# US 2019/0168167 A1 · Composite porous hollow fiber membrane, production method for composite porous hollow fiber membrane, composite porous hollow fiber membrane module, and operation method for composite porous hollow fiber membrane module

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- Number: US 2019/0168167 A1
- Document ID: US20190168167A1
- Status: Published application
- Kind: A1
- Application number: 16/312,852
- Filed: 2017-06-23
- Published: 2019-06-06
- Earliest claimed: 2016-06-24
- Assignees: Toray Industries, Inc.
- Applicants: Toray Industries, Inc.
- Inventors: Shun SHIMURA; Kenta IWAI; Masayuki HANAKAWA; Tamotsu KITADE; Masahiro KIMURA
- Web page: https://patentgrep.com/patent/US20190168167A1

## CPC

- B01D 67/0027: {by stretching}
- B01D 67/0009: {by phase separation, sol-gel transition, evaporation or solvent quenching}
- B01D 67/00165: {Composition of the coagulation baths}
- B01D 67/0018: {Thermally induced processes [TIPS]}
- B01D 69/02: characterised by their properties
- B01D 69/08: Hollow fibre membranes (manufacture of hollow fibres D01D5/24, D01F1/08)
- B01D 69/12: Composite membranes; Ultra-thin membranes
- B01D 71/34: Polyvinylidene fluoride
- B01D 2323/08: Specific temperatures applied
- B01D 2323/10: Specific pressure applied
- B01D 2323/12: Specific ratios of components used
- B01D 2325/021: Pore shapes
- B01D 2325/0283: Pore size
- B01D 2325/24: Mechanical properties, e.g. strength
- B01D 2325/34: Molecular weight or degree of polymerisation
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)

## 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 the first layer has a columnar texture oriented in a longitudinal direction of the composite porous hollow-fiber membrane, the columnar texture has an average value v of a Raman orientation parameter calculated with the specific formula, 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.

## Claims

### Claim 1

A composite porous hollow-fiber membrane comprising a first layer and a second layer which each comprise a fluororesin-based polymer,
wherein the first layer has a columnar texture oriented in a longitudinal direction of the composite porous hollow-fiber membrane,
the columnar texture has an average value v of a Raman orientation parameter calculated with the following formula (1) of 1.5-4.0, 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:
Raman orientation parameter=(I1270-parallel/I840-parallel)/(I1270-vertical/I840-vertical) (1),
provided that,
I1270-parallel: Raman band intensity at 1,270 cm−1 under parallel conditions,
I1270-vertical: Raman band intensity at 1,270 cm−1 under vertical conditions,
I840-parallel: Raman band intensity at 840 cm−1 under the parallel conditions,
I840-vertical: Raman band intensity at 840 cm−1 under the vertical conditions,
the parallel conditions: the longitudinal direction of the composite porous hollow-fiber membrane is parallel with a polarization direction, and
the vertical conditions: the longitudinal direction of the composite porous hollow-fiber membrane is orthogonal with the polarization direction.

### Claim 2 (depends on 1)

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 an aspect ratio of 3 or higher.

### Claim 3 (depends on 1)

The composite porous hollow-fiber membrane according to claim 1, wherein the columnar texture has a thickness uniformity of 0.50 or higher.

### Claim 4 (depends on 1)

The composite porous hollow-fiber membrane according to claim 1, wherein molecular chains in the columnar texture have a ratio between a maximum Raman orientation parameter M and a minimum Raman orientation parameter m, M/m, of from 1.5 to 4.0.

### Claim 5 (depends on 1)

The composite porous hollow-fiber membrane according to claim 1, wherein molecular chains in the columnar texture have a maximum Raman orientation parameter M of 4.0 or less.

### Claim 6 (depends on 1)

The composite porous hollow-fiber membrane according to claim 1, wherein the first layer has a porosity of 40-80%.

### Claim 7 (depends on 1)

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 m3/m2/hr or higher, a breaking strength of 23 MPa or higher, and a Young's modulus of 0.15 GPa to 0.40 GPa.

### Claim 8 (depends on 1)

The composite porous hollow-fiber membrane according to claim 1, wherein 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 less than 0.4, or the molecular chains of the fluororesin-based polymer are in a non-oriented state, the degree of orientation π being calculated with the following formula (4):
Degree of orientation π=(180°−H)/180° (4),
provided that H is a half-value width (°) of a circumferential-direction diffraction intensity distribution of a wide-angle X-ray diffraction image.

### Claim 9

A process for producing a composite porous hollow-fiber membrane, the process comprising the following steps 1) to 3):
1) a step in which a porous hollow fiber having a columnar texture which is oriented in a longitudinal direction and which has a thickness uniformity of 0.50 or higher but less than 1.00 is formed, by thermally induced phase separation, from a membrane-forming raw liquid containing a fluororesin-based polymer;
2) a step in which a porous hollow fiber having a three-dimensional network texture is formed, by nonsolvent-induced phase separation, from a membrane-forming raw liquid containing a fluororesin-based polymer; and
3) a step in which at least the porous hollow fiber obtained in the step 1) is drawn in the longitudinal direction 1.8-2.4 times at a rate of 1-150%/sec.

### Claim 10 (depends on 9)

The process for producing a composite porous hollow-fiber membrane according to claim 9, wherein the thermally induced phase separation in the step 1) includes at least one of the following cooling steps a) and b):
a) a step in which the membrane-forming raw liquid is immersed in a cooling bath having a temperature Tb which satisfies Tc−30° C.<Tb≤Tc; and
b) a step in which the membrane-forming raw liquid is immersed in a cooling bath having a temperature Tb1 which satisfies Tb1≤Tc−30° C. and is then immersed in a cooling bath having a temperature Tb2 which satisfies Tc−30° C.<Tb2≤Tc,
provided that Tc is a crystallization temperature of the membrane-forming raw liquid containing the fluororesin-based polymer.

### Claim 11 (depends on 1)

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.

### Claim 12 (depends on 11)

A method for operating the composite porous hollow-fiber membrane module according to claim 11, 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.

### Claim 13 (depends on 11)

A method for operating the composite porous hollow-fiber membrane module according to claim 11, 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.

### Claim 14 (depends on 12)

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.

### Claim 15 (depends on 14)

The method for operating the composite porous hollow-fiber membrane module according to claim 14, 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.

### Claim 16 (depends on 13)

The method for operating the composite porous hollow-fiber membrane module according to claim 13, 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.

### Claim 17 (depends on 16)

The method for operating the composite porous hollow-fiber membrane module according to claim 16, 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.