the invention relates to a new polyamine of the following composition : ## str1 ## wherein 1 ≧ n ≧ 6 , r represents the hydrocarbon radical of a aliphatic , araliphatic or aromatic diisocyanate having 6 - 20 c atoms or a trimer thereof and wherein when 2 ≧ n ≧ 6 , r 1 represents an n - valent organic radical such as is formed by removal of n oh groups from a polyhydroxy compound which optionally contains ether oxygen atoms and has an average molecular weight mn of between 60 and 5 , 000 ; and when n = 1 , r 1 represents ## str2 ## it furthermore relates to a process for the preparation of a polyamine , in which certain diisocyanates , adducts of diisocyanates with polyols or trimers thereof are reacted with the schiff base of the following composition : ## str3 ## wherein r 2 = h or a branched or unbranched c 1 - 14 - alkyl radical and r 3 = a branched or unbranched c 1 - 14 - alkyl radical , an c 1 - 14 alkyl - substituted phenyl radical or a c 1 - c 8 - cycloalkyl radical and , when the reaction has taken place , the polyazomethine formed is hydrolyzed completely with excess water and the carbonyl compound formed is distilled off . the polyamine according to the invention is employed for curing epoxy resins .