Catalytic preparation of polyamide or polyamide-polymide with N,N'-dimethyl alkylene urea solvent

摘要

A polyamide and/or polyimide is prepared by using N,N'-dimethylethyleneurea or N,N'-dimethylpropyleneurea as a solvent upon polycondensation of a polycarboxylic acid and a diisocyanate at a temperature above 100 DEG C. in the presence of an alkali metal carbonate, alkali metal hydrogencarbonate, alkali metal hydroxide or an alkali metal salt of a polycarboxylic acid.