Improved procedure for the preparation of polyesters

A process for producing a polyester comprising the steps of a) producing a polyester having a molecular weight M b) compounding the obtained in step a) the polyester in the presence of at least one di- or polyfunctional compound that is reactive with the polyester, a polyester is obtained which has a higher molecular weight than the polyester obtained in step a); as well as polyester produced by the above method.