Biodegradable polyester polymer and method for preparing the same using compressed gas

• US 6,913,826 B2
• Filed: 10/08/2003
• Issued: 07/05/2005
• Est. Priority Date: 10/08/2002
• Status: Expired due to Fees

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Pack, Ji Won, Kim, Soo Hyun, Park, Jong Min, Lee, Youn-Woo, Lim, Jong Sung, Kim, Young Ha
• Primary Examiner(s): Acquah, Samuel A.
• Application Number:
  US10/682,760
• Publication Number:
  US 20040072985A1
• Time in Patent Office: 636 Days
• Field of Search: 528/355, 528/357, 528/359, 525/461, 525/471, 428/402, 526/62, 526/65, 524/755, 524/765, 524/770, 524/783, 524/784, 524/786
• US Class Current: 428/402
• CPC Class Codes: C08G 63/08 Lactones or lactides
• CPC Class Codes: C08G 63/64 Polyesters containing both carboxylic ester groups and carbonate groups
• CPC Class Codes: C08G 63/6882 derived from hydroxy carboxylic acids
• CPC Class Codes: C08G 63/81 using solvents C08G63/79 takes precedence
• CPC Class Codes: C08G 63/823 for the preparation of polylactones or polylactides
• CPC Class Codes: Y02P 20/54 using solvents, e.g. supercritical solvents or ionic liquids
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

In polymerizing biodegradable polymer material, a compressed gas is used as a reaction solvent for a solution-polymerization, in order to prepare biodegradable polyester homopolymer and copolymer with a high molecular weight in a fine powder form with a particle size of 0.01˜1000 μm.

Claims

1. A method for preparing polyester polymer in a particle form comprising:

adding one or more cyclic monomer in a high pressure reactor;

adding an organic metal catalyst or acid catalyst and an initiator; and

pressurizing and injecting a compressed gas solvent selected from the group consisting of HFC-23, HFC-32, HFC-152a, HFC-143a, HFC-134a, HFC-125, HFC-227ea, HFC-236fa, HFC-245fa, HFC-254cb, SF₆, HFC-4-10-mee, C-318 (perfluoro cyclobutane), HCFC-22, HCFC-141b, HCFC-142b, HCFC-225ca/cb, dimethylether, N₂O, propane, butane and their mixtures, or their mixtures with CO₂, to solution-polymerize the monomer.

2. The method of claim 1, additionally comprising the step after polymerization is completed, in which an antisolvent dissolving the reaction solvent but not dissolving the produced polymer to form a single phase is introduced, and thereby the pure polymer is precipitated.

3. The method of claim 2, wherein the antisolvent is directly introduced into a reaction container.

4. The method of claim 2, wherein the polymer in the polymerization-completed reaction container is sprayed into a precipitator and the antisolvent is introduced into the precipitator.

5. The method of claim 2, wherein as the antisolvent, CO₂, HFCs, HCFCs, SF₆, FCs, hydrocarbon, ether or their mixture is used.

6. The method of claim 1, wherein as the cyclic monomer, one or more selected from the group consisting of lactides, lactones, cyclic carbonates, cyclic anhydrides and thiolactones are used.

7. The method of claim 1, wherein as the cyclic monomer, one or more compounds selected from the group consisting of a compound (A) represented by the general formula (I) and a compound (B) represented by the general formula (II) are used:

(wherein R₁ and R₂ are hydrogen atom or alkyl group of C₁-C₄)

(wherein n is an integer of 2 to

     5).

8. The method of claim 7, wherein the compound (A) is L-lactide, D-lactide, D,L-lactide, or glycolide.

9. The method of claim 7, wherein the compound (B) is ε

-caprolactone.

10. The method of claim 1, wherein two or more monomers are used to be co-polymerized.

11. The method of claim 1, wherein the organic metal catalyst is selected from the group consisting of a tin-based catalyst comprising stannous octoate, stannic chloride, stannous oxide, stannous octylester, stannous chloride dihydrate and tetraphenyl tin;

a zinc-based catalyst comprising zinc powder, diethyl zinc, zinc octoate, zinc chloride and zinc oxide; and

an aluminum-based catalyst comprising aluminum chloride and aluminum ethoxide.

12. The method of claim 1, wherein the acid catalyst is zinc bis(2,2-dimethyl-3,5-heptanedionato-O,O′

).

13. The method of claim 1, wherein as the initiator, 1,6-hexanediol is used.

14. The method of claim 1, wherein the compressed gas reaction solvent completely dissolves polymer to perform a uniform solution-polymerization.

15. The method of claim 1, wherein a reaction temperature is 25 to 250°

C.

16. The method of claim 1, wherein reaction time is 0.2 to 50 hours, and an yield is 70% or higher.

17. The method of claim 1, wherein a reaction pressure is 40 to 700 bar.

18. The method of claim 1, wherein the amount of monomer is 1˜

50 wt % based on the supercritical fluid.

19. The method of claim 1, wherein the molar ratio of the catalyst and the initiator is 10⁻

4 to 10<sup>−

2</sup> based on monomer, respectively.

20. A biodegradable polyester homopolymer or copolymer polymerized according to the preparation method of claim 1, which has a molecular weight of 2,000 to 1,000,000 g/mol and a particle size of 0.01 to 1,000 μ

m, and does not include a residual harmful solvent.