Polyamides are among the most common thermo-plastic synthetic materials. Caprolactam (CPL) is the main raw material for these polymers, especially for PA6 (nylon 6). The monomer caprolactam is produced in a complex process, consisting of 4 main parts:
- synthesis of raw caprolactam
- separation and crystallization of ammoniumsulphate
- purification and preparation of raw caprolactam
- polymerisation of polycaprolactam (PA6)
The raw caprolactam production is based on the key intermediate cyclohexanone oxime, which is usually made by cyclohexanone, hydroxylamine and H2SO4. By adding of ammonia and oleum, the raw caprolactam is synthesized and separated of the ammonium sulphate phase. The following steps for the monomer caprolactam are the purification and concentrating (extraction, destillation and crystallization) and the polymerization step. Finally, residual monomers are separated from the polymer (recovery CPL).