There are two major types of coatings in the world. Epoxy and Polyurethane. Both epoxy and polyurethane coatings are used in industrial settings across the globe. Both types of products offer their own set of advantages and considerations, which can make choosing between the two difficult and should be done depending on the situation .
Generally, a polyurethane coating is highly flexible and elastic, while epoxy is harder and more brittle. This makes polyurethane coatings more resistant to scratches, abrasion and similar damage and it is why often polyurethanes are chosen for covering floors in heavy traffic areas – such as multi-story car parks. This extra flexibility also makes them desirable for applications in extreme temperature situations as the coating can expand and contract with the changes in temperature – preventing cracks from occurring. As this reason polyurethanes provide superior heat, cold and thermal shock tolerance. Epoxies on the other hand are naturally more rigid and are able to move with a concrete substrate when exposed to heat fluctuations. To exemplify this, a standard two-pack, 100% solids epoxy coating, has a heat resistance of up to 65 °C, whereas some polyurethane systems can tolerate 120°C.
Epoxies have excellent adhesion to many substrates. The excellent adhesive properties of epoxy resins are due to the attractive forces between the epoxy and the surface of the substrate. Polyurethanes on the other hand do not bond well to concrete and metal and need a primer which is usually an Epoxy primer.
Polyurethanes are known for their outstanding UV resistance, gloss retention and color stability. One concern with polyurethanes is their sensitivity to humidity and moisture. As a rule of thumb, it is best to apply these coatings between 10 AM – 4 PM, which is when the humidity is generally at its lowest point of the day. Depending on the product, polyurethanes can have better chemical resistance and provide better abrasion and impact resistance than the epoxies.
Polyurethanes could be installed successfully at temperatures between 20 and 100 degrees Fahrenheit(-7 to 38 degrees centigrade) , while epoxy resins requires temperatures above 50 degrees Fahrenheit(10 degrees centigrade) . If applied as a coating for concrete, polyurethane typically cures in two to four days, while epoxy can take up to eight days to cure.
Whilst a polyurethane system will initially cost more compared to an epoxy, it is far more cost effective in the long term. In fact, the lifespan of the polyurethane system is roughly double that of the epoxy, clocking an impressive ten-year’s compared to the epoxy’s five. PU systems also benefit from their increased wear, abrasion and impact resistance properties.
To cover Epoxies and Polyurethanes disadvantages most of the manufacturers and appliers suggest a coating system of Epoxy and Polyurethane together . Epoxy should be used as the base coating (to bond to concrete or steel ) and the polyurethane can be used as a topcoat (flexible, scratch resistant, UV stable, abrasion resistant, impact resistant).
But there is an important problem regarding using these coating systems. That is disbanding the overcoat. As the various layers has different molecular structure in case of expansion and contraction with changes in temperature this problem will occur for the coating system .
The advantage of Petro Chem Coat Inc. productions over common Epoxy and Polyurethane coatings is Combining the Polyurethane and Epoxy.
Epoxy phase has been introduced in the polyurethane network to generate interpenetrating polymer network (IPN).
PetroChemCoat products which are Polyurethane/epoxy IPN by holding excellent polyurethane properties like abrasion resistance, impact resistance, heat resistance, flexibility, thermal shock tolerance, allowed application temperature and corrosion resistance it improves the adhesion to most substrates including steel , concrete , wood and glass and chemical resistance . Also this product has more flammability resistance in comparison with two other coatings. The only drawback of the product is the yellowish against UV but with an exceptional resistance to UV degradation power which makes it an excellent choice for outdoor industrial protective coating that decorative aspects are less important and the structure and substrate protection is vital.
Below table compares Polyurethane, Epoxy and the PetroChemCoat Products general properties. Below classification is based on general Epoxy and Polyurethane properties and maybe the product of some manufacturer differ from this information.
