JP2003112022A - Complex semipermeable membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a complex semipermeable membrane which retains highly selective-separating performance and is excellent in oxidizing resistance and water permeability. SOLUTION: In the complex semipermeable membrane comprising a thin membrane and a porous supporting membrane which supports the thin membrane, the thin membrane comprises a polyamide resin having a constitutional unit in which a diamine residue and a di- or tricarboxylic acid residue have been brought into amido bonding to each other and the diamine residue results from bonding an aliphatic diamine to each of both sides of an aromatic ring through a sulfonamido bond.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite semipermeable membrane for selectively separating components of a liquid mixture, and more specifically, a practical semi-permeable membrane provided with a thin film containing polyamide as a main component on a porous support. Relates to a composite semipermeable membrane having excellent water permeability, salt blocking property and durability.

Such a composite semipermeable membrane is suitable for the production of ultrapure water, desalination of salt water or seawater, and stains, which cause pollution such as dyeing drainage and electrodeposition paint drainage,
It can contribute to the closure of wastewater by removing and recovering the pollution source or effective substance contained in it. Also,
It can also be used for concentration of active ingredients in food applications and the like.

[0003]

2. Description of the Related Art As a semipermeable membrane used for the above-mentioned applications, an asymmetric membrane having an asymmetric structure made of the same material by a phase separation method or the like and a thin film having a selective separation property on a porous support are used. A composite semipermeable membrane formed of different materials is known.

Currently, as the latter semipermeable membrane, a composite semipermeable membrane made of polyamide obtained by an interfacial polycondensation reaction of a polyfunctional aromatic amine and a polyfunctional acid halide is a reverse membrane having high water permeability and high selective separation. Permeation membrane (JP-A-55-14710)
6, JP-A-62-1212603, JP-A-63-21
8208, JP-A-2-187135, etc.).

On the other hand, a composite semipermeable membrane made of a polyamide obtained by an interfacial polycondensation reaction of ethylenediamine, which is an aliphatic diamine, and a polyfunctional acid halide is a reverse osmosis membrane which is excellent in oxidant resistance and has high selective separation. As JP-A-5
No. 8-24303, JP-A-59-26101 and JP-A-59-179103.

Furthermore, a composite semipermeable membrane made of polyamide obtained by an interfacial polycondensation reaction of a secondary diamine such as piperazine, which is a diamine having a heterocyclic ring, and a polyfunctional acid halide is also excellent in oxidation resistance. It is well known that

[0007]

However, these membranes also do not have sufficient water permeability, salt-inhibiting property and oxidant resistance required for a practical semipermeable membrane, and higher properties are desired. It is rare. That is, in the polyamide-based reverse osmosis membrane, the polyamide composed of an aliphatic diamine having no aromatic ring in the main chain is excellent in oxidation resistance as described above, but is not satisfactory in terms of water permeability. It was
In addition, a polyamide composed of a polyfunctional aromatic amine has high water permeability and high selective separation, but is inferior in oxidant resistance.

[0008] Therefore, an object of the present invention is to provide a composite semipermeable membrane which has a high level of selective separation at a practical level and is excellent in both oxidation resistance and water permeability.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, by bonding an aliphatic diamine to both sides of an aromatic ring, water permeation while maintaining high selective separation. To improve the resistance to oxidants than the usual amide bond by forming a sulfonamide bond as the bonding group between the aromatic ring and the aliphatic diamine, and complete the present invention. Came to.

That is, the composite semipermeable membrane of the present invention is a composite semipermeable membrane comprising a thin film and a porous support membrane supporting the thin film, wherein the thin film has the following general formula (I) and / or (II). It is characterized in that it contains a polyamide resin having a constitutional unit represented.

