FILTRATION MEMBRANE WITH TUBULAR SUPPORT

• US 20100108599A1
• Filed: 11/03/2008
• Published: 05/06/2010
• Est. Priority Date: 11/03/2008
• Status: Abandoned Application

• Current Assignee: Zenon Technology Partnership
• Original Assignee: Zenon Technology Partnership
• Inventors: Pelle, Krisztina, Koops, Geert-Henk, Vizvardi, Kristof, Pozsgay, Andras Gyorgy, Mahendran, Mailvaganam
• Application Number:
  US12/263,725
• Publication Number:
  US 20100108599A1
• Time in Patent Office: Days
• US Class Current: 210/500.230
• CPC Class Codes: B01D 2323/12 Specific ratios of components used
• CPC Class Codes: B01D 2323/22 Specific non-solvents or non-solvent system
• CPC Class Codes: B01D 2323/42 Details of membrane preparation apparatus
• CPC Class Codes: B01D 67/0011 Casting solutions therefor
• CPC Class Codes: B01D 67/0013 Casting processes
• CPC Class Codes: B01D 67/00135 Air gap characteristics
• CPC Class Codes: B01D 69/04 Tubular membranes
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 69/12 Composite membranes; Ultra-thin membranes
• CPC Class Codes: B01D 71/34 Polyvinylidene fluoride
• CPC Class Codes: B01D 71/68 Polysulfones; Polyethersulfones

Abstract

A membrane generally comprises a tubular support, and a polymeric membrane film on the support. The polymeric membrane film comprises three zones cast simultaneously from a single dope. The three zones include an inner zone on the support comprising macro-void pores, an intermediate zone on the inner zone comprising macro-void pores smaller than the macro-void pores of the inner zone, and a skin on the intermediate zone comprising pores of less than 1 micron.

Claims

1. A membrane comprising:

a) a tubular support; and

b) a polymeric film on the support, the polymeric film comprising three zones cast simultaneously from a single dope, the three zones comprising;

i) an inner zone on the support comprising macro-void pores;

ii) an intermediate zone on the inner zone comprising macro-void pores smaller than the macro-void pores of the inner zone; and

iii) a skin on the intermediate zone comprising pores of less than 1 micron.

2. The membrane of claim 1, wherein the inner zone has a macrovoid pore density of 40-90%.

3. The membrane of any one of claim 1, wherein the intermediate zone has a macrovoid pore density of 60-90%.

4. The membrane of any one of claim 1, wherein the inner zone is additionally in the support.

5. The membrane of any one of claim 1, wherein the inner zone has a pore size of between about 40 and about 200 microns.

6. The membrane of any one of claim 1, wherein the intermediate zone has a pore size of between about 5 and about 30 microns.

7. The membrane of any one of claim 1, wherein the polymeric coating has a thickness of between about 50 microns and 230 microns.

8. The membrane of any one of claim 1, wherein the polymeric coating has a thickness of between about 100 microns and 160 microns.

9. The membrane of any one of claim 1, wherein the macrovoids of the inner zone are connected by pores having a size of between about 0.1 microns to 01 microns.

10. The membrane of any one of claim 1, wherein the polymeric coating is selected from the group consisting of polysulfone, polyethersulfone, polyether ether ketone, polyvinyl chloride, polyvinylidene dichloride, chlorinated polyvinylchloride, polyvinylidene difluoride, polyvinylfluoride, other fluoro polymers or co-polymers, cellulose acetate, cellulose nitrate, cellulose triacetate, cellulose butyrate, polyacryloniyrile, sulfonated polyether ether ketone, sulfonated polysulfone, sulfonated polyethersulfone, polyimides, polyamides, polymethyl methacrylate, and polystyrene.

11. The membrane of any one of claim 1, wherein the dope comprises a solvent and a film forming polymer having a concentration of between 10 wt. % and 25 wt. %

12. The membrane of any one of claim 1, wherein the dope further comprises at least one of a non-solvent and/or a weak non-solvent having a concentration of between 0 wt. % and 20 wt. %

13. The membrane of any one of claim 1, wherein the dope further comprises a hydrophilic polymer additive having a concentration of between 0 wt. % and 15 wt. %.

14. A casting dope for producing a polymeric membrane film on a tubular support, the casting dope comprising:

a) a solvent; and

b) a film forming polymer soluble in the solvent and having a concentration of between 10 wt. % and 25 wt. %

15. The casting dope of claim 14, further comprising at least one of a non-solvent and/or a weak non-solvent having a concentration of between 0 wt. % and 20 wt. %.

16. The casting dope of any of claim 14, further comprising a hydrophilic polymer additive having a concentration of between 0 wt. % and 15 wt. %.

17. A process for casting a dope onto a tubular support to produce a polymeric membrane film on the tubular support, the process comprising:

a) providing a dope according to any of claims 14 to 16 comprising a solvent; and

a film forming polymer soluble in the solvent and having a concentration of between 10 wt. % and 25 wt. %.

b) advancing the tubular support through a rounding orifice of a coating nozzle;

c) introducing the dope into a coating nozzle at a flow rate correlatable to a speed at which the tubular support is advanced through the rounding orifice of the coating nozzle to form a dope-coated tubular support; and

d) leading the dope-coated tubular support into a coagulating bath.

18. A membrane comprising:

a) a tubular support; and

b) an integrally and externally skinned polymeric membrane film on the support, the polymeric membrane film having macro-void pores with a length of 10 microns or more present at a density of at least 40% through at least 90% of the thickness of the membrane measured from the outside of the support to the outside of the skin.