Process for the production of polytetramethylene adipamides

The invention relates to a process for the production of high-molecular-weight polytetramethylene adipamide from equivalent amounts of 1,4-diaminobutane and adipic acid at lower pressures. By supplying 1,4-diaminobutane at an advanced stage of the polycondensation a first polycondensate is obtained that can be extruded very well and that can be aftercondensed in the solid phase to obtain a product with a high molecular weight within a short time. Because of this a substantial overall gain in time is realized. It even appears to be possible to prepare a first polycondensate with a relative viscosity that is high enough for the polycondensate to be further processed into shaped objects. The polycondensation can be carried out both in the melt and in solution. The diaminobutane can be supplied both via the liquid and via the vapour phase.