Establishment of recovery method of available substances from polyurethane by chemical decomposition

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The purpose of this study is to establish the recovery method of polyol from polyurethane foam by chemical decomposition. Methylendiphenylisocyanate (MDI) -based polyurethane foam was decomposed by monoethanolamine (MEA) or isopropanolamine (IPA) at 170ﾟC.The decomposing liquid was separated into two layrs regardless of decomposing agent. MEA was superior to IPA because polyol was contained only in the upper layr in the case of MEA decomposition, and was distributed in the both layrs for IPA decomposition.The upper layr obtained by MEA decomposition was extracted by hexane to raise the purity of polyol. The extracted liquid was separated into three layrs. A large amount of polyol existed in the middle layr, in which polyol was contained 72% by weight, hexane 20%, and by-products 8%. The by-products were found to be diphenylmethanediamine (DAM) or polymeric DAM, which were derived from MDI or polymeric MDI, by GPC, HPLC, and NMR analyzes.The recovered polyol containing hexane and by-products, was used for re-producing polyurethane foam by mixing in various ratios with virgin polyol. A good cellular structure foam was obtained with recovered polyol weight up to 30%.