Extraction of polylactams
AssigneeBadische Anilin- & Soda-Fabrik Aktiengesellschaft
InventorsErnst Kissel, Eckart Neumann, Ernst Guenther, Guenter Valentin, Werner Hoerauf
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Abstract
The continuous countercurrent extraction of polylactam granules with hot water in an extraction zone for the removal of monomer and/or oligomers, the extraction zone being subdivided into subzones by at least one heating zone. The density of the extract-containing water differs by at least 0.0002 between the subzones.
Claims7
A process for the extraction of monomer-containing and/or oligomer-containing polylactam granules which comprises continuously extracting polylactam granules with a countercurrent of water at temperatures above 80.degree. C, under the following conditions:
- a. the water flows upwardly through a substantially vertical extraction zone at a mean of from 0.5 to 20 cm/min and the polylactam granules pass downwardly through said extraction zone at a rate of from 0.2 to 5 cm/min,
- b. the temperature at the upper end of the extraction zone is higher than at its lower end,
- c. the extraction zone is divided into subzones by at least one heating zone so that the density of the water containing extractables in an upper subzone is lower than that of the water contained in the subzone immediately below by at least 0.0002, and
- d. the uppermost heating zone divides the entire extraction zone into lengths bearing a ratio to each other of from 50:50 to 85:15, the shorter section being at the upper end of the extraction zone and said heating zone or the total of said heating zones constitutes 1/7 to 1/20 of the length of the vertical exraction zone.
Dependencies are inferred from the claim text.