The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 02, 1982
Filed:
Apr. 21, 1980
Shuzo Yamashita, Kurashiki, JP;
Taku Tanaka, Kurashiki, JP;
Hirokuni Tanii, Kurashiki, JP;
Akira Kubotsu, Soja, JP;
Syuji Kawai, Kurashiki, JP;
Kuraray Co., Ltd., Kurashiki, JP;
Abstract
A hollow fiber membrane made of an ethylene-vinyl alcohol copolymer is provided, which is characterized in that, when observed in a dry state with an electron microscope, the hollow fiber membrane has at least one dense, active layer (or skin layer) on the inside and/or outside surface thereof and further a three-layered structure comprising two layers respectively contacting the inside and outside surfaces and each consisting of a plurality of particles bonded together and having particle sizes of 0.01 to 2 microns and a substantially particle-free homogeneous layer lying between the two layers. A method of producing such hollow fiber membranes is also provided comprising spinning a spinning solution prepared by dissolving an ethylene-vinyl alcohol copolymer in a solvent mainly consisting of dimethyl sulfoxide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone or a mixture of these through a spinneret for hollow fiber production while simultaneously introducing a coagulating liquid through the central aperture of said spinneret, passing the spun fiber through a gaseous atmosphere such that the fiber is drawn to 3 to 30 times its extrusion rate, and coagulating the fiber in a coagulation bath at a temperature within the range specified below: