Method for continuously preparing anhydrous solvent for synthesizing PPTA

Abstract

The invention relates to a method for continuously preparing anhydrous solvent for synthesizing PPTA, comprising the following steps: (1) firstly, compounding a flux into an aqueous solution, removinga plurality of undissolved substances and then obtaining an aqueous solution without solid impurities through precise filteration; (2) mixing the filtered aqueous solution and solvent to obtain an aqueous solvent system; and (3) continuously and stably obtaining the solvent system for synthesizing the PPTA by rectifying and dewatering the aqueous solvent system. As flux aqueous solvent is used and does not contain the undissolved impurities, even if the flux dosage (larger than 20 percent) is increased, the resin ash content can not be increased, which is beneficial to enhancing the resin viscosity. By utilizing the method, the adverse effects of weather and operation on polymerized solvent system water is overcome, and continuous, closed and clean production is realized.

Description

A method for continuous preparation of anhydrous solvent for synthesizing PPTA technical field The invention relates to an industrial method for preparing an anhydrous solvent for synthesizing PPTA, in particular to a method for continuously preparing an anhydrous solvent for synthesizing PPTA. Background technique The synthesis of poly-p-phenylene terephthalamide (PPTA) uses low-temperature solution polycondensation. When the water content in the reaction system exceeds 200PPm, it will have a very adverse effect on the reaction. Such a low water requirement greatly increases the industrialization of aramid 1414. Difficulty of production. At present, the commonly used method for preparing anhydrous solvent for synthesizing PPTA is: refining the NMP recovered after polymerization to a water content of ≤200ppm, and then using high-temperature burning to remove crystal water in calcium chloride and other co-solvents (the burning temperature is generally 300-500 ° C, the time...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the co-solvent calcium chloride is a strong water-absorbing agent, the crystal water in the calcium chloride is not easy to remove, and the calcium chloride is easy to agglomerate when burned at high temperature, and it needs to be crushed before it can be used. It consumes a lot of energy, and after burning, it inevitably absorbs a certain amount of water in the process of cooling, crushing, weighing, storage, etc., and the water content can easily exceed 200ppm; and this method is greatly affected by the weather. Or it is more difficult to ensure moisture in very humid weather; in addition, this method is discontinuous in the preparation of anhydrous solvents, and the production efficiency is low

In addition, solid industrial CaCl2 contains a large amount of water-insoluble inorganic impurities, and these inorganic impurities are difficult to remove from the solid resin, so that the ash content in the final resin seriously exceeds the standard, which is not conducive to large-scale industrial production