Patent ID: 8461296

Claim:
A process for preparing mechanically stabilized polyazole polymers which comprises the following steps: a) producing a film comprising polyazoles with at least one amino group in a repeat unit, b) treating the film from step a) with a solution comprising (i) at least one strong acid and (ii) at least one stabilizing reagent, the total content of stabilizing reagents in the solution being in the range from 0.01 to 30% by weight, c) performing the stabilization reaction in the membrane obtained in step b) directly or in a subsequent membrane processing step by heating to a temperature greater than 60° C., d) optionally additionally doping the membrane obtained in step c) with a strong acid or concentrating the strong acid present by removing water present, said stabilizing reagent comprising at least one compound which has A) at least one aldehyde group and at least one hydroxyl group or B) at least one hemiacetal group or C) at least one acetal group.