Patent ID: 7615606

Claim:
A method for continuously producing copolyamides having calorimetric melting points of more than about 265° C., in which, in a multistage and continuous method, partly aromatic and semicrystalline polyamides of the following chemical systems having defined mole percentages of the individual components are produced in the polymer synthesis: from 25 to 50 mol % of aromatic dicarboxylic acids which are derived from terephthalic acid, from 25 to 49.5 mol % of aliphatic diamines which are derived from hexamethylenediamine, or cycloaliphatic diamines having at least 6 carbon atoms, and 0.5-25 mol % of aromatic diamines, the sum of all polymer-forming components producing a composition of 100 mol % and there being a stoichiometric ratio between amines and carboxylic acids, wherein in a first reactor, a polycondensation is carried out by the controlled removal of water at approximately constant pressures of from 6 to 50 bar, temperatures of 180° C.-260° C. under adiabatic conditions and with residence times from 0.5 to 2.5 hours, and the process is continued to a chemical polycondensate/water equilibrium, and in that the polycondensation is controlled by establishing constant vapor pressures in the gas space of the reactor. the melt being passed from the exit of the first reactor into a second reactor, in which the polycondensation is carried out by the controlled removal of water at pressures of 0-30 bar (gage pressure), at temperatures of 250° C.-340° C. under adiabatic conditions, with residence times from 0.5 to 2.5 hours, the course of the polycondensation in the individual reaction stages being controlled via resulting viscoelastic melt flow behavior as a function of the aromatic content of the chemical systems, the polycondensation within the second reactor being carried out with simultaneous introduction of shear stress into the total melt volume, and the process is continued to a chemical polycondensate/water equilibrium.