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Recycling flexible foam PUR – part 3 – chemical processes

von Dipl.-Chem. Bernhard W. Naber, Prof. Dr. Dr. h. c. Gerhard Behrendt

Flexible polyurethane foams (referred to here as PUR-FF) can be broken down (depolymerised) by chemical reaction. The aim of such processes is to produce liquid products, which, with their content of OH-, NH- and NH₂- groups reactive to isocyanate, can be used again in the synthesis of new polyurethanes and poly(urethane ureas). Processes for recovering pure flexible foam polyols are known but have not become established. Methods of glycolytic decomposition with simultaneous amine removal are in industrial use.

Glycolysates of this kind can not, as a rule, be re-incorporated in PUR-FF, but they are valuable raw materials for the manufacture of hard and semi rigid foams, as well as casting and coating materials. By a new processing technique polyol recyclates are produced containing nanoscale urea particles, which enable the production of polyurethanes with unusual properties.