PA6 resin continuous polymerization process

Abstract

The invention relates to a PA6 resin continuous polymerization process, which comprises: (1) heating, stirring and mixing caprolactam, water, a catalyst and a molecular weight regulator to obtain an auxiliary agent solution, feeding a formed mixture into a storage tank, conducting heating, and carrying out thermal insulation; (2) mixing and preheating caprolactam and an auxiliary agent solution, pumping a heated mixture into the top of a polymerization tube, and carrying out catalytic ring-opening polymerization reaction; (3) pumping the reaction system into a vertical film devolatilization device, and carrying out high-vacuum devolatilization; (4) feeding the system into a single-screw or helical ribbon extruder, and carrying out high-vacuum devolatilization; and (5) feeding the material into a multi-screw extruder for screw extrusion devolatilization, and conducting cooling, pelletizing and drying to obtain PA6 resin pellets. The process provided by the invention can replace and reduce four working procedures of recovering caprolactam through water extraction, preparing deionized water, refining recovered monomers and post-polymerizing, the relative intrinsic viscosity of the product is high, the content of monomers and low-molecular substances is low, the process is close to the level of the existing hydrolytic polymerization process, the process is simple, the production period is short, the energy consumption is low, the investment is small, and the process is suitable for industrial production.

Description

technical field [0001] The invention relates to a resin continuous polymerization process, in particular to a PA6 resin continuous polymerization process. Background technique [0002] In the past ten years, my country's polyamide 6 (PA6) resin synthesis industry has developed rapidly, with a total output of more than 5 million tons per year, becoming the world's largest PA6 resin production base. It is expected that in the next five years, the output of PA6 resin will reach 10 million tons. [0003] The PA6 resin synthesis process is the continuous hydrolysis polymerization process of caprolactam, and its production process includes pre-polymerization, post-polymerization, cooling and pelletizing, water extraction, drying, packaging, extraction water distillation and recovery of monomers, and deionized water preparation. The post-polymerization viscosity-increasing process is used to increase the molecular weight of PA6, and the unreacted caprolactam monomer in PA6 resin i...

AI Technical Summary

Problems solved by technology

However, the use of three-stage serial thin-film evaporators for devolatilization cannot meet the requirements of spinning grade volatiles. The monomer content of PA6 functional masterbatch obtained by this method reaches 5%. In the actual production process, the monomer content of the melt ranges from 10% It is easy to go down to 5%, but it is very difficult to go from 5% to below 0.5%

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