Reducing the mass of passenger vehicles has become one of today’s top priorities for the automotive industry worldwide. Weight reduction is key to decrease fuel consumption and emissions to comply with CAFE and other environmental legislation. Meanwhile, styling trends for passenger cars have evolved to include very complex shapes and contours, which are difficult to manufacture using traditional materials like steel and sheet molding compound (SMC).
A number of engineering thermoplastics (ETPs) have been positioned to address these important issues in automotive exterior body panels, while also providing design flexibility for parts integration and increased functionality - all while being recyclable (melt reprocessable). Recent ETP developments have yielded materials that are capable of being processed with the rest of the body-in-white on-line through E-coat and that are intrinsically conductive to allow for direct electrostatic painting without additional conductive primer. This technology helps reduce the cost, number of variables to control, and volume of in-plant VOC emissions, all while improving the part quality. Yet another breakthrough in polymer technology is the development of a molded-in-color weatherable PC/PBT blend with a polyurethane clear coat. This new weatherable polymer system can not only provide dramatic savings in weight, but also virtually eliminates the traditional painting process.
This paper will outline trends affecting materials selection and design developments for the exterior body and will provide an overview of new resin technologies developed to address these needs.