Process for making poly(glycolic acid) for containers and films with reduced gas permeability

A process for making a high molecular weight poly(hydroxy acid) polymer having good thermal stability and a weight average molecular weight of >100,000 by GPC. The process includes mixing glycolic acid and/or lactic acid, and a diol or di-acid initiator, and at least one multifunctional initiator to form a liquid monomer mixture in an agitated polycondensation reactor. Polycondensing to form a liquid reaction mixture comprising a pre-polymer having a weight average molecular weight of >10,000 by GPC, and greater than 80 percent by mole hydroxyl or carboxyl end-group termination, then crystallizing to form a first solid reaction mixture. Then solid state polycondensing the solid reaction mixture to form a solid reaction mixture having a moisture level less than 50 ppm by weight. Then mixing the solid reaction mixture with an appropriate reactive coupling agent in a melting and mixing extruder to couple and form the reaction mixture and form the poly(hydroxy acid) polymer.

Patent family as of 21.7.2026
US11155677 BB, US2021198424 AA