Chemical Recycling of Mixed Polyurethane Foam Stream Recovered from Shredder Residue into Polyurethane Polyols

Abstract

Recently, Troy Polymers, Inc. developed a chemical process for recycling of polyurethane foam scrap from shredder residue into polyols for polyurethanes (Sendijarevic, V. (2004). Process for Chemical Recycling of Polyurethane-containing Scrap, U.S. Patent No. 6,750,260 (assigned to Troy Polymers, Inc. and Polyventure, Inc.), June 15). This process is ideally suited for recycling polyurethane (PU) foam scrap from shredder residue (SR), which is a mixture of different types of PU foams based on different types of polyether and polyester polyols and different types of isocyanates, TDI and MDI. The PU foams separated from SR are contaminated with other types of cellular (foam) and fluff non-urethane materials. In stage one of this process, the PU foam is subjected to glycolysis, followed by filtration of the liquid glycolyzed product. In stage two, the glycolyzed products are used as initiators in reaction with propylene oxide to prepare novel PU polyols. A number of successful laboratory glycolyses have been carried out utilizing two different types of PU foams recovered from SR: (1) the best case scenario – handpicked PU foams from SR with > 80% conversion into liquid initiator and (2) the worst case scenario – mixed PU materials separated by an automated separation process from ELV shredder residue with 50% conversion into a liquid initiator. Both TDI-and PMDI-based flexible foams are prepared from the novel recycled polyols prepared by propoxylation of the glycolyzed products (initiators) obtained from the mixed PU materials. Preliminary economic analysis indicates that the commercial production of the polyols from the foam scrap can be cost effective.