| 摘要 |
<p>PURPOSE: To obtain a multilayered membrane wherein high constant separation efficiency is not changed in a disadvantageous form even during continuous operation by providing a regular structure containing a large amt. of non-porous microcrystals having specific physical properties to a separation layer comprising polyvinyl alcohol. CONSTITUTION: The substrate of a multilayered membrane comprises a polyamide fiber, a polyvinylidene difluoride fiber, a polyester fiber or a glass fiber and the porous support layer thereof comprises polysulfone, polyimide, polyvinyl alcohol, polyurethane, polyvinyliden difluoride, polyether sulfone, polyacrylonitrile or polyetherimide and the separating layer thereof comprises polyvinyl alcohol and has a regular structure containing a large amt. of non-porous microcrystals and these microcrystals have reflection with width 1.2-1.5 deg. at a time of diffraction 2θ=19.6-20 deg. in an X-ray diffraction diagram. This multilayered membrane has high constant separation efficiency.</p> |
