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Devolatilization method of nylon 6 melt

A devolatilization and melt technology, applied in the field of nylon materials, can solve problems such as increased melt viscosity, pipe blockage, and molding difficulties

Active Publication Date: 2020-06-26
ZHEJIANG HENGYI PETROCHEMICAL RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, to achieve a large amount of hot water extractables removal, the device needs to have a higher devolatilization area and vacuum degree, and under this high-efficiency devolatilization, the molecular weight of nylon 6 will increase rapidly, and the melt viscosity will increase significantly lead to molding difficulties
In addition, how to collect volatiles, avoid pipeline blockage, and effectively reuse volatiles also affects PA6 production efficiency

Method used

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  • Devolatilization method of nylon 6 melt
  • Devolatilization method of nylon 6 melt
  • Devolatilization method of nylon 6 melt

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0083] A method for devolatilization of nylon 6 melt, comprising the following steps:

[0084] 1) The nylon 6 melt and the hot nitrogen with a water content of 0.1wt% are passed through the respective channels into the front-end devolatilization reactor for devolatilization, and most of the hot water extractables in the nylon 6 melt are removed. The hot water extractables are mixed with hot nitrogen to form a gaseous mixture and discharged from the devolatilization reactor. The devolatilized nylon 6 melt is transported to the devolatilization reactor at the rear end for secondary devolatilization without nitrogen gas. The resulting Nylon 6 melt and gaseous mixture are respectively discharged from the devolatilization reactor. Wherein, the absolute pressure in the devolatilization reactor located at the front end is 500 Pa, the temperature is 240°C, and the residence time of nylon 6 melt in the devolatilization reactor is 0.5h; The absolute pressure is below 500Pa, the tempera...

Embodiment 2

[0095] A method for devolatilization of nylon 6 melt, comprising the following steps:

[0096] 1) The nylon 6 melt and hot nitrogen with a water content of 10wt% are passed through their respective channels into the front-end devolatilization reactors (two in parallel) for devolatilization, and most of the hot water in the nylon 6 melt can be extracted The extractables are removed, the hot water extractables are mixed with hot nitrogen to become a gaseous mixture and discharged from the devolatilization reactor, and the devolatilized nylon 6 melt is transported to the devolatilization reactor at the rear end (located in series at the rear end) for further processing The secondary devolatilization without nitrogen, the nylon 6 melt and the gaseous mixture generated after the second devolatilization are respectively discharged from the devolatilization reactor. Wherein, the absolute pressure in the devolatilization reactor located at the front end is 1000 Pa, the temperature is ...

Embodiment 3

[0107] The difference between embodiment 3 and embodiment 1 is:

[0108] (1) The diameter of the air holes on the devolatilization plate is 1mm;

[0109] (2) The water content of the hot nitrogen is 0.5wt%;

[0110] (3) The absolute pressure of the devolatilization reactor at the front end is 800Pa, the temperature is 260°C, and the residence time is 1.5h. The absolute pressure of the back-end devolatilization reactor is below 500Pa, the temperature is 260°C, and the residence time is 20min.

[0111] (4) The working temperature of the high boiling point component removal tower is 180°C, the rotation speed of the spiral blade is 80r / min, and the temperature of the pipeline from the high boiling point component removal tower to the low boiling point component removal tower is kept at 90°C.

[0112] (5) The working temperature of the high boiling point component removal tower is 75°C; the spraying medium is caprolactam, and the spraying temperature is 75°C. The temperature of ...

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Abstract

The invention relates to the field of nylon materials, and discloses a devolatilization method of a nylon 6 melt. The method comprises the following steps: 1) introducing nylon 6 melt and water-containing hot nitrogen into a front-end devolatilization reaction kettle, carrying out devolatilization, conveying the devolatilized nylon 6 melt into a rear-end devolatilization reaction kettle, and carrying out secondary devolatilization; 2) feeding a gaseous mixture into a high-boiling-point component removal tower, condensing the high-boiling-point components in the gaseous mixture, and then discharging; and 3) feeding the remaining gaseous mixture into a low-boiling-point component removal tower, carrying out spraying, fractionation and condensation on the gaseous mixture in a rising process,discharging the low-boiling-point components, and discharging the remaining gas after vacuum treatment. According to the invention, efficient devolatilization can be carried out on nylon 6 melt, and the condensation polymerization reaction of the nylon 6 can be inhibited in the devolatilization process, so that the influence on the spinning forming process due to the violence of the molecular weight of the nylon 6 under the vacuum condition is avoided, time is provided for nylon 6 amide exchange, the molecular weight distribution is narrowed, and the melt quality is improved.

Description

technical field [0001] The invention relates to the field of nylon materials, in particular to a devolatilization method for nylon 6 melt. Background technique [0002] The conversion rate of caprolactam hydrolysis polymerization is generally about 90%, which means that there are about 10% caprolactam monomers and oligomers left in the polymer (also known as hot water extractables, of which monomers account for about 75%, oligomers Accounting for about 25%), the impurities in these melts have a great impact on spinning. Therefore, before PA6 spinning, the slices need to be extracted. According to FZ / T51004-2011, the hot water extractable content of PA6 slices should be less than 0.5wt% (superior product). Nowadays, the hot water continuous extraction process is widely used in the industry to extract the monomers and oligomers in the PA6 slices, so that the extractables content in the slices is less than 0.5wt%, which meets the requirements of high-speed spinning. However, ...

Claims

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Application Information

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IPC IPC(8): C08G69/46C08G69/14
CPCC08G69/46C08G69/14
Inventor 汤廉王松林徐锦龙黄家鹏何宁艳王华平王朝生
Owner ZHEJIANG HENGYI PETROCHEMICAL RES INST CO LTD
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