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US 7,247,238 B2Granted
Poly(ethylene chlorotrifluoroethylene) membranes
AssigneeSiemens Water Technologies Corp.
InventorsDaniel Mullette, Heinz-Joachim Muller
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AssigneeSiemens Water Technologies Corp.
InventorsDaniel Mullette, Heinz-Joachim Muller
Estimating the term…
Porous polymeric membranes including Halar (poly (ethylene chlorotrifluoroethylene)) and related compounds and the methods of production thereof which avoid the use of toxic solvents. Preferred solvents, coating agents and pore forming agents are citric acid ethyl ester or glycerol triacetate. The membranes may be in the form of a hollow fiber or flat sheet, and may include other agents to modify the properties of the membrane, such as the hydrophilic/hydrophobic balance. Leachable agents may also be incorporated into the membranes.
A porous polymeric membrane, the membrane comprising poly(ethylene chlorotrifluoroethylene) and silica, wherein the porous polymeric membrane further comprises a coating comprising a coating agent comprising at least one compound according to formula I or formula II:
Dependencies are inferred from the claim text.
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After-treatment of organic or inorganic membranes: physical treatment with compounds, e.g. swelling, coating or impregnation
By phase separation, sol-gel transition, evaporation or solvent quenching: thermally induced processes [TIPS]
By mechanical treatment, e.g. pore-stretching: by stretching
By selective elimination of components, e.g. by leaching: by elimination of at least one of the blocks of a block copolymer
Term ended 12 Feb 2023 (estimated)
The invention relates to Halar (ethylene chlorotrifluoroethylene copolymer, or poly (ethylene chlorotrifluoroethylene)) and related membranes for use in ultrafiltration and microfiltration and in particular to membranes in the form of hollow fibres, and to methods of preparing said membranes.
The following discussion is not to be construed as an admission with regard to the common general knowledge in Australia.
Synthetic polymeric membranes are well known in the field of ultrafiltration and microfiltration for a variety of applications including desalination, gas separation, filtration and dialysis. The properties of the membranes vary depending on the morphology of the membrane i.e. properties such as symmetry, pore shape, pore size and the chemical nature of the polymeric material used to form the membrane.
FIGS. 1a and 1b are diagrams of alternative TIPS processes used to prepare HF membranes
FIGS. 2a and 2b are Scanning Electron Micrographs of the membranes of the present invention.
FIGS. 3a and 3b are Scanning Electron Micrographs of the membranes of the present invention.
The TIPS process is described in more detail in PCT AU94/00198 (WO 94/17204) AU 653528, the contents of which are incorporated herein by reference. The current method used to prepare the membranes of the present invention is described herein in simplified form.
In one preferred form of the invention, poly (ethylene chlorotrifluoroethylene) is formed as a hollow fibre. The poly (ethylene chlorotrifluoroethylene) is dissolved in a suitable solvent and then passed through an annular co-extrusion head.
There are two possible ways to conduct the methods of the present invention in relation to hollow fibres. One is via a coextrusion head having three concentric passageways, as shown in cross section FIG. 1b, the other is via a quadruple co-extrusion head having four concentric passageways is shown in cross section in FIG. 1a. The principle is broadly the same in both cases, except for the way the quench fluid is contacted with the fibre.