JPH06327953A - Production of composite reverse osmotic membrane - Google Patents

Abstract

PURPOSE:To provide a producing method of a composite reverse osmotic membrane having high water permeability at a relatively low pressure and capable of selectively separating components in a liquid mixture. CONSTITUTION:A thin film mainly containing a polyamide is formed after applying a water solution containing a compound having >=2 reactive amino groups on a porous supporting body, allowing an organic solvent containing a multifunctional acid halide to contact with the aq. solution phase to carry out interfacial reaction and just after the interfacial reaction, treating with alcohols to allow the alcohols to react with the unreacted acid halide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite reverse osmosis membrane which has high water permeability at a relatively low pressure and which can selectively separate the components of a liquid mixture, and more particularly, to a porous support. Relates to a method for producing a composite reverse osmosis membrane having a high salt rejection and a high water permeability, which comprises a thin film containing polyamide as a main component. The resulting composite reverse osmosis membrane is suitable for the production of ultrapure water, desalination of brackish water, etc., and also from the pollution sources such as stain drainage and electrodeposition paint drainage, etc. Effective substances can be removed and recovered to contribute to the closure of wastewater.

[0002]

2. Description of the Related Art Conventionally, as a reverse osmosis membrane having a structure different from that of an asymmetric reverse osmosis membrane, there is known a composite reverse osmosis membrane formed by forming an active thin film having substantially selective separation on a porous support. Has been.

At present, as such a composite reverse osmosis membrane, many are known in which a thin film made of polyamide obtained by interfacial polymerization of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide is formed on a support. (For example, JP-A-55-147106, JP-A-62-121603, JP-A-63-2182).
08, JP-A-2-187135).

However, in these reverse osmosis membranes, the required separation performance of organic substances and water permeation performance depend on the combination of an amine component and an acid halogen component, and a satisfactory one can be obtained depending on the application. Didn't.

[0005]

SUMMARY OF THE INVENTION According to the present invention, even if a single combination of each reactive component is used, an organic substance, particularly isopropyl alcohol (I
It is an object of the present invention to provide an excellent composite reverse osmosis membrane capable of controlling the balance between the separation performance of PA) and the water permeation performance.

[0006]

[Means for Solving the Problems] That is, according to the present invention, a porous support is coated with an aqueous solution containing a compound having two or more reactive amino groups, and then an organic compound containing a polyfunctional acid halide is prepared. A solvent is brought into contact with the aqueous solution phase to cause an interfacial reaction, and immediately after the interfacial reaction, the alcohol is reacted with an unreacted acid halide to form a thin film containing polyamide as a main component. A method for producing a composite reverse osmosis membrane, which is characterized by the above.

The amine component used in the present invention is not particularly limited as long as it is a polyfunctional amine having two or more reactive amino groups, and examples thereof include aromatic, aliphatic or alicyclic polyfunctional amines. .

Examples of such aromatic polyfunctional amines include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene and 3,5-diaminobenzoic acid. Acid, 2,4-diaminotoluene,
2,4-diaminoanisole, amidole, xylylenediamine and the like can be mentioned. As the aliphatic polyfunctional amine, for example, ethylenediamine, propylenediamine,
Examples include tris (2-aminoethyl) amine and the like. Further, as the alicyclic polyfunctional amine, for example, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-
Diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminomethylpiperazine and the like can be mentioned.
These amines may be used alone or as a mixture.

The polyfunctional acid halide used in the present invention is not particularly limited, and examples thereof include aromatic, alicyclic and other polyfunctional acid halides. Examples of such aromatic polyfunctional acid halides include trimesic acid chloride, terephthalic acid chloride, isophthalic acid chloride, biphenyldicarboxylic acid chloride, naphthalenedicarboxylic acid dichloride and the like. Examples of the alicyclic polyfunctional acid halide include cyclopropane tricarboxylic acid chloride, cyclobutane tetracarboxylic acid chloride, cyclopentane tricarboxylic acid chloride, cyclopentane tetracarboxylic acid chloride, cyclohexane tricarboxylic acid chloride, and tetrahydrofuran tetracarboxylic acid. Examples thereof include acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxylic acid chloride, cyclohexanedicarboxylic acid chloride, and tetrahydrofurandicarboxylic acid chloride.

In the present invention, the amine component and the acid halide component are interfacially polymerized on a porous support and immediately treated with alcohol to obtain a thin film containing polyamide as a main component. In the present invention, by such alcohol treatment, the alcohol is reacted with an acid halide which has not reacted to form an ester,
Since a functional group can be introduced into the molecular chain of the thin film, the effect of being able to control the separation performance can be obtained depending on the type of the alcohol.

The alcohol is not particularly limited as long as it is a liquid at room temperature and has a boiling point lower than that temperature when heat-treated after film formation, and examples thereof include methyl alcohol, ethyl alcohol and t-. Examples thereof include aliphatic alcohols such as butyl alcohol, alicyclic alcohols such as cyclohexanol, and aromatic alcohols such as benzyl alcohol.

