| 摘要 |
<p>The invention relates to a method for the continuous production of textile polyamide 6 from e -caprolactam using oligomer -containing lactam fed back from the extraction stages. In the method according to the invention , the extract water from a continuous evaporation stage is treated in a targeted manner over several stages. The extract water is concentrated by evaporation of excess water, the ring -opening and polyaddition reactions are started and the oligomers are decomposed , such that an oligomer fraction of no more than 0.7 % by weight is achieved after the addition of fresh lactam and additives at the end of the third stage. Then the polymer/caprolactam and additive mixture is fed to the final polymerisation reactor (VC tube). It is important here that the starting oligomer content at the inlet of the VC tube is well below the equilibrium value of approx. 0.85 % by weight. The oligomer content in the VC tube thus builds up during the main polycondensation reaction to a value of 0.65 % by weight in the final polymer. The invention further relates to a device for carrying out a method of this type and to the use of polyamide 6 produced in this manner for POY filaments.</p> |
