JP2001179061A - Composite semipermeable membrane and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite semipermeable membrane which is excellent in water permeability with a high removal ratio and a manufacturing method thereof. SOLUTION: A separation function layer is formed on a porous supporting film by performing an interfacial polycondensation in such a way that the aqueous solution of a multifunctional amine comes in contact with an organic solvent. The ratio of the actual length of the surface of the separation function layer to 1 μm of the porous supporting film to the film thickness of the separation function layer is 50 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to desalination of seawater and irrigation water, production of ultrapure water used for cleaning semiconductors, purification of clean water, production of boiler water, and reuse of wastewater and sewage. The present invention relates to a composite semipermeable membrane and a method for producing the same, which can be suitably used for processing, recovery of an electrodeposition paint used for undercoating of an automobile, concentration of fruit juice, and food industry applications such as wine production.

[0002]

2. Description of the Related Art In recent years, since it is advantageous for energy saving and cost reduction, liquid separation technology using a membrane such as a reverse osmosis membrane has been developed. The development of a composite membrane provided with a separation function layer has been advanced. These composite membranes are mainly made of, for example, aliphatic polyamides or aromatic polyamides.However, in order to achieve higher water permeability and solute rejection, there is a limit only in research from the material side. there were.

Therefore, for example, Japanese Patent Application Laid-Open No. 9-85068
Japanese Patent Application Laid-Open No. Hei 9-141071 discloses that the form of the surface of the separation function layer is optimized, but there is still a shortage of water permeability and solute rejection simply by specifying the form of the surface. Was.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a composite semipermeable membrane having excellent water permeability and high rejection, and a method for producing the same.

[0005]

Means for Solving the Problems According to the present invention, there is provided a separation function layer provided on a porous support membrane, wherein the thickness of the separation function layer is T (μm). The actual length of the surface of the separation function layer per 1 μm length of the porous support membrane is represented by L
(Μm) is characterized by a composite semipermeable membrane in which T and L satisfy the following expression.

L / T ≧ 50 Here, it is also preferable that the separation functional layer contains a crosslinked polyamide.

Further, in contacting an aqueous solution of a polyfunctional amine with a solution of a polyfunctional acid chloride in an organic solvent on a porous support membrane to form a separation functional layer on the porous support membrane by interfacial polycondensation, As the aqueous solution and the organic solvent solution,
100μm of suspended substance with a circumscribed circle equivalent diameter of 10μm or more
The above method for producing a composite semipermeable membrane using a solution having 5,000 or less per liter is also preferable.

Further, it is preferable that the interfacial polycondensation is carried out in the presence of a compound containing at least one functional group selected from the group consisting of an ester group, an ether group, a sulfonic acid group, a hydroxyl group and a carboxyl group. Is preferably performed in the presence of an acylation catalyst.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The composite semipermeable membrane of the present invention has a separation functional layer provided on a porous support membrane, and the thickness of the separation functional layer is T (μm). When the actual length of the surface of the separation function layer per 1 μm length is L (μm), T
And L satisfy the relationship of L / T ≧ 50. L / T
Is less than 50, the film thickness becomes too large with respect to the surface area of the separation functional layer, and the permeation flux and the rejection ratio tend to decrease. To further increase the permeation flux and rejection, L / T
Is preferably 100 or more, and more preferably 150 or more.

Here, the thickness T of the separation function layer and the actual length L of the surface of the separation function layer per 1 μm of the porous support film are values measured by the method described below.

First, a sample is embedded with a water-soluble polymer to prepare an ultrathin section for TEM. Any water-soluble polymer can be used as long as it can maintain the shape of the sample. Next, in order to facilitate cross-sectional observation, OsO ₄
And cut with an ultramicrotome to make ultrathin sections. A cross-sectional photograph of the obtained ultrathin section is taken using a transmission electron microscope (TEM). The observation magnification may be appropriately determined depending on the film thickness of the separation function layer. However, in order to observe the cross-sectional shape of the separation function layer and prevent the measurement from being localized, the observation magnification is, for example, 10 to 10 μm.
If it is about 0 nm, the observation magnification should be 50 to 100,000 times.

