High toughness hollow fiber membranes based on vinylidene fluoride polymers

Patent metadata

Field	Value
Publication number	US-10322381-B2
Application number	US-201515328115-A
Country	US
Kind code	B2
Filing date	Jul 21, 2015
Priority date	Jul 22, 2014
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

Hollow fiber membranes having improved toughness and durability are prepared using a vinylidene fluoride polymer-containing component, such as Kynaro resins, having relatively low crystallinity. One aspect of the invention provides a membrane in the form of a fiber, wherein i) the fiber has a porous wall of a polymeric component enclosing a central hollow space extending the length of the fiber, ii) the polymeric component has a crystallinity as determined by wide angle x-ray diffraction of less than about 35%, iii) the polymeric component is comprised of at least one homopolymer or copolymer of vinylidene fluoride and iv) the membrane has an energy to break of at least about 0.5 J per square mm of membrane cross section.

First claim

What is claimed is:

1. A membrane in the form of a fiber, wherein i) the fiber has a porous wall of a polymeric component enclosing a central hollow space extending the length of the fiber, ii) the polymeric component has a crystallinity as determined by wide angle x-ray diffraction of less than about 35%, iii) the polymeric component is comprised of at least one homopolymer or copolymer of vinylidene fluoride and iv) the membrane has an energy to break of at least about 0.5 J per square mm of membrane cross section.

2. The membrane of claim 1 , wherein the polymeric component is selected from the group consisting of:
a) a polymer which is a copolymer of from about 80% to about 99% by weight of vinylidene fluoride and from about 1% to about 20% by weight of one or more co-monomers;
b) a blend of from about 10% to about 80% by weight vinylidene fluoride homopolymer and from about 20% to about 90% by weight of a copolymer comprising from about 60% to about 99% by weight of vinylidene fluoride and from about 1% to about 40% by weight of one or more co-monomers;
c) a blend of from about 10% to about 80% by weight high crystallinity vinylidene fluoride homopolymer and from about 20% to about 90% by weight low crystallinity vinylidene fluoride homopolymer;
d) a vinylidene fluoride homopolymer or copolymer containing long chain branching; and
e) a vinylidene fluoride copolymer containing a fraction of very high molecular weight vinylidene fluoride homopolymer or copolymer.

3. The membrane of claim 1 , wherein the polymeric component has a crystallinity as determined by wide angle x-ray diffraction of at least about 20%.

4. The membrane of claim 1 , wherein the polymeric component is a polymer which is a copolymer of from about 80% to about 99% by weight of vinylidene fluoride and from about 1% to about 20% by weight of one or more co-monomers selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, tetrafluoroethylene, trifluoroethylene, vinylacetate, vinylsulfonic acid, vinyltrimethylsilane, tetrafluoropropylene, acrylic acid and methacrylic acid.

5. The membrane of claim 1 , wherein the polymeric component is a blend of from about 10% to about 80% by weight vinylidene fluoride homopolymer and from about 20% to about 90% by weight of a copolymer comprising from about 80% to about 99% by weight of vinylidene fluoride and from about 1% to about 20% by weight of one or more co-monomers selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, tetrafluoroethylene, trifluoroethylene, vinylacetate, vinylsulfonic acid, vinyltrimethylsilane, tetrafluoropropylene, acrylic acid and methacrylic acid.

6. The membrane of claim 1 , wherein the polymeric component is a blend of from about 10% to about 80% by weight of a first vinylidene fluoride homopolymer having a degree of crystallinity of greater than 35% and from about 20% to about 90% by weight of a second vinylidene fluoride homopolymer having a degree of crystallinity of less than 20%.

7. The membrane of claim 1 , wherein the porous wall is substantially free of macrovoids.

8. The membrane of claim 1 , wherein the membrane is unsupported.

9. A membrane module, wherein i) the membrane module comprises a plurality of hollow porous fibers of a polymeric component, ii) the polymeric component has a crystallinity as determined by wide angle x-ray diffraction of less than about 40%, the polymeric component is comprised of at least one homopolymer or copolymer of vinylidene fluoride and iv) the membrane has an energy to break of at least about 0.5 J per square mm of membrane cross section.