[0011]

[Chemical 4] (However, R ₁₁ , R ₁₂ , R ₁₅ , and R ₁₆ represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms and may be the same or different. R ₁₃ and R _{14 each} have 2 carbon atoms. And each of them may be the same or different, R ₁₇ is a substituent having an arbitrary substitution position and number of substitutions, and H, COOH, SO ₃ H, NO ₂ , OH, CH ₃ ,
Or Cl. R ₁₈ represents a divalent organic group. )

[Chemical 5] (However, R ₂₁ , R ₂₂ , R ₂₅ , and R ₂₆ represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and each may be the same or different. R ₂₃ and R ₂₄ have 2 carbon atoms. The alkylene groups are represented by 10 to 10, each of which may be the same or different, and R ₂₇ is a substituent having any substitution position and number of substitutions, such as H, COOH, SO ₃ H, NO ₂ , OH, CH ₃ ,
Or Cl. R ₂₈ represents a trivalent organic group. ) Another composite semipermeable membrane of the present invention is a composite semipermeable membrane comprising a thin film and a porous support membrane supporting the thin film, wherein the thin film comprises a diamine component represented by the following general formula (III): It is characterized by containing a polyamide resin having a constitutional unit obtained by a condensation reaction with a polyfunctional acid halide having a valence of 3 or more.

[0012]

[Chemical 6] (However, R ₃₁ , R ₃₂ , R ₃₅ , and R _{36 each} represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and may be the same or different. R ₃₃ and R _{34 each} have 2 carbon atoms. And each of them may be the same or different, R ₃₇ is a substituent having an arbitrary substitution position and number of substitutions, and H, COOH, SO ₃ H, NO ₂ , OH, CH ₃ ,
Or Cl. ) In the above, it is preferable that the polyfunctional acid halide is an aromatic polyfunctional acid halide.

[Operation and Effect] According to the composite semipermeable membrane of the present invention, by using a diamine component in which an aliphatic diamine is bound to both sides of an aromatic ring through a sulfonamide bond,
As shown by the results of the examples, it is possible to maintain a high level of selective separation at a practical level and to have both excellent oxidant resistance and water permeability.

When the polyfunctional acid halide to be reacted with the diamine component is an aromatic polyfunctional acid halide,
The reactivity of the monomer, the salt blocking property of the film formation, the water permeability, and the like are improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The composite semipermeable membrane of the present invention comprises a thin film and a porous support film supporting the thin film, and the thin film comprises a polyamide resin having a structural unit represented by the general formula (I) and / or (II). It is characterized by including. Further, it is characterized by containing a polyamide-based resin having a constitutional unit obtained by a condensation reaction of the diamine component represented by the general formula (III) and a polyfunctional acid halide having a valence of 2 or more.

R in the general formulas (I) to (III)₁₁,
R₁₂, R₁₅, And R₁₆, R_{twenty one}, R_{twenty two}, R _{twenty five}, And R₂₆,
And R₃₁, R₃₂, R₃₅, And R₃₆Is a hydrogen atom or
Indicates an alkyl group having 1 to 5 carbon atoms, even if each is the same
It may be different. Specific examples of the alkyl group include-
CH₃ , -C₂ H_Five , -C₃ H₇ , -C_Four H₉ , -C_Five 
H ₁₁Etc., and may be linear or branched. Na
However, from the viewpoint of steric hindrance during the reaction, hydrogen atoms or carbon
A linear alkyl group having a prime number of 1 to 3 is preferable.

R in the general formulas (I) to (III)₁₃,as well as
R₁₄, R_{twenty three}, And R_{twenty four}, And R ₃₃, And R₃₄Is charcoal
Indicates an alkylene group having a prime number of 2 to 10, each having the same
May also be different. Specific examples of alkylene groups
Is -C₂ H_Four -, -C₃ H₆-, -C_Four H₈ -, -C_Five
 H_Ten-, -C₆ H₁₂-, -C₇ H₁₄-, -C₈ H
₁₆-, -C₉ H₁₈-, -C_TenH₂₀−
It may be chained or branched. Among them, steric hindrance during reaction
From the standpoint of harm, an alkylene group having 2 to 6 carbon atoms is preferred.
Yes.

Further, R ₁₇ , R ₂₇ and R ₃₇ are substituents having arbitrary substitution positions and substitution numbers on the aromatic ring, such as H, COO.
Indicates H, SO ₃ H, NO ₂ , OH, CH ₃ or Cl. Above all, from the viewpoint of water permeability and salt blocking property of film formation,
R ₁₇ , R ₂₇ , and R ₃₇ are preferably H. When the number of substitutions is plural, they may be the same or different. The number of substitutions on the aromatic ring is usually 0 to 1.

