US4051300A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hollow synthetic fibers
Assignee: TOPS SYSTEMS Inc
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Filing: 1976-02-27
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Granted: 1977-09-27
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Expires: 1996-02-27
Abstract
Abstract Hollow synthetic fibers useful in reverse osmosis, ultrafiltration, gas separation and the like, having high hydraulic permeability to the solvent and capable of operation at pressures from 600 psi and up, are prepared by forming a solution of a fiber-forming polymer in a suitable solvent, adding to the solution a second polymer soluble in the solvent but with limited compatibility with the first polymer when their total concentration increases on coagulation, extruding the resulting solution through an orifice equipped for coaxial extrusion so that coagulating fluid within tube flow results, precipitating with a liquid which is miscible with the solvent for the fiber-forming material, is a non-solvent for the first polymer and a solvent for the second, contacting the extruded solution with the precipitating liquid either coaxially through the extrusion device or by passing the extrudate through the precipitating liquid, and finally washing the resulting hollow fiber free of residual solvents and non-solvents, and air drying. The coagulating fluid and the precipitating liquid may be the same material. The coagulating fluid may be air or another gas.
Inventors
- 👤 Elias Klein
- 👤 James K. Smith
- 👤 Frederick C. Morton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:42
CPC Classifications
D; D01; D01D; D01D5/00; D01D5/24; B; B01; B01D; B01D67/00; B01D67/0002; B01D67/0023; B01D67/003; B01D69/00; B01D69/08; B01D2323/00; B01D2323/12; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2973; Y10T428/2975
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
211 words
In the method of forming a microporous high strength hollow fiber suitable for reverse osmosis, ultrafiltration and gas separations, said fiber having a continuous axial channel, said micropores having a size range less than 0.25 microns and said fibers capable of withstanding over 600 psi of applied pressure, the steps comprising: a. forming a solution of a fiber-forming polymer, and adding to said solution a second polymer consisting of polyvinylpyrrolidone having an average molecular weight of at least 2000 to form a stable two polymer solution from which the two polymers separate on coagulation, where the sum of the weight percent of the fiber-forming polymer and the weight percent of the second polymer of polyvinylpyrrolidone is at least 15 and not over 65, and the ratio of the fiber-forming polymer to the weight percent of the second polymer of polyvinylpyrrolidone is at least 0.5 and not over 55; b. extruding the resulting polymer solution through an orifice equipped for coaxial extrusion; c. contacting the extrudate with a precipitating liquid that is miscible with the solvent for the fiber-forming polymer, is a non-solvent for the fiberforming polymer, and is a solvent for the second polymer of polyvinylpyrrolidone, and d. washing the resulting hollow fiber substantially free of residual solvents and non-fiber-forming material.
Claim 2
Dependent Claim
211 words
In the method of forming a microporous high strength hollow fiber suitable for reverse osmosis, ultrafiltration and gas separations, said fiber having a continuous axial channel, said micropores having a size range less than 0.25 microns and said fibers capable of withstanding over 600 psi of applied pressure, the steps comprising: a. forming a solution of a fiber-forming polymer, and adding to said solution a second polymer consisting of polyvinylpyrrolidone having an average molecular weight of at least 2000 to form a stable two polymer solution from which the two polymers separate on coagulation, where the sum of the weight percent of the fiber-forming polymer and the weight percent of the second polymer of polyvinylpyrrolidone is at least 15 and not over 65, and the ratio of the fiber-forming polymer to the weight percent of the second polymer of polyvinylpyrrolidone is at least 0.5 and not over 55; b. extruding the resulting polymer solution through an orifice equipped for coaxial extrusion; c. contacting the extrudate with a precipitating liquid that is miscible with the solvent for the fiber-forming polymer, is a non-solvent for the fiberforming polymer, and is a solvent for the second polymer of polyvinylpyrrolidone, and d. washing the resulting hollow fiber substantially free of residual solvents and non-fiber-forming material.
Claim 3
Dependent Claim
33 words
The process of claim 1 in which the sum of the weight percent of the fiber-forming polymer and the weight percent of the second polymer is at least 25 and not over 50.
Claim 4
Dependent Claim
13 words
The process of claim 1 including the drying of the washed hollow fiber.
Claim 5
Dependent Claim
14 words
The process of claim 1 in which the fiber-forming polymer is an aromatic polysulfone.
Claim 6
Dependent Claim
14 words
The process of claim 1 in which the fiber-forming polymer is an aromatic polyamide.
Claim 7
Dependent Claim
16 words
The process of claim 4 in which the solvent for the fiber-forming polymer is dimethyl acetamide.
Claim 8
Dependent Claim
15 words
The process of claim 1 in which the solvent for the fiber-forming polymer is dimethylformamide.
Claim 9
Dependent Claim
21 words
The process of claim 6 in which the precipitating liquid is a mixture of dimethyl acetamide containing at least 25% water.
Claim 10
Dependent Claim
16 words
The process of claim 7 in which the precipitating agent is an aqueous solution of dimethylformamide.
Claim 11
Dependent Claim
17 words
The process of claim 1 in which the precipitating liquid is introduced coaxially through the extrusion device.
Claim 12
Dependent Claim
22 words
The process of claim 1 in which an inert gas is introduced coaxially through the extrusion device to coagulate the polymer solution.
Claim 13
Dependent Claim
17 words
The process of claim 1 in which the precipitating liquid is a mixture of water and isopropanol.
Claim 14
Dependent Claim
51 words
A microporous high strength hollow fiber suitable for reverse osmosis, ultrafiltration and gas separation, said fiber having a continuous axial channel, said micropores having a size range less than 0.25 microns and said fiber capable of withstanding at least 600 psi of applied pressure made by the process of claim 1.
Claim 15
Dependent Claim
33 words
The process of claim 1 in which the ratio of the weight percent of the fiber-forming polymer to the weight percent of the second polymer is at least 1.0 and not over 35.0.
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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) | 1980-09-26 | 1981-03-28 | 1981-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-26 | 1985-03-28 | 1985-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-26 | 1989-03-28 | 1989-09-27 | $7700.00 | Window Closed / Lapsed |