JPH1015367A - Manufacture of highly permeable composite reverse osmotic membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a highly permeable composite reverse osmotic membrane which maintains high water permeating performance and also has a high salt inhibiting rate. SOLUTION: In a method for manufacturing a composite reverse osmotic membrane consisting of a polyamide skin layer and a fine porous support which supports the former, a solution A containing a chemical compound with at least, two reactive amino groups is applied on the fine porous support to form a coated layer. In addition, a solution B containing a multifunctional acid halogen compound with at least two reactive acid halide groups is brought into contact with the coated layer to undergo a crosslinking reaction. This crosslinking reaction is caused to take place by adding a material for promoting the crosslinking reaction to at least either of the solution A or the solution B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite reverse osmosis membrane for selectively separating components in a liquid mixture, and more particularly, to an active layer or a thin film containing polyamide as a main component on a microporous support. The present invention relates to a method for producing a composite reverse osmosis membrane having both a high salt rejection and a high permeability provided with a skin layer, also called a skin layer. Such a composite reverse osmosis membrane is suitably used for production of ultrapure water, desalination of seawater or brackish water, etc., and is included in stains and the like that cause pollution such as dyeing wastewater and electrodeposition paint wastewater. Pollution sources or effective substances can be removed and collected, which can contribute to closing wastewater. Also,
It can also be used for concentration of active ingredients for food use and the like.

[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, a composite reverse osmosis membrane comprising an active skin layer having substantially selective separation formed on a microporous support. It has been known.

[0003] At present, many of such composite reverse osmosis membranes are known in which a skin layer made of a polyamide obtained by a crosslinking reaction between 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-63-121
218208, JP-A-2-187135, etc.).

[0004] Further, there is known a skin layer formed of a polyamide obtained by a cross-linking reaction between a polyfunctional aromatic amine and a polyfunctional alicyclic acid halide on a support (for example, see Japanese Patent Application Laid-Open No. H11-157556). No. 61-42308).

Although the above composite reverse osmosis membrane has high desalination performance and water permeation performance, it is desired to further improve water permeation from the viewpoint of reduction of operation cost and equipment cost, efficiency, and the like. I have. To meet these requirements, various additives have been proposed. For example, use of sodium hydroxide or trisodium phosphate capable of removing hydrogen halide generated by a crosslinking reaction, or use of an acylation catalyst or the like as a catalyst, or an interface of a reaction field during the crosslinking reaction Compounds that reduce the tension have been proposed.
(For example, JP-A-63-12310, JP-A-6-47260, Japanese Patent Application No. 6-319716, etc.). However, although the performance has been improved, it is still insufficient, and in particular, there is a tendency for problems such as a decrease in desalination performance and a variation in water permeability,
There is a need for a composite reverse osmosis membrane with even higher performance.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a composite reverse osmosis membrane which maintains high water permeability and has a high salt rejection ratio.

[0007]

SUMMARY OF THE INVENTION The method of the present invention for producing a highly permeable composite reverse osmosis membrane comprises a method of producing a composite reverse osmosis membrane comprising a polyamide skin layer and a microporous support for supporting the same. A solution A containing a compound having two or more reactive amino groups is coated on a microporous support to form a coating layer, and a polyfunctional compound having two or more reactive acid halide groups is provided. In the crosslinking reaction in which the solution B containing an acid halide is brought into contact with the coating layer, at least one of the solution A and the solution B contains a substance that promotes the crosslinking reaction and is crosslinked.

Examples of the substance for promoting the crosslinking reaction used in the present invention include transition metal salts such as transition metal chlorides and transition metal acetates, and compounds such as phosphoric acid and polyphosphoric acid. Phosphoric acid is preferably used in consideration of the stability that no precipitate is formed in the solution B or the solution B.

The content of the substance for accelerating the crosslinking reaction used in the present invention is preferably 1.0 × 10 ^-4 % by weight to 10% by weight.
And more preferably 1.0 × 10 ^-4 % by weight to 1% by weight. The above content,
When the content is less than 1.0 × 10 ⁻⁴ wt%, the effect of accelerating the crosslinking reaction is not sufficiently exhibited. On the other hand, when the content exceeds 10% by weight, the water permeability of the obtained composite reverse osmosis membrane decreases, and it becomes difficult to obtain a highly permeable composite reverse osmosis membrane. Since a substance that promotes the cross-linking reaction remains, it may be mixed into the permeated water subjected to the membrane separation treatment to lower the quality of the permeated water.

