REACTOR APPARATUS FOR PREPARING A POLYMERIC MATERIAL

A polycondensation reactor for processing low viscosity polyester or another polymer into relatively highly viscosity polymer comprises a substantially cylindrical horizontal reactor vessel with a polymer inlet and a polymer outlet adjacent its opposite ends and a vapour exhaust opening in the upper side of the vessel at its outlet end. A polymer agitator is rotated axially within the chamber and includes plural alternating annular overflow and underflow baffles and multiple perforated film-forming screens disposed therebetween in parallel spaced relation to one another. The overflow baffles are in peripheral polymer-sealing relation to the vessel while the underflow baffles have multiple underflow recesses in their outer peripheries, whereby the baffles define a tortuous polymer flow path alternately through their respective polymer overflow and underflow openings to control residence time, distribution and viscosity growth as the polymer flows between the baffles. The baffles and screens are integrally fixed coaxially at their outer peripheries by axially extending wiper bars. Aligned openings in the baffles and screens along the rotational axis of the agitator provide for free flow of volatiles to the exhaust opening.