A reprocessing study for reground painted thermoplastic olefin parts

The recycling of painted automotive body panels is complicated by the presence of thermoset paint particles. The contamination has been shown to reduce the performance of the base thermoplastic resin. It is thought that reducing the size of the included particles may improve the quality the contaminated material.; The goals of this study were to show that a new extrusion screw mixing section could be used to breakdown the paint flake contaminants enough to make painted TPO scrap more valuable. For this study a single screw mixing section that imparts a “grating action” has been developed, built and tested. Experimental trials were conducted using reground, painted thermoplastic olefin automobile bumpers. This material was extruded using several extrusion screw configurations, including the mixing screw design. In addition, this study conducted a heat history evaluation of the base material (neat) as a supplemental study to evaluate the inherent recyclability of the base TPO.; Results showed that the new grater screw design did improve the material quality by reducing the particle size of the paint chip contaminante. The study also showed that multiple reprocessings of the virgin material had little negative effect on the quality of the material as it retained most of its properties very well.