United States Patent [19] [ii] Patent Number: 4,968,733
Miiller et al. [45] Date of Patent: Nov. 6,1990
U.S. Patent Nov. 6,1990 Sheet 1 of 4 4,968,733
[54] PROCESS FOR PRODUCING
MICROPOROUS POWDERS AND
MEMBRANES
[75] Inventors: Heinz-Joachim Miiller; Friedbert
Wechs, both of Worth, Fed. Rep. of
Germany
[73] Assignee: Akzo N.V., Arnhem, Netherlands
[21] Appl. No.: 401,854
[22] Filed: Sep. 1,1989
[30] Foreign Application Priority Data
Sep. 1, 1988 [DE] Fed. Rep. of Germany 3829766
[51] Int. C1.5 C08J 9/28
[52] U.S. CI 521/64} 521/50;
521/61; 521/90; 424/DIG. 7; 210/500.21
[58] Field of Search 521/50, 64, 90, 61;
524/98
[56] References Cited
U.S. PATENT DOCUMENTS 4,806,291 2/1989 Susa 521/61
A process produces microporous powders or shaped articles, in particular membranes in the form of flat films, tubular films or hollow fibers, which may be used for controlled release of an active compound, for dialysis, gas separation, ultrafiltration or microfiltration, from polyvinylidene fluoride and/or polyphenylene sulfide and/or polysulfone and/or polyacrylonitrile and/or ethylene/vinyl alcohol copolymer and/or ethylene/chlorotrifluoroethylene copolymer and/or polyethersulfone and/or polyether-imide and/or polymethyl methacrylate and/or polycarbonate and/or cellulose triacetate. The process utilizes phase separation by means of thermally induced triggering or triggering induced by a non-solvent of a solution of the polymer in a mixture containing e-caprolactam as the essential dissolving constituent. The solution may be formed before the phase separation is triggered.
11 Claims, 4 Drawing Sheets
