Three-phase hydrolytic polymerization process for nylon 6

Abstract

The invention relates to a three-phase hydrolytic polymerization process for nylon 6. The process includes the steps of raw material preparing, pre-early polymerization reaction, early polymerization reaction, later polymerization reaction and cooling and slicing. The three-phase hydrolytic polymerization process for the nylon 6 has the advantages that a pre-early polymerization reaction kettle is added according to the hydrolytic polymerization reaction characteristics of fresh caprolactam, the highest pressure bearing ability of the pre-early polymerization reaction kettle is 15Bar, the early stage of the polymerization reaction of the fresh caprolactam is completed in the pre-early polymerization reaction kettle, and problems such as high product quality fluctuation caused by instable early polymerization liquid level can be solved; process controllability can be increased by adding the pre-early polymerization reaction kettle, product quality is increased, and the occurrence rate of polymerization accidents is reduced.

Description

technical field [0001] The invention relates to a process for producing nylon 6, in particular to a three-stage hydrolysis polymerization process for nylon 6. Background technique [0002] my country's nylon 6 industry began in the late 1950s and has a history of 50 years. In terms of polymerization process, it has experienced small capacity to large capacity; from intermittent production to continuous production, from trial production to industrialization, and the equipment structure has been continuously improved and perfected. , the process technology is becoming more and more reasonable and mature. [0003] At present, the preparation of high-quality nylon 6 adopts the hydrolytic polymerization process. The hydrolytic polymerization process of nylon 6 mainly includes three major reactions: chain initiation, chain growth, and chain balance. With the continuous expansion of nylon production capacity, the normal pressure continuous polymerization process has been unable to ...

AI Technical Summary

Problems solved by technology

[0007] At present, the maximum negative pressure capacity of the conventional pre-polymerization reactor is about 3 Bar. If a pre-polymerization reactor with higher negative pressure capacity is required, the manufacturing cost will increase

The initial stage of hydrolysis polymerization of fresh caprolactam is mainly hydrolysis ring-opening and addition reaction, in which the addition reaction is an exothermic reaction, but the two-step reaction of hydrolysis and addition is interspersed in the early stage, and the addition reaction is carried out one hour before the polymerization reaction It is also the most violent, because the addition reaction exothermic is very easy to cause pressure fluctuations, which will cause the instability of the pre-polymerization liquid level, affect the polymerization process, and finally affect the quality of the product