Various kinds of diamine components represented by the general formula (III) are commercially available, and any of them can be used. Further, those produced by the reaction of benzenedisulfochloride and diamine can be used.

On the other hand, R ₁₈ in the general formulas (I) to (II)
And R ₂₈ is a divalent or trivalent organic group, and is a divalent or higher polyfunctional acid halide which forms the thin film of the present invention by a condensation reaction with the diamine component represented by the general formula (III) as described above. Corresponding to the residue of. The polyfunctional acid halide is not particularly limited, for example, propane tricarboxylic acid chloride, butane tricarboxylic acid chloride, pentane tricarboxylic acid chloride, glutaryl halide, adipoyl halide, cyclopropane tricarboxylic acid chloride, cyclobutane tetra. Carboxylic acid chloride, cyclopentane tricarboxylic acid chloride, cyclopentane tetracarboxylic acid chloride,
Cyclohexane tricarboxylic acid chloride, tetrahydrofuran tetracarboxylic acid chloride, cyclopentane dicarboxylic acid chloride, cyclobutane dicarboxylic acid chloride, cyclohexane dicarboxylic acid chloride,
Examples thereof include tetrahydrofurandicarboxylic acid chloride. However, from the viewpoints of reactivity, salt-inhibiting property of film formation, water permeability, and the like, polyfunctional aromatic acid halides are preferable. Examples of such polyfunctional aromatic acid halides include trimesic acid chloride and trimethic acid chloride. Examples thereof include meritic acid chloride, terephthalic acid chloride, isophthalic acid chloride, pyromellitic acid chloride, biphenyldicarboxylic acid chloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonic acid chloride, benzenedisulfonic acid chloride and chlorosulfonylbenzenedicarboxylic acid chloride.

On the other hand, the polyamide resin in the present invention preferably has a crosslinked structure, and in that case, it is preferable to use a trifunctional or higher polyfunctional acid halide. When using a trifunctional or higher polyfunctional acid halide,
In the crosslinked portion, it becomes a constitutional unit represented by the general formula (II), but when an uncrosslinked portion exists, it becomes a constitutional unit represented by the general formula (I), and R ₁₈ represents a carboxyl group or a salt thereof. Becomes a remaining divalent organic group.

The polyamide resin forming the thin film is
Although it may be a homopolymer, it may be a copolymer containing a plurality of constitutional units as described above or other constitutional units, or a blend obtained by mixing a plurality of homopolymers. For example, a polyamide resin having a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II) can be mentioned. Examples of the above-mentioned other structural units include a diamine component containing an aromatic ring in the main chain but not having a sulfonamide bond, and other diamine components used in a polyamide semipermeable membrane.

The polyamide resin of the present invention contains 50 or more structural units represented by the general formulas (I) and / or (II).
It is preferably contained in an amount of not less than mol%, more preferably not less than 80% by mol. When it is less than 50 mol%, the effect of the aromatic ring which is a substituent of the aliphatic diamine becomes small, and it tends to be difficult to satisfy practical water permeability and excellent salt-inhibiting property and oxidant resistance at the same time.

The thickness of the thin film (separation active layer) in the present invention is preferably 0.01 to 100 μm, more preferably 0.1 to 10 μm, though it depends on the method of manufacturing the thin film. This is because the thinner the thickness, the better in terms of the permeation flux. However, if the thickness is too thin, the mechanical strength of the thin film is reduced, defects are likely to occur, and salt blocking performance tends to be adversely affected.

In the present invention, the porous support membrane that supports the thin film is not particularly limited as long as it can support the thin film. For example, polysulfone, polyarylethersulfone such as polyethersulfone, polyimide, polyfluoride. Various materials such as vinylidene can be used, but a porous support membrane made of polysulfone or polyarylethersulfone is preferably used because it is chemically, mechanically, and thermally stable. Such a porous support membrane is usually about 25 to 125 μm, preferably about 40 to 75 μm.
Although it has a thickness of μm, the thickness is not necessarily limited thereto.