[0010]

According to the structure of the present invention, in a method for producing a composite reverse osmosis membrane comprising a polyamide skin layer and a microporous support for supporting the same, two or more reactive amino groups A solution A containing a compound having the formula (I) is coated on a microporous support to form a coating layer, and a solution B containing a polyfunctional acid halide having two or more reactive acid halide groups is coated with the coating layer. A cross-linking reaction in which at least one of the solution A and the solution B contains a substance for accelerating the cross-linking reaction and is cross-linked to maintain a high water permeation performance and a high salt rejection ratio. A reverse osmosis membrane can be realized.

That is, the present inventors have found that there is a close relationship between the performance of the composite reverse osmosis membrane and the substance that promotes the crosslinking reaction, and at least one of the solution A and the solution B has a substance that promotes the crosslinking reaction. It has been found that, by containing and cross-linking, a composite reverse osmosis membrane having high water permeation performance and high salt rejection can be obtained, and the present invention has been accomplished.

The compound having two or more reactive amino groups contained in the solution A used in the present invention is not particularly limited as long as it is a polyfunctional amine, and may be an aromatic, aliphatic or alicyclic polyamine. Functional amines. The above amines may be used alone or as a mixture.

Examples of such aromatic polyfunctional amines include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, and 3,5-diaminobenzo. Acid, 2,4-diaminotoluene,
Examples include 2,6-diaminotoluene, 2,4-diaminoanisole, amidole, xylylenediamine and the like.

Examples of the aliphatic polyfunctional amine include ethylenediamine, propylenediamine, and tris (2-diaminoethyl) amine.

The alicyclic polyfunctional amine includes, for example, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine,
2,5-dimethylpiperazine, 4-aminomethylpiperazine and the like.

The polyfunctional acid halide having two or more reactive acid halide groups contained in the solution B used in the present invention is not particularly limited, and may be an aromatic, aliphatic or alicyclic polyhydric acid halide. Functional acid halides are included.

Such aromatic polyfunctional acid halides include, for example, trimesic acid chloride, terephthalic acid chloride, isophthalic acid chloride, biphenyldicarboxylic acid dichloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonic acid chloride, benzenedisulfonic acid chloride, chloromethane And sulfonylbenzenedicarboxylic acid chloride.

Examples of the aliphatic polyfunctional acid halides include, for example, propanetricarboxylic acid chloride, butanetricarboxylic acid chloride, pentanetricarboxylic acid chloride, glutaryl halide, and adipoyl halide.

The alicyclic polyfunctional acid halides include, for example, cyclopropanetricarboxylic acid chloride,
Cyclobutanetetracarboxylic acid chloride, cyclopentanetricarboxylic acid chloride, cyclopentanetetracarboxylic acid chloride, cyclohexanetricarboxylic acid chloride, tetrahydrofurantetracarboxylic acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxylic acid chloride, cyclohexanedicarboxylic acid chloride, tetrahydro And furan carboxylic acid chloride.

In the present invention, the microporous support for supporting the skin layer is not particularly limited as long as it can support the skin layer. Examples thereof include polysulfone, polyarylethersulfone such as polyethersulfone, polyimide, Although various materials such as polyvinylidene fluoride can be mentioned, a microporous support made of polysulfone or polyarylethersulfone is particularly preferably used because it is chemically, mechanically and thermally stable. Such a microporous support usually has a thickness of about 25 to 125 μm, preferably about 40 to 75 μm, but is not necessarily limited thereto.

[0021]

In the present invention, the compound having two or more reactive amino groups and the polyfunctional acid halide having two or more reactive acid halide groups are crosslinked. By reacting, a composite reverse osmosis membrane in which a polyamide skin layer containing a crosslinked polyamide as a main component is formed on a microporous support is obtained.

