Composite porous hollow fiber membrane, composite porous hollow fiber membrane module, and operation method for composite porous hollow fiber membrane module

Patent metadata

Field	Value
Publication number	US-2019330085-A1
Application number	US-201716312768-A
Country	US
Kind code	A1
Filing date	Jun 23, 2017
Priority date	Jun 24, 2016
Publication date	Oct 31, 2019
Grant date	—

Abstract

The present invention relates to a composite porous hollow-fiber membrane including a first layer and a second layer which each include a fluororesin-based polymer, in which at least a part of molecular chains of the fluororesin-based polymer is oriented in a longitudinal direction of the composite porous hollow-fiber membrane, the molecular chains of the fluororesin-based polymer have a degree of orientation it in the longitudinal direction of the composite porous hollow-fiber membrane of 0.4 or higher but less than 1.0, the degree of orientation it being calculated with the specific formula.

First claim

1 . A composite porous hollow-fiber membrane comprising a first layer and a second layer which each comprise a fluororesin-based polymer,
wherein at least a part of molecular chains of the fluororesin-based polymer is oriented in a longitudinal direction of the composite porous hollow-fiber membrane, the molecular chains of the fluororesin-based polymer have a degree of orientation π in the longitudinal direction of the composite porous hollow-fiber membrane of 0.4 or higher but less than 1.0, the degree of orientation π being calculated with the following formula (1), the first layer has a columnar texture oriented in the longitudinal direction of the composite porous hollow-fiber membrane, and the second layer has a three-dimensional network texture and has an average surface-pore diameter of 5.0 nm to 5.0 μm:
Degree of orientation π=(180°− H )/180°  (1),

provided that H is a half-value width (°) of a circumferential-direction diffraction intensity distribution of a wide-angle X-ray diffraction image.

2 . The composite porous hollow-fiber membrane according to claim 1 , wherein the columnar texture has a short-side length of 0.5 μm to 3 μm and has an aspect ratio of 3 or higher.

3 . The composite porous hollow-fiber membrane according to claim 1 , wherein the columnar texture has a thickness uniformity of 0.60 or higher.

4 . The composite porous hollow-fiber membrane according to claim 1 , wherein the half-value width H is a half-value width of an intensity distribution obtained by wide-angle X-ray diffractometry, by scanning, in a circumferential direction, a crystal peak (2θ=20.4°) assigned to a (110) plane of poly(vinylidene fluoride).

5 . The composite porous hollow-fiber membrane according to claim 1 , wherein, in a case where measuring points on the composite porous hollow-fiber membrane which are located at intervals of 1 cm in the longitudinal direction thereof are examined by wide-angle X-ray diffractometry, the degree of orientation π is 0.4 or higher but less than 1.0 in 80% or more of the measuring points.

6 . The composite porous hollow-fiber membrane according to claim 1 , wherein the columnar texture has an average value v of a Raman orientation parameter obtained by Raman spectrometry of 3.0 or larger.

7 . The composite porous hollow-fiber membrane according to claim 1 , wherein the fluororesin-based polymer is poly(vinylidene fluoride).

8 . The composite porous hollow-fiber membrane according to claim 1 , wherein the first layer has a porosity of 50-80%.

9 . The composite porous hollow-fiber membrane according to claim 1 , which has a pure-water permeation performance at 50 kPa and 25° C. of 0.1 m 3 /m 2 /hr or higher and a breaking strength of 25 MPa or higher.

10 . A composite porous hollow-fiber membrane module comprising:
a tubular case having, in a height direction thereof, a first end and a second end; a plurality of the composite porous hollow-fiber membranes according to claim 1 disposed in the tubular case; a fluid inflow/outflow port located in a sidewall of the tubular case further toward the second-end side than the center of the tubular case; and a fluid inflow/outflow port located in a first-end-side end face of the tubular case, wherein hollows of the composite porous hollow-fiber membranes are opened on the second-end side and closed on the first-end side.

11 . A method for operating the composite porous hollow-fiber membrane module according to claim 10 , the method comprising simultaneously performing the following step (A) and step (B):
(A) a step in which a liquid to be filtrated is introduced into the tubular case through the fluid inflow/outflow port located in the first-end-side end face, and the liquid to be filtrated is discharged from the tubular case through the fluid inflow/outflow port located in the sidewall on the second-end side; and (B) a step in which a filtrate is taken out from the hollows of the composite porous hollow-fiber membranes toward the second end.

12 . A method for operating the composite porous hollow-fiber membrane module according to claim 10 , the method comprising simultaneously performing the following step (B) and step (C):
(B) a step in which a filtrate is taken out from the hollows of the composite porous hollow-fiber membranes toward the second end; and (C) a step in which a liquid to be filtrated is introduced into the tubular case through the fluid inflow/outflow port located in the sidewall on the second-end side, and the liquid to be filtrated is discharged from the tubular case through the fluid inflow/outflow port located in the first-end-side end face.

13 . The method for operating the composite porous hollow-fiber membrane module according to claim 11 , wherein the step (B) and the following step (D) are repeatedly performed:
(D) a step in which, after the step (B), a fluid is filtrated by passing the fluid from the hollows of the composite porous hollow-fiber membranes on the second-end side to an outside of the composite porous hollow-fiber membranes.

14 . The method for operating the composite porous hollow-fiber membrane module according to claim 13 , wherein the step (B) and the step (D) are repeatedly performed and the following step (E) is further performed:
(E) a step in which a gas is introduced into the tubular case through the fluid inflow/outflow port located in the first-end-side end face, and the gas is discharged from the tubular case through the fluid inflow/outflow port located in the sidewall on the second-end side.

15 . The method for operating the composite porous hollow-fiber membrane module according to claim 12 , wherein the step (B) and the following step (D) are repeatedly performed:
(D) a step in which, after the step (B), a fluid is filtrated by passing the fluid from the hollows of the composite porous hollow-fiber membranes on the second-end side to an outside of the composite porous hollow-fiber membranes.

16 . The method for operating the composite porous hollow-fiber membrane module according to claim 15 , wherein the step (B) and the step (D) are repeatedly performed and the following step (E) is further performed:
(E) a step in which a gas is introduced into the tubular case through the fluid inflow/outflow port located in the first-end-side end face, and the gas is discharged from the tubular case through the fluid inflow/outflow port located in the sidewall on the second-end side.

Assignees

• Toray Industries

Inventors

• SHIMURA Shun
• Hanakawa Masayuki
• Iwai Kenta
• Kitade Tamotsu
• Kimura Masahiro

Classifications

• C02F1/444

  by ultrafiltration or microfiltration · CPC title

• B01D67/0027

  by stretching · CPC title

• B01D67/0088

  Physical treatment with compounds, e.g. swelling, coating or impregnation · CPC title

• B01D2325/28

  Degradation or stability over time · CPC title

• B01D2325/30

  Chemical resistance · CPC title