Chemical recycling of reinforced polyurethane from the automotive industry

Abstract

R‐RIM PU (reinforced‐reaction injection molding polyurethanes) from the automotive industry (production scrap and parts at the end of their life cycle) can be recycled for the production of new RIM PU by a chemical process. Among the various possible chemical processes (hydrolysis, alcoholysis, aminolysis, and pyrolysis), we have examined glycolysis, a particular form of alcoholysis, for the purpose of obtaining a mixture of oligomers sufficiently similar to a polyol to be used in the production of new R‐RIM PU. Glycolysis with dipropylene glycol (DPG) of R‐RIM PU forms a monophasic product that could be used in the preparation of new, highly crosslinked polymers, similar to those used in the preparation of rigid thermal insulation foams. The same product, because of its high hydroxyl number, cannot be directly re‐used in the production of new RIM PU. Partial substitution of free DPG in the glycolysis product with a triol having high molecular weight forms a homogeneous mixture suitable for production of new RIM PU. This final product has been used in the original R‐RIM application introducing an appropriate optimization of formulation. In comparison with RIM PU obtained from only virgin materials, the loss in properties of molded parts based on even high amounts of regenerated polyol was only marginal.