Abstract: This invention relates to a continuous and efficient method for the manufacture of highly pure caprolactam suitable for the polycondensation of Polyamide 6 (polycaprolactam) from polyamide waste. In particular the invention relates to a method for the manufacture of caprolactam from waste containing polyamides, including the steps a) depolymerisation of the waste containing polyamides, whereby a caprolactam raw material and a flow containing secondary constituents or additives is obtained, b) at least one distillation of the caprolactam raw material, and c) at least one crystallisation of the caprolactam material obtained in step b), by which means caprolactam is obtained, whereby at least part of the caprolactam obtained in step c) with a permanganate number of<10000 sec. and a UV transmission of<85% is added to the waste containing polyamides before and/or during the depolymerisation.

Abstract: This invention relates to a continuous and efficient method for the manufacture of highly pure caprolactam suitable for the polycondensation of Polyamide 6 (polycaprolactam) from polyamide waste. In particular the invention relates to a method for the manufacture of caprolactam from waste containing polyamides, including the steps a) depolymerisation of the waste containing polyamides, whereby a caprolactam raw material and a flow containing secondary constituents or additives is obtained, b) at least one distillation of the caprolactam raw material, and c) at least one crystallisation of the caprolactam material obtained in step b), by which means caprolactam is obtained, whereby at least part of the caprolactam obtained in step c) with a permanganate number of <10000 sec. and a UV transmission of <85% is added to the waste containing polyamides before and/or during the depolymerisation.

Abstract: The invention comprises a process of producing .epsilon.-caprolactam from extract water of polycaprolactam obtained by hydrolytic polymerization, wherein(i) the extract water is concentrated by distillation of water,(ii) from the concentrated extract water from stage (i) an extract of .epsilon.-caprolactam and oligomers including dimers is obtained by separating an .epsilon.-caprolactam/water vapor mixture,(iii) the extract from stage (ii) is depolymerized in the presence of a catalyst and superheated steam, where a vapor mixture of .epsilon.-caprolactam and water is obtained, and(iv) from the .epsilon.-caprolactam/water vapor mixtures of process stages (ii) and (iii) .epsilon.-caprolactam with a dimer content of .ltoreq.0.2 wt-% is obtained by distillation of water.