With respect to the cross-sectional photograph obtained as described above, the thickness of the separation function layer and the actual length of the surface of the separation function layer per 1 μm length of the porous support film are measured. The method of measurement will be described with reference to FIG. FIG. 1 is a schematic diagram showing a cross section of a composite semipermeable membrane according to one embodiment of the present invention,
A separation function layer 2 is provided on a porous support membrane 1. First, the points a, b, and 10 at which the porous support membrane is divided into 10 points at equal intervals.
Are defined as points A, B,... On the surface of the separation function layer corresponding to. Then, the thicknesses T _A , T _B ,... Of the separation function layer in the direction perpendicular to the tangents of the points A, B,. At this time, for example, the point corresponding to the point b is the point B1,
When there are a plurality of B2 and B3, measurement is performed for each of them, and the average value (T _B1 + T _B2 + T _B3 ) / 3 is defined as T _B. The average value (T _A +... + T _J ) / 10 of the obtained thicknesses T _A , T _B ,.

The actual length L of the surface of the separation function layer refers to the actual length of the surface of the separation function layer at a portion corresponding to the length of the porous support membrane of 1 μm, and is represented by a solid line M in FIG. Refers to the length of the part.

According to the value obtained as described above, L /
Calculate T.

The material of the separation functional layer is preferably a material having high water permeability such as permeation flux and capable of enhancing selective separation performance represented by an exclusion rate, for example, polyamide and polyester. , Cellulose, polyacryl, polymethacryl and the like can be used.
In particular, polyamide can increase both the permeation flux and the rejection, and if it is a crosslinked polyamide, its performance can be further improved, and its mechanical strength and chemical resistance can be improved. preferable.

As the porous support membrane, uniform and fine pores,
Alternatively, it is preferable to have a form having fine pores having a gradually larger pore diameter from one surface to the other surface. The pore size is preferably in the range of 1 to 100 nm. If the pore size is less than 1 nm, the permeation flux tends to decrease,
If it exceeds 100 nm, the strength of the porous support membrane tends to decrease. The thickness of the porous support membrane is 1 μm to 5 m.
m, more preferably in the range of 10 to 100 μm. If the thickness is less than 1 μm, the strength of the porous support membrane tends to decrease, and if it exceeds 5 mm, it becomes difficult to handle.

The above pore size can be measured using a scanning electron microscope.

Materials used for the porous support membrane include polysulfone, polyamide, polyester, cellulosic polymer, vinyl polymer, polyphenylene sulfide,
A homopolymer or copolymer such as polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide can be used alone or as a blend. Among the above, it is preferable to use cellulose acetate and cellulose nitrate as the cellulosic polymer, and polyethylene, polypropylene, polyvinyl chloride, polyacrylonitrile and the like as the vinyl polymer. Among them, homopolymers and copolymers such as polysulfone, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferred. Further, among these materials, it is particularly preferable to use polysulfone which has high chemical, mechanical and thermal stability and is easy to mold.

The porous support membrane is preferably backed with cloth, nonwoven fabric, paper or the like to increase the mechanical strength.

As the porous support membrane, for example, “Office of Saline Water Research and Development Progress Report”, N
o. As described in US Pat. No. 359 (1968), a solution of polysulfone in dimethylformamide (DMF) is cast to a constant thickness on a densely woven polyester or nonwoven fabric, and the surface is exposed to air for a certain period of time. After the solvent is removed, one obtained by coagulation in a coagulation liquid such as water can be used.

Next, a method for producing a composite semipermeable membrane will be described.

The composite semipermeable membrane of the present invention can be manufactured by providing a separation function layer on a porous support membrane. It can be coated on a support film, or can be further subjected to a crosslinking reaction of a polymer after coating to form a separation functional layer. By performing a cross-linking reaction, durability such as chemical resistance and abrasion resistance, an exclusion rate, and the like can be improved.
In addition, a polyfunctional amine and a polyfunctional acid chloride can be brought into contact on a porous support membrane and interfacial polycondensation to form a separation functional layer. The use of the interfacial polycondensation reaction is preferable because the thickness of the separation function layer can be easily controlled and a very thin film can be formed.

