METHOD FOR CONTINUOUSLY RECOVERING DIMETHYLFORMAMIDE FROM WASTE SOLUTION RESULTING FROM PRODUCTION OF POLYIMIDE
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United States of America Patent
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Oct 10, 2024
app pub date -
Aug 2, 2022
filing date -
Aug 6, 2021
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Abstract
A method for recovering dimethylformamide from a polyimide production waste solution containing dimethylformamide, acetic acid, a catalyst, and water, includes (a) a neutralization process of forming the acetic acid into a non-volatile acetate by adding a metal hydroxide to the waste solution, (b) a first distillation process of removing the water contained in the waste solution that has gone through the step (a), (c) a second distillation process of separating and removing the non-volatile acetate from the waste solution, (d) a water content control process of controlling the water content in the waste solution by adding water to the waste solution such that the dimethylformamide and the catalyst contained in the distilled waste solution in the step (c) do not form an azeotropic mixture, and (e) a third distillation process of separating and recovering dimethylformamide through fractional distillation from the waste solution in which the water content has been controlled.
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