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USE OF THE BOTTOM PHASE RESIDUE FROM POLYURETHANE GLYCOLYSIS AS POLYOL POLYMERISATION INITIATOR

Simón Herrero Diego ^(1)*, Borreguero Simón Ana María ⁽¹⁾, de Lucas Martínez Antonio ⁽²⁾, Molero Cerezo Carolina ⁽³⁾, Rodríguez Romero Juan Francisco ⁽³⁾

⁽¹⁾ Chemical Engineering Department, University of Castilla- La Mancha - Ciudad Real - Spain, ⁽²⁾ Chemical Engineering Department, University of Castilla - La Mancha - Ciudad Real - Spain, ⁽³⁾ Chemical Engineering Deparment, University of Castilla - La Mancha - Ciudad Real - Spain

Polyurethanes (PU) are one of the most used polymers. Flexible PU foams represent 29 wt%. This commercial success involves an increasing quantity of wastes disposed in landfills. Flexible PU foams are synthesised from polyols and polyisocianates. The recovery of polyols from their wastes would be an alternative to minimize this environmental problem at the time that reduces the consumption of natural resources. In previous works, an integrated process for the recovery of polyols from flexible PU foams was designed. By means of an excess of glycolysis agent, the reaction product splits in two phases, where the upper layer is mainly formed by the recovered polyol and the bottom layer by the excess of glycolysis agent and reaction by-products. However, the bottom phase obtained implies an environmental problem due to the toxicity of some of their components, such as aromatic amines or carbamates; but also and economic problem, since the 80 molar percentage of the glycol used as glycolysis agent remains in this phase. Both problems must be solved to achieve a feasible process for the complete recovery of flexible PU wastes. The main purpose of this work is to give value to the bottom phase by-products. To make this, most of the glycol was recovered by means of vacuum distillation. The recovered glycol was used in the glycolysis process obtaining reaction times and polyol concentrations in the upper phase similar to that achieved with raw glycol, confirming the feasibility of reusing it in the process. On the other hand, the vacuum residue, containing the glycolysis by-products, was investigated as initiator of anionic polymerization for the synthesis of polyether polyols, comparing its activity with that of the commercial TDA based initiator. Propoxylation was carried out using both of them to obtain polyols. The calculated rate constants with the residue and the commercial initiator were quite similar, as expected since both initiators presented close functionality. Finally, foaming assays were performed using the residue-based polyols in replacement of the commercial one, showing successful results even for the complete replacement of the TDA – based polyol.