Verfahren zur Herstellung eines Polyesters sowie Zusammensetzung und Formkörper umfassend einen derartigen Polyester

Producing a polyester comprises (a) taking a hydroxycarboxylic acid or dihydroxy compound and dicarboxylic acid, (b) taking a zinc containing catalyst (I) or (II), (c) performing dehydration to reduce the water content and/ or partial condensation of the materials taken in the step (a), and (d) performing polycondensation of the material obtained in the step (c) in the presence of the catalyst at 160-240[deg] C under a pressure of less than 100 hPa. Producing a polyester comprises (a) taking a hydroxycarboxylic acid or dihydroxy compound and dicarboxylic acid, (b) taking a zinc containing catalyst of formula (L nZnX 2) (I) or (A kG lZnX 2) (II), (c) performing dehydration to reduce the water content and/or partial condensation of the materials taken in the step (a), and (d) performing polycondensation of the material obtained in the step (c) in the presence of the catalyst at 160-240[deg] C under a pressure of less than 100 hPa. L : ligand of formula A-L'-G (III); X : an anionic ligand; either k : 1-3; and l : 1-3; or k+l : 2, 3 or 4; n : 1 or 2; A : ligand or corresponding group of ligand L coordinating via-nitrogen atom; G : guanidine ligand or corresponding group ligand L coordinating via-nitrogen atom; and L' : linker which connects the groups A and G together with the zinc atom to form 5 or 6-membered metallacyclic ring. An independent claim is also included for a composition comprising polyester and a zinc compound and/or a guanidine derivative.