US Patent 7850926 Process of discontinuous polycondensation and stirring reactor thereof

A process for the discontinuous production of granules from polycondensation polymers by precondensation of an oligomer at 5 to 400 mbar and subsequent polycondensation in a stirring reactor and subsequent granulation. In the vicinity of the outlet port, the density of the entraining surfaces lies between 1 and 8 m2 per m3 reactor space and constantly increases with increasing distance from the discharge region. Inside the reactor, there is a viscosity gradient between the region most remote from the discharge port and the zone of the discharge port. The thermal decomposition of the polymer melt flowing out of the reactor is compensated during granulation.