Carbon based porous hollow fiber membrane and method for producing same

• US 5,089,135 A
• Filed: 11/13/1989
• Issued: 02/18/1992
• Est. Priority Date: 01/20/1988
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Rayon Company Limited (Mitsubishi Chemical Holdings Corporation)
• Original Assignee: Mitsubishi Rayon Company Limited (Mitsubishi Chemical Holdings Corporation)
• Inventors: Yoneyama, Hiroaki, Nishihara, Yoshihiro
• Primary Examiner(s): SPEAR JR, FRANK
• Application Number:
  US07/442,325
• Time in Patent Office: 827 Days
• Field of Search: 55/16158, 429/44, 210/500.25, 210/500.21, 210/500.23, 210/500.43, 264/29.1, 264/29.2, 264/29.6, 264/29.7, 264/29.5, 264/83, 264/85, 264/288.8
• US Class Current: 210/500.23
• CPC Class Codes: B01D 2325/02 Details relating to pores or porosity of the membranes
• CPC Class Codes: B01D 2325/0283 Pore size
• CPC Class Codes: B01D 67/0067 by carbonisation or pyrolysis
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 71/021 Carbon
• CPC Class Codes: B01J 20/28004 Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/28021 Hollow particles, e.g. hollow spheres, microspheres or cenospheres
• CPC Class Codes: B01J 20/28023 Fibres or filaments fibres or filaments in the form of membranes B01J20/28038; B01J20/28007 takes precedence
• CPC Class Codes: B01J 20/28033 Membrane, sheet, cloth, pad, lamellar or mat
• CPC Class Codes: B01J 20/28069 Pore volume, e.g. total pore volume, mesopore volume, micropore volume
• CPC Class Codes: B01J 20/28078 Pore diameter
• CPC Class Codes: D01F 9/22 from polyacrylonitriles

Abstract

A carbon based porous hollow fiber membrane excellent in heat resistance wherein it has pores which continuously penetrate from inner wall surface to outer wall surface of the membrane, maximum value of pore radius obtained from pore volume differential curve is in 10-1000 nm, total pore volume is 0.1-1 cm³ /g, curvature radius at flexing is 10 cm or less, and temperature at which 10% by weight of the membrane is decomposed and which is measured by TGA is at least about 300° C. and a method for producing the abovementioned carbon based porous hollow fiber membrane having excellent heat resistance, characterized by comprising mixing an acrylonitrile based polymer (A) containing 90-100 mol % of acrylonitrile unit, a heat decomposable polymer (B) which is heat decomposed at a temperature of 600° C. or lower to become low in molecular weight, and a solvent (C), then spinning and drawing the mixture to obtain an acrylonitrile based hollow fiber, subjecting this hollow fiber to oxidizing treatment and then subjecting the hollow fiber to carbonizing treatment at 400° C. or higher to make it porous.

Claims

1. A carbon based porous hollow fiber membrane excellent in heat resistance, having an internal diameter of 20 μ

m to 1,000 μ

m with a wall thickness of 2 μ

m to 250 μ

m, pores which continuously penetrate from inner wall surface to outer wall surface of the membrane, a pore size distribution such that the distribution curve of pore radius has a maximum value of 10-1000 nm, a total pore volume of 0.1-1 cm³ /g, and a curvature radius at flexing of 10 cm or less, and wherein the temperature at which 10% by weight of the membrane is decomposed as measured by TGA is at least about 300°

C.

2. A hollow fiber membrane according to claim 1, which has a tensile elongation of at least 0.8%.

3. A method for producing a carbon based porous hollow fiber membrane excellent in heat resistance, having pores which continuously penetrate from inner wall surface to outer wall surface of the membrane, a pore size distribution such that the distribution curve of pore radius has a maximum value of 10-1000 nm, a total pore volume of 0.1-1 cm³ g, and a curvature radius at flexing of 10 cm or less, and wherein the temperature at which 10% by weight of the membrane is decomposed as measured by TGA is at least about 300°

C., which comprises mixing an acrylonitrile based polymer (A) containing 90-100 mol% of acrylonitrile units, a heat decomposable polymer (B) which is heat decomposed at a temperature of 600°

C. or lower to become low in molecular weight, and a solvent (C), then spinning and drawing the mixture to obtain an acrylonitrile based hollow fiber, subjecting this hollow fiber to oxidizing treatment and then subjecting the hollow fiber to carbonizing treatment at 400°

C. or higher to make it porous.

4. A method according to claim 3, wherein a compatibilizer (C) is further mixed with acrylonitrile based polymer (A), heat decomposable polymer (B) and solvent (C).

5. A method according to claim 3 or 4, wherein the acrylonitrile based polymer (A) is polyacrylonitrile, acrylonitrile-methacrylic acid copolymer, acrylonitrile-methyl acrylate-itaconic acid copolymer or acrylonitrile-methyl acrylate-methacrylic acid copolymer.

6. A method according to claim 3 or 4, wherein the heat decomposable polymer (B) is a homopolymer of aromatic vinyl monomer, aliphatic vinyl monomer or methacrylate type monomer or a copolymer comprising 51 mol% or more of the above monomer and 49 mol % or less of copolymerizable monomer unit other than acrylonitrile.

7. A method according to claim 3 or 4, wherein the heat decomposable polymer (B) is styrene based polymer, vinyl chloride based polymer or methyl methacrylate based polymer.

8. A method according to claim 3 or 4, wherein specific viscosity of the acrylonitrile based polymer (A) is 0.1-0.4.

9. A method according to claim 3 or 4, wherein specific viscosity of the acrylonitrile based polymer (A) is 0.2-0.3.

10. A method according to claim 3 or 4, wherein specific viscosity of the heat decomposable polymer (B) is 0.1-0.4.

11. A method according to claim 3 or 4, wherein specific viscosity of the heat decomposable polymer (B) is 0.2-0.3.

12. A method according to claim 4, wherein the compatibilizer (D) is a graft copolymer or a block copolymer which contains in the same polymer chain a segment (A) having compatibility with the acrylonitrile based polymer (A) or comprising the same monomer and a segment (B) having compatibility with the heat decomposable polymer (B) or comprising the same monomer.

13. A method according to claim 4, wherein the compatibilizer (D) comprises 30 mol% or more of acrylonitrile, 10 mol% or more of monomer constituting the heat decomposable polymer (B) and 10 mol% or less of other monomer copolymerizable with these monomers.

14. A method according to claim 3 or 4, wherein the mixing is carried out so that the acrylonitrile based polymer (A) is in an amount of 10-90% by weight, the heat decomposable polymer (B) is in an amount of 10-90% by weight and the compatibilizer (D) is in an amount of 0-5% by weight.

15. A method according to claim 3 or 4, wherein the mixing is carried out so that the acrylonitrile based polymer (A) is in an amount of 20-80% by weight, the heat decomposable polymer (B) is in an amount of 20-80% by weight and the compatibilizer (D) is in an amount of 0-5% by weight.

16. A method according to claim 3 or 4, wherein the solvent (C) is selected from dimethylformamide, dimethylcetamide and dimethylsulfoxide.

17. A method according to claim 3 or 4, wherein the spinning is carried out by dry jet-wet type spinning method.

18. A method according to claim 3 or 4, wherein drawing is carried out under the condition of 3 times or more in total drawing ratio by multi-stage drawing method.

19. A method according to claim 3 or 4, wherein the oxidizing treatment is carried out with controlling the elongation within the range of 15% or less.

20. A method according to claim 3 or 4, wherein the carbonizing treatment is carried out with controlling the tension.