Patent US4564488A successfully refreshed from Google Patents.
US4564488A
Expired / Lapsed
US
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Methods for the preparation of porous fibers and membranes
Assignee: Membrana GmbH
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Filing: 1983-01-10
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Granted: 1986-01-14
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Expires: 2003-01-10
Abstract
Abstract The invention concerns porous fibers and membranes, methods for their preparation and for their use. The fibers are characterized by a smooth porous surface and an apparent density of between about 10 and 90% of the true density of the polymeric starting material employed. The process involves the formation of a homogeneous mixture of at least two components, one of which is a meltable polymer and another liquid inert with respect to the polymer. The mixture formed must be of a binary type, in which there is a temperature range of complete miscibility and a range in which there is a miscibility gap. The mixture is extruded at a temperature above the separation temperature into a bath containing at least some of the inert liquid which is at a temperature below the separation temperature. Upon introduction of the mixture into the bath, the fiber structure of the product is fixed.
Inventors
- 👤 Klaus Gerlach
- 👤 Erich Kessler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:16
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/26; B01D71/262; B01D69/00; B01D69/02; B01D69/08; B01D69/087; B29; B29C; B29C67/00; B29C67/20; B29C67/205; C; C08; C08J; C08J9/00; C08J9/28; D; D01; D01D; D01D5/00; D01D5/24; D01D5/247; C08J2201/00; C08J2201/04; C08J2201/054; C08J2201/0542; C08J2201/0543; C08J2201/0545; C08J2201/0546
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
127 words
A process for preparation of porous fibers and membranes in the form of flat foils, tube foils or hollow fibers, comprising forming a homogeneous mixture of at least two components, wherein one component is a meltable polymer and a second component is a liquid inert to said polymer which forms a binary mixture with said polymer in its liquid state, said binary mixture in liquid aggregate form exhibiting a temperature range of complete miscibility and a range with a miscibility gap; and extruding said mixture at a temperature above the temperature at which said components separate directly into a bath containing at least some of said inert liquid, said bath having a temperature below said separation temperature, whereby the fiber structure of said porous fiber is fixed.
Claim 2
Dependent Claim
127 words
A process for preparation of porous fibers and membranes in the form of flat foils, tube foils or hollow fibers, comprising forming a homogeneous mixture of at least two components, wherein one component is a meltable polymer and a second component is a liquid inert to said polymer which forms a binary mixture with said polymer in its liquid state, said binary mixture in liquid aggregate form exhibiting a temperature range of complete miscibility and a range with a miscibility gap; and extruding said mixture at a temperature above the temperature at which said components separate directly into a bath containing at least some of said inert liquid, said bath having a temperature below said separation temperature, whereby the fiber structure of said porous fiber is fixed.
Claim 3
Dependent Claim
17 words
A process as defined in claim 1, wherein said fiber is washed after fixing with a solvent.
Claim 4
Dependent Claim
12 words
A process as defined in claim 2, wherein said solvent is acetone.
Claim 5
Dependent Claim
26 words
A process as defined in claim 1, wherein the temperature of said bath is at least 100° C. below said separation temperature of said binary mixture.
Claim 6
Dependent Claim
26 words
A process as defined in claim 1, wherein said homogeneous mixture is extruded into a spinning tube arranged before said bath and filled with bath liquid.
Claim 7
Dependent Claim
12 words
A process as defined in claim 1, wherein said polymer is polypropylene.
Claim 8
Dependent Claim
13 words
A process as defined in claim 1, wherein said inert liquid is N,N-bis-(2-hydroxyethyl)-hexadecylamine.
Claim 9
Dependent Claim
31 words
A process as defined in claim 1, wherein said polymer and said liquid are selected from the group of polymer/liquid systems consisting of low pressure polyethylene/1-dodecanol, high pressure polyethylene/methylnonylketone, and polymethylpentene/2-undecanol.
Claim 10
Dependent Claim
27 words
A process as defined in claim 1, wherein said bath is a temperature-step bath comprising two or more separate baths, each of which has a different temperature.
Claim 11
Dependent Claim
28 words
A process as defined in claim 1, wherein said mixture comprises between about 10 to 90 weight % polymer and about 90 to 10 weight % inert liquid.
Claim 12
Dependent Claim
16 words
A process as defined in claim 1, wherein said components are continuously mixed prior to extrusion.
Claim 13
Dependent Claim
20 words
A process as defined in claim 1, wherein said mixing is effected by means of a rod or pin mixer.
Claim 14
Dependent Claim
42 words
A process as defined in claim 1, wherein said bath is a temperature-gradient bath comprising one or more portions with a temperature gradient of the type in which the temperature from the beginning of the bath until the end is continuously reduced.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-13 | 1989-07-15 | 1990-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-13 | 1993-07-15 | 1994-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-13 | 1997-07-15 | 1998-01-14 | $7700.00 | Window Closed / Lapsed |