The type of the alcohol can be appropriately selected depending on the intended use of the obtained composite reverse osmosis membrane. For example, when isopropyl alcohol (IPA) is to be separated as an organic substance, benzyl alcohol is particularly preferably used. The treatment method includes a dipping method and the like.

In the present invention, the porous support for supporting the thin film is not particularly limited as long as it can support the thin film, and examples thereof include polysulfone, polyarylethersulfone such as polyethersulfone, polyimide, polyvinylidene fluoride. Although various things can be mentioned, in particular, from the viewpoint of being chemically, mechanically, and thermally stable,
A porous support membrane made of polysulfone or polyarylethersulfone is preferably used. Such a porous support is usually about 25 to 125 μm, preferably about 40.
It has a thickness of ˜75 μm, but is not necessarily limited to these.

More specifically, a first layer containing an amine component is formed on a porous support, and then a layer consisting of a water-immiscible organic solvent solution containing an acid halide component is formed on the first layer. Formed on the layer of, and subjected to interfacial polycondensation, immediately followed by treatment with alcohol, and then, if necessary, at 100 ° C., for example.
The heat treatment as described above can be obtained by forming a thin film of crosslinked polyamide on a porous support.

The aqueous solution containing a polyfunctional amine is used for facilitating the film formation or improving the performance of the obtained composite reverse osmosis membrane. A polymer or a polyhydric alcohol such as sorbitol or glycerin may be contained.

Further, a surface active agent such as sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium lauryl sulfate can be contained. These surfactants are effective in improving the wettability of the aqueous solution containing the polyfunctional amine to the porous support. Further, in order to accelerate the polycondensation reaction at the interface, use of sodium hydroxide or trisodium phosphate capable of removing hydrogen halide generated in the interface reaction, or use of an acylation catalyst or the like as a catalyst. Is also beneficial.

The organic solvent for preparing the water-immiscible organic solvent solution containing the above acid halide component may be any organic solvent which dissolves the acid halide used well and does not dissolve the porous support used. Examples thereof include hydrocarbons such as n-hexane and cyclohexane, and halogenated hydrocarbons such as Freon (trademark of DuPont) containing trichlorotrifluoroethane.

In the organic solvent solution containing the acid halide and the aqueous solution containing the polyfunctional amine, the concentrations of the acid halide and the polyfunctional amine are not particularly limited, but the acid halide is usually 0.01 to 5 parts by weight. %,Preferably
0.05 to 1% by weight, the polyfunctional amine is usually 0.1 to 10
%, Preferably 0.5 to 5% by weight.

Further, in the present invention, Japanese Patent Publication No. Sho 63-36803.
As described in Japanese Patent Laid-Open Publication No. JP-A No. 2003-242, it is also possible to further improve the salt-inhibiting performance by performing chlorine treatment with hypochlorous acid or the like.

[0020]

The composite reverse osmosis membrane obtained by the present invention is
It has both high salt rejection and high water permeability, and even if a single combination of each reactive component is used, organic matter, especially isopropyl alcohol (IP
The balance between the separation performance and the water permeation performance of A) can be controlled, and it can be suitably used for desalination by desalting brackish water, seawater, etc., or for producing ultrapure water required for semiconductor production. it can.

[0021]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. Example 1 A porous polysulfone support membrane was immersed in an aqueous solution of 2.0% by weight m-phenylenediamine for 1 minute to remove excess aqueous solution, and then 0.10% by weight 1,3,5-benzenetricarboxylic acid chloride. After dipping in an n-hexane solution containing 0.15 wt% 1,3-benzenedicarboxylic acid chloride, the excess solution was removed. Then, the obtained membrane was immediately immersed in 100% by weight of ethyl alcohol for 1 minute, and then the excess solution was removed to obtain a composite reverse osmosis membrane.

The performance of the obtained composite reverse osmosis membrane was 1,500.
Saline solution containing ppm sodium chloride (adjusted to pH 6.5)
, Or 1500 ppm of isopropyl alcohol (I
15 kg using an aqueous solution containing PA) (adjusted to pH 6.5)
A reverse osmosis test was performed at 25 ° C./cm ² , and the results are shown in Table 1.

Comparative Example 1 A composite reverse osmosis membrane was obtained in the same manner as in Example 1 except that it was not treated with ethyl alcohol. The results are also shown in Table 1.

Examples 2 and 3 Example 2 was repeated except that the ethyl alcohol was changed to t-butyl alcohol or benzyl alcohol.
A composite reverse osmosis membrane was obtained in the same manner as in Example 1. The results are also shown in Table 1.

From the above results, the composite reverse osmosis membrane obtained according to the present invention has an I / I ratio while maintaining the NaCl removal rate.
It can be seen that the PA removal rate can be improved.

[0026]

Claims (1)

[Claims] 1. A porous support is coated with an aqueous solution containing a compound having two or more reactive amino groups, and then an organic solvent containing a polyfunctional acid halide is brought into contact with the aqueous solution phase. A composite reverse osmosis membrane characterized by forming a thin film containing polyamide as a main component by causing an interfacial reaction and treating with an alcohol immediately after the interfacial reaction to react with the alcohol and an unreacted acid halide. Manufacturing method.