We apply polymer coatings on metal substrate in order to protect it from environmental factors and improve its aesthetic appearance.

Polymer coating is a system comprised by single or multiple layers of various coatings. One-layer and two-layer coatings are the most widespread.

• One-layer coatings are used for applications with reduced protective and decorative requirements (reverse side of PPGI intended for household appliances, sandwich panels, cladding, etc. that is not directly exposed to the environment and hidden from view);
• Two-layer coatings have enhanced end user performance. Such coatings are applied to front side of strip, or both sides if necessary.

In order to protect the coating from damage during transportation and processing we can apply protective film on top of it. The figure below shows a cross-section of PPGI with one-layer coating on the backside, two-layer coating on the front side, and protective film on top.

Coil coating technology uses primers and topcoats based on the following types of polymers:

• Acrylate (AY)
• Polyether (polyester, PE)
• Epoxy resins (EP)
• Polyvinylidene fluoride resins (PVDF)
• Fluorine resins (FEVE)
• Polyurethane resins (PU, PUR)
• Polyvinyl chloride (PVC)

Various copolymers and additives can be added to these base materials to enhance their end user performance both in liquid state and as the finished coating.

Choice of polymer is based on the requirements to finished coating properties and its cost, PPGI performance and the type of finished products made of PPGI. The most widespread topcoats are based on PE, PVDF, PUR and PVC.

Polyester coatings (PE) are popular due to their low cost, good adhesion to substrate and elasticity. Finished PPGI is processed well by press-forming, rollforming, bending, etc. However, PE coatings’ end user performance, namely UV-resistance, corrosion resistance and mechanical stability leave much to be desired.

PVDF and FEVE resins are considered premium coatings. They demonstrate excellent corrosion resistance even in aggressive environments, UV-resistance and environmental stability.

Polyvinylidene Difluoride (PVF2) coatings are high-end, strong and resistant to low (-60 deg. C) and high (+120 deg. C) temperatures. These coatings are 80% polyvinylfluoride and 20% acryl. PVF2 coatings are UV-resistant, have attractive glossy surface that withstands bleaching and is mechanically stable. They show outstanding corrosion resistance even in aggressive environments.

PVF2 are available in wide variety of colors, can be glossy, mat, or metallic.

PVF2 are especially well suited for applications in aggressive environments, such as seaside locations, chemical industry buildings, etc.

Polyurethane (PUR) coatings are also premium grade with good adhesion to substrate and elasticity. They are mechanically stable and resistant to adverse weather conditions (UV, low/high temperatures, temperature drops).

PVC-based coatings (plastisoles) have been used in construction applications for decades. PVC coatings are the thickest ones (from 80 microns) and are therefore strong and durable. They provide corrosion resistance even in aggressive environments, however, they are less resistant to UV radiation and temperature drops, even though there have been improvements achieved in these performance parameters recently.

The chart below shows comparative characteristics of coatings in points, where 1 point is for the poorest performance, and 5 points are for the best one.