Process for Producing Porous Object and Porous Object Obtained By the Same

• US 20070282024A1
• Filed: 03/10/2006
• Published: 12/06/2007
• Est. Priority Date: 03/10/2006
• Status: Abandoned Application

• Current Assignee: JMS Company Limited
• Original Assignee: JMS Company Limited
• Inventors: Sajiki, Toshinobu, Ide, Junichi, Hanaki, Naoyuki, Matsuura, Yoji
• Application Number:
  US11/791,192
• Publication Number:
  US 20070282024A1
• Time in Patent Office: Days
• US Class Current: 521/62
• CPC Class Codes: A61L 27/18 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: C08J 2201/048 Elimination of a frozen liquid phase
• CPC Class Codes: C08J 2367/04 Polyesters derived from hydroxy carboxylic acids, e.g. lactones C08J2367/06 takes precedence
• CPC Class Codes: C08J 9/28 by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence

Abstract

A process for producing a porous object is provided that makes it possible to control pore sizes, particularly not only smaller pore sizes but also larger pore sizes. The pore sizes are controlled by: preparing a mixed solution containing a polymer including a copolymer of lactide and caprolactone, a solvent in which the polymer has a relatively low solubility, and a solvent in which the polymer has a relatively high solubility and that is compatible with the solvent in which the polymer has a relatively low solubility; varying the content of the solvent in which the polymer has a relatively low solubility in the mixed solution, when the mixed solution is frozen and dried to produce the porous object; and cooling the mixed solution at a rate of 300° C./hr or lower in freeze-treating. Thus a porous object with a pore size of 30 to 1800 μm can be obtained.

Claims

1. A process for producing a porous object, the process comprising:

preparing a mixed solution containing;

a polymer containing a copolymer of lactide and caprolactone;

a solvent in which the polymer has a relatively low solubility; and

a solvent in which the polymer has a relatively high solubility and that is compatible with the solvent in which the polymer has a relatively low solubility, freeze-treating the mixed solution; and

drying the mixed solution that has been freeze-treated, under reduced pressure,

wherein a pore size of the porous object to be produced is controlled by varying the content of the solvent in which the polymer has a relatively low solubility in the mixed solution in the process of preparing the mixed solution, and cooling the mixed solution at a rate of 300°

C./hr or lower in the process of freeze-treating.

2. The process for producing a porous object according to claim 1, wherein the mixed solution is cooled at a constant rate of 300°

C./hr or lower.

3. The process for producing aporous object according to claim 1, wherein in the process of freeze-treating, the mixed solution is placed in a container, and then the mixed solution is cooled from a bottom of the container.

4. The process for producing a porous object according to claim 3, wherein in the process of freeze-treating, a freezer is used for cooling the mixed solution, the container including the mixed solution is placed on a cooling rack of the freezer, and a temperature of the cooling rack is controlled to decrease at a constant rate of 300°

C./hr or lower.

5. The process for producing a porous object according to claim 3, wherein the container is a stainless steel container.

6. The process for producing a porous object according to claim 1, wherein the process of freeze-treating employs a cooling rate in a range of 3 to 180°

C./hr.

7. The process for producing a porous object according to claim 1, wherein the solvent in which the polymer has a relatively low solubility is water.

8. The process for producing a porous object according to claim 1, wherein the solvent in which the polymer has a relatively high solubility is 1,4-dioxane.

9. The process for producing a porous object according to claim 1, wherein the content of the solvent in which the polymer has a relatively low solubility in the mixed solution is in a range of 6 to 12.5 weight %.

10. The process for producing a porous object according to claim 1, wherein in the copolymer of lactide and caprolactone, the lactide and the caprolactone have a mole ratio in a range of 90:

10 to 10;

90.

11. The process for producing a porous object according to claim 1, wherein in the process of freeze-treating, a final temperature that is used for freeze-treating the mixed solution is an eutectic point or lower.

12. The process for producing a porous object according to claim 1, wherein in the process of freeze-treating, a final temperature that is used for freeze-treating the mixed solution is −

10°

C. or lower.

13. The process for producing a porous object according to claim 12, wherein the final temperature that is used for freeze-treating the mixed solution is in a range of −

50 to −

10°

C.

14. The process for producing a porous object according to claim 11, wherein in the process of freeze-treating, the mixed solution is treated at the final temperature that is used for freeze-treating the mixed solution for a range of longer than zero hour but not longer than 12 hours.

15. The process for producing a porous object according to claim 1, wherein in the process of freeze-treating, the mixed solution has a temperature in a range of 10°

C. to room temperature at the start of freeze-treating the mixed solution.

16. The process for producing a porous object according to claim 15, wherein the mixed solution has a temperature of 10°

C. at the start of freeze-treating the mixed solution.

17. The process for producing a porous object according to claim 1, wherein the polymer has a concentration in a range of 0.1 to 24 weight % in the mixed solution.

18. The process for producing a porous object according to claim 1, wherein a weight ratio between the polymer and the solvent in which the polymer has a relatively high solubility is in a range of 0.1:

99.9 to 24;

76.

19. The process for producing a porous object according to claim 18, wherein the weight ratio between the polymer and the solvent in which the polymer has a relatively high solubility is 4:

96.

20. The process for producing a porous object according to claim 1, wherein a weight ratio between the polymer and the solvent in which the polymer has a relatively low solubility is in a range of 3.2:

20 to 4;

0.5.

21. A porous object obtained by a process for producing a porous object according to claim 1.

22. The porous object according to claim 21, wherein an average pore size is in a range of 30 to 1800 μ

m.

23. The porous object according to claim 21, wherein the porous object is a scaffold material for a cultured cell.

24. The porous object according to claim 21, wherein the porous object is a porous object for medical use.

25. The process for producing a porous object according to claim 1,

wherein an average pore size is more than 200 μ

m and not more than 800 μ

m,

the mixed solution is cooled at a constant rate of about −

180°

C./hr,

the content of the solvent in which the polymer has a relatively low solubility in the mixed solution is in a range of 10.5 to 12.25 weight %.

26. The process for producing a porous object according to claim 1,

wherein an average pore size is more than 1600 μ

m and not more than 1800 μ

m,

the mixed solution is cooled at a constant rate of about −

10°

C./hr,

the content of the solvent in which the polymer has a relatively low solubility in the mixed solution is in a range of 11.25 to 12 weight %.

27. The process for producing a porous object according to claim 1,

wherein an average pore size is more than 800 μ

m and not more than 1200 μ

m,

the mixed solution is cooled at a constant rate of about −

10°

C./hr,

the content of the solvent in which the polymer has a relatively low solubility in the mixed solution is about 11 weight %.

28. The process for producing a porous object according to claim 1,

wherein an average pore size is more than 800 μ

m and not more than 1500 μ

m,

the mixed solution is cooled at a constant rate of about −

5°

C./hr,

the content of the solvent in which the polymer has a relatively low solubility in the mixed solution is in a range of 10.75 to 11.5 weight %.