Patent ID: 6140458
Filing Date: 2000-10-31
Classification: B29B,B29K,C08G

Abstract:
A process for producing aliphatic polyesters having a weight-average molecular weight (Mw.sub.2) that falls within a numerical range as defined by the following numerical formula (2) and numerical formula (3) and having at least 50% of aliphatic hydroxycarboxylic acid units, which comprises polymerizing a crystallized, aliphatic polyester prepolymer having a weight-average molecular weight (Mw.sub.1) that falls within a numerical range as defined by the following numerical formula (1) and having at least 50% of aliphatic hydroxycarboxylic acid units, in a solid phase in the presence of a catalyst:2.times.10.sup.3 .ltoreq.Mw.sub.1 .ltoreq.1.times.10.sup.5 ( 1),5.times.10.sup.4 .ltoreq.Mw.sub.2 .ltoreq.1.times.10.sup.6 ( 2),Mw.sub.1 <Mw.sub.2 ( 3).