Cryogenic Polishing of Highly Elastic Two-Component Topcoats

Coatings employed for exterior automotive plastic parts have to meet criteria which, in many respects, surpasses those for the metal substrates. They must be comparable in appearance, chemical/solvent resistance, and weatherability. As well, they must cure at temperatures below the deformation temperature of the plastic and be highly flexible to avoid negative effects on low temperature impact values. Two-component (2K) polyurethane coatings have proven to satisfy these requirements and are employed world-wide for this application. Until recently, sanding and polishing such highly elastic coatings was not possible. As a consequence, the repair of small surface imperfections was a very costly and time-consuming operation. A method has been developed, using cryogenic polishing, which allows the sanding and polishing of even the most elastic coatings in a relatively short time.