More specifically, a first layer made of a solution A containing the compound having two or more reactive amino groups is formed on a microporous support, and then a first layer of the acid halide is formed. Can be obtained by forming a layer composed of the solution B containing on the first layer, performing interfacial polycondensation, and forming a polyamide skin layer composed of a crosslinked polyamide on a microporous support. .

The solution A containing a compound having two or more reactive amino groups is further used for facilitating membrane formation or improving the performance of the obtained composite reverse osmosis membrane.
For example, polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid, and polyhydric alcohols such as sorbitol and glycerin can be contained in water.

Also, amine salts described in JP-A-2-187135, for example, salts of a tetraalkylammonium halide or a trialkylamine with an organic acid, may be added to a support film of an amine solution to facilitate film formation. It is preferably used in order to improve the absorbability of the compound and to promote the condensation reaction.

Further, a surfactant such as sodium dodecylbenzenesulfonate, sodium dodecyl sulfate and sodium lauryl sulfate can be contained in the solution A. These surfactants are effective in improving the wettability of the aqueous solution containing the polyfunctional amine on the microporous support.

Further, in order to accelerate the polycondensation reaction at the interface, sodium hydroxide or trisodium phosphate capable of removing hydrogen halide generated by a cross-linking reaction at the interface is used. It is also beneficial to use a solution catalyst or the like in the solution A.

A compound having a solubility parameter of 8 to 14 (cal / cm ³ ) ^1/2 can be added to the solution A in order to increase the permeation flux. These compounds include te
rt-butyl alcohol, acyl alcohol, hexyl alcohol, diethylene glycol dimethyl ether,
Diethylene glycol diethyl ether, ethylene glycol dimethyl ether and isopropyl alcohol are preferably used.

Examples of the solvent of the solution B containing the polyfunctional acid halide having two or more reactive acid halide groups include a water-immiscible organic solvent, and in particular, hexane, heptane, octane, nonane, Hydrocarbons such as cyclohexane, carbon tetrachloride, trichlorotrifluoroethane,
Halogenated hydrocarbons such as difluorotetrachloroethane and hexachloroethane are preferably used. Also, 2
It can also be used as a mixture of more than one kind of the above solvents.

The concentrations of the polyfunctional amine and the acid halide in the solution A containing the compound having two or more reactive amino groups and the solution B containing the acid halide are not particularly limited. However, the acid halide is usually 0.01 to 5% by weight, preferably 0.05 to 1% by weight.
The polyfunctional amine is usually 0.1 to 10% by weight, preferably 0.5 to 5% by weight.

As a substance that promotes a crosslinking reaction in at least one of the solution A and the solution B, for example, a phosphoric acid concentration is
It is contained so as to be 1.0 × 10 ^-4 % by weight to 10% by weight.

Thus, the solution A containing the compound having two or more reactive amino groups is coated on the microporous support, and then the solvent is an unsaturated hydrocarbon,
After coating a solution B containing a polyfunctional acid halide having two or more reactive acid halide groups thereon, the excess solution is removed, and then usually about 20 to 150
C., preferably at about 70-130.degree. C. for about 1-10 minutes,
Drying is preferably carried out for about 2 to 8 minutes to form a water-permeable skin layer composed of a crosslinked polyamide. This skin layer has a thickness of usually about 0.05 to 2 μm, preferably about 0.
It is in the range of 1 to 1 μm.

[0032]

According to the present invention, a highly permeable composite reverse osmosis membrane having high water permeation performance and high salt rejection can be realized. For example, it can be suitably used for desalination by desalination of brackish water, seawater or the like, production of ultrapure water required for production of semiconductors, and the like.

[0033]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples.
In addition, a polysulfone ultrafiltration membrane was used as the microporous support. The performance of the obtained composite reverse osmosis membrane was determined by allowing an aqueous solution of pH 6.5 containing 1500 ppm of sodium chloride to pass through the composite reverse osmosis membrane at an operating pressure of 15 kg / cm ² and a temperature of 25 ° C. for 1 hour. Rejection and permeation flux were measured. The sodium chloride rejection was determined by ordinary conductivity measurement.

