Aliphatischer Polyester und/oder Copolyester und Verfahren zu seiner Herstellung

The invention relates to an aliphatic polyester and/or copolyester, obtained from a polyreaction of at least one monomer from the group comprising lactides, lactones, cyclic carbonates and cyclic anhydrides. To be able to prepare the aliphatic polyester and/or copolyester in a one-stage process, the invention proposes that in the polyreaction a reaction mixture is used which contains at least one catalyst of the general formula (M) (X1, X2... Xm), M being a metal selected from the group 3 to 12 of the periodic system and from the elements A1, Ga, In, Tl, Sn, Pb, Sb and Bi, (X1, X2... Xm) being a substituent selected from one of the families of alkyls, aryls, oxides, carboxylates, halogenides, alkoxides and compounds with elements from group 15 and/ or 16 of the periodic system, m being an integer in the range of from 1 to 6, and n being an integer in the range of from 0 to 6, and which also contains a co-catalyst of the general formula (Y) (R1, R2... Rq)p, Y being an element selected from the group 15 or 16 of the periodic system, (R1, R2... Rq) being a subst ituent selected from one of the families of the alkyls, aryls, oxides, halogenides, oxyalkyls, aminoalkyls, thiolkyles, phenoxides, aminoaryls, thioaryls, and q and p corresponding to the values for m and n. The invention also relates to a representation of polylactides with a combination of tin-bis(2-ethylhexanoate) and triphenylphosphine, and a process for preparing the aliphatic polyester and/or copolyester in an extruder.