| 摘要 |
A process is proposed for the treatment of a recycling stream (1) from a plant for the production of polyarylene ether sulfones via polycondensation of aromatic bishalogen compounds and of aromatic bisphenols or their salts in the presence of at least one alkali metal carbonate or ammonium carbonate or alkali metal hydrogencarbonate or ammonium hydrogencarbonate in an N-alkyl-2-pyrrolidone as solvent, comprising
from 60 to 90% by weight of water,from 10 to 40% by weight of N-alkyl-2-pyrrolidone and, as contaminant detrimental to specification, up to 5000 ppm by weight of the alkylsuccinimide corresponding to the N-alkyl-2-pyrrolidone and, alongside this, up to 1000 ppm by weight of other substances with higher boiling point than N-alkyl-2-pyrrolidone, in particular inorganic salts, based in each case on the total weight of the recycling stream (1), where the entirety of the components gives 100% by weight,
giving a pure N-alkyl-2-pyrrolidone stream (2) which can be returned to the plant for the production of polyarylene ether sulfones, via a final distillation, which comprises carrying out the final distillation process in a partitioned column (TK), with a partition (T) arranged in the longitudinal direction of the column and dividing the space within the partitioned column (TK) into an input region (A), an output region (B), an upper undivided region (C) of the column, and a lower undivided region (D) of the column, the recycling stream (1) being introduced into the column in the input section (A) of the same, and being separated, in the partitioned column (TK), into a bottom stream (7) comprising N-methylsuccinimide, an overhead stream (8) comprising water, and a pure NMP stream, as side stream (2) from the output section (B). |
