Evaluation of Polar Conventional and Non-Polar Olefinic Paint Technologies in Thermoplastic Olefins

Recently a non-polar colorcoat based on a hydrogenated polybutadiene diol and melamine resin for thermoplastic olefins bumper fascia was invented. The break through technology allows the elimination of the TPO pretreatment step such as adhesion promoter, flame, or plasma during manufacturing. The paintability of two different types of metallocene plastomers as well as two different types of ethylene-propylene rubbers were assessed in a benchmark composition. A new friction induced damage test, the Ford STATRAM, was used to compare the paint tribology of the non-polar olefinic white and conventional polar white production paints. The olefinic white paint was found to provide excellent paint adhesion for both types of metallocene plastomers. No paint peeling was observed under any of the test conditions. For the conventional white paint, only the ethylene-butene plastomer was found to pass the STATRAM without paint loss. Paintability of both types of ethylene-propylene modifiers were found to be inferior to the metallocene plastomers with varied amounts of paint loss in both types of white paints. The ethylene-butene plastomer, the most versatile modifier, performed equally well in both types of paint technologies. The fine dispersion of the ethylene-butene plastomer, observed by low voltage scanning electron microscopy, at and near the TPO surface explains its excellent paintability.