| 摘要 |
A process for preparing permeable membranes which comprises mixing in the molten state two different kinds of thermoplastic synthetic resins which are partly compatible with each other, shaping the molten mixture into a sheet- or film-like melt, passing the film- or sheet-like melt through a heated zone, cooling and solidifying it, the time from the shaping of the molten mixture into the film- or sheet-like melt to its cooling and solidification (melt maintenance time) being adjusted to 10 to 600 seconds, treating the resulting film or sheet with a solvent which is a good solvent for one of the component resins but is a poor solvent for the other to dissolve and remove the soluble resin, and drying the product. In place of the resin to be removed by the solvent, rubbers or oligomers having partial compatibility with the resin which remains undissolved can be used.
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