Flerlagsmembran og fremgangsmåde til fremstilling deraf

摘要

Multilayered membrane comprises (a) a carrier layer; (b) a porous support layer; and (c) a sepn. layer. The improvement is that layer (a) comprises polyamide-, polyvinylidenedifluoride-, polyester- or glass fibres; layer (b) comprises a polysulphone, polyimide, polyvinylalcohol, polyurethane, polyvinylidene difluoride; polyether sulphone, polyacrylonitrile or polyetherimide; and layer (c) comprises polyvinylalcohol. Layer (c) is pore free and has an ordered structure with large microcrystalline components, the crystallites of which in the x-ray diffraction pattern, at a diffraction angle 2 theta of 19.6 deg. to 20 deg., have a reflex having a breadth of 1.2 deg. to 1.5 deg.