Claims
- 1. A process for producing a polyvinyl alcohol-based hollow fiber membrane, which comprises forming said polyvinyl alcohol-based hollow fiber membrane by dry-jet wet spinning or wet spinning of a spinning dope with a spinneret having a heat insulated structure, thereby preventing said spinning dope from undergoing partial phase separation by cooling in the spinneret.
- 2. The process of claim 1, wherein said spinning dope comprises a solution of a vinyl alcohol-based polymer as a principal component, a pore-forming agent and a solvent capable of dissolving said vinyl alcohol-based polymer and said pore-forming agent and having an upper critical separation temperature of from about 30 to 95.degree. C.
- 3. The process of claim 2, which further comprises spinning the spinning dope at a temperature of an external coagulating bath with an internal coagulating liquid being set lower than said upper critical separation temperature.
- 4. The process of claim 2, wherein said pore-forming agent is selected from the group consisting of polyethylene glycol, polypropylene glycol, tetraethylene glycol, triethylene glycol, ethylene glycol, lower alkyl alcohols, polyhydric alcohols and lower alkyl esters.
- 5. The process of claim 4, wherein said polyhydric alcohol is glycerine or butanediol or a mixture thereof.
- 6. The process of claim 4, wherein said lower alkyl ester is ethyl lactate or butyl lactate or a mixture thereof.
- 7. The process of claim 2, wherein said solvent is selected from the group consisting of water, alcohol/water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide and N-methylpyrrrolidone.
- 8. The process of claim 7, wherein said solvent is water.
- 9. The process of claim 2, wherein said spinning dope further comprises boric acid, acetic-acid, a surfactant or an anti-foaming agent or a mixture thereof.
- 10. The process of claim 9, wherein said spinning dope has a an upper critical separation temperature of from 50 to 90.degree. C.
- 11. The process of claim 1, wherein said vinyl alcohol-based polymer has a degree of polymerization of from about 500 to 16,000.
- 12. The process of claim 11, wherein said vinyl alcohol-based polymer has a degree of polymerization of at least about 1,700.
- 13. The process of claim 1, wherein a bath draft thereof is set at about 1.0 to 20.0.
- 14. The process of claim 1, wherein the spinning dope has a concentration of vinyl alcohol-based polymer of from about 1 to 50% by weight.
- 15. The process of claim 14, wherein the spinning dope has a concentration of vinyl alcohol-based polymer of from about 3 to 20% by weight.
- 16. The process of claim 1, which further comprises treating said formed polyvinyl alcohol-based hollow fiber membrane with treatment comprising drawing, neutralization, water washing, wet heat treatment, sodium sulfate substitution, membrane modification or drying or a combination thereof.
- 17. The process of claim 16, wherein said membrane modification comprises acetalization, etherification, esterification or crosslinking.
Priority Claims (1)
Number |
Date |
Country |
Kind |
7-137803 |
Jun 1995 |
JPX |
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Parent Case Info
This application is a Division of application Ser. No. 08/655,974, filed on May 31, 1996, now U.S. Pat. No. 5,789,081.
US Referenced Citations (8)
Foreign Referenced Citations (2)
Number |
Date |
Country |
54-15268 |
Jun 1979 |
JPX |
54-40654 |
Dec 1979 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
655974 |
May 1996 |
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