Polymerization process and product
AssigneeEli Lilly and Company
InventorRobert S. Nevin
Life of this patent
Estimating the term…
Abstract
Lactic-glycolic copolymers having molecular weights of about 6000 to about 35000 are prepared by condensation of lactic acid and glycolic acid in the presence of readily removable strong acid ion-exchange resins.
Claims11
A copolymer derived from the polymerization of about 60 to about 95 weight percent of lactic acid and about 40 to about 5 weight percent of glycolic acid, having an inherent viscosity in chloroform of about 0.08 to about 0.30 and a molecular weight of about 6000 to about 35000, said copolymer being substantially free of polymerization catalyst.
A process for preparing a copolymer derived by the polymerization of about 60 to about 95 weight percent of lactic acid and about 40 to about 5 weight percent of glycolic acid, said copolymer having a molecular weight of about 6000 to about 35000, with an inherent viscosity in chloroform of about 0.08 to about 0.30, comprising reacting lactic acid with glycolic acid in the presence of a readily removable strong acid ion-exchange resin at a temperature from about 100.degree. to about 250.degree. C. for about 3 to about 172 hours, and removing the strong acid ion-exchange resin therefrom.
Dependencies are inferred from the claim text.