EP0330072A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Semipermeable membrane for separating fluids, process for preparing and using the membrane for microfiltration, distillation and special fabrics
Assignee: Separem SpA
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Filing: 1989-02-16
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Granted: —
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Expires: 2009-02-16
Abstract
Abstract The present invention relates to a semipermeable membrane for separating fluids, comprising hydrophobic PVDF. The membrane is asymmetrical and is prepared with a succession of steps comprising: a) preparing a solution comprising PVDF and an organic solvent; b) treating this solution to form a preformed membrane; c) evaporating at least part of the solvent contained in the preformed membrane; d) gelifying the preformed membrane in a coagulation bath; e) washing the preformed membrane to extract the solvent.
Inventors
- 👤 Enrico Drioli
- 👤 Soccorso Gaeta
- 👤 Marco Sogliano
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 01:07
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/28; B; B01; B01D; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/34; D; D06; D06N; D06N3/00; D06N3/04; D06N3/047; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/16
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
18 words
Semipermeable membrane for separating fluids, characterized in that it comprises hydrophobic PVDF and in that it is asymmetrical.
Claim 2
Dependent Claim
18 words
Semipermeable membrane for separating fluids, characterized in that it comprises hydrophobic PVDF and in that it is asymmetrical.
Claim 3
Dependent Claim
32 words
Membrane according to claim 1, characterized in that it is made of substantially pure hydrophobic PVDF and in that it has an average porosity higher than 50% and preferably higher than 80%.
Claim 4
Dependent Claim
25 words
Membrane according to claim 1, characterized in that its thickness is comprised between 50 and 250 microns and preferably comprised between 70 and 120 microns.
Claim 5
Dependent Claim
26 words
Membrane according to claim 1, characterized in that it has pores with an average diameter of 0.01 to 1 micron, preferably of 0.1 to 0.3 microns.
Claim 6
Dependent Claim
16 words
Membrane according to claim 1, characterized in that it used in membrane distillation and/or microfiltration processes.
Claim 7
Dependent Claim
25 words
Membrane according to claim 1, characterized in that it is used in combination with fabrics to produce barriers permeable to vapor and impermeable to water.
Claim 8
Dependent Claim
67 words
Process for preparing a membrane according to claim 1, characterized in that it comprises the following steps: a) preparing a solution comprising PVDF and an organic solvent; b) treating said solution to form a preformed membrane; c) evaporating at least part of the solvent contained in said preformed membrane; d) gelifying said preformed membrane in a coagulation bath; e) washing said preformed membrane to extract the solvent.
Claim 9
Dependent Claim
16 words
Process according to claim 7, characterized in that it comprises a further thermal treatment step f).
Claim 10
Dependent Claim
31 words
Process according to claim 7, characterized in that said treatment for forming said preformed membrane comprises the application of said solution on a support so as to form a planar film.
Claim 11
Dependent Claim
25 words
Process according to claim 7, characterized in that said treatment for forming said preformed membrane comprises the extrusion of said solution to form capillary fibers.
Claim 12
Dependent Claim
35 words
Process according to claim 7, characterized in that the preparation of said solution of PVDF and organic solvent is performed at a temperature comprised between 35°C and 110°C and preferably comprised between 40°C and 70°C.
Claim 13
Dependent Claim
29 words
Process according to claim 7, characterized in that said organic solvent comprises DMF preferably with the addition of PVP so as to control the transport characteristics of the membrane.
Claim 14
Dependent Claim
19 words
Process according to claim 13, characterized in that the PVDF concentration is comprised between 5 and 30% by weight.
Claim 15
Dependent Claim
19 words
Process according to claim 13, characterized in that the PVP concentration is comprised between 0 and 10% by weight.
Claim 16
Dependent Claim
19 words
Process according to claim 7, characterized in that said solution is completely degassed and filtered before said step b).
Claim 17
Dependent Claim
28 words
Process according to claim 9, characterized in that said solution is applied on a fiber support having a weight comprised between 50 and 100 g per square meter.
Claim 18
Dependent Claim
19 words
Process according to claim 16, characterized in that said support has a rib weave and not a plain one.
Claim 19
Dependent Claim
20 words
Process according to claim 9, characterized in that the speed of said application is comprised between 1 and 10 m/min.
Claim 20
Dependent Claim
32 words
Process according to claim 7, characterized in that the humidity in the evaporation region is comprised between 50 and 80% and preferably between 60 and 70% during said solvent evaporation step c).
Claim 21
Dependent Claim
23 words
Process according to claim 7, characterized in that said washing step e) entails a complete extraction of the solvent from said preformed membrane.
Claim 22
Dependent Claim
30 words
Process according to claim 8, characterized in that said thermal treatment is performed for a time comprised between 10 and 100 minutes at a temperature comprised between 70°C and 100°C.
Claim 23
Dependent Claim
16 words
Use of the membrane according to any one of the preceding claims in membrane distillation processes.
Claim 24
Dependent Claim
27 words
Use of the membrane according to any one of the preceding claims, characterized in that it allows to prepare hydrophobic water-repellent fabrics permeable to gases and vapors.
Claim 25
Dependent Claim
13 words
Semipermeable membrane for separating fluids comprising hydrophobic PVDF according to what is described.
Claim 26
Dependent Claim
13 words
Semipermeable membrane for separating fluids comprising hydrophobic PVDF according to what is described.
Claim 27
Dependent Claim
16 words
Process for preparing a semipermeable membrane for separating fluids comprising PVDF according to what is described.
Claim 28
Dependent Claim
16 words
Process for preparing a semipermeable membrane for separating fluids comprising PVDF according to what is described.
References Cited (Backward Citations)
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