Nanofiber containing composite membrane structures

Patent metadata

Field	Value
Publication number	US-11154821-B2
Application number	US-201213436043-A
Country	US
Kind code	B2
Filing date	Mar 30, 2012
Priority date	Apr 1, 2011
Publication date	Oct 26, 2021
Grant date	Oct 26, 2021

Abstract

A composite liquid filtration platform including a composite filtration medium featuring an electrospun polymeric nanofiber layer collected on a porous membrane. When in use, the porous membrane acts as a prefilter used upstream from the polymeric nanofiber layer to remove particles from a liquid stream flowing through the composite filtration structure. The nanofiber layer, positioned downstream from the porous membrane, is used as the retentive layer for critical filtration to provide biosafety assurance, and is responsible for capturing microorganisms like bacteria, mycoplasma or viruses. The composite liquid filtration platform provided herein exhibits permeability advantages over conventional porous membranes or nanofiber mats spun on coarse non-wovens.

First claim

We claim:

1. A porous composite media comprising:
a porous asymmetric polyethersulfone (PES) flat sheet membrane prefilter having a tight side and an open side and a pore size increasing in size between the tight side and the open side, and a porous polyamide electrospun nanofiber mat retentive layer consisting essentially of Nylon 6 located on the tight side of the porous asymmetric PES flat sheet membrane wherein the porous polyamide electrospun nanofiber mat retentive layer has an average fiber diameter of about 25 nm to about 130 nm and an effective pore size of from about 50 nm to about 500 nm based on the bubble point of the polymeric electrospun nanofiber retentive layer,
wherein the pore size of the porous polyamide electrospun nanofiber mat retentive layer consisting essentially of Nylon 6 is smaller than the pore size of the tight side of the porous asymmetric PES flat sheet membrane prefilter.

2. The porous composite media of claim 1 , having a bubble point, as measured with a liquid, which is at least 20% greater than the bubble point of the porous flat sheet membrane prefilter alone.

3. The porous composite media of claim 1 , having a total thickness from about 10 μm to about 500 μm.

4. The porous composite media of claim 1 , having a total thickness from about 50 μm to about 200 μm.

5. The porous composite media of claim 1 , wherein the porous polyamide electrospun nanofiber mat retentive layer has a thickness from about 1 μm to about 200 μm.

6. The porous composite media of claim 1 , wherein the porous polyamide electrospun nanofiber mat retentive layer has a thickness from about 1 μm to about 100 μm.

7. The porous composite media of claim 1 , wherein the porous polyamide electrospun nanofiber mat retentive layer has a thickness from about 1 μm to about 25 μm.

8. The porous composite media of claim 1 , wherein the porous asymmetric PES flat sheet membrane has a thickness from about 10 μm to about 500 μm.

9. The porous composite media of claim 1 , wherein the porous asymmetric PES flat sheet membrane has a thickness from about 50 μm to about 200 μm.

10. The porous composite media of claim 1 , wherein the porous asymmetric PES flat sheet membrane comprises one or more layers produced by solution phase inversion.

11. The porous composite media of claim 1 , having a mean flow bubble point for isopropanol ranging from about 10 psi to about 130 psi.

12. The porous composite media according to claim 1 , wherein the retentive filter layer comprises a porosity ranging from 80% to 95%.

13. The porous composite media according to claim 1 , wherein the porous polyamide electrospun nanofiber mat retentive layer consisting essentially of Nylon 6 is produced from a spinning solution of about 12-14% Nylon 6 in acetic acid and formic acid at a 2:1 weight ratio or about 12-14% Nylon 6 in acetic acid, formic acid and water at a weight ratio of 2:2:1.

14. The porous composite media of claim 1 , wherein the porous asymmetric polyethersulfone (PES) flat sheet membrane prefilter has a first surface on the tight side and a second surface on the open side and wherein the first surface on the tight side is smooth.

15. A filtration device for use in critical filtration comprising a composite media comprising:
a prefilter layer having a porous asymmetric polyethersulfone (PES) flat sheet membrane having a tight side, an open side and a pore size increasing in size between the tight side and the open side, and a retentive filter layer having a porous polyamide electrospun nanofiber mat consisting essentially of Nylon 6 located on the tight side of the porous asymmetric PES flat sheet membrane wherein the polyamide electrospun nanofiber mat has an effective pore size of from about 50 nm to about 500 nm based on the bubble point of the polyamide electrospun nanofiber mat and has an average fiber diameter of about 25 nm to about 130 nm,
wherein the pore size on the tight side of the porous asymmetric PES flat sheet membrane is larger than pore size of the porous polyamide electrospun nanofiber mat consisting essentially of Nylon 6.

16. The filtration device of claim 15 ,
wherein said composite filtration media is positioned in said device such that said porous asymmetric PES flat sheet membrane is upstream, in the direction of filtration, of said porous polyamide electrospun nanofiber mat, whereby said porous asymmetric PES flat sheet membrane provides prefiltration of said sample and said porous polymeric electrospun nanofiber mat provides further filtration of said sample.

17. The filtration device of claim 16 , wherein said composite filtration media has a bubble point as measured with a liquid, of at least 20% greater than the bubble point of the porous asymmetric PES flat sheet membrane alone.

18. The filtration device of claim 16 , wherein said composite filtration media has a total thickness from about 10 μm to about 500 μm.

19. The filtration device of claim 16 , wherein said composite filtration media has a total thickness from about 50 μm to about 200 μm.

20. The filtration device of claim 16 , wherein the retentive filter layer has a thickness from about 1 μm to about 200 μm.

21. The filtration device of claim 16 , wherein the retentive filter layer has a thickness from about 1 μm to about 100 μm.

22. The filtration device of claim 16 , wherein the retentive filter layer has a thickness from about 1 μm to about 25 μm.

23. The filtration device of claim 16 , wherein the porous PES flat sheet membrane has a thickness from about 10 μm to about 500 μm.

24. The filtration device of claim 16 , wherein the porous PES flat sheet membrane has a thickness from about 50 μm to about 200 μm.

25. The filtration device of claim 16 , wherein the porous PES flat sheet membrane is produced by solution phase inversion.

26. The filtration device of claim 16 , wherein said composite media has a mean flow bubble point for isopropanol from about 10 psi to about 130 psi.

27. The porous composite media according to claim 15 , wherein the porous polyamide electrospun nanofiber mat retentive layer consisting essentially of Nylon 6 is produced from a spinning solution of about 12-14% Nylon 6 in acetic acid and formic acid at a 2:1 weight ratio or about 12-14% Nylon 6 in acetic acid, formic acid and water at a weight ratio of 2:2:1.

Assignees

• Kas Onur Y
• Kozlov Mikhail
• Tkacik Gabriel
• Nhiem David
• Goddard Philip
• Leon Sherry A
• Emd Millipore Corp

Inventors

• Kas Onur Y
• Kozlov Mikhail
• Tkacik Gabriel
• Nhiem David
• Goddard Philip
• Leon Sherry A

Classifications

• B01D2325/0283

  Pore size · CPC title

• D04H1/728

  by electro-spinning {(electro-spinning methods and apparatus D01D5/0007)} · CPC title

• B01D69/12 Primary

  Composite membranes; Ultra-thin membranes · CPC title

• B01D2323/39

  Electrospinning · CPC title

• D01D5/0084

  Coating by electro-spinning, i.e. the electro-spun fibres are not removed from the collecting device but remain integral with it, e.g. coating of prostheses · CPC title