10. The membrane module of claim 9 , wherein the polymeric component is selected from the group consisting of:
a) a polymer Which is a copolymer of from about 80% to about 99% by weight of vinylidene fluoride and from about 1% to about 20% by weight of one or more co-monomers;
b) a blend of from about 10% to about 80% by weight vinylidene fluoride homopolymer and from about 20% to about 90% by weight of a copolymer comprising from about 60% to about 99% by weight of vinylidene fluoride and from about 1% to about 40% by weight of one or more co-monomers;
c) a blend of from about 10% to about 80% by weight high crystallinity vinylidene fluoride homopolymer and from about 20% to about 90% by weight low crystallinity vinylidene fluoride homopolymer;
d) a vinylidene fluoride homopolymer or copolymer containing long chain branching; and
e) a vinylidene fluoride copolymer containing a fraction of very high molecular weight vinylidene fluoride homopolymer or copolymer.

11. The membrane module of claim 10 , wherein the polymeric component has a crystallinity as determined by wide angle x-ray diffraction of at least about 20%.

12. The membrane module of claim 10 , wherein the polymeric component is a polymer which is a copolymer comprising from about 80% to about 99% by weight of vinylidene fluoride and from about 1% to about 20% by weight of one or more co-monomers selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, tetrafluoroethylene, trifluoroethylene, vinylacetate, vinylsulfonic acid, vinyltrimethylsilane, tetrafluoropropylene, acrylic acid and methacrylic acid.

13. The membrane module of claim 10 , wherein the polymeric component is a blend of from about 10% to about 80% by weight vinylidene fluoride homopolymer and from about 20% to about 90% by weight of a copolymer comprising from about 60% to about 99% by weight of vinylidene fluoride and from about 1% to about 40% by weight of one or more co-monomers selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, tetrafluoroethylene, trifluoroethylene, vinylacetate, vinylsulfonic acid, vinyltrimethylsilane, tetrafluoropropylene, acrylic acid and methacrylic acid.

14. The membrane module of claim 10 , wherein the polymeric component is a blend of from about 10% to about 80% by weight of a first vinylidene fluoride homopolymer having a degree of crystallinity of greater than 35% and from about 20% to about 90% by weight of a second vinylidene fluoride homopolymer having a degree of crystallinity of less than 20%.

15. The membrane module of claim 10 , wherein the polymeric component is a blend of vinylidene fluoride homopolymer or copolymer and methyl methacrylate homopolymer or copolymer.

16. A method of making a hollow porous fiber useful in manufacturing membrane modules, comprising:
a) extruding a composition comprised of a polymeric component, a pore enhancement agent and a solvent capable of dissolving the polymeric component and the pore enhancement agent to form a hollow fiber; and
b) removing the solvent and pore enhancement agent from the hollow fiber to form the hollow porous fiber;
wherein the polymeric component has a crystallinity as determined by wide angle x-ray diffraction of less than about 35% and the polymeric component is comprised of at least one homopolymer or copolymer of vinylidene fluoride.

17. The method of claim 16 , wherein the polymeric component is selected from the group consisting of:
a) a polymer which is a copolymer of from about 80% to about 99% by weight of vinylidene fluoride and from about 1% to about 20% by weight of one or more co-monomers;
b) a blend of from about 10% to about 80% by weight vinylidene fluoride homopolymer and from about 20% to about 90% by weight of a copolymer comprising from about 60% to about 99% by weight of vinylidene fluoride and from about 1% to about 40% by weight of one or more co-monomers;
c) a blend of from about 10% to about 80% by weigh

Assignees

• Arkema Inc

Inventors

• Kosar Walter P
• Reber Iii Roderick
• O'Brien Gregory S
• Gaboury Scott R
• Wille Roice A

Classifications

• B01D2325/24

  Mechanical properties, e.g. strength · CPC title

• B01D2323/18

  Pore-control agents or pore formers · CPC title

• B01D2323/12

  Specific ratios of components used · CPC title

• B01D71/34 Primary

  Polyvinylidene fluoride · CPC title

• B01D71/32

  containing fluorine atoms · CPC title