Solvent recovery method for para-aramid fiber production

A technology of para-aramid fibers and recycling methods, applied in the direction of organic chemistry, etc., to reduce the risk of decomposition, reduce the decomposition rate, and improve the recovery rate

Active Publication Date: 2019-01-04
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The method of the invention not only effectively solves the problem of rectification waste liquid treatment and extraction agent decomposition and acidification, but also improves the recovery rate and recovery quality of NMP, and does not affect the stable and continuous operation of solvent recovery production

Method used

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  • Solvent recovery method for para-aramid fiber production

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Embodiment 1

[0030] Use calcium carbonate to neutralize the washing solution after PPTA polymerization until the pH reaches about 6. Then the neutralized washing liquid is transported to the extraction tower for extraction and separation, and the extraction agent is chloroform. The extraction phase extracted from the bottom of the extraction tower is sent to the rough division section for the separation of extractant and NMP. The main equipment of the rough division is two falling film evaporators. The primary evaporator maintains the operating temperature at around 60°C and the vacuum at around -0.06MPa. The operating temperature of the secondary evaporator is kept at about 80°C, and the vacuum degree is kept at about -0.07MPa. Chloroform is extracted from the top of the two evaporators, and crude fraction material is extracted from the bottom. The content of extractant in the coarse material is about 10%; the coarse material is sent to the fine separation section to further separate t...

Embodiment 2

[0033] Use calcium carbonate to neutralize the washing solution after PPTA polymerization until the pH reaches about 6. Then the neutralized washing liquid is transported to the extraction tower for extraction and separation, and the extraction agent is chloroform. The extraction phase extracted from the bottom of the extraction tower is sent to the rough division section for the separation of extractant and NMP. The main equipment of coarse separation is a falling film evaporator. The primary evaporator maintains an operating temperature of around 80°C and a vacuum of around -0.06MPa. Chloroform is extracted from the top of the evaporator, and the crude material is extracted from the bottom. The content of extractant in the coarse material is about 15%; the coarse material is sent to the fine separation section to further separate the extractant. The fine separation equipment adopts a rectification tower. Before entering the rectification tower, 8% hot water with a temper...

Embodiment 3

[0035] Use calcium carbonate to neutralize the washing solution after PPTA polymerization until the pH reaches about 6. Then the neutralized washing liquid is transported to the extraction tower for extraction and separation, and the extraction agent is chloroform. The extraction phase extracted from the bottom of the extraction tower is sent to the rough division section for the separation of extractant and NMP. The main equipment of coarse fractionation is a plate distillation column. The operating temperature of the distillation tower is kept at about 70°C, and the vacuum degree is kept at about -0.06MPa. Chloroform is extracted from the top of the evaporator, and the crude material is extracted from the bottom. The content of extractant in the coarse material is about 10%; the coarse material is sent to the fine separation section to further separate the extractant. The fine separation equipment adopts a rectification tower. Before entering the rectification tower, 2% ...

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Abstract

The invention relates to a solvent recovery method for para-aramid fiber production, and belongs to the field of fine chemical engineering. The solvent recovery method includes the steps: firstly, adding calcium carbonate into PPTA (poly-para-phenylene terephthalamide) polymerized washing liquid to neutralize hydrochloric acid generated by polymerization; secondly, conveying the neutralized washing liquid to an extraction column for extraction separation; thirdly, conveying an extraction phase to a crude separation device for separating extraction agents and NMP (non-methane products) to obtain crude separation materials; fourthly, adding the crude separation materials into hot water, conveying the crude separation materials to a fine separation device for further separating the extractionagents to obtain fine separation materials; fifthly, conveying the fine separation materials into a purification evaporator for NMP purification and recovery; sixthly, performing ion substitution andsedimentation treatment on rectification waste liquid, filter-pressing deposits and then conveying filtrate again to the extraction column for extraction separation; seventhly, mixing, cooling and conveying the NMP and calcium chloride water solution to a polymerization system to prepare p-phenylenediamine solution. The method effectively solves the problems of rectification waste liquid treatment and extraction agent decomposition and acidification, NMP recovery rate and recovery quality are improved, and stable and continuous operation of solvent recovery production cannot be affected.

Description

technical field [0001] The invention relates to a solvent recovery method for para-aramid fiber production, which belongs to the field of fine chemical industry. Background technique [0002] Para-aramid fiber is an important polymer material, which is widely used in aerospace, national defense and many civil fields. The production of para-aramid fiber is generally divided into three parts: polymerization, solvent recovery and spinning. Wherein the polymerization is the monomer p-phenylenediamine and terephthaloyl chloride in the solvent N-methylpyrrolidone (NMP) / cosolvent calcium chloride (CaCl 2 ) The low-temperature solution in the system is polycondensed into a polymer resin (PPTA), and then washed with water to remove NMP, CaCl 2 , by-product hydrochloric acid and trace oligomers are separated from PPTA to become pure polymer powder and washing liquid respectively; solvent recovery is to first neutralize the hydrochloric acid in the washing liquid to form a salt, and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D207/267
CPCC07D207/267
Inventor 庹新林
Owner TSINGHUA UNIV
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