Claims
- 1. A method of producing polymeric membranes, comprising, enabling a substantial increase of draw ratios while at least maintaining the selectivity and mechanical properties of said membrane, by
- supplying a spin dope of a hydrophillic, aromatic polymer that has a non-linear subunit in the repeating unit of the main polymer chain to an extrusion means to extrude a continuous, nascent preform of said polymer which travels through an air-gap prior to contacting said nascent preform with fluid to coagulate said nascent preform into a polymeric membrane,
- drawing said membrane by a drawing means, and
- controlling said supplying and said drawing to provide polymeric membranes that show improved selectivity and mechanical properties.
- 2. The method of claim 1 wherein said drawing means is a roll.
- 3. The method of claim 1 wherein said polymer is selected from the group of polyaramides, polyamides, polyimides, polyamide/imides, polyamidehydrazides, polyhydrazides, polyimidazoles, polybenzoxazoles, polyester, polyester/amide, polyester/imide, polycarbonate, polycarbonate/amides, polycarbonate/imides, polysulfone/amides, and polysulfone/imides.
- 4. The method of claim 1 wherein said polymer is polyaramide.
- 5. The method of claim 4 wherein said polyaramide is selected from the group of ##STR5## and mixtures thereof.
- 6. The method of claim 1 wherein said hollow nascent preforms are hollow fibers.
- 7. The method of claim 6 further including the step of injecting a bore fluid into the interior of said hollow nascent preform during extruding of said preform.
- 8. The method of claim 7 wherein said fluid is a gas.
- 9. The method of claim 8 wherein said gas is nitrogen.
- 10. The method of claim 7 wherein said bore fluid is selected from the group of dimethylacetamide, N-methylpyrollidone, dimethylformamide, water and mixtures thereof.
- 11. The method of claim 1 wherein said fluid is water or an aqueous solution of a solvent selected from the group of dimethylacetamide, N-methylpyrolidone, dimethylformaide, and aliphatic alcohols.
- 12. The method of claim 1 wherein said drawing and said supplying is performed to provide a draw ratio between 1-30.
Parent Case Info
This is a division of application Ser. No. 574,870, filed Aug. 30, 1990.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4071454 |
Yamamoto et al. |
Jan 1978 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
574870 |
Aug 1990 |
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