Published: February 1988
This supplementary report updates PEP Reports 78 issued in January 1976, and 41A issued in July 1976. It addresses the recent developments and improvements in the technology for the manufacture of caprolactam and nylon 6 since the issuance of those reports.
Caprolactam can be produced from cyclohexane, phenol, or toluene by the following four routes:
- From oyclohexane via cyclohexanone by oxidation, oximation, and Beckmann rearrangement
- From phenol via cyclohexanone by hydrogenation, oximation, and Beckmann rearrangement
- From toluene via cyclohexane carboxylic acid by oxidation, hydrogenation, nitrosation, and rearrangement
From cyclohexane by photonitrosatlon and rearrangement.
The first two routes are used by most of the caprolactam producers in the world today, followed by the third route, which is used by two producers in Western Europe at the present time. The last route is the least-used, with Toray Industries in Japan as the only producer. In this report, we present economics for three alternative processes using the first route, and one process each using the second and third routes.
Nylon 6 is manufactured by polymerization of caprolactam by two different routes as follows:
- Hydrolytic polymerization by hydrolysis of caprolactam followed by polyaddition and polycondensation
- Anionic polymerization of caprolactam beginning with the formation of an initiation species followed by polyaddition.
The first route is employed mostly for fiber production while the second one is used for extrusion
and casting resins at a much lower production volume. Economics of two alternative hydrolytic polymerization processes are presented in this report, one producing nylon 6 chips, and the other producing nylon 6 melt for direct spinning.