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:
Jan. 20, 1976
Filed:
Apr. 26, 1973
Yasuo Hashino, Matsudoshi, JA;
Masatsugu Yoshino, Tokyo, JA;
Hitoshi Sawabu, Tokyo, JA;
Sukeo Kawashima, Osaka, JA;
Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, JA;
Abstract
Membranes of acrylonitrile polymers having water-permeability greater than 0.2 ml/cm.sup.2.min.atm and useful as an inexpensive superior ultrafilter, comprising (1) a porous layer or layers existing near and on the surfaces of said membranes, the average sizes of pores contained in said porous layer or layers and existing on each of assumptive parallel planes to the surfaces of said membranes, having such a gradient that said average sizes become smaller toward the surfaces of said membranes, and (2) a reticulate porous layer adjacent to said porous layer or layers (1) and containing therein a succession of voids of cylindrical shape or revolving ellipsoid shape having diameters of 5 - 50.mu. and lengths of at least 10.mu., are prepared by dissolving an acrylonitrile polymer in an aqueous solution of nitric acid of 65 - 95% by weight concentration, casting the resulting solution on a support followed by coagulation in a coagulation bath, or extruding the resulting solution from a slit into a coagulation bath, the coagulation bath being water alone or a nitric acid aqueous solution of 30% by weight or less.