A method for the production of polytetrahydrofuran having a reduced content of oligomeric cyclic ethers

摘要

The subject matter of the present invention is a method for the production of polytetrahydrofuran or tetrahydrofuran - copolymers having an average molecular weight of from 650 to 6000 and a content of cyclic oligomeric ethers of less than 1 w -%, by treatment with a solvent, characterized in that one dollar a a) of pthf - or thf - copolymers at temperatures of from 20 to 120 deg c with an aliphatic, linear or branched, cycloaliphatic or olefinic hydrocarbon having 1 to 15 carbon atoms; mixtures of these hydrocarbons or mixtures with at least 50 w -% of these hydrocarbons extracted a - or more stages, dollar a b) of pthf - or thf - copolymer phase and the hydrocarbon phase is separated from one another, dollar a is c) the pthf - or thf - copolymer phase largely freed of hydrocarbon, dollar a d) from the hydrocarbon phase obtained in step b), the hydrocarbons are separated by distillation and dollars a e) the mixture obtained in stage d) from cyclic oligomeric ethers and linear pthf - oligomers or oligomers of thf - copolymers on catalysts to thf back splits and thf, if appropriate, returns into the polymerization.