# US 10,478,782 B2 · Composite hollow fiber membrane and method for producing same

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- Number: US 10,478,782 B2
- Document ID: US10478782B2
- Status: Granted
- Kind: B2
- Application number: 15/569,859
- Filed: 2016-04-28
- Published: 2018-05-03
- Granted: 2019-11-19
- Earliest claimed: 2015-04-28
- Assignees: Toray Industries, Inc.
- Applicants: Toray Industries, Inc.
- Inventors: Gohei Yamamura; Koichi Takada; Ryuichiro Hiranabe; Hiroki Tomioka
- Web page: https://patentgrep.com/patent/US10478782B2

## CPC

- B01D 69/081: {characterised by the fibre diameter}
- B01D 69/00: Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D 69/02: characterised by their properties
- B01D 69/08: Hollow fibre membranes (manufacture of hollow fibres D01D5/24, D01F1/08)
- B01D 69/1218: {Layers having the same chemical composition, but different properties, e.g. pore size, molecular weight or porosity}
- B01D 71/14: Esters of organic acids
- B01D 61/02: Reverse osmosis; Hyperfiltration {; Nanofiltration}
- B01D 69/1216: {Three or more layers}
- B01D 2323/60: Co-casting; Co-extrusion
- B01D 2325/24: Mechanical properties, e.g. strength
- 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

Problems that the invention is to solve is to provide a composite hollow fiber membrane being excellent in separation performance and permeation performance, having high membrane strength, and capable of being easily produced, and a method for producing the same. The present invention relates to a composite hollow fiber membrane including at least a layer (A) and a layer (B), in which the composite hollow fiber membrane has an outer diameter of 20 to 350 μm and an inner diameter of 14 to 250 μm, the tensile modulus of the composite hollow fiber membrane is from 1,000 to 6,500 MPa, the layer (A) contains a cellulose ester, the thickness of the layer (A) is from 0.01 to 5 μm, and the open pore ratio HA of the layer (A) and the open pore ratio HB of the layer (B) satisfy HA<HB.

## Claims

### Claim 1

A composite hollow fiber membrane comprising at least a layer (A) and a layer (B), wherein:
the composite hollow fiber membrane has an outer diameter of 20 to 350 μm and an inner diameter of 14 to 250 μm,
a tensile modulus of the composite hollow fiber membrane is from 1,000 to 6,500 MPa, the layer (A) contains a cellulose ester,
a thickness of the layer (A) is from 0.01 to 5 μm, and
an open pore ratio HA of the layer (A) and an open pore ratio HB of the layer (B) satisfy HA<HB, the open pore ratio HA of the layer (A) is from 0 to 10%, and the open pore ratio of HB of the layer (B) is from 5 to 55%.

### Claim 2 (depends on 1)

The composite hollow fiber membrane according to claim 1, wherein an outermost layer of the composite hollow fiber membrane is the layer (A).

### Claim 3 (depends on 1)

The composite hollow fiber membrane according to claim 1, wherein the layer (B) contains a cellulose ester.

### Claim 4 (depends on 1)

The composite hollow fiber membrane according to claim 1, wherein the cellulose ester contained in the layer (A) is at least one compound selected from the group consisting of cellulose acetate propionate and cellulose acetate butyrate.

### Claim 5 (depends on 1)

The composite hollow fiber membrane according to claim 1, wherein the cellulose ester contained in the layer (B) is at least one compound selected from the group consisting of cellulose acetate propionate and cellulose acetate butyrate.

### Claim 6 (depends on 1)

The composite hollow fiber membrane according to claim 1, wherein the layer (B) has a continuous pore.

### Claim 7 (depends on 1)

The composite hollow fiber membrane according to claim 1, having a stress at 5% elongation in a longitudinal direction thereof of 30 MPa or more.

### Claim 8 (depends on 1)

The composite hollow fiber membrane according to claim 1, having a salt rejection ratio of from 90.0 to 99.9% at the time of filtrating an aqueous solution having a sodium chloride concentration of 500 mg/l at 25° C. and a pressure of 0.5 MPa.

### Claim 9 (depends on 1)

A method for producing the composite hollow fiber membrane of claim 1 comprising the following steps 1 to 3:
1. a step of heating and thereby melting a resin composition constituting each of the layers of the composite hollow fiber membrane, in which a resin composition constituting at least one of the layers contains the cellulose ester,
2. a step of combining and thereby compounding the melted resin compositions of respective layers within a spinneret having a multi-annular nozzle where a gas channel is arranged in a central part thereof, and
3. a step of either
winding the compounded resin composition at a draft ratio of 200 to 1,000 while discharging it into air from the multi-annular nozzle, or
spinning out the compounded resin composition at a draft ratio of 10 to 200 to obtain a hollow fiber membrane, drawing the hollow fiber membrane at a ratio of 1.1 to 2.5 times, and subsequently winding the hollow fiber membrane.