The case where the interfacial polycondensation reaction is used will be described below.

First, a polyfunctional amine is brought into contact with the porous support membrane. The contact may be carried out by uniformly and continuously distributing the polyfunctional amine on the porous support membrane. For example, a method of coating the polyfunctional amine on the porous support membrane, or a method of applying the porous support membrane to the porous support membrane. A method of dipping in a functional amine can be used.

As the polyfunctional amine, an amine compound having at least two primary and / or secondary amino groups in one molecule can be used. For example, two amino groups have ortho, meta, para, Phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene bonded to benzene in any positional relationship,
Aromatic polyfunctional amines such as 3,5-diaminobenzoic acid and xylylenediamine; aliphatic amines such as ethylenediamine and propylenediamine; 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine and 4-aminomethylpiperazine It is preferable to use an alicyclic polyfunctional amine such as. These amines may be used alone or as a mixture. Further, it is preferable to add a monofunctional amine because the permeation flux of the membrane can be improved.
The polyfunctional amine may be used as it is, but is preferably used in a solution state in order to appropriately control the thickness of the separation function layer. As the solvent to be used, water is preferable in consideration of the solubility of the polyfunctional amine, toxicity, flammability, cost, and the like.

When water is used, the concentration of the polyfunctional amine in the aqueous solution is adjusted to 0.1 to 20% by weight, more preferably 0.5 to 20% by weight.
When the content is within the range of 10 to 10% by weight, the thickness of the separation function layer can be accurately controlled.

Here, if suspended substances such as dust, iron rust, monomer insolubles, polymer debris, and algae are present in the aqueous solution of the polyfunctional amine, the form of the formed separation function layer is easily damaged, For example, pinholes may be generated and solute separation performance may be significantly reduced. Therefore, in the present invention, as an aqueous solution of the polyfunctional amine, 100 μl of a suspended substance having a circumscribed circle equivalent diameter of 10 μm or more is used.
An aqueous solution having 5,000 or less, more preferably 1,000 or less, and still more preferably 500 or less is used. The same applies to the case where an organic solvent solution of a polyfunctional acid chloride described later is used.

Here, the diameter of the circumscribed circle and the content of the suspended substance are measured by using a particle counter of a system that derives the diameter of the circumscribed circle by measuring the shadow generated by irradiating the suspended substance with light. .

As a method for removing suspended substances in the solution, for example, membrane filtration or distillation can be used.
Speaking of membrane filtration, microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, etc. can be used, among which ultrafiltration membranes and microfiltration membranes can remove finer suspended substances. It is preferable. In addition, after removing fine suspended matter by filtration with a reverse osmosis membrane, filtration is further performed using a microfiltration membrane to remove large particles mixed in from a container, etc. It is also effective to perform filtration in combination, for example, by using a microfiltration membrane or an ultrafiltration membrane in advance to perform the filtration efficiently.

The contact time between the aqueous solution prepared as described above and the porous support membrane is preferably within a range of 5 seconds to 10 minutes from the viewpoint of appropriately controlling the thickness of the separation function layer. More preferably, it is within the range of 3 minutes.

Next, the polyfunctional amine or an aqueous solution thereof is sufficiently drained so as not to remain on the film. If a droplet remains, the remaining portion of the droplet tends to become a film defect after film formation, resulting in a decrease in film performance. For example, as described in Japanese Patent Application Laid-Open No. 2-78428, a liquid draining method is a method in which a porous support membrane is vertically oriented to allow excess liquid to flow down naturally, or blowing air such as nitrogen from an air nozzle. For example, a method of forcibly draining the liquid may be used.

The thus obtained polyfunctional amine is contacted with a polyfunctional acid chloride on a membrane provided on a porous support membrane.
The method of contact is not particularly limited, but since it is easy to appropriately control the film thickness, the polyfunctional acid chloride is dissolved in a solvent, and the solution is contacted by, for example, coating, spraying, or dipping. It is preferable to form a separation functional layer containing a crosslinked polyamide by an interfacial polycondensation reaction.

