Continuous polyamide extraction process
AssigneeBASF SE
InventorsPeter Hildenbrand, Reinhard Lang, Alfons Ludwig, Gunter Pipper
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Abstract
A process for continuous extraction of polyamide particles in an essentially vertical extraction column using an aqueous extractant comprises using an extraction column that is divided into two zones and performing an extraction with a recirculating 15-40% strength by weight aqueous ε-caprolactam solution in the first zone and then with countercurrent water at a from 5 to 40° C. lower temperature in the second zone. The process provides for economical extraction of polyamides with a low level of monomers and oligomers.
Claims11
A process for continuous extraction of polyamide particles in an essentially vertical extraction column using an aqueous extractant, which comprises using an extraction column that is divided into two zones and performing an extraction with a recirculating 15-40% strength by weight aqueous ε-caprolactam solution in the first zone and then with countercurrent water in the second zone, wherein the first zone of the extraction column has a larger diameter than the second zone and wherein the transition from the first zone to the second zone is equipped with a flow barrier.
Dependencies are inferred from the claim text.