Polyurethane Painting

Polyurethane or urethane is a type of polymer composing of organic units which are joined by a specific link called carbamate link. Generally, polyurethane does not melt when heated as they are thermosetting polymers which make them a good choice for coating on various types of surface, especially metals. Such materials are usually produced by reactions between polyol and isocyanate but have been replaced by non-isocyanate paints due to toxicity issues. Polyurethane coating still remained as one of the most widely used protective coating services for industrial facilities due to its rust and heat resistant properties.

Polyurethane paints are generally composed of two types of materials mixed together in the base which are polyester and epoxy/acrylic resins where the mixture contains a high concentration of hydroxyl groups. On the other hand, aromatic or aliphatic isocyanate could be found in the hardener when reaction with the base occurs, contributing to the pot life of the polyurethane paints. Depending on the purpose for applying polyurethane coating, different surface conditions will require different types of choices of the paint. For example:

• Polyurethane coating paint which consists of aromatic hardeners is generally used for indoor purposes which are chemical resistant and provide a good barrier against the moist environment inside an enclosed space.
• Polyurethane coating paint which consists of aliphatic hardeners is generally used for outer surfaces especially on roof and walls which need to be weather resistant and provide sufficient protection against corrosion and rusting as well as leakage.

One of the most obvious advantages of polyurethane coating is its strong chemical resistant property which makes it very suitable for exterior painting purpose. Hence they are usually applied as topcoats on top of other coatings for external environment. Besides the thermal resistant properties also serves good ventilation for buildings and the coating is easy to clean with good gloss and colour retention. As they do not chalk like epoxy paint, they are usually applied as topcoats on top of epoxy coating for maximum protection against corrosion and rusting. Hence with several coatings applied on industrial facilities, corrective maintenance is not required often and coating costs could be reduced as well.