# US 7,407,609 B2 · Membranes and their manufacture

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 7,407,609 B2
- Document ID: US7407609B2
- Status: Granted
- Kind: B2
- Application number: 10/481,517
- Filed: 2002-06-26
- Published: 2004-12-02
- Granted: 2008-08-05
- Earliest claimed: 2001-06-26
- Assignees: Victrex Manufacturing Limited
- Inventors: Philip J. Brown
- Web page: https://patentgrep.com/patent/US7407609B2

## CPC

- B01D 71/5222: {Polyetherketone, polyetheretherketone, or polyaryletherketone}
- B01D 53/228: {characterised by specific membranes}
- B01D 67/0011: {Casting solutions therefor}
- B01D 69/08: Hollow fibre membranes (manufacture of hollow fibres D01D5/24, D01F1/08)
- B01D 2323/081: Heating
- B01D 2323/30: Cross-linking
- 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

Membranes comprising an aromatic ether ketone polymer (e.g. polyetherketone) in sheet or hollow fibre form are made by preparing at least a 12 wt % solution of the polymer in a solvent which is chemically inert to the polymer (e.g. concentrated sulphuric acid); forming a film of the solution in sheet or hollow form; and contacting the film with a non-solvent (e.g. more dilute sulphuric acid or acetic acid) thereby to precipitate the film.

## Claims

### Claim 1

A method of making a membrane of sheet or hollow fibre form, the membrane comprising an aromatic ether ketone polymer comprising O-phenyl-C(O)- units substantially free of —O-phenyl-O— or other electron rich readily sulphonatable units, the method comprising the steps of:
a) preparing a solution of the polymer in a solvent which is chemically inert to the polymer, the concentration of the polymer in the solution being in the range 15-20%;
b) forming a film of the solution in sheet or hollow fibre form; and
c) contacting the film with sulphuric acid of concentration in the range 55-72%, thereby precipitating the membrane of said polymer.

### Claim 2 (depends on 1)

A method according to claim 1, wherein the film is contacted with sulphuric acid thereby precipitating the membrane of said polymer and the interval between the addition of the sulphuric acid and the completion of the precipitation is at least 5 minutes.

### Claim 3 (depends on 1)

A method according to claim 1, wherein the solvent and sulphuric acid are selected such that when they are mixed the temperature rises by not more than 30° C.

### Claim 4 (depends on 1)

A method according to claim 1, wherein said aromatic ether ketone polymer is partially crystalline.

### Claim 5 (depends on 1)

A method according to claim 1, which comprises a polyetherketone homopolymer or copolymer.

### Claim 6 (depends on 1)

A method according to claim 1, wherein the solvent used in the preparation of said solution of the polymer is a strong acid.

### Claim 7 (depends on 1)

A method according to claim 1, wherein the solvent used in the preparation of said solution of the polymer comprises concentrated sulphuric acid of concentration at least 90%.

### Claim 8 (depends on 1)

A method according to claim 1, wherein a film of the solution is cast onto a plane non-porous surface.

### Claim 9 (depends on 1)

A method according to claim 1, wherein the concentration of the polymer in solution in the solvent is at least 16%.