Hollow fiber membrane, and method for producing hollow fiber membrane

Patent metadata

Field	Value
Publication number	US-10744467-B2
Application number	US-201515128385-A
Country	US
Kind code	B2
Filing date	Feb 26, 2015
Priority date	Mar 26, 2014
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

One aspect of the present invention concerns a porous hollow fiber membrane containing a vinylidene fluoride-based resin. The hollow fiber membrane has a gradient structure in which a pore diameter of pores in the hollow fiber membrane gradually becomes smaller at least toward one of inner and outer peripheral surface sides and is hydrophilized by containing a crosslinked body of a polyvinylpyrrolidone-based resin.

First claim

The invention claimed is:

1. A porous hollow fiber membrane, comprising a vinylidene fluoride-based resin, wherein the hollow fiber membrane has a gradient structure in which a pore diameter of pores in the hollow fiber membrane gradually becomes smaller at least toward one of inner and outer peripheral surface sides;
the hollow fiber membrane is hydrophilized by containing from 0.1 to 15 mass % of a crosslinked body of a polyvinylpyrrolidone-based resin; and
a ratio (FD10/FW) of a water permeation speed (FD10) at an inter-membrane differential pressure of 0.1 MPa in the dry state after wet and dry states are alternately repeated ten times to a water permeation speed (FW) at an inter-membrane differential pressure of 0.1 MPa in the wet state is 40% or higher;
wherein a K-value of the polyvinylpyrrolidone-based resin is from 60 to 120.

2. The hollow fiber membrane according to claim 1 , wherein:
a water permeation amount at an inter-membrane differential pressure of 0.1 MPa is 1000 to 40000 L/m 2 /hr; and
a fractionation particle diameter is 0.001 to 0.5 μm.

3. The hollow fiber membrane according to claim 1 , wherein the hollow fiber membrane comprises a single layer.

4. The hollow fiber membrane according to claim 1 , wherein the crosslinked body is obtained by crosslinking the polyvinylpyrrolidone-based resin contained in the hollow fiber membrane before crosslinking in forming the hollow fiber membrane before crosslinking.

5. A method for producing the hollow fiber membrane according to claim 1 , the method comprising:
extruding a membrane forming solution comprising the vinylidene fluoride-based resin, the polyvinyl-pyrrolidone-based resin, and a solvent into a hollow fiber;
solidifying the membrane forming solution extruded into the hollow fiber and forming a hollow fiber membrane before crosslinking;
washing the hollow fiber membrane before crosslinking; and
crosslinking the polyvinylpyrrolidone-based resin in the hollow fiber membrane before crosslinking,
wherein a mass ratio of the vinylidene fluoride-based resin to the polyvinylpyrrolidone-based resin is from 1.54 to 4.38.

6. The method according to claim 5 , wherein said crosslinking comprises immersing the hollow fiber membrane before crosslinking in an aqueous solution comprising a radical initiator.

7. The hollow fiber membrane according to claim 1 , wherein a pure water permeability coefficient is from 0.4×10 −11 ×L (m 2 ) to 6×10 −11 ×L (m 2 ) when a thickness of the hollow fiber membrane is L (m).

Assignees

• Kuraray Co

Inventors

• Yabuno Youhei
• Yoshitoshi Tsukasa
• Hayashi Yusuke

Classifications

• B01D67/0093

  Chemical modification · CPC title

• B01D2325/0231

  Dense layers being placed on the outer side of the cross-section · CPC title

• B01D63/02

  Hollow fibre modules · CPC title

• B01D67/0016

  Coagulation · CPC title

• B01D67/0011

  Casting solutions therefor · CPC title