| 摘要 |
PURPOSE: To highly separate the concentrated solution by high separating performance when the reverse osmosis separation is carried out under the high pressure by composing asymmetrically two kinds of films with specified porous diameter or more, or less respectively. CONSTITUTION: A composite film cover with a separating function film 1 having the separating performance is used on a porous support film 2 as a film for separating a liquid mixture. The porous substrate film 2 to be used is provided with two layers consisting of an A layer 4 having the porous diameter mainly of 200nm or less and a B layer 5 having the porous diameter mainly of 200nm or more, and the thickness of A layer 4 is 2μm or more and the thickness of B layer 5 is 8μm or more, and the ratio X of the thickness A layer 4 to the total of the thickness of A layer 5 and B layer 5 is 20% or more. The film thus formed is of high resistance to pressure, and even when the pressure of 70atm is applied, the variation of the separating characteristics of the film is small, and when the operation is carried out under the pressure of 70atm or more, the variation with time of the film is small.
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