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AssigneeBayer Aktiengesellschaft
InventorsGeorg Niederdellmann, Norbert Roemer, Jurgen Schenk, Hartmut Hetzel, Ernst Grigat
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The present invention is directed to a process for separating polyurethane hydrolyzates, preferably polyurethane foam hydrolyzates, into substantially amine-free foamable polyethers and diamines, comprising (a) (i) briefly expanding a hot polyurethane hydrolyzate obtained in a continuous screw extruder to normal pressure or in vacuo and, without using readily volatile components (ii) spraying said hydrolyzate directly into a tubular coil evaporator which is heated to 180.degree.-300.degree. C. and at the end of which a pressure of from 0.1 to 20 mbar is applied and (iii) separating a hydrolyzate containing less than 1% by weight of NH.sub.2 in a following cyclone from most of the diamine evaporated and all the solvent used, the diamine being separated from the solvent used in a following distillation column, optionally without any further heat input; (b) precipitating any diamine still present quantitatively in the form of its hydrochloride by introducing excess hydrogen chloride into the hydrolyzate, optionally diluted with inert solvents; and (c) the regenerated polyether obtained after removal by filtration of the precipitated amine salt being freed under reduced pressure from inert solvent and excess hydrogen chloride.
A process for separating polyether polyurethane hydrolysates obtained by hydrolysis of polyether polyurethanes into substantially amine-free foamable polyethers and diamines comprising:
Dependencies are inferred from the claim text.