Patent ID: 8138283
Filing Date: 2012-03-20
Classification: C08G

Abstract:
1. A process for changing the mean molecular weight Mn in the continuous preparation of polytetrahydrofuran or tetrahydrofuran copolymers, the mono- or diesters of polytetrahydrofuran or of tetrahydrofuran copolymers, the process comprising: a) Continuously polymerizing tetrahydrofuran in the presence of a telogen and/or of a comonomer over an acidic catalyst, b) changing the molar ratio, during the polymerization, of telogen to tetrahydrofuran or to tetrahydrofuran and comonomer, c) then determining the mean molecular weight of at least one sample, d) establishing that the mean molecular weight thus determined is the mean molecular weight Mn to be achieved by the change, and at least partly depolymerizing the already formed polytetrahydrofuran or the tetrahydrofuran copolymers, the mono- or diesters of polytetrahydrofuran or tetrahydrofuran copolymer over an acidic catalyst, and e) recycling the tetrahydrofuran recovered by depolymerization at least partly into the polymerization.