PURPOSE: To concentrate and separate a polymer without modifying the same, by treating an org. solution containing a monomer and a polymer thereof with an org. solvent resistant semipermeable membrane.
CONSTITUTION: A polymer solution wherein the M.W. of a solvent is 50W200, the M.W. of a monomer is 50W1,000, the average M.W. of a polymer is 1,000W 1,000,000 and the M.W. ratio of the monomer and the polymer is 1/10 or less is subjected to membrane separation under pressure of 1W25kg/cm2 corresponding to the M.W. of the polymer by using an ultrafiltration membrane or a reverse osmosis membrane with fractionation M.W. of 500W500,000. As a semipermeable membrane, a tubular membrane comprising polyimide, polyamide or polyamidimide is used. If this method is applied, a membrane permeated liquid can be re-utilized as a polymerization stock liquid because contains substantially no polymer.
ISHII SHINJI
TAKANASHI KOUICHI
Next Patent: JPS5939304