Recycling of Reaction Injection Molded Polyurethanes

Abstract

Several processes have been developed to recycle RIM thermoset polymers, including reuse of reground scrap, compression molding and extrusion, recovery and recycle of chemical components, and energy recovery. For recovery and recycle of scrap from Reaction Injection Molding (RIM) processing, size reduction is a critical first operation. RIM scrap is granulated in a first step, and subsequendy pulverized to 180-300 micron size in an impact disc mill. At this size, the RIM regrind can be used as an inexpensive extender in the original applications, such as automotive fascia, with no loss in physical or mechanical properties. Surface quality of the parts is excellent. RIM regrind can also be used as a filler in thermoplastics such as polyethylene. Compatibilizing polymers have been developed which allow incorporation of 25% polyurethane RIM regrind into polyethylene without appreciable loss of impact properties. Energy recovery from polyurethane RIM scrap can be accomplished in suitable combustors, without generating excessive stack emissions. These recycle/recovery technologies augment the favorable energy savings which accrue from the use of lightweight polyurethane parts in automotive applications.