Process for the preparation of copolyphosphonates having high toughness

摘要

Polyester-phosphonates, polycarbonatophosphonates and polyester-carbonatophosphonates having improved impact strength and notched impact strength as compared with melt-condensation products can be prepared in such a way that, in the first stage, oligophosphonates with hydroxyl end groups are prepared by melt-transesterification and melt-condensation and these are subjected in a second stage to a phase boundary process.