Akzo N.v.

Heinz-Joachim Muller

Heinz-Dieter Sluma

Gunter Eberhard

Ernst Spindler

Lothar Krauss

Helmut Volker

Membranes are based on a homogeneous mixture of polyvinylidene fluoride and a second polymer which can be rendered hydrophilic by chemical reaction. The membranes contain 70 to 98 percent by weight of polyvinylidene fluoride and 2 to 30 percent by weight of a polymer formed essentially from polymethyl and/or polyethyl acrylate, and have a maximum pore size in the range from 0.005 to 10 .mu.m. They can be rendered hydrophilic by means of at least partial hydrolysis, at least partial transesterification with an alcohol which is at least trihydric and contains 3 to 12 carbon atoms, and/or at least partial aminolysis with an amino compound having 2 to 8 carbon atoms. The flat or capillary membranes which have been rendered hydrophilic can contain on their total surface 0.001 to 10 milliequivalents/g of membrane, preferably 0.01 to 5 m equivalents/g of membrane, of --COOH, --OH or --NH.sub.2 groups or corresponding mixtures of these hydrophilic functional groups. Such membranes can be used, in particular, for immobilizing biochemically active compounds.

Flat or capillary membrane based on a homogeneous mixture of

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 .epsilon.-caprolactam as the essential dissolving constituent. The solution may be formed before the phase separation is triggered.

Growing community of inventors

Worth, Germany

Heinz-Joachim Muller