As the polyfunctional acid chloride, an acid chloride compound having at least two acid chloride groups in one molecule can be used. For example, trimesic acid chloride, which is a trifunctional acid chloride, 1, 3,5-cyclohexanetricarboxylic acid trichloride and 1,2,4-cyclobutanetricarboxylic acid trichloride can be used. Examples of the bifunctional acid chloride include biphenyl dicarboxylic acid dichloride, biphenylene dicarboxylic acid dichloride, azobenzene dicarboxylic acid dichloride,
Aromatic difunctional acid chlorides such as terephthalic acid chloride, isophthalic acid chloride, and naphthalenedicarboxylic acid chloride, and aliphatic bifunctional acid chlorides such as adipoyl chloride and sebacoyl chloride, cyclopentanedicarboxylic acid dichloride, and cyclohexanedicarboxylic acid Alicyclic bifunctional acid chlorides such as dichloride and tetrahydrofurandicarboxylic acid dichloride can be used.
These acid chlorides may be used alone or in a mixture. It is also preferable to mix a monofunctional acid chloride to improve the permeation flux.

The concentration of the polyfunctional acid chloride in the above solution is preferably in the range where the film thickness can be easily controlled, specifically, in the range of 0.01 to 5% by weight, more preferably 0.1 to 5% by weight.
It may be in the range of 02 to 2.0% by weight.

When a polyfunctional amine aqueous solution is used, the solvent used in the above solution is immiscible with the aqueous solution and dissolves the polyfunctional acid chloride. It is preferable that the resin does not react and does not break the porous support membrane by dissolution or the like. Further, those having low toxicity, flammability, cost and the like are preferable. Examples of solvents satisfying these conditions include, for example, n-hexane, n-heptane, n-heptane,
-Hydrocarbons such as octane and n-nonane n-decane; and halogenated hydrocarbons such as chloroform, carbon tetrachloride, trichloroethane, dichloromethane and trichlorotrifluoroethane. Above all, from the viewpoint of protection of the ozone layer, it is preferable to use a hydrocarbon in consideration of the fact that the ozone layer is not easily destroyed, the availability, and the ease of handling. Furthermore, since it is easy to handle if it is hard to volatilize at normal temperature and normal pressure, it is preferable to use a hydrocarbon having 6 or more carbon atoms, and a hydrocarbon having 8 or more carbon atoms or a flash point of 10 ° C. or more is used. It is more preferable to use a hydrocarbon having a flash point in the range of 10 to 300 ° C. If the flash point is less than 10 ° C., it tends to volatilize and handling is inconvenient. If the flash point exceeds 300 ° C., the viscosity increases and the handling becomes difficult. Examples of the solvent satisfying the above conditions include linear hydrocarbons such as n-octane, n-nonane, n-decane, n-undecane, n-dodecane and n-tridecane, and branched chains having the same carbon number. Hydrocarbons can also be suitably used. These may be used alone or as a mixture.

In the organic solvent solution containing the polyfunctional acid chloride, as in the case of the aqueous solution of the polyfunctional amine, it is preferable to remove suspended substances in the solution as much as possible. A solution is used in which the number of suspended substances having an equivalent diameter of 10 μm or more is 5,000 or less, more preferably 1,000 or less, and still more preferably 500 or less per 100 μl. The method for removing the suspended substance can be carried out by membrane filtration or distillation as in the case of the aqueous solution of the polyfunctional amine.

The contact time of the solution containing the polyfunctional acid chloride is:
It is sufficient that the contact time is sufficient for the polyfunctional amine to react with the polyfunctional acid chloride and form a thin film on the porous support membrane. Specifically, it is preferably in the range of 1 second to 10 minutes, and more preferably in the range of 20 seconds to 2 minutes. If the contact time is less than 1 second, defects tend to occur in the film, and if it exceeds 10 minutes, the film becomes too thick and the permeation flux tends to decrease.

As described above, the separation functional layer can be formed by interfacial polycondensation by bringing the polyfunctional amine and the polyfunctional acid chloride into contact on the porous support membrane. By performing the reaction in the presence of the above additive, the reaction rate and the membrane morphology can be controlled, and the performance of the composite semipermeable membrane can be improved.

As the additive, for example, those which promote an interfacial polycondensation reaction, such as an acylation catalyst, and those which do not directly participate in the reaction but change the reaction field, and polar compounds can be used. .

