What is a quality Spray Bedliner made from? If you do research about the large bedliner vendors (Rhino Lining, Line-X, Scorpion, etc) you will see boasts about polyurea bedliners as well as the words polyurea/polyurethane and polyurethane. When trying to understand the differences between materials one can be overwhelmed quickly.
What is a PolyureaA polyurea coating is the result of a one-step reaction between an isocyanate component and a resin blend component. The isocyanate can be monomer based, a prepolymer, a polymer or a blend. For the prepolymer, amine- and/or hydroxylterminated resins can be used. ……. uh, what? Though a true polyurea has no VOCs or solvents, it is a product of isocyanates which makes it caustic and dangerous.
What is a polyurethane?Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics. Polyurethanes are produced by reacting an isocyanate containing two or more isocyanates groups per molecule (R-(N=C=O)n ≥ 2) with a polyol containing on average two or more hydroxy groups per molecule (R’-(OH)n ≥ 2), in the presence of a catalyst………. Again…. What? What are the benefits of polyurea versus polyurethane?
- Both of these materials are excellent for spray coating applications. Here are functional differences/similarities of polyurea and polyurethane:
- both systems can use the same or similar “A” components. Therefore, the main properties differences are provided by the “B” component side of the system.
- In polyurethanes, The “B” component is comprised of various polyols (polyether, polyester) and typically need a catalyst to support fast curing. Because this catalyst can be adjusted to control the reaction profile to fit the application it is seen as a benefit. The result is a smoother finish though variable textures can easily be achieved.
- When the material is required to flow into the corners or hard-to-spray areas and need a few extra seconds before gelling, polyurethane is a great choice because it can be set to cure slowly compared to polyurea. The catalyst can be adjusted for a urethane to cure as fast as 10 secs and at low temperatures.
- Polyurea is very reactive and does not require a catalyst (auto-catalytic polymer). This reactivity usually between 5-15 seconds and cures well on cold surfaces.
- The reaction time also causes polyureas to be moisture insensitive and do not easily react with humidity and moist substrates.
- Pure Polyureas are not the correct solution when requiring a smooth surface or a delay time before the system gels.