PRODUCTION OF THE POLYMER IN THE PRESENCE OF HETEROPOLY PHOSPHORIC ACID AS CATALYST

摘要

PROBLEM TO BE SOLVED: To obtain a tetrahydrofuran polymer reduced in a content of residual catalyst by effectively removing the catalyst from the polyether diol and undergoing no deterioration during storage by polymerizing tetrahydrofuran in the presence of a heteropolyphosphoric acid catalyst reduced in a content of free phosphoric acid. SOLUTION: An excess of an inorganic acid is added to an aqueous solution of a mixture of an alkali phosphate or phosphoric acid with an alkali tungstate or an alkali molybdate under heating and agitation to obtain a tungsten- or molybdenum-containing heteropolyphosphoric acid. This acid is extracted with an ether to separate a salt and the inorganic acid therefrom to thereby obtain a heteropolyphosphoric acid catalyst having a content of free phosphoric acid of at most 1 mol.% and an Al content of at most 4 ppm. Tetrahydrofuran is polymerized at 30-80 deg.C for 0.5-20 hr in the presence of the heteropolyphosphoric acid catalyst to obtain a tetrahydrofuran polymer.