The porous support membrane may have a symmetric structure or an asymmetric structure, but an asymmetric structure is preferable in order to achieve both a thin film support function and liquid permeability. The average pore diameter on the thin film formation side of the porous support film is preferably 1 to 1000 nm.

When the thin film of the present invention is formed on the porous support film, any known method can be used without any limitation on the method. For example, an interfacial condensation method, a phase separation method, a thin film coating method and the like can be mentioned. Among them, after applying an aqueous solution containing a diamine component on the porous support film, a thin film is formed on the porous support film by contacting the porous support film with a water-insoluble solution containing a polyfunctional acid halide. The interfacial condensation method of forming is preferred. Details of the conditions of the interfacial condensation method are described in JP-A-58-58.
It is described in JP-A No. 24303, JP-A No. 1-180208, etc., and those known techniques can be appropriately adopted.

Various reagents can be present in the reaction field for the purpose of facilitating film formation or improving the performance of the obtained composite semipermeable membrane. Examples of these reagents include polyvinyl alcohol, polyvinylpyrrolidone, polymers such as polyacrylic acid, polyhydric alcohols such as sorbitol and glycerin, and tetraalkylammonium halides and trialkylammonium described in JP-A-2-187135. Amine salts such as salts of organic acids, surfactants such as sodium dodecylbenzenesulfonate, sodium dodecylsulfate, sodium laurylsulfate, sodium hydroxide capable of removing hydrogen halide produced by polycondensation reaction, trisodium phosphate , Triethylamine, camphorsulfonic acid, or known acylation catalysts, and JP-A-8-2244
The solubility parameter described in JP-A-52-52 is 8 to 14 (c
Al / cm ³ ) ^1/2 compounds and the like.

The composite semipermeable membrane in the present invention is characterized in that the resistance to the oxidant is greatly improved, and therefore, raw water containing salt and / or organic matter is subjected to membrane separation treatment using such a composite membrane, In the method of obtaining permeated water in which such salts and / or organic substances are practically sufficiently removed, it is possible to perform water treatment by adding an oxidizing agent having an effect as a bactericide to raw water.

[0030]

EXAMPLES Examples and the like specifically showing the constitution and effects of the present invention will be described below. In the examples and the like, the inhibition rate (desalination rate) was calculated by the following formula.

Rejection rate (%) = (1- (solute concentration in membrane permeate / solute concentration in membrane feed)) × 100 (Example 1) Porous polysulfone supporting membrane (average pore diameter on the thin film forming side: 20 nm, 2% by weight of 1,3-benzenesulfonic acid bis (2-ethylamino) amide on the surface of the asymmetric membrane),
After being immersed in an aqueous solution containing 0.2% by weight of sodium lauryl sulfate for 30 seconds, the supporting film was slowly pulled up to remove the excess aqueous solution from the surface of the supporting film. Then, the surface of the supporting film is brought into contact with an n-hexane solution containing 0.1% by weight of trimesic acid chloride for 10 seconds to cause an interfacial polycondensation reaction, and a polymer thin film (thickness 1 μm) is formed on the porous supporting film. Was formed and then dried in a hot air dryer set at 120 ° C. for 3 minutes to obtain a composite semipermeable membrane.

The composite semipermeable membrane obtained in this manner was treated with 0.
Using 15 wt% saline as raw water, 25 ° C., pH 6.5,
When a reverse osmosis test was performed under a pressure of 1.5 MPa, the salt rejection was 97.2% and the permeation flux was 0.35.
It was m ³ / (m ² · day). This film has a free chlorine concentration of 1
Immerse in a 00 ppm sodium hypochlorite aqueous solution, and
When the test was conducted under the same conditions after 0 hour, the rejection of salt was 97.5% and the permeation flux was 0.81 m ³ / (m ²
・ Day)

(Example 2) The same test as in Example 1 was carried out except that the sample was immersed in an aqueous sodium hypochlorite solution having a free chlorine concentration of 100 ppm and 100 hours later. The results are shown in Table 1.

