気体分離用ポリイミド非対称膜の研究-1-製膜法の基礎

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Asymmetric membrane of polyimid which has thermal stability upto 703K and good solvent resistivity was tried to fabricate through casting its precursor polyamic acid solution of dimethylacetamide on a flat glass plate. For the purpose to obtain better membrane, preparative condition such as coagulation solutions, additives and imidization were examined. As for coagulation solution, toluene and xylene give good membranes in thirteen of solutions tested. As for additives the only phenanthrene give a membrane. The imidization was carried out at 573K for 1 hour in the dioctyl sebacate under the nitrogen atmosphere. The imidized membrane was submerged in methanol more than 10 hours and then dried at room temperature at 5 torr. The dried membrane was tested for separation of gaseous mixture of CO2-CH4 ration of 1 : 1 and for permeability of pure gases. The best membrane showed that separation factors was 3 for CO2-CH4 mixture and permeability was 2×10-10mol/ (m2 ·s·Pa) at 423K, with the increase of temperature upto 473K separation factors downed to 2.5 and permeability increased to 3×10-10 mol/ (m2 ·s·Pa). The logarithm of the permeability of gases such as N2, CH4, CO2, CH2OH, C6 H5CH3, H2 O increase linearly with the increase of the boiling point of the gases except hydrogen and helium. The permeability of organic gases such as methanol and toluene show smaller value than inorganic gases.
日本膜学会の論文