Long chain branched fluoropolymer membranes

Patent metadata

Field	Value
Publication number	US-2016008772-A1
Application number	US-201414770125-A
Country	US
Kind code	A1
Filing date	Feb 27, 2014
Priority date	Mar 4, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

The invention relates to membranes formed from long chain branched fluoropolymers, and especially long chain branched homopolymers and copolymers of polyvinylidene fluoride such as KYNAR resins. The novel membranes retain all the advantages of a fluoropolymer membrane (excellent chemical resistance especially to strong acids and oxidizing agents, and good mechanical strength), and additionally offer improved permeability, improved strain hardening, and even better resistance to caustic attacks. The improvements are believed to be related to an improvement to the microstructure of the membranes, producing a more open structure due to the long chain branched fluoropolymers. Further improvements in the mechanical properties of the membranes can be induced by strain hardening.

First claim

1 . A membrane comprising from 5 to 100 weight percent of long-chain branched fluoropolymer.

2 . The membrane of claim 1 comprising from 10 to 80 weight percent of long-chain branched fluoropolymer.

3 . The membrane of claim 1 , wherein said long-chain branched fluoropolymer comprises polyvinylidene fluoride

4 . The membrane of claim 2 , wherein said long-chain branched fluoropolymer is a vinylidene fluoride homopolymer, or a copolymer comprising from 70 to 99.9 weight percent of vinylidene fluoride monomer units and from 0.1 to 30 weight percent of one or more other fluoromonomer units.

5 . The membrane of claim 1 , wherein said membrane is a flat membrane or a hollow fiber membrane.

6 . The membrane of claim 5 , wherein said membrane has a thickness of from 50-500 microns.

7 . The membrane of claim 1 , wherein said membrane further comprises up to 95 weight percent of linear fluoropolymer.

8 . The membrane of claim 6 , wherein said membrane further comprises from 20 to 90 weight percent of linear fluoropolymer.

9 . The membrane of claim 6 wherein said linear fluoropolymer is a vinylidene fluoride homopolymer, or a copolymer comprising from 70 to 99.9 weight percent of vinylidene fluoride monomer units and from 0.1 to 30 weight percent of one or more other fluoromonomer units.

10 . The membrane of claim 1 , wherein said membrane further comprises from 2 to 40 weight percent of linear acrylic polymer.

11 . The membrane of claim 10 , wherein said linear acrylic polymer comprises (meth) acrylic monomer units.

12 . The membrane of claim 1 , wherein said membrane further comprises from 1 to 20 weight percent of other additives, selected from the group consisting of pore-formers, metallic salts, alcohols, glycols, silica, carbon nanotubes, other nano materials and compounds for increasing the viscosity of the solution.

13 . The membrane of claim 1 , wherein said membrane has been strain hardened.

Assignees

• Arkema Inc

Inventors

• Kosar Walter P
• Hedhli Lotfi
• Reber Roderick

Classifications

• B01D2325/24

  Mechanical properties, e.g. strength · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• B01D69/08

  Hollow fibre membranes (manufacture of hollow fibres D01D5/24, D01F1/08) · CPC title

• B01D71/34 Primary

  Polyvinylidene fluoride · CPC title

• B01D69/02

  characterised by their properties · CPC title