Process for the continuous production of polyesters

Abstract

Continuous process of forming aliphatic polyesters The process includes continuously providing cyclic ester monomer and polymerization catalyst to a continuous mixing loop reactor (CMLR) having static mixing elements and operated at a temperature between 100 and 240° C. to form a pre-polymerized reaction mixture. The conversion is between 40 and less than 90 wt. %, wherein the cyclic ester monomer comprises lactide having a free acid content lower than 50 milli-equivalents per kg. The pre-polymerized reaction mixture is continuously provided to a plug flow reactor that is a static mixer reactor having static mixing elements and is operated at a temperature between 110-240° C., wherein the reaction mixture is polymerized to a conversion of at least 90%, to form polymer wherein the flow ratio of the CMLR and the plug flow reactor is between 1.5 an d50. The process includes continuously removing polymer from the plug flow reactor devolitizing the polymer.