| 摘要 |
PURPOSE:To obtain a highly pure refined caprolactam, at a low cost, by distilling crude caprolactam, and passing the molten caprolactam through a cation exchange material. CONSTITUTION:Crude caprolactam is distilled to remove the impurities which can be removed by distillation. The distillation is preferably carried out under reduced pressure at a lowest possible temperature to prevent the decomposition of caprolactam, generally at about 130 deg.C under a vacuum of 5Torr. The distilled caprolactam is passed in a molten state through a cation exchange material, especially a strongly acidic cation exchange material such as sulfonated polystyrene. A high-purity refined caprolactam can be obtained by this process in an extremely high ion exchange performance. The whole treatment from the distillation to the ion exchange treatment is preferably carried out in the absence of oxygen.
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