SURFACE TREATMENT OF SEPARATING MEMBRANE

摘要

PURPOSE: To improve the sepn. characteristics of a separating membrane with not so much degradation in its gas permeation performance and to improve gas permeating and selecting characteristics without variations by subjecting the dense layer surface consisting of an org. macromolecule of the separating membrane to a low-temp. plasma treatment of a gaseous mixture composed of a chlorine-contg. compd. and a fluorine-contg. compd. CONSTITUTION: The hollow yarn composite membrane is put in the form of a yarn bundle of a length of about 20cm and number of yarn of 30 pieces into the rear part about 40cm from the high-frequency coil part for generating low- temp. plasma wound on a reaction vessel 4 consisting of quartz glass and having a bore of about 10cm, and the inside of this vessel is evacuated to vacuum of 1×10<-3> Torr by a vacuum pump of a rotary type. The pump is thereafter kept operated and while gaseous chlorine and tetrafluorocarbon are passed constantly respectively at about 8Ncm<3> /min and total gas flow rate of 16Ncm<3> / min, a valve 6 is so regulated as to stabilize the vacuum degree in the reaction vessel 4 at 0.17Torr and the low-temp. plasma is generated for two minutes by an electric discharge at high-frequency output of about 200W. The treatment of the hollow yarn membrane is thus executed.