US4482514A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of an ultrafiltration membrane from polyamide
Assignee: Membrana GmbH
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Filing: 1981-07-20
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Granted: 1984-11-13
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Expires: 2001-07-20
Abstract
Abstract A process is disclosed for the production of a membrane suitable for ultrafiltration and cast from a solution in formic acid of a polyamide or a mixture of polyamides, characterized by bringing the solution produced with the addition of about 1 to 7% polyethylene glycol to a temperature below about 18 DEG C., applying the solution as thin layer onto a carrier film resistant to the constituents of the solution, conducting this solution through a precipitating and washing bath moving in the reverse direction, with said layer, subsequent to emerging from the bath, being stripped from the carrier film as a coagulated and washed membrane and dried thereafter. Preferred embodiments include stretching the membrane, prior to drying, to a ratio from 1.5:1 to 2.5:1; subjecting it to heat setting in conjunction with the drying; using a minimum formic acid concentration of 80% for the solution or mixture; using 12 to 22% polyamide in the solution or mixture; and employing an air stretch of 2 seconds, before the precipitating and washing bath.
Inventors
- 👤 Erich Schindler
- 👤 Franz Maier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:46
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/56
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
160 words
Process for the production of a cast membrane suitable for ultrafiltration, composed of an ultrafiltration skin and a porous support layer, from a solution in formic acid of a polyamide or a mixture of polyamides, comprising providing as a casting solution about 12 to 22% polyamide and about 1 to 7% polyethylene glycol in formic acid having a minimum concentration of 75%, bringing said solution to a temperature of below about 18° C., applying said solution as a thin layer onto a carrier film resistant to the components of said solution, moving said applied solution on said carrier film through a precipitating and washing bath moving countercurrent to said moving carrier film, removing said applied solution from said precipitating and washing bath, stripping said applied solution as a coagulated and washed membrane from said carrier film, stretching said coagulated and washed membrane in at least one direction from about 1.5:1 to 2.5:1 and drying said stretched coagulated and washed membrane.
Claim 2
Dependent Claim
160 words
Process for the production of a cast membrane suitable for ultrafiltration, composed of an ultrafiltration skin and a porous support layer, from a solution in formic acid of a polyamide or a mixture of polyamides, comprising providing as a casting solution about 12 to 22% polyamide and about 1 to 7% polyethylene glycol in formic acid having a minimum concentration of 75%, bringing said solution to a temperature of below about 18° C., applying said solution as a thin layer onto a carrier film resistant to the components of said solution, moving said applied solution on said carrier film through a precipitating and washing bath moving countercurrent to said moving carrier film, removing said applied solution from said precipitating and washing bath, stripping said applied solution as a coagulated and washed membrane from said carrier film, stretching said coagulated and washed membrane in at least one direction from about 1.5:1 to 2.5:1 and drying said stretched coagulated and washed membrane.
Claim 3
Dependent Claim
18 words
Process according to claim 1, wherein said stretching is effected by drawing said membrane over a drawing rod.
Claim 4
Dependent Claim
27 words
Process according to claim 2, wherein said membrane is stretched by drawing over a drawing rod which has been uniformly heated to about 130° to 140° C.
Claim 5
Dependent Claim
19 words
Process according to claim 1, further comprising subjecting the membrane to heat setting in conjunction with the drying procedure.
Claim 6
Dependent Claim
35 words
Process according to claim 4 wherein the membrane is initially warmed for heat setting to about 130° C. and then is finish-dried at about 60° to 80° C. with prevention of longitudinal and/or lateral contraction.
Claim 7
Dependent Claim
19 words
Process according to claim 1, employing, for preparing the solution, formic acid with a minimum concentration of about 80%.
Claim 8
Dependent Claim
23 words
Process according to claim 1, employing in the solution, about 14 to 20% polyamide in formic acid having a minimum concentration of 75%.
Claim 9
Dependent Claim
11 words
Process according to claim 1 using nylon 6 as the polyamide.
Claim 10
Dependent Claim
11 words
Process according to claim 1 using nylon 6,6, as the polyamide.
Claim 11
Dependent Claim
23 words
Process according to claim 1, wherein the solution contains a copolymer of a polyamide from AH salt and ε-caprolactam dissolved in formic acid.
Claim 12
Dependent Claim
15 words
Process according to claim 1, wherein the solution contains about 2 to 5% polyethylene glycol.
Claim 13
Dependent Claim
16 words
Process according to claim 1, wherein the temperature of the solution is below approximately 15° C.
Claim 14
Dependent Claim
35 words
Process according to claim 1, wherein the solution applied to the carrier film is put into the washing and precipitating bath after having remained in the ambient air for a minimum of about 2 seconds.
Claim 15
Dependent Claim
19 words
Process according to claim 1, wherein the temperature of the washing bath is held to below about 15° C.
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) | 1987-11-13 | 1988-05-14 | 1988-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-13 | 1992-05-14 | 1992-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-13 | 1996-05-14 | 1996-11-13 | $7700.00 | Window Closed / Lapsed |