Verfahren zum Extrahieren von Polyamiden

摘要

Low molecular weight constituents are extracted from a polylactam composition by passing a solvent downward through the composition in particle form at elevated temperature. The polymer which may be in the form of flakes or granules may be derived by polymerization of an o -amino-carboxylic acid or an amide forming derivative thereof. Suitable solvents are those of lower S.G. than the polymer and extractible material e.g. water, MeOH, EtOH and PriOH. The process may be carried out at 70-120 DEG C. and may be continuous, the polymer being raised in counter-current to the falling solvent. In Example (1) the solvent is allowed to flow down a stationary column of polycaprolactam. In Example (2) the apparatus of Fig. 2 is used. Solvent is run down the column and the polymer is raised by removing containers of treated polymer from the top of the column and replacing them by fresh ones inserted at the bottom. In Example (3) the solvent is run down a column of polymer which is raised by supplying fresh polymer at the bottom with a screw feeder and removing treated polymer from the top.