EXAMPLE 1 2.5% by weight of triethylamine, 5.0% by weight of camphorsulfonic acid and 5.0% by weight of isopropyl alcohol were added to an aqueous solution containing 2.5% by weight of m-phenylenediamine and 0.15% by weight of sodium lauryl sulfate. An aqueous solution containing 20% by weight of phosphoric acid and 3.0 × 10 ^-4 % by weight of phosphoric acid as a substance for accelerating the cross-linking reaction was brought into contact with the microporous polysulfone support membrane for several seconds as a solution A, and excess solution A was removed. Thus, a layer of the solution A was formed on the support film. Next, the surface of the support membrane is brought into contact with solution B containing 0.18% by weight of trimesic acid chloride and the solvent being isoparaffin. Then, it was kept in a hot air dryer at 120 ° C. for 3 minutes to form a skin layer on the support film, thereby obtaining a composite reverse osmosis membrane. When the performance of the obtained composite reverse osmosis membrane was evaluated, the rejection of salt was 99.2% and the permeation flux was 2.2 m ³ / m ² · day.

Example 2 In Example 1, the content of phosphoric acid in the solution A was 3.0 × 10
Except for ^-3 % by weight, a composite reverse osmosis membrane was obtained in the same manner as in Example 1. Table 1 shows the results.

[Table 1]

Example 3 In Example 1, the content of phosphoric acid in the solution A was 3.0 × 10
^A composite reverse osmosis membrane was obtained in the same manner as in Example 1, except that the content was changed to ^-2 % by weight. Table 1 shows the results.

Example 4 A composite reverse osmosis membrane was obtained in the same manner as in Example 1, except that the phosphoric acid content in the solution A was changed to 1.0% by weight. Table 1 shows the results.

Example 5 A composite reverse osmosis membrane was obtained in the same manner as in Example 1 except that the phosphoric acid content in the solution B was changed to 3.0 × 10 ^-4 wt% instead of in the solution A. Was. Table 1 shows the results.

Example 6 A composite reverse osmosis membrane was prepared in the same manner as in Example 1 except that the phosphoric acid content was changed to 3.0 × 10 ^-4 wt% in solution A as well as in solution B. I got Table 1 shows the results.

Comparative Example 1 In Example 1, except that phosphoric acid was not contained.
A composite reverse osmosis membrane was obtained in the same manner as in Example 1. Table 1 shows the results.

[0041] In Comparative Example 2 Example 1, except that the sodium phosphate 3.0 × 10 ^-4 wt% instead of the phosphoric acid 3.0 × 10 ^-4% by weight, the composite reverse osmosis membrane in the same manner as in Example 1 Obtained. Table 1 shows the results.

As is clear from the comparative examples, a solution A containing a compound having two or more reactive amino groups was coated on a microporous support to form a coating layer, and two or more reactive groups were formed. A crosslinking reaction in which a solution B containing a polyfunctional acid halide having an acidic acid halide group is brought into contact with the coating layer,
Compound reverse osmosis formed in a system in which at least one of the solution A and the solution B contains a substance that promotes a cross-linking reaction and is cross-linked by not containing a substance that promotes a cross-linking reaction. A highly permeable composite reverse osmosis membrane having a higher salt rejection than the membrane is obtained.

Claims (3)

[Claims] 1. A method for producing a composite reverse osmosis membrane comprising a polyamide skin layer and a microporous support for supporting the same, wherein a solution A containing a compound having two or more reactive amino groups is prepared. This is a crosslinking reaction in which a coating layer is formed by coating on a microporous support, and a solution B containing a polyfunctional acid halide having two or more reactive acid halide groups is brought into contact with the coating layer. A method for producing a highly permeable composite reverse osmosis membrane, characterized in that at least one of the solution A and the solution B contains a substance that promotes a crosslinking reaction and is crosslinked. 2. The method for producing a highly permeable composite reverse osmosis membrane according to claim 1, wherein the substance that promotes the crosslinking reaction is phosphoric acid. 3. The content of a substance which promotes a crosslinking reaction is
3. The method for producing a highly permeable composite reverse osmosis membrane according to claim 1, wherein the content is 1.0 × 10 ⁻⁴ % by weight to 10% by weight.