the invention concerns a process and device for producing high - viscosity or highly stabilized , reaction - stable polyamides , in particular polyamide 6 , with reactive amino end groups of less than 50 μeq / g and for continuously demonomerizing polyamides . the object of the invention is to produce simply , reliably and economically a high - viscosity or highly stabilized reaction - stable polyamide , in particular polyamide 6 , and if necessary to carry out continuous demonomerization . according to the invention , the molten polyamide is brought into intimate contact , or intimately mixed with preheated nitrogen in a reaction system in at least one stage and a specific dwell time is set for the melt in a liquid phase . during the production of polyamide 6 , expelled lactam is processed and fed to a polymerization reactor .