Method for continuously recycling solvent-flux for industrially compounding PPTA

Abstract

The invention relates to a method for recycling a solvent-flux for industrially compounding PPTA, comprising the following steps: (1) a mother solution which comprises NMP solvent, salt, water and trace oligomer and is obtained after synthetic PPTA resin is washed by water is extracted and separated to respectively obtain an extract phase NMP-extractant system and a raffinate phase salt-water-extractant system; (2) water obtained after an raffinate phase is stripped and separated is used for washing the resin, and the obtained extractant is recycled; (3) water obtained after an extract phase is rectified and delaminated is used for washing the resin, the obtained extractant is recycled, and coarse NMP obtained through separation is recycled after being purified. By extraction for desalination, the method solves the problem that NMP is thermally cracked under the condition of salt existence because the salty mother solution is directly distilled, largely enhances the solvent recovery rate (reaching above 97 percent), has low energy consumption, and recycles the flux simultaneously, such as calcium chloride. The method can realize closed, continuous and clean production and is beneficial to protecting the environment.

Description

technical field [0001] The invention relates to a continuous recovery and recycling method of solvent / solvent / water for industrial synthesis of poly-p-phenylene terephthalamide (PPTA), belonging to the field of polymer material synthesis. Background technique [0002] In the process of synthesizing PPTA resin, it is often necessary to use a large amount of solvent (NMP) and co-solvent (calcium chloride) to carry out low-temperature solution polycondensation reaction, and the hydrochloric acid generated by the reaction needs to use neutralizer (hydroxide or oxide of alkali metal) ) for neutralization, a large amount of new hydrochloride is formed after the neutralization reaction, and then water is added to wash the PPTA resin system containing solvent NMP, salt, water and trace oligomers. Usually, the treatment and discharge of washing water need to spend a lot of money , and a large number of expensive solvents and co-solvents cannot be recycled, resulting in a lot of waste...

AI Technical Summary

Problems solved by technology

With this method, since the distillation is carried out in the presence of salt, during the distillation process, the salt will be deposited at the bottom of the tower, and the salt at the bottom of the tower needs to be continuously removed, resulting in discontinuity of production, resulting in a reduction in production efficiency. In this method, the recovery rate of NMP can reach 91%, and the salt is not recycled

[0005] The current recovery methods are intermittent, and the recovery efficiency is relatively low, which is not conducive to industrialized large-scale production to a certain extent.