Patent ID: 6326457
Filing Date: 2001-12-04
Classification: B01D,C08G

Abstract:
A process for continuous extraction of polyamide particles in an essentially linear extraction column using an aqueous extractant, which comprises using an extraction column that is divided into two zones, treating the polyamide with a recirculating aqueous extractant comprising from 40 to 95% by weight of .epsilon.-caprolactam in a first zone, wherein the temperature in the first zone is within the range from 95 to 140.degree. C., and then effecting a countercurrent aftertreatment with cold water at a flow rate of from 0.2 to 6.0 m/h and a residence time of the polyamide within the range from 2 to 60 minutes in a second zone, wherein the ratio of the tube diameter of the first zone to that of the second zone is within the range from 8:1 to 2:1.