PRODUCTION OF GAS PERMEABLE COMPOSITE FILM

PURPOSE:To produce the film having gas permeability and gas separability highly resistant to a change with lapse of time by exposing the surface of a thin film consisting of poly-substd. acetylene having a specific constitutional formula to the plasma of an inert gas. CONSTITUTION:The surface of the thin film 5 consisting of the poly-substd. acetylene expressed by the formula (R is 1 to 4C alkyl group) is exposed to the plasma of the inert gas, by which the gas permeable composite film is produced. After the polymer film 5 is mounted on a holder 4, the pressure in a chamber is once reduced to a vacuum and in succession, the inert gas is introduced therein and is regulated to an arbitrary specified pressure. The plasma is thereafter generated by electrodes 3 and the surface of the polymer film 5 is exposed to the inert gaseous plasma. The surface of the polymer film 5 is crosslinked in this way and is further oxidized by the oxygen in the air when the film is taken out into the atm. The gas permeable film having the gas permeability stable over a long period of time is thus obtd.