Abstract:
A process for treating a recycling stream from a plant for the production of polyarylene ether sulfones comprising 60 to 90% water, 10 to 40% N-alkyl-2-pyrrolidone, up to 5000 ppm by weight of the alkylsuccinimide corresponding to the N-alkyl-2-pyrrolidone, up to 1000 ppm by weight of other substances with higher boiling point than N-alkyl-2-pyrrolidone, giving N-alkyl-2-pyrrolidone which can be recycled via a distillation column , preceded by preliminary purification in evaporator stage(s), giving vapor stream(s) which are introduced as feed streams into the distillation column, the bottom stream from the last evaporator stage being discharged and the bottom stream from the distillation column being recycled into the last evaporator stage, and the vapor stream from the last evaporator stage being introduced fully or partly into an additional column from which a top stream is introduced into the distillation column and a bottom stream is discharged.
Abstract:
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 the 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 process in a final column (K), which comprises preceding the final distillation by a preliminary purification by evaporation in one or more evaporator stages for reducing the level of inorganic salts, where one or more vapor streams (3, 4, 5) are obtained which are introduced as feed streams into the final column (K), and where the bottom stream from the last evaporator stage is removed and the bottom stream from the final column (K) is recycled in full into the last evaporator stage.
Abstract:
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).
Abstract:
N-alkylpyrrolidone and, as contaminant alongside this, the corresponding N-alkyl-succinimide, to give a pure solvent stream which meets the requirements for use in a process for the production of polymers, where compounds of higher and lower boiling point than the N-alkylpyrrolidone are removed by distillation, which comprises, prior to, during, or after the distillative purification process, adding a hydroxide of an alkali metal or of an alkaline earth metal in a molar amount corresponding to a molar ratio of at least 0.1:1 for this hydroxide with respect to the respective N-alkylsuccinimide in the appropriate solvent stream present prior to, during, or after the distillative purification process.
Abstract:
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 in a final column (K), which comprises preceding the final distillation by a preliminary purification by evaporation in one or more evaporator stages for reducing the level of inorganic salts, where one or more vapor streams (3, 4, 5) are obtained, which are introduced as feed streams into the final column (K), and where the bottom stream from the last evaporator stage is removed, and where a substream (9) comprising 1.0% by weight to 10% by weight of the bottom stream (7) from the final column (K) is removed, and the rest of the bottom stream from the final column (K) is recycled into the last evaporator stage.
Abstract:
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 in a final column (K), which comprises preceding the final distillation by a preliminary purification by evaporation in one or more evaporator stages for reducing the level of inorganic salts, where one or more vapor streams (3, 4, 5) are obtained which are supplied as feed streams to the final column (K), and where the bottom stream from the last evaporator stage is removed and the bottom stream from the final column (K) is supplied in part or in full to an additional column (K), in which it is separated into a bottom steam (11), which is removed, and into an overhead stream (12), which is recycled to the final column (K).