2K Polyurethane automotive clearcoats | Spray Finishing News

2K Polyurethane automotive clearcoats


Tree sap, acid rain and bird droppings can damage a vehicle’s finish. In order to achieve optimum finishing results and a maximum of protection against nature’s nasty side, the company Bayer is offering its two-component (2K) polyurethane clearcoats, which provide very long-term durability, color retention and chemical resistance compared with previously available coatings.

Originally, 2K polyurethane clearcoats were introduced to replace thermoset acrylic (TSA) clearcoats, an acrylic resin that was crosslinked with a melamine rather than a polyisocyanate. 2K polyurethane clearcoats consist of an aliphatic (weatherable) polyisocyanate that is used to crosslink a hydroxyl, functional acrylic resin.

Prior to application, the two components (polyisocyanate and acrylic resins) are mixed in a spray gun during the spray operation, thus avoiding pot life issues. Once mixed, a chemical reaction begins to take place that ultimately leads to a cured coating with a hard, glossy finish.

Most one-component technologies require a minimum temperature for a crosslinking reaction to take place. Unless that temperature threshold is met, the coating will not fully cure. Conversely, 2K polyurethane coatings begin to cure as soon as the polyisocyanate and the co-reactant are mixed, and will eventually fully cure regardless of temperature. These benefits provide OEMs with a potentially time-saving process that also produces high-performance exterior automotive clear coats.

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