Epoxy resin is a synthetic polymer that is an adhesive, paint, or other material containing a cyclic three-atom ring. Epoxy resins can be found in paints, resins, and a variety of other substances used to prevent corrosion. Organic zinc-rich coatings are anti-corrosion primers used to protect steel surfaces. They contain a high proportion of zinc dust which can have a sacrificial effect when in direct contact with iron or steel. Zinc dust provides cathodic protection for metals, similar to cold galvanizing. Binders for organic zinc-rich coatings are usually epoxy resins.
Many industries use organic zinc-rich coatings to protect steel substrates from corrosion. They are used in industrial, automotive, highway and infrastructure applications.
Organic zinc-rich paints provide cathodic protection, while ordinary paints protect by creating an impermeable barrier between the metal surface and moisture in the atmosphere. When the cathode cell is formed, it protects the steel at the expense of the zinc. Here, zinc acts as a sacrificial source. Additionally, the zinc primer provides some barrier protection to the surface.
While zinc-rich primers are sometimes used as a stand-alone coat, they are also often topcoated with paint or epoxy. These coatings provide an alternate or additional method to protect steel from corrosion under epoxy or polyurethane paint finishes by providing better adhesion properties.
There are two types of zinc-rich coatings:
Inorganic Zinc Rich Coatings (IOZ Coatings) - These coatings are applied by spraying. Without a topcoat, they provide better steel protection than organozinc primers without a topcoat.
Organic Zinc Rich Coatings - These coatings are usually applied by brush, roller or spray. Without a top coat, they will not protect the steel like IOZ coatings.
