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:
Sep. 22, 1998
Filed:
Feb. 21, 1997
Hisao Hachisuka, Osaka, JP;
Kenichi Ikeda, Osaka, JP;
Nitto Denko Corporation, Osaka, JP;
Abstract
A laminated asymmetric membrane comprising first and second asymmetric membranes having different molecular structures, in which the first and second asymmetric membranes are laminated. Consequently, the laminated asymmetric membrane having the excellent property of the separation and permeability can be provided at a low cost. The laminated asymmetric membranes of the present invention is manufactured by the following steps: a film-forming dope (1) was prepared by synthesizing fluorine-containing polyimide having a repeating unit expressed by the following Chemical Formula by using diethylene glycol dimethyl ether as a solvent; a film-forming dope (2) was prepared by dissolving polysulfone in diethylene glycol dimethyl ether; the dope (2) from the resulted two dopes was cast on a polyester nonwoven cloth to a thickness of approximately 50 .mu.m by means of an applicator; the dope (1) was lap coated thereon to a thickness of 30 .mu.m; the dope (2) on which the dope (1) is coated was dipped in water as a solidifying solution at a temperature of 25.degree. C. for 5 minutes and in a water at a temperature of 20.degree. C. for one hour, thus forming a laminated asymmetric membrane. Chemical Formula ##STR1##