US4879036A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Asymmetrical membrane of polyester-amide and process for preparing it
Assignee: Eni Tecnologie SpA
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Filing: 1987-06-09
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Granted: 1989-11-07
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Expires: 2007-06-09
Abstract
Abstract An asymmetrical membrane for use in dialysis and ultra-filtration is prepared using a polyester-amide (TATE) n , wherein T represents a radical of terephthalic acid, A represents a radical of hexamethylenediamine, and E represents a radical of hexanediol, in a solvent of formic acid or in a solvent comprising a solution of lithium chloride in dimethylformamide or dimethylacetamide. The polyester-amide (TATE) n is formed into a thin layer and placed into an aqueous coagulation bath to coagulate the resulting membrane. The membrane has a thickness of from 15 to 190 μm, a water permeability of from about 3 up to about 9 liters/m 2 /hour for a ΔP of 300 mm HG and is permeable for substances having a molecular weight of up to about 17,000.
Inventors
- 👤 Francesco Pittalis
- 👤 Francesco Bartoli
- 👤 Otello Farias
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:53
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/56
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
114 words
An asymmetrical membrane suitable for dialysis and ultrafiltration comprising: polyester-amide (TATE) n , wherein T represents a radical of terephthalic acid, A represents a radical of hexamethylenediamine, and E represents a radicla of hexanediol, said polyester-amide having a relative viscosity of from 2 to 2.5, a content of free carboxy groups of from 15 to 25 meq/kg, and a melting point of from 252° to 260° C., said membrane displaying a thickness of from 15 to 190 μm, a water permeability of from about 3 up to about 9 liters/m 2 /hour, for a ΔP of 300 mm Hg and being effectively permeable for substances having a molecular weight of up to about 17,000.
Claim 2
Dependent Claim
114 words
An asymmetrical membrane suitable for dialysis and ultrafiltration comprising: polyester-amide (TATE) n , wherein T represents a radical of terephthalic acid, A represents a radical of hexamethylenediamine, and E represents a radicla of hexanediol, said polyester-amide having a relative viscosity of from 2 to 2.5, a content of free carboxy groups of from 15 to 25 meq/kg, and a melting point of from 252° to 260° C., said membrane displaying a thickness of from 15 to 190 μm, a water permeability of from about 3 up to about 9 liters/m 2 /hour, for a ΔP of 300 mm Hg and being effectively permeable for substances having a molecular weight of up to about 17,000.
Claim 3
Dependent Claim
16 words
The asymmetrical membrane according to claim 1, having a thickness of from 30 to 180 μm.
Claim 4
Dependent Claim
116 words
A process for preparing an asymmetrical membrane having permeability for substances of up to a high molecular weight for use in dialysis and ultra-filtration comprising: (a) preparing a solution of polyester-amide (TATE) n , wherein T represents a radical of terephthalic acid, A represents a radical of hexamethylenediamine, and E represents a radical of hexanediol, in a solvent comprising formic acid or in a solvent comprising a solution of lithium chloride in dimethylforamide or dimethylacetamide; (b) spreading said solution of polyester-amide (TATE) n on a flat support to form a thin layer; (c) dipping said coated support into an aqueous coagulation bath to coagulate said membrane on top of said support; and (d) recovering said membrane.
Claim 5
Dependent Claim
116 words
A process for preparing an asymmetrical membrane having permeability for substances of up to a high molecular weight for use in dialysis and ultra-filtration comprising: (a) preparing a solution of polyester-amide (TATE) n , wherein T represents a radical of terephthalic acid, A represents a radical of hexamethylenediamine, and E represents a radical of hexanediol, in a solvent comprising formic acid or in a solvent comprising a solution of lithium chloride in dimethylforamide or dimethylacetamide; (b) spreading said solution of polyester-amide (TATE) n on a flat support to form a thin layer; (c) dipping said coated support into an aqueous coagulation bath to coagulate said membrane on top of said support; and (d) recovering said membrane.
Claim 6
Dependent Claim
21 words
The process according to claim 3, wherein said layer of polyester-amide (TATE) n is from 20 to about 200 μm thick.
Claim 7
Dependent Claim
19 words
The process according to claim 3, wherein said solvent comprises formic acid at a concentration higher than about 99%.
Claim 8
Dependent Claim
40 words
The process according to claim 3, wherein said polyester-amide has a relative viscosity of from 2 to 2.5, a content of free carboxy groups of from 15 to 25 meq/kg, and a melting point of from 252° to 260° C.
Claim 9
Dependent Claim
34 words
The process according to claim 6, wherein said polyester-amide has a relative viscosity of about 2.3, a content of free carboxy groups of about 22 meq/kg, and a melting point of abou 255° C.
Claim 10
Dependent Claim
57 words
The process according to claim 3, wherein said solvent is a solution of 2-7 parts by weight of lithium chloride in 100 parats by weight of dimethylformamide or of dimethylacetamide and in said solvent said polyester-amide is dissolved in an amount of from 15 to 35 parts by weight per each 100 parts by weight of solvent.
Claim 11
Dependent Claim
30 words
The process according to claim 8, wherein said solvent is a solution of 4-6 parts by weight of lithium chloride in 100 parts by weight of dimethylformamide or of dimethylacetamide.
Claim 12
Dependent Claim
31 words
The process according to claim 3, wherein said polyester-amide is dissolved in said formic acid up to an amount of from 15 to 35 parts by weight of said formic acid.
Claim 13
Dependent Claim
23 words
The process according to claim 3, wherein the solution of said polyester-amide is spread at a temperataure of from 8° to 100° C.
Claim 14
Dependent Claim
27 words
The process according to claim 3, wherein said aqueous coagulation bath is kept at about room temperature and the coagulation time is from 1 to 10 minutes.
Claim 15
Dependent Claim
16 words
The process according to claim 12, wherein the coagulation time is from 3 to 5 minutes.
Claim 16
Dependent Claim
12 words
An asymmetrical membrane is produced according to the process of claim 3.
Claim 17
Dependent Claim
15 words
The membrane according to claim 14 having a thickness of from 30 to 180 μm.
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) | 1992-11-06 | 1993-05-08 | 1993-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-06 | 1997-05-08 | 1997-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-06 | 2001-05-08 | 2001-11-07 | $7700.00 | Window Closed / Lapsed |