PURPOSE: To obtain a dry hollow yarn separation membrane for separating oxygen without shrinking said membrane, in drying a wet hollow yarn separation membrane comprising cellulose acetate, by preliminarily heat treating this separation membrane at a specifide temp.
CONSTITUTION: A wet hollow yarn separation membrane comprising cellulose acetate is heat treated at 85W99°C. In this case, the moisture content of this separation membrane is adjusted to about 35W55% and the membrane is dried by a freeze drying method or a solvent replacement method. Herein, when the heat treatment temp. is below the lower limit, shrinkage becomes large and the reversibility of a membrane structure is lost in a dry and a wet conditions and, when the temp. exceeds the upper limit, the membrane is largely shrunk during heat treatment and the performance thereof becomes unsuitable for practical purposes.
MORINO MORIO
KUZUMOTO EIJI
UKAI TETSUO
| JPS5289574A | 1977-07-27 | |||
| JPS51112917A | 1976-10-05 |