Porous polymer film and production method for porous polymer film

Patent metadata

Field	Value
Publication number	US-9283525-B2
Application number	US-201214127674-A
Country	US
Kind code	B2
Filing date	Jun 20, 2012
Priority date	Jun 22, 2011
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

The present invention aims to provide a porous polymer membrane that is excellent not only in water permeability and alkali resistance but also in mechanical strength. The porous polymer membrane of the present invention includes a fluoropolymer (A) that includes a vinylidene fluoride unit and a tetrafluoroethylene unit.

First claim

The invention claimed is:

1. A porous polymer membrane comprising a fluoropolymer (A) that includes a vinylidene fluoride unit and a tetrafluoroethylene unit,
wherein the membrane is a hollow fiber membrane,
wherein the fluoropolymer (A) includes the vinylidene fluoride unit and the tetrafluoroethylene unit in a molar ratio of the vinylidene fluoride unit/tetrafluoroethylene unit of 50 to 90/50 to 10; and
wherein the porous polymer membrane has a surface that has a ratio of oxygen/fluorine content (0/F) on the surface of not less than 0.050 but not more than 0.118 when measured by X-ray photoelectron spectroscopy (XPS).

2. The porous polymer membrane according to claim 1 ,
wherein the porous polymer membrane has a surface that has a (C—F/C—H) ratio representing a ratio of C—F bonds to C—H bonds on the surface of larger than 0.50 when measured by X-ray photoelectron spectroscopy (XPS).

3. The porous polymer membrane according to claim 1 ,
wherein the fluoropolymer (A) has a unit represented by the following formula (1):
—CHX 1 —CX 2 (OR)—  (1)

wherein one of X 1 and X 2 is a hydrogen atom, and the other is a fluorine atom; and R is a hydrogen atom or a C 1 -C 8 alkyl group.

4. The porous polymer membrane according to claim 3 ,
wherein the R in the formula (1) is a hydrogen atom, a methyl group, or an ethyl group.

5. The porous polymer membrane according to claim 1 ,
wherein the membrane is for treating water.

6. A method of producing the porous polymer membrane according to claim 1 , comprising at least a step of forming a porous membrane from a fluoropolymer (A′) that includes a vinylidene fluoride unit and a tetrafluoroethylene unit.

7. The method of producing the porous polymer membrane according to claim 6 ,
wherein the step of forming a porous membrane produces a porous membrane-shaped product through a non-solvent induced phase separation method and/or a thermally induced phase separation method.

8. The method of producing the porous polymer membrane according to claim 6 ,
further comprising a step of performing an alkali treatment in the presence of water and/or a C 1 -C 8 alcohol.

9. The method of producing the porous polymer membrane according to claim 8 ,
wherein the alcohol is ethanol or methanol.

10. The method of producing the porous polymer membrane according to claim 6 ,
wherein the fluoropolymer (A′) includes the vinylidene fluoride unit and the tetrafluoroethylene unit in a molar ratio of the vinylidene fluoride unit/tetrafluoroethylene unit of 50 to 90/50 to 10.

Assignees

• Shiotani Yuko
• Tanaka Yoshito
• Miki Jun
• Daikin Ind Ltd

Inventors

• Shiotani Yuko
• Tanaka Yoshito
• Miki Jun

Classifications

• B01D71/36 Primary

  Polytetrafluoroethylene · CPC title

• B01D69/08

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

• C08G61/121

  derived from organic halides · CPC title

• C08F214/26

  Tetrafluoroethene · CPC title

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title