Patent US2747021A successfully refreshed from Google Patents.
US4399035A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polyvinylidene fluoride type resin hollow filament microfilter and process for producing the same
Assignee: Asahi Kasei Corp
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Filing: 1980-05-13
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Granted: 1983-08-16
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Expires: 2000-05-13
Abstract
Abstract A screen type hollow filament microfilter made of a polyvinylidene fluoride type resin and having a layer structure of two kinds of layers with the support layer and the internal and external skin layers having an easily-controllable and wide average effective pore diameter of 0.05 to 1.0 μm, characterized by having a high selectivity in permeation, a high permeability, a high porosity, an excellent mechanical strength and an excellent chemical resistance and an excellent inertness to living bodies. The microfilter, which has a number of excellent performances, can be produced by extruding a spinning solution comprising a polyvinylidene fluoride type resin, a solvent therefor and at least one kind of surfactant from an annular hollow filament spinning orifice and coagulating the extrudate by using coagulating liquids.
Inventors
- 👤 Takashi Nohmi
- 👤 Takao Yamada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:50
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/34; B01D61/00; B01D61/14; B01D61/145; B01D61/147; B01D61/18; B01D69/00; B01D69/08; B01D69/082; D; D01; D01D; D01D5/00; D01D5/24
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
159 words
A hollow filament microfilter which comprises a polyvinylidene fluoride type resin membrane having a substantially annular shape in cross-section and comprising internal and external surface skin layers and a support layer connected thereto; said skin layers being uniformly porous layers with a average pore diameter (2r s ) of 0.05 to 1.0 μm, said support layers being a uniformly porous layer with an average pore diameter (2r a ) of 1 to 10 μm, a relationship represented by the formula r a /r s ≧4 being satisfied, said support layer having a plurality of macrovoids extending radially in the substantially annular cross-section of the resin membrane, said macrovoids each having a length of at least 10% and at most 80%, based on the thickness of the resin membrane, in the radially extending axis direction in said cross-section, said resin membrane having an average effective pore diameter (2r) of 0.05 to 1.0 μm and a porosity of 60 to 85%.
Claim 2
Dependent Claim
159 words
A hollow filament microfilter which comprises a polyvinylidene fluoride type resin membrane having a substantially annular shape in cross-section and comprising internal and external surface skin layers and a support layer connected thereto; said skin layers being uniformly porous layers with a average pore diameter (2r s ) of 0.05 to 1.0 μm, said support layers being a uniformly porous layer with an average pore diameter (2r a ) of 1 to 10 μm, a relationship represented by the formula r a /r s ≧4 being satisfied, said support layer having a plurality of macrovoids extending radially in the substantially annular cross-section of the resin membrane, said macrovoids each having a length of at least 10% and at most 80%, based on the thickness of the resin membrane, in the radially extending axis direction in said cross-section, said resin membrane having an average effective pore diameter (2r) of 0.05 to 1.0 μm and a porosity of 60 to 85%.
Claim 3
Dependent Claim
22 words
A hollow filament microfilter according to claim 1, which has a water permeability of at least 8 m 3 /m 2 .day.atm.
Claim 4
Dependent Claim
23 words
A hollow filament microfilter according to claim 1, which has a change of up to 30% in water permeability by repeated drying operations.
Claim 5
Dependent Claim
19 words
A hollow filament microfilter according to claim 1, which has a burst strength of 2.5 kg/cm 2 or more.
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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) | 1986-08-15 | 1987-02-14 | 1987-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-15 | 1991-02-14 | 1991-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-15 | 1995-02-14 | 1995-08-16 | $7700.00 | Window Closed / Lapsed |