PROCESS FOR PRODUCING AN INTRAMOLECULAR DIESTER OF A HYDROXYCARBOXYLIC ACID AND PROCESS FOR PRODUCING A POLYHYDROXYCARBOXYLIC ACID.

摘要

The present invention relates to a process for producing an intramolecular diester of a hydroxycarboxylic acid, wherein in a first step a hydroxycarboxylic acid is polycondensed to form an oligomeric hydroxycarboxylic acid. This is followed by a cyclizing depolymerization of the oligomeric hydroxycarboxylic acid obtained in the first stage to form the intramolecular diester. The present invention is characterised in that in the cyclizing depolymerization stage a plastics recyclate is added. This plastics recyclate contains for example a polyhydroxycarboxylic acid derived from the hydroxycarboxylic acid employed in the first stage. The plastics recyclate may likewise contain a copolyhydroxycarboxylic acid or a blend containing the abovementioned (co)polyhydroxycarboxylic acid(s).