Continuous polymerization production process of high-viscosity polyamide 6

Abstract

The invention relates to a continuous polymerization process of high-viscosity polyamide 6, comprising the following steps of: preparing caprolactam with de-ionized water; pre-heating the mixed caprolactam to a temperature in a range of 220+ / -30 DEG C by a pre-heater and conveying the mixed caprolactam into a pre-polymerizer by a feeding pump to carry out hydrolyzed ring opening and pre-polymerization on the caprolactam, wherein the pressure of the ring opening and the pre-polymerization is 2.50+ / -0.50 bar, the temperature is in a range of 270+ / -15 DEG C and the flow of the caprolactam is 2200+ / -500 kg / h; then, discharging materials into a post-polymerizer to carry out post-polymerization to obtain a polymer melt, wherein the pressure of the post-polymerization is 0.35+ / -0.25 bar and the temperature is 250+ / -30 DEG C; treating the polymer melt by a polymer filter, a casting strip head, an underwater granulator and a vibrating screen to obtain slices; adding the slices into a pre-extracting water pot to carry out pre-extraction with hot water at the temperature in a range of 115+ / -10 DEG C; then, conveying the treated slices into an extracting tower and extracting with the hot water at the temperature in a range of 100+ / -20 DEG C; conveying the extracted slices into a drying tower and carrying out counter-current drying by nitrogen gas; drying at the temperature in a range of 120+ / -30 DEG C and discharging the dried slices into a slice cooling bin; and conveying the cooled slices into a slice storage bin and a slice packaging bin by the nitrogen gas and packaging to obtain the high-viscosity polyamide 6 slices with the relative viscosity of 3.4-4.0.

Description

Technical field [0001] The invention relates to a high-viscosity polyamide 6 continuous polymerization production process; in particular, a large-scale continuous production of high-viscosity polyamide 6 chips with a relative viscosity of 3.4 to 4.0. Background technique [0002] For the same polymer, high melt viscosity is a reflection of high molecular weight, and high molecular weight means higher physical and mechanical properties. Therefore, high-viscosity polyamide 6 has application advantages in extrusion and blow molding to prepare pipes, bottles, sheets, films, engineering plastics and high-performance fibers. In the above applications, the high melt viscosity has a beneficial effect on the processing performance and the properties of the resulting product. [0003] The method of producing polyamide 6 has long been known. For example, it is published in "Handbook of Plastics Industry-Polyamide", Chemical Industry Press, Beijing, 2001, P54-55. According to these methods,...

AI Technical Summary

Problems solved by technology

[0022] Through the above process analysis, it can be seen that the current production method of high-viscosity polyamide 6 chips is quite different from the production process of conventional polyamide 6 chips with a relative viscosity of 2.6 to 3.0, whether it is the process flow or the addition of additives, so its implementation Difficult to implement in conventional industrial-scale VK tubes, or implementation requires major modifications to existing conventional devices

More importantly, the above-mentioned processes are currently still in the stage of conception and industrialization, and there is no evaluation of the intrinsic quality of the obtained high-viscosity polyamide 6 chips, which will undoubtedly directly affect downstream applications, especially in high-end fields. Therefore, the industrial application effect of the above process is also unknown

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