| 摘要 |
The invention relates to the use of coil tube evaporators for concentrati ng aqueous extract solutions from the extraction of polyamides based on poly amide (6). A method for the production of polyamides based on polyamide (6) comprises the steps (b) one-phase or two-phase reaction of aqueous extract s olutions from the extraction of polyamides based on polyamide (6), which are possibly enriched with caprolactam, aminocapronitrile, aminocaproic acid, o r mixtures thereof, in a pre-reactor at pressures in the range of 5 to 40 ba r and temperatures in the range of 150 to 300°C, wherein in the two-phase re action, the evolved gaseous phase can be separated from the liquid phase, c) discharge of the reaction mixture obtained from step b) by means of a coil tube evaporator at a temperature in the range of 220 to 300°C with a reducti on of pressure to approximately atmospheric pressure and separation of a gas eous phase, producing a liquid phase, d) further reaction of the liquid phas e obtained from step c) at temperatures in the range of 240 to 300°C and pre ssures in the range of atmospheric pressure to 2 bar, with a separation of a gaseous phase.
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