METHOD OF STABILIZING CONDENSED PHASE COMPOSITION CONTAINING CYCLIC ESTER DURING PRODUCTION OF POLYESTER FROM LACTIDE Russian patent published in 2020 - IPC C08G63/08 C08G63/78 C08F2/42 

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of stabilizing a condensed phase composition during production of a polyester from a cyclic ester monomer. Method includes steps of producing a cyclic ester, polymerising a cyclic ester in the presence of a catalyst and an initiator in a reactor to form a reaction mixture, degassing the reaction mixture to obtain purified polyester in form of molten residue and steam, condensation of the stream of steam to obtain a condensed phase composition. At least one polymerisation inhibitor is added to the reaction mixture and/or to the condensed phase composition as a stabilizer in an amount such that the degree of conversion of the polymerisable cyclic ester in the condensed phase composition does not exceed 15 %. At least a portion of the polymerisation inhibitor is added to the reaction mixture until degassing. Degassing is performed at 203 °C and pressure below 4 mbar or at 220 °C and pressure lower than 5 mbar.

EFFECT: said method enables to avoid undesired reaction of oligomerisation or polymerisation of cyclic ester and, as a result, undesirable consumption of cyclic ester and undesirable increase in viscosity or hardening of composition of condensed phase, while allowing use of stabilized composition of condensed phase for the intended purpose.

11 cl, 4 dwg, 3 tbl, 5 ex