US4863761A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous process for making coated composite hollow fiber membranes
Assignee: Air Products and Chemicals Inc
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Filing: 1988-02-23
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Granted: 1989-09-05
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Expires: 2008-02-23
Abstract
Abstract The present invention is a process for applying a semi-permeable coating on a hollow fiber substrate. The hollow fiber substrate is continuously passed through a polymeric coating solution and withdrawn from the solution through a coating die to form a uniform polymeric solution coating on the outer surface of the hollow fiber. The coated hollow fiber is dried by passing it through a convective flow tunnel in which the rate of drying is controlled both by a pre-determined temperature profile in the tunnel and by a controlled air flow rate through the tunnel. The resultant material is a semi-permeable, coated composite hollow fiber membrane which can be used in gas and/or liquid separations.
Inventors
- 👤 Pushpinder S. Puri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:51
CPC Classifications
B; B01; B01D; B01D69/00; B01D69/08; B01D69/12; B01D2323/00; B01D2323/06; B01D2323/12; B01D2325/00; B01D2325/20
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
142 words
A continuous process for applying a generally uniform, semi-permeable coating on a hollow fiber substrate to produce a coated composite hollow fiber membrane, said process comprising: (a) passing a hollow fiber substrate suitable as a component of said membrane, at both fixed tension and speed, into a polymeric solution capable of forming a semi-permeable coating on the hollow fiber substrate; (b) removing said hollow fiber substrate from the polymeric solution by axially drawing said substrate through a coating die having a circular annulus such that a polymer solution coating is formed on the substrate surface by axial annular drag flow; and (c) drying said coated hollow fiber by passing it through a convective flow tunnel in which the rate of drying is controlled both by a pre-determined temperature profile within the tunnel and by a controlled air flow rate through the tunnel.
Claim 2
Dependent Claim
142 words
A continuous process for applying a generally uniform, semi-permeable coating on a hollow fiber substrate to produce a coated composite hollow fiber membrane, said process comprising: (a) passing a hollow fiber substrate suitable as a component of said membrane, at both fixed tension and speed, into a polymeric solution capable of forming a semi-permeable coating on the hollow fiber substrate; (b) removing said hollow fiber substrate from the polymeric solution by axially drawing said substrate through a coating die having a circular annulus such that a polymer solution coating is formed on the substrate surface by axial annular drag flow; and (c) drying said coated hollow fiber by passing it through a convective flow tunnel in which the rate of drying is controlled both by a pre-determined temperature profile within the tunnel and by a controlled air flow rate through the tunnel.
Claim 3
Dependent Claim
17 words
A process in accordance with claim 1 wherein said polymeric solution contains less than about 15% solids.
Claim 4
Dependent Claim
25 words
A process in accordance with claim 1 wherein said polymer solution coating on the hollow fiber substrate, after drying, has a thickness between 0.1-100 microns.
Claim 5
Dependent Claim
29 words
A process in accordance with claim 1 wherein said pre-determined temperature profile within the convective flow tunnel is controlled by a heating device encasing a portion of the tunnel.
Claim 6
Dependent Claim
34 words
A process in accordance with claim 4 wherein said heating device encases a portion of said convective flow tunnel which is downstream in relation to the directional movement of the fiber through the tunnel.
Claim 7
Dependent Claim
24 words
A process is accordance with claim 5 wherein said controlled air flow through the convective flow tunnel is counter directional to the hollow fiber.
Claim 8
Dependent Claim
37 words
A process in accorance with claim 6 wherein said controlled air flow enters the convective flow tunnel at a point such that said air flow is heated by said heating device prior to contacting the hollow fiber.
Claim 9
Dependent Claim
34 words
A process in accordance with claim 1 wherein said polymeric solution comprises a solvent containing a polymeric material selected from the group consisting of polysulfones, polyacrylonitriles, polycarbonates, polyacetylenes polyarylethers, polyolefins, and substituted derivatives thereof.
Claim 10
Dependent Claim
20 words
A process in accordance with claim 1 wherein said polymeric solution has a viscosity between 100-25,000 centipoise at room temperature.
Claim 11
Dependent Claim
17 words
A process in accordance with claim 1 wherein said hollow fiber substrate is a microporous polymeric material.
Claim 12
Dependent Claim
29 words
A process in accordance with claim 1 wherein said hollow fiber substrate is initially unwound at a fixed tension and speed from a spool in a continuous, on-line process.
Claim 13
Dependent Claim
27 words
A process in accordance with claim 1 wherein said coated hollow fiber substrate is removed from the convective flow tunnel and continuously wound on a take-up spool.
Claim 14
Dependent Claim
54 words
A process in accordance with claim 1 which further comprises passing said hollow fiber substrate through a series of polymeric solutions and coating dies, wherein each successive coating die has an equal or larger diameter than the previous coating die, such that a plurality of coating layers are formed on the hollow fiber substrate.
Claim 15
Dependent Claim
20 words
A process in accordance with claim 13 wherein the coated hollow fiber is dried after passing through each coating die.
Claim 16
Dependent Claim
24 words
A process in accordance with claim 13 wherein the coated hollow fiber is dried only after passing through all of the successive coating dies.
Claim 17
Dependent Claim
16 words
A process in accordance with claim 13 wherein each polymeric solution contains a different polymer concentration.
Claim 18
Dependent Claim
16 words
A process in accordance with claim 13 wherein each polymeric solution contains a different polymer material.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-04 | 1993-03-06 | 1993-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-04 | 1997-03-06 | 1997-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-04 | 2001-03-06 | 2001-09-05 | $7700.00 | Window Closed / Lapsed |