Method of enzymatic depolymerization of polylactic acid and process for producing polylactic acid from depolymerization product

• US 20050233425A1
• Filed: 07/30/2003
• Published: 10/20/2005
• Est. Priority Date: 08/05/2002
• Status: Active Grant

• Current Assignee: KEIO University
• Original Assignee: KEIO University
• Inventors: Matsumura, Shuichi
• Granted Patent: US 7,396,667 B2
• Time in Patent Office: Days
• US Class Current: 435/134
• CPC Class Codes: C08G 63/823 for the preparation of polylactones or polylactides
• CPC Class Codes: C08J 11/105 by treatment with enzymes
• CPC Class Codes: C08J 2367/04 Polyesters derived from hydroxy carboxylic acids, e.g. lactones C08J2367/06 takes precedence
• CPC Class Codes: C12P 7/56 Lactic acid
• CPC Class Codes: C12P 7/62 Carboxylic acid esters
• CPC Class Codes: Y02P 20/54 using solvents, e.g. supercritical solvents or ionic liquids
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling

Abstract

A depolymerizing process of polylactic acid, wherein the polylactic acid is depolymerized in the presence of a hydrolase in an organic solvent or a supercritical fluid, thereby producing a re-polymerizable oligomer. A producing process of polylactic acid, wherein the re-polymerizable oligomer obtained by the above-mentioned depolymerization process is polymerized in the presence of a hydrolase or a polymerization catalyst.

Claims

1. A depolymerizing process of polylactic acid, wherein the polylactic acid is depolymerized in the presence of a hydrolase in an organic solvent, thereby producing a re-polymerizable oligomer.

3. The depolymerizing process of polylactic acid according to claim 1, wherein the polylactic acid is poly(L-lactic acid).

5. The depolymerizing process of polylactic acid according to claim 1, wherein the polylactic acid is poly(DL-lactic acid).

7. The depolymerizing process of polylactic acid according to claim 1, wherein the polylactic acid is a polylactic acid copolymer.

9. The depolymerizing process of polylactic acid according to claim 1, wherein the hydrolase is lipase.

11. A producing process of polylactic acid, wherein the re-polymerizable oligomer obtained by the depolymerization process according to claim 1 is polymerized in the presence of a hydrolase.

13. The producing process of polylactic acid according to claim 11, wherein the hydrolase is lipase.

15. The producing process of polylactic acid according to claim 11, wherein one or more monomers or oligomers selected from cyclic lactone monomers or oligomers, cyclic or linear carbonate monomers or oligomers, cyclic or linear ester oligomers, hydroxy acids, or hydroxy acid esters are used as comonomers.

17. A producing process of polylactic acid, wherein the re-polymerizable oligomer obtained by the depolymerization process according to claim 1 is polymerized in the presence of a polymerization catalyst.

19. The producing process of polylactic acid according to claim 17, wherein one or more monomers or oligomers selected from cyclic lactone monomers or oligomers, or cyclic carbonate monomers or oligomers are used as comonomers.

2. A depolymerizing process of polylactic acid, wherein the polylactic acid is depolymerized in the presence of a hydrolase in a supercritical fluid, thereby producing a re-polymerizable oligomer.

4. The depolymerizing process of polylactic acid according to claim 2, wherein the polylactic acid is poly(L-lactic acid).

6. The depolymerizing process of polylactic acid according to claim 2, wherein the polylactic acid is poly(DL-lactic acid).

8. The depolymerizing process of polylactic acid according to claim 2, wherein the polylactic acid is a polylactic acid copolymer.

10. The depolymerizing process of polylactic acid according to claim 2, wherein the hydrolase is lipase.

12. A producing process of polylactic acid, wherein the re-polymerizable oligomer obtained by the depolymerization process according to claim 2 is polymerized in the presence of a hydrolase.

14. The producing process of polylactic acid according to claim 12, wherein the hydrolase is lipase.

16. The producing process of polylactic acid according to claim 12, wherein one or more monomers or oligomers selected from cyclic lactone monomers or oligomers, cyclic or linear carbonate monomers or oligomers, cyclic or linear ester oligomers, hydroxy acids, or hydroxy acid esters are used as comonomers.

18. A producing process of polylactic acid, wherein the re-polymerizable oligomer obtained by the depolymerization process according to claim 2 is polymerized in the presence of a polymerization catalyst.

20. The producing process of polylactic acid according to claim 18, wherein one or more monomers or oligomers selected from cyclic lactone monomers or oligomers, or cyclic carbonate monomers or oligomers are used as comonomers.