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Process for converting caprolactam to nylon 6

a technology of caprolactam and nylon, which is applied in the direction of sustainable manufacturing/processing, chemical industry, climate sustainability, etc., can solve the problems of long reaction residence time and slow extraction/drying step

Inactive Publication Date: 2002-12-05
INVISTA NORTH AMERICA R L
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0026] The main advantage of the process of the present invention is expected to be that the countercurrent operation of the column will result in continual stripping of caprolactam from the lower parts of the column reactor, with high conversion, and re-condensing it at the upper parts, with low conversion, so that a nylon-6 product with low free caprolactam content is achieved.

Problems solved by technology

While this process has met with commercial success, it has a long reaction residence time and a slow extraction / drying step.

Method used

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  • Process for converting caprolactam to nylon 6
  • Process for converting caprolactam to nylon 6
  • Process for converting caprolactam to nylon 6

Examples

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[0036] A counter-current column with 12 stages was simulated using the mathematical model, with a pre-reactor operating at 150 psia (1.03 MPa) and 220 degrees C. A caprolactam solution containing 17% water by weight is fed to the pre-reactor at a rate of 172 lb / hr. Pre-reactor was chosen to have a 30 minute holdup time under these conditions. Reaction mixture from the pre-reactor is predicted to contain 49.6% caprolactam by weight, 10% residual water by weight, remainder being a polymeric mixture with a degree of polymerization of 14. This mixture is continuously fed to the top stage of the reactor which is maintained at 160 C. Superheated steam is injected at the bottom stage of the reactor at a rate of 80 lb / hr. The bottom one-third of the reactor is maintained at 240 C. Stage temperatures for the upper one third of the column are allowed to reach adiabatic conditions. Column pressure is controlled at 7.5 psia (0.052 MPa).

[0037] A vapor is expected to leave the top stage entering ...

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Abstract

A process for making nylon 6, in which caprolactam and water are reacted in a multistage reactive distillation column.

Description

[0001] 1. Field of the Invention[0002] The present invention concerns a process for the conversion of caprolactam to nylon-6.[0003] 2. Related Art[0004] Nylon-6 is produced commercially using caprolactam as the starting material. A commercial process typically involves heating caprolactam in a VK tube at atmospheric pressure for 12 to 24 hours. This process produces a nylon-6 product that contains 7 to 10% caprolactam in the product. Excess caprolactam is extracted using an 8 to 12 hour aqueous extraction process. The extracted product is then dried for 8 to 12 hours producing a dry product containing 0.2 to 0.3% caprolactam. While this process has met with commercial success, it has a long reaction residence time and a slow extraction / drying step.[0005] U.S. Pat. No. 6,201,096 discloses a process for the production of a polyamide by reaction of an omega-aminonitrile with water in a vertical multistage reactor that is swept by steam. For example, this process can convert 6-aminocapr...

Claims

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Application Information

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IPC IPC(8): C08G69/04C08G69/16
CPCC08G69/16C08G69/04Y02P20/10
Inventor FERGUSSON, STUART B.MARCHILDON, ERNEST KEITHMUTEL, AHMET TURGUT
Owner INVISTA NORTH AMERICA R L
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