To provide a method for controlling a membrane forming stock solution controlling fluctuation of composition in a specified range even using a dope obtained by solving at least two kind of polymers as a stock solution for membrane forming and to provide a method for producing porous membrane using the method for controlling the stock solution.
The invention relates to the method for controlling the membrane forming stock solution comprising characterization of fluctuation of composition of the stock solution which contains the dope obtained by solving at least two kinds of polymers. The fluctuation of the composition is controlled by characterizing the fluctuation of the viscosity and the refractive index wherein the accuracy of measurement of the viscosity is preferably set within ±500 cP and the accuracy of measurement of the refractive index is preferably set within ±0.0002. The method for producing the porous membrane comprises wet forming of the stock solution controlled by the method, into the porous membrane, wherein stock solutions obtained by dissolving polyvinylidene fluoride or polyvinylpyrrolidone are preferably used.
FUKUBA YOSHINORI
MINAGAWA MASAKAZU
MURASE KEI
