| 摘要 |
<p>The invention relates to the use of coil tube evaporators for concentrating aqueous extract solutions from the extraction of polyamides based on polyamide (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 solutions from the extraction of polyamides based on polyamide (6), which are possibly enriched with caprolactam, aminocapronitrile, aminocaproic acid, or mixtures thereof, in a pre-reactor at pressures in the range of 5 to 40 bar and temperatures in the range of 150 to 300°C, wherein in the two-phase reaction, 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 reduction of pressure to approximately atmospheric pressure and separation of a gaseous phase, producing a liquid phase, d) further reaction of the liquid phase obtained from step c) at temperatures in the range of 240 to 300°C and pressures in the range of atmospheric pressure to 2 bar, with a separation of a gaseous phase.</p> |