Example 3 In Examples 1 and 2, the diamine component was replaced with 1,3-benzenesulfonic acid bis (N, N ′).
- Diethyl 2-ethylamino) amide: Chemical formula _{H 5 C 2 HNC 2 H 4} NHSO 2 PhSO 2 NHC 2 H
_{The same} test was conducted except that ₄ NHC ₂ H ₅ was used. The results are shown in Table 1.
It was shown to.

Comparative Example 1 The same test as in Example 1 was carried out except that the diamine component was m-phenylenediamine. The results are shown in Table 1.

(Comparative Example 2) The same test as in Example 2 was conducted except that m-phenylenediamine was used as the diamine component. The results are shown in Table 1.

Comparative Example 3 The same test as in Example 2 was carried out except that ethylenediamine was used as the diamine component. The results are shown in Table 1.

[0038]

[Table 1] As shown by the results in Table 1, the composite semipermeable membranes of Examples show an increase in permeation flux while maintaining the salt rejection after 50 hours of immersion in an aqueous solution of sodium hypochlorite, but the 100% thereafter.
Since it is stable in time immersion, it retains a high level of selective separation at a practical level, and is excellent in both oxidation resistance and water permeability. On the other hand, in Comparative Examples 1 and 2 in which the diamine component was m-phenylenediamine, the inhibition rate decreased due to the immersion in the aqueous sodium hypochlorite solution. Further, in Comparative Example 3 in which the diamine component was ethylenediamine, the permeation flux was small from the initial stage.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D006 GA03 MA07 MA25 MB02 MB06                       MB11 MB18 MC29 MC45 MC54X                       MC58 MC61X MC62X NA04                       NA10 NA40 NA45 NA46 NA64                       PA01 PB02 PB03 PB08                 4J001 DA01 DB01 DC08 DC14 EB03                       EB04 EB14 EB28 EB67 EB69                       EC33 EC44 FB03 FB05 FC03                       FD05 GA16 HA03 JA12 JC01

Claims (3)

[Claims] 1. A composite semipermeable membrane comprising a thin film and a porous support film supporting the thin film, wherein the thin film has a polyamide system having a structural unit represented by the following general formula (I) and / or (II). A composite semipermeable membrane comprising a resin. [Chemical 1] (However, R ₁₁ , R ₁₂ , R ₁₅ , and R ₁₆ represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms and may be the same or different. R ₁₃ and R _{14 each} have 2 carbon atoms. And each of them may be the same or different, R ₁₇ is a substituent having an arbitrary substitution position and number of substitutions, and H, COOH, SO ₃ H, NO ₂ , OH, CH ₃ ,
Or Cl. R ₁₈ represents a divalent organic group. ) [Chemical 2] (However, R ₂₁ , R ₂₂ , R ₂₅ , and R ₂₆ represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and may be the same or different. R ₂₃ and R ₂₄ have 2 carbon atoms. And each of them may be the same or different, and R ₂₇ is a substituent having an arbitrary substitution position and number of substitutions, and H, COOH, SO ₃ H, NO ₂ , OH, CH ₃ ,
Or Cl. R ₂₈ represents a trivalent organic group. ) 2. A composite semipermeable membrane comprising a thin film and a porous support film supporting the thin film, wherein the thin film comprises a diamine component represented by the following general formula (III) and a divalent or higher polyfunctional acid halogen. A composite semipermeable membrane, comprising a polyamide resin having a structural unit obtained by a condensation reaction with a compound. [Chemical 3] (However, R ₃₁ , R ₃₂ , R ₃₅ , and R _{36 each} represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and may be the same or different. R ₃₃ and R _{34 each} have 2 carbon atoms. And each of them may be the same or different, R ₃₇ is a substituent having an arbitrary substitution position and number of substitutions, and H, COOH, SO ₃ H, NO ₂ , OH, CH ₃ ,
Or Cl. ) 3. The composite semipermeable membrane according to claim 2, wherein the polyfunctional acid halide is an aromatic polyfunctional acid halide.