Apparatus and process for a polycondensation reaction

A process for manufacturing a polyester of one or more aromatic dicarboxylic acids and one or more glycols in a molten state in which an inert gas is employed to assist in removing a volatile condensation by-product, wherein the improvement comprises, employing a horizontally disposed cylindrical reactor vessel partly filled with a polymerization reaction mass in the form of a melt, which reactor vessel is equipped with the following:

• a) a reactor inlet for introducing a polymerizable feed into the reactor vessel;
• b) a gas inlet for introducing an inert gas at or near one end of the reactor vessel and a gas outlet for removing the inert gas at or near an opposite end of the reactor vessel, thereby resulting in gas flow past the reaction mass in the reactor vessel;
• c) means for maintaining the reaction mass in the molten state;
• d) an agitator that rotates on its axis during operation, said agitator comprising a plurality of elements that are longitudinally disposed to convey a portion of the melt as said elements move through the reaction mass, the elements being positioned such that said elements generate films, the planes of the films being parallel to the central axis of the agitator and the flow of inert gas which is predominantly in the axial direction;
• and
• e) a reactor outlet for removing product polymer from the reactor vessel.