JP2851417B2 - Orientation separation membrane and method for producing the same - Google Patents

Description

The present invention relates to a separation membrane such as a microfiltration membrane, an ultrafiltration membrane, or a reverse osmosis membrane used for various separations. The present invention relates to a separation membrane oriented in a thickness direction.

[Problems to be solved by conventional technology and invention]

Separation membranes used for membrane separation such as reverse osmosis processes include
Various resistances such as heat resistance, mechanical strength, and chemical resistance are required, and none of them satisfy all of them.

For example, composite reverse osmosis membranes are usually obtained by interfacial polymerization reactions between immiscible solutions of two reactants. By performing such a reaction on the surface of the microporous support, a dense layer obtained by interfacial polymerization is formed on the surface of the porous support. The composite membrane obtained by such a method usually has excellent selectivity, but when the thickness of the dense layer is several tens μm or more, the permeability is too small. Although the ultrathin film has good transmission performance, it has problems that it is difficult to eliminate defects and that it has poor chemical resistance and mechanical resistance.

[Means for solving the problem]

The inventors of the present invention have conducted intensive studies to solve the above-described problems. It has been found that the present invention has been achieved.

That is, the present invention provides an alignment separation film formed by interfacial polymerization in a state where a DC voltage is applied, and a method for manufacturing an alignment separation film including the following steps.

(A) applying a bifunctional reactant (A) solution to a support; (b) applying a DC voltage to the coated support in a direction perpendicular to the surface thereof; and (c) applying a DC voltage. In the state, on the coated support (A)
Contacting a solution of a bifunctional reactant (B) that reacts with

In the present invention, the bifunctional reactant (A) includes:
From the point that the polymerization reaction can be performed under ordinary conditions, NH groups and NH ₂
Those having two reactive groups such as a group are preferable, for example, metaphenylenediamine, paraphenylenediamine, And the like, and one or more of such amine reactants.
As the solution of the reactant, water is preferably used. The solution may further contain other polyfunctional reactants,
Additives for wetting the support (for example, ionic surfactants such as SLS, hydrochloric acid such as HCl,
Tetraethylamine, benzenesulfonic acid, etc.) can also be added.

As the reactant (B) to be interfacially polymerized with the reactant (A), those having two reactive groups are necessary because they need to react with the reactant (A) to form a linear polymer chain. Those which are preferable and which can be used for the solvents described below are preferable.
For example, para methoxy chloride, meta methoxy chloride, One or more of these are used. Examples of the solution of the reactant (B) include, for example, benzene, DMF, DMAc, and IP solvents (aliphatic hydrocarbon solvents having 6 to 7 carbon atoms) which are not mixed with the solution of the reactant (A). .

In the present invention, the two kinds of reactants are interfacially polymerized on a support under a DC voltage applied state, and then dried under a voltage applied state, whereby the separation membrane of the present invention can be obtained. If necessary, the support may be peeled off to form a separation membrane.

Here, the DC voltage application condition depends on the type of the reactants, the distance between the electrodes, the temperature, the target film thickness, and the like.
There is no particular limitation. Normally, 20 to 200 ° C, DC voltage several V
To several KV, preferably 1 to 10 KV.

As the support, for example, a microfiltration membrane or an ultrafiltration membrane made of polysulfone, polyimide, cellulose acetate or the like is used.

In the separation membrane of the present invention, the molecular chains of the dense layer are oriented and grown in the voltage application direction, that is, the thickness direction of the membrane, by the above specific method.

〔The invention's effect〕

The orientation separation film in the present invention has higher permeation performance and rejection performance than the conventional film.

〔Example〕

A 0.25% aqueous solution of metaphenylenediamine was applied to the polysulfone ultrafiltration membrane. This coated film was placed between two electrodes made of stainless steel and kept at room temperature for 50 minutes.
V or 100 V DC voltage was applied. Next, an IP solvent solution containing 0.1% of paramethoxy chloride and 0.23% of metamethoxychloride was brought into contact with the above-mentioned membrane in a state where a voltage was applied, and kept for 30 minutes to obtain a separation membrane of the present invention.

The separation membrane was evaluated under the conditions of pH 7 and 15 kgf / cm ² using a saline solution containing 1500 ppm of NaCl. The results are shown in the table.

(Comparative example)

The evaluation results of the separation membrane obtained in the same manner as in the example except that no DC voltage is applied are also shown in the table.

As can be seen from the table, the separation membrane of the present invention is excellent in permeation performance despite the same rejection performance.

Claims (2)

(57) [Claims] An orientation separation film formed by interfacial polymerization in a state where a DC voltage is applied. 2. The method for producing an orientation separation film according to claim 1, comprising the following steps. (A) applying a bifunctional reactant (A) solution to a support; (b) applying a DC voltage to the coated support in a direction perpendicular to the surface thereof; and (c) applying a DC voltage. In the state, on the coated support (A)
Contacting a bifunctional reactant (B) solution that reacts with