Process for the continuous production of biodegradable polyester polymer

The present invention provides a process for the continuous production of a biodegradable polyester polymer with an excellent quality useful in the field of medicine, coating material and packaging material by eliminating difficulty in uniform agitation and heat removal caused by the rise in the viscosity of reactants in the production of a high molecular biodegradable polyester polymer by ring-opening polymerization. In some detail, the present invention provides a process for the continuous production of a biodegradable polyester polymer having a melt viscosity of not more than 500,000 poise and a weight-average molecular weight of not less than 10,000, which comprises continuously supplying monomers or polymers selected from the group consisting of intermolecularly cyclized ester of hydroxycarboxylic acid, lactone, and polymer having hydroxyl group and/or ester bond into a continuous reaction apparatus equipped with a static mixer where the reactants are subjected to continuous polymerization reaction at a polymerization temperature of 125 DEG to 270 DEG C., a maximum system reaction pressure of 2 to 15 Kg/cm2 and a conversion (one pass) of not less than 85% in the presence or absence of solvent without coming into contact with oxygen and water in the atmosphere, and then subjected to devolatilization to remove and recover residual monomers and solvent for reuse.