Patent ID: 6590064
Filing Date: 2003-07-08
Classification: C08G

Abstract:
The method of reducing the extractable content of polyamides in a process for producing polyamides by polymerization of lactams and optionally further polyarnide-formino monomers, wherein ther polymerization is performed in the presence of metal oxides as heterogeneous catalysts wherein the metal oxides are used in a form which permits mechanical removal from the reaction mixture and are removed from the reaction mixture during or after the polymerization, and the polymerization is effected in two stages, the first stage being performed under an elevated pressure at which the reaction mixture with the exception of the heterogeneous catalyst forms a single liquid phase and the last stage being a postcondensation under pressure within the range from 0.01 to 10Ã—105 Pa, wherein the heterogeneous catalyst is present in either or both stages.