Recycling technology for laminates composed of thermoplastic polyolefin elastomer and crosslinked polypropylene foam

The laminates composed of thermoplastic polyolefin elastomer (TPO) skin lay ers and crosslinked polypropylene (PP) foam layers have often been used for inner components of automobiles, such as instrument panels and door trim. In recycling the laminates by a simple melt-kneading method, the recycled m aterial shows very poor mechanical properties, because the PP foam cannot b e dispersed into the TPO matrix due to its crosslinked structure. In this s tudy, a new recycling technology has been developed by using reactive extru der to eliminate the deterioration of mechanical property. This technology is based on resolving the crosslinked structure of PP foam by a reactive ag ent injected into the extruder, and finely dispersing decrosslinked PP foam into the TPO matrix by high shear force. Such reactive processing is also useful for decomposing azodicarbonamide, which is used as foaming agent for PP foam and causes deterioration of the surface flatness and the light res istance of TPO. The recycled material shows the properties similar to those of TPO. It is possible to use the recycled materials in place of TPO skin layers.