| 摘要 |
PROBLEM TO BE SOLVED: To easily obtain a non-porous resin film through which a gas can easily pass and a liquid is difficult to pass, by a method wherein a porous resin film made porous by at least being uniaxially stretched is shrunk by being thermally treated at a temperature above the melting point of the resin film so as to substantially block through holes. SOLUTION: A porous resin film made porous by at least being uniaxially stretched is shrunk by being thermally treated at a temperature above the melting point of the resin film so as to substantially block through holes. The shrinkage factor of the resin is preferably 1.0 to 2.0 times as much as the length of the resin film before stretching. As the stock resin, a fluoroplastic is the most favorable one and a PTFE, a tetrafluoroethylene-perfluoroalkylvinylether copolymer or the like is favorable. The preferable heat treatment temperature of PTFE porous tube is 355 to 400 deg.C. A deaerating device 2 is equipped with the inlet 31 and the outlet 32 of a liquid to be treated, and the connecting port 33 with a vacuumizing device. Fluoroplastic tube bundles 4 are arranged within a vacuum chamber 3. |