As the acylation catalyst, for example, ε-caprolactam, N-methyl-ε-caprolactam, N-
Methylpyrrolidone, 2-pyrrolidone, 2-piperidone,
Tetramethylurea, bis (pentamethylene) urea,
1,1′-carbonyldipyrrolidine, N, N′-dimethylpropyleneurea, dimethylsulfoxide, hexamethylphosphamide, N, N-dimethylformamide,
Amide compounds such as N, N-diethylformamide and N, N-dibutylformamide can be used.

As another catalyst, a phase transfer catalyst can be used. The phase transfer catalyst has the effect of promoting the reaction between the aqueous phase and the organic phase, and is effective when performing interfacial polycondensation using an aqueous solution of a polyfunctional amine and a solution of a polyfunctional acid chloride. Specifically, for example, a quaternary ammonium salt such as n-heptyltriethylammonium chloride, trioctylmethylammonium chloride, benzyltriethylammonium chloride (Makosza's catalyst), hexadecyltributylphosphonium chloride, or a phosphonium salt is used. Can be.

As the surfactant, for example, sodium dodecyl sulfate (DSS) or sodium dodecyl benzene sulfonate can be used.

As the polar compound, a compound containing a functional group such as an ether group, an ester group, a hydroxyl group, a carboxyl group, a sulfonic acid group, or a polarized bond in the molecule is preferable. Among them, compounds containing an ester group, an ether group or a carboxyl group are preferred because they have a high effect of increasing the permeation flux.

The amount of the additive as described above may be appropriately determined according to the effect of the additive to be obtained, the type of the polyfunctional compound to be used, the solvent, and the like. When it is used, it is preferable that the content is 5% by weight or less based on the amount of the solution, because it works effectively.
When a surfactant or a polar compound is used, it is preferable that the content be 30% by weight or less based on the amount of the solution, since it works effectively.

After the application of the polyfunctional acid chloride solution to form the separation functional layer on the porous support membrane, a step of removing excess solvent and polyfunctional acid chloride may be performed. It can be carried out by maintaining the direction, allowing the excess solvent to flow naturally, blowing air to forcibly drain the liquid, extracting with a liquid, or washing.

Next, the film is dried. For this, for example, a method of naturally drying, blowing, or replacing with a highly volatile solvent can be used. Of the above, for example, when drying by blowing,
As described in JP-B-76740, the wind speed on the film surface is in the range of 2 to 20 m / sec, preferably 3 to 1 m / sec.
A gas having a temperature in the range of 0 m / sec and a temperature in the range of 10 to 80 ° C., preferably in the range of 20 to 40 ° C. may be blown to the film. By using a gas within the above range, excessive evaporation of water and shrinkage of the porous support film are less likely to occur, and a film with a higher water permeation rate can be obtained.

The composite semipermeable membrane obtained as described above has a sufficiently good separation performance by itself, but is further subjected to a step of contacting with an aqueous alkali solution such as sodium carbonate to hydrolyze the remaining acid chloride. , In the range of 50 to 150 ° C, preferably in the range of 70 to 130 ° C.
By adding a step of heat treatment for 0 minute, preferably 2 to 8 minutes, or a step of immersion in an oxidizing liquid such as a chlorine-containing aqueous solution as described in JP-A-63-54905, It is possible to improve the rejection rate and the water permeation rate.

It is also preferable to further provide a coating layer on the separation function layer to suppress physical damage to the composite semipermeable membrane due to abrasion or the like, and to control surface charge.
It is also preferable to modify the surface of the separation function layer to control the amount of permeated water, the rejection, and the like. As a material constituting the coating layer, for example, polyvinyl alcohol is preferably used. In order to perform surface modification, there are methods such as the above-mentioned coating. However, chemical treatment, plasma treatment, UV treatment, etc., change the surface chemical structure and increase hydrophilic groups such as hydroxyl groups and carboxyl groups. As a result, the permeation flux of the membrane can be improved.

The form of the composite semipermeable membrane is preferably a flat membrane or a hollow fiber membrane. Also, for example, by disposing a composite semi-permeable membrane on a substrate such as cloth, non-woven fabric, and paper,
The mechanical strength of the composite semipermeable membrane can be improved.

