Author(s)

C. Molero, M. J. Ramos, A. de Lucas & J. F. Rodríguez

Abstract

The development of a chemical process for the recovery of polyols from flexible polyurethane foam wastes with enough quality to be reutilized in foaming has been a major challenge for scientists during recent years. In that way the objective of chemical recycling of PU wastes is the recovery of its major constituent, the polyol, in an environmental friendly way that is performed with the lowest cost and without hazardous residues production. The glycolysis of PU wastes in the presence of a large excess of glycolitic agent allows one to obtain a polyol rich upper phase and a bottom phase containing mainly glycol and isocyanate derivatives. Different metal octoates derived from cycloaliphatic carboxylic acids can be used as the catalyst with suitable catalytic activity. The optimization of process conditions has demonstrated that there is a narrow window of process conditions (relation between phases, temperature, catalyst, etc) in which the split phase glycolysis can be carried out. The recovered polyols have to be subjected to purification by aqueous liquid-liquid extraction before refoaming in a conventional formulation mixed with fresh ones in a large range of proportions. The excess of glycolyzing agent in the bottom phase has to be returned to the cycle by vacuum distillation. The vacuum residue containing the isocyanate derivatives can be applied as an initiator in the synthesis of rigid polyols, allowing the complete use of the glycolyzates from PU recycling. Keywords: glycolysis, PU wastes, octoates, plastic recycling. 1 Introduction Since polyurethanes (PU) were discovered in 1937, it has turned out to be one of the most important groups of plastics. They are produced by the reaction of an

Keywords

glycolysis, PU wastes, octoates, plastic recycling