous metal substrates. An autodepositing coating is one which coats a substrate because of a chemical reaction between the paint and metal upon immersion in the aqueous paint tank. The new epoxy coating has a high level of corrosion protection, excellent appearance, and can be used as either a single coat or primer. Typical epoxy Autophoretic coating application conditions and performance data will be presented.