| abstract |
(57) [Summary] [Structure] In the method of dehydration polycondensation of hydroxycarboxylic acids in the presence or absence of a catalyst, in the presence or absence of an organic solvent, all steps of dehydration polycondensation or dehydration polycondensation A method for producing a polyhydroxycarboxylic acid, characterized in that, in a part of the condensation step, a thin film evaporator is used to perform thermal polycondensation while separating and removing low boiling point components. [Effect] The polymer having a high molecular weight can be industrially obtained in a short time and at low cost by direct dehydration polycondensation from a hydroxycarboxylic acid or an oligomer thereof. |