Nonwoven fabric and process for producing the same

• US 8,636,942 B2
• Filed: 07/07/2008
• Issued: 01/28/2014
• Est. Priority Date: 03/31/2003
• Status: Expired due to Fees

• Current Assignee: Teijin Limited
• Original Assignee: Teijin Limited
• Inventors: Komura, Shinya, Miyoshi, Takanori, Sumi, Yoshihiko, Minematsu, Hiroyoshi
• Primary Examiner(s): Cano, Milton I
• Assistant Examiner(s): SMITH, JEREMIAH R
• Application Number:
  US12/168,720
• Publication Number:
  US 20080272520A1
• Time in Patent Office: 2,031 Days
• Field of Search: 264/466, 264/465, 264/172, 264/464, 264/484, 264/167
• US Class Current: 264/465
• CPC Class Codes: D01D 5/0038 the fibre formed by solvent evaporation, i.e. dry electro-spinning
• CPC Class Codes: D01D 5/247 Discontinuous hollow structure or microporous structure
• CPC Class Codes: D01D 5/253 with a non-circular cross section; Spinnerette packs therefor D01D5/38 takes precedence
• CPC Class Codes: D01F 1/08 for forming hollow filaments
• CPC Class Codes: D01F 6/625 derived from hydroxy-carboxylic acids, e.g. lactones
• CPC Class Codes: D04H 1/43838 Ultrafine fibres, e.g. microfibres
• CPC Class Codes: D04H 1/43912 fibres with noncircular cross-sections
• CPC Class Codes: D04H 1/43916 microcellular fibres, e.g. porous or foamed fibres
• CPC Class Codes: D04H 3/02 characterised by the method of forming fleeces or layers, e.g. reorientation of yarns or filaments
• CPC Class Codes: Y10T 442/608 Including strand or fiber material which is of specific structural definition
• CPC Class Codes: Y10T 442/614 Strand or fiber material specified as having microdimensions [i.e., microfiber]

Abstract

A process for production of a nonwoven fabric, which comprises a step wherein a thermoplastic polymer is dissolved in a mixed solvent composed of a volatile good solvent and a volatile poor solvent, a step wherein the resulting solution is spun by an electrospinning method and a step wherein a nonwoven fabric accumulated on a collecting sheet is obtained, is employed to provide a nonwoven fabric having a surface area sufficiently large as a matrix for cell culturing in the field of regenerative medicine, with large gaps between filaments and a low apparent density suitable for cell culturing.

Claims

1. A process for production of a nonwoven fabric, which comprises a step wherein a thermoplastic polymer is dissolved in a mixed solvent composed of a volatile good solvent for the polymer and a volatile poor solvent for the polymer, a step wherein the resulting solution is spun by an electrospinning method and a step wherein a nonwoven fabric accumulated on a collecting sheet is obtained, which process yields a nonwoven fabric with a mean fiber size of 0.1-20 μ

m, wherein the nonwoven fabric is an aggregate of filaments and any given lateral cross-section of said filaments is irregular, and a mean apparent density in the range of 10-95 kg/m³,

wherein the irregular shape is at least one selected from the group consisting of 0.1-1 μ

m pits on filament surfaces, 0.1-1 μ

m protrusions on filament surfaces, pits formed in a linear fashion in the fiber axis direction on filament surfaces, protrusions formed in a linear fashion in the fiber axis direction on filament surfaces and micropores in filament surfaces, formed either alone or present in combinations so long as any given lateral cross-section is irregular,

the thermoplastic polymer is polylactic acid or poly(lactic-co-glycolic acid),

the volatile good solvent for the polymer is methylene chloride, and

the volatile poor solvent for the polymer is ethanol, methanol, isopropanol, acetone, or acetonitrile,

wherein the ratio of the volatile poor solvent for the polymer and volatile good solvent for the polymer in said mixed solvent is in the range of (23;

77) to (40;

60), based on weight.

2. A process for production of a nonwoven fabric according to claim 1, wherein the thermoplastic polymer is polylactic acid.

3. A process for production of a nonwoven fabric according to claim 1, wherein the volatile poor solvent for the polymer is ethanol.

4. A process for production of a nonwoven fabric according to claim 1, wherein the ratio of the volatile poor solvent for the polymer and volatile good solvent for the polymer in said mixed solvent is in the range of (25:

75) to (40;

60), based on weight.

5. A process for production of a nonwoven fabric according to claim 4, wherein the ratio of the volatile poor solvent for the polymer and volatile good solvent for the polymer in said mixed solvent is in the range of (30:

70) to (40;

60), based on weight.

6. A process for production of a nonwoven fabric according to claim 1, wherein the mean apparent density in the range of 50-95 kg/m³.

7. A process for production of a nonwoven fabric according to claim 1, wherein the volatile poor solvent for the polymer is methanol.

8. A process for production of a nonwoven fabric according to claim 1, wherein the volatile poor solvent for the polymer is isopropanol.

9. A process for production of a nonwoven fabric according to claim 1, wherein the nonwoven fabric has a thickness of at least 100 μ

m.

10. A process for production of a nonwoven fabric according to claim 1, wherein the nonwoven fabric has a thickness of at least 170 μ

m.

11. A process for production of a nonwoven fabric according to claim 1, further comprising forming a stack of the nonwoven fabric.

12. A process for production of a nonwoven fabric according to claim 10, wherein the thermoplastic polymer is polylactic acid.

13. A process for production of a nonwoven fabric according to claim 10, wherein the volatile poor solvent for the polymer is ethanol.

14. A process for production of a nonwoven fabric according to claim 10, wherein the volatile poor solvent for the polymer is methanol.

15. A process for production of a nonwoven fabric according to claim 10, wherein the volatile poor solvent for the polymer is isopropanol.