| 摘要 |
Hydrophobic planar membrane, made from vinyl fluoride polymer comprising a wall, a first surface and a second surface. On the first surface thereof, the membrane has a network structure comprising open pores and, on the second surface thereof, has a continuous skin in which pores are formed, as well as, adjacent to the skin on the second surface, a support layer comprising pore structures which are isotropic over the wall thickness and which extend over at least 80% of the wall thickness, and the pores of which have a mean diameter of at least 1 µm. The average molecular weight MW of the vinyl fluoride polymer is in the range from 300,000 to 500,000 daltons, and the polydispersity MW/MN is greater than 5.5. The pores in the skin of the second surface have a closed circumference in the plane of the skin, and a mean ratio of the extension in the direction of the longitudinal axis thereof to the extension in the direction of the shortest axis thereof of 5 at the most. The pores in the first surface and in the second surface have a substantially isotropic distribution in the orientation thereof. The porosity of the membrane is in the range from 50 to 90 vol.%, and the wall thickness is in the range from 50 to 300 µm. The membrane has a maximum separation pore diameter dmax in the range from 0.05 to 1.5 µm. |
