Process for separating polyurethane hydrolyzates into polyether

Details Process for separating polyurethane hydrolyzates into polyether Process for separating polyurethane hydrolyzates into polyether

1981-09-04

1983-08-16

Jacobs, Lewis T.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Process of treating scrap or waste product containing solid...

C08J 1104, C08G 1848

Patent

active

043992366

ABSTRACT:
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.

REFERENCES:
patent: 4035314 (1977-07-01), Lohr, Jr. et al.
patent: 4051212 (1977-09-01), Grigat et al.
patent: 4143072 (1979-03-01), Hetzel et al.
patent: 4281197 (1981-07-01), Oblinger
patent: 4282367 (1981-08-01), Niederdellmann et al.
Environmental Science and Technology, vol. 8, No. 2, Feb. 1974, pp. 135-138.

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