Production process for preparing fiber-grade nylon 6 chips with extracted aqueous concentrated solution and apparatus thereof

Abstract

The invention relates to a production process for preparing fiber-grade nylon 6 chips with extracted aqueous concentrated solution, which includes the following steps: filter pressing: the extracted aqueous concentrated solution is filter-pressed by a high-temperature filter press; preparation: the extracted aqueous concentrated solution is first added into a melting kettle, solid caprolactam andmolecular weight stabilizer are then added into a melting kettle, and after heating, caprolactam melt is obtained; prepolymerization: the caprolactam melt is heated by an energy saver, and then enters a prepolymerization reactor, and the prepolymerization reactor is heated and pressurized, so that prepolymerized material is obtained; postpolymerization: the prepolymerized material is sent into a postpolymerization reactor, and the postpolymerization reactor is depressurized to remove residual moisture, removes reaction heat, and keeps the temperature, so that the prepolymerized material carries out polycondensation reaction; dicing; chip extraction; chip drying; and packaging. The technical scheme of the invention can effectively reduce material consumption, energy consumption and pollution, the quality of the nylon 6 chips is high, and moreover, the invention can create high economic and social benefits.

Description

technical field [0001] The invention relates to a production process and a device for recycling caprolactam monomers and oligomers in nylon 6 extracts to produce spinning-grade nylon 6 chips. Background technique [0002] The production of Nylon 6 is mainly hydrolytic polymerization. After the polymerization reaction, there are always about 10% monomers and oligomers that will be extracted by the subsequent process. At present, in the mature process of producing high-quality spinning grade nylon 6 chips at home and abroad, there is no process of directly recycling the extracted water concentrate. [0003] Due to the high melting point of the oligomer, especially the melting point of the β variant in the dimer can reach 347-348 ° C, and their solubility is very low. With the elimination of mother liquor water content and the reduction of caprolactam, the bottom solution is more likely to solidify and block equipment and pipelines, which directly restricts the recovery and ut...

AI Technical Summary

Problems solved by technology

The prerequisite for using this chemical equilibrium model is that all incorporated cyclic oligomers can participate in the reaction, while ignoring the characteristics and state of the cyclic oligomer itself: low solubility, low reactivity; partial structure Some key technical difficulties such as high melting point; foreign impurities introduced in the production process, and the complexity of reversible reactions to generate multi-component low-molecular substances

Due to the high difficulty of actual operation, many enterprises fail to invest, and the product quality cannot meet the requirements of spinning grade chips

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