The composite semipermeable membrane obtained by the present invention can be used, for example, by incorporating it into a spiral, tubular, plate and frame module, or by bundling hollow fiber membranes and incorporating it into a module. .

When the composite semipermeable membrane of the present invention is used by being incorporated in a module, it is preferably used at a pressure within the range of 0.1 to 10 MPa, preferably at a pressure within the range of 0.2 to 8 MPa. . When the pressure is lower than 0.1 MPa, the separation performance such as the rejection ratio tends to decrease.
If it exceeds a, the film may be deformed and characteristics such as permeation flux may change.

Examples of the object to be treated include an aqueous solution and a solution containing an organic substance, etc., but it is particularly preferable to use an aqueous solution. Further, it can be used for producing fresh water from highly concentrated brine or seawater, or for producing ultrapure water.

[0053]

EXAMPLES In Examples and Comparative Examples, the rejection rate (Rej) and permeation flux (Flux) of the composite semipermeable membrane were calculated using the following equations (1) and (2), respectively.

Rej (%) = ((Solute concentration in feed solution−Solute concentration in permeate solution) / Solute concentration in feed solution) × 100 (1) Flux (m ³ · m ⁻² · day) ^-1 ) = permeated liquid amount per day / membrane area (2) Further, the porous support reinforced with fibers used in Examples and Comparative Examples (hereinafter referred to as fiber-reinforced porous support) is: Was created by the following method.

Taffeta made of polyester fiber having a size of 30 cm in length and 20 cm in width (both warp and weft are 150 denier multifilament yarn, weaving density: 90 / inch, width: 67 / inch, thickness: 160 μm) It is fixed on a glass plate, and polysulfone (Ude by Amoco)
1 P-3500) in a dimethylformamide (DMF) solution at a thickness of 200 μm was cast at room temperature (20 ° C.), immediately immersed in pure water and allowed to stand for 5 minutes to obtain a fiber-reinforced porous support. Obtained. The pure water permeability coefficient of this fiber-reinforced porous support is 0.005 to 0.01 kg / c when measured at a pressure of 0.1 MPa and a temperature of 25 ° C.
m ² · sec · atm. The surface pore size is 20
〜50 nm. (Example 1) 2.0% by weight of m-phenylenediamine,
An aqueous solution containing 1.5% by weight of N-methylpyrrolidone as an additive was filtered through an ultrafiltration membrane to remove suspended substances in the solution. About the solution after filtration, Rion PA
When measured using RTICLE COUNTER KL-11, there were 500 suspended substances per 100 μl having a circumscribed circle equivalent diameter of 10 μm or more. After the solution was brought into contact with the fiber-reinforced porous support for 2 minutes, the solution was drained so that no water droplets remained on the membrane surface. The suspended substance was removed from the thus obtained m-phenylenediamine-coated membrane in the same manner as described above (the suspended substance having a circumscribed circle equivalent diameter of 10 μm or more, which was measured by the same method as described above, was 1%).
100 per 100 μl), 0.05% by weight of trimesic acid chloride and 1% of ethyl caprylate as an additive.
Hexane solution containing 1% by weight was contacted for 1 minute. Thereafter, the liquid was drained for one minute, and dried by blowing a gas at 20 ° C. using a blower. Next, the obtained membrane was washed with Na ₂ C
An aqueous solution containing 1% by weight of O ₃ and 0.3% by weight of DSS
The reaction was stopped by soaking for a minute. The membrane thus obtained was washed with hot water at 90 ° C. for 2 minutes, and then 500 ppm, p
The composite semipermeable membrane was obtained by immersing in an aqueous solution having a chlorine concentration of H7 for 2 minutes. The obtained composite semipermeable membrane was stored in an aqueous solution containing 0.1% by weight of sodium bisulfite (SBS).

The composite semipermeable membrane obtained as described above is
Table 1 shows the results of a reverse osmosis test conducted under the conditions of 0.5 MPa and 25 ° C. using 1,500 ppm saline solution adjusted to pH 6.5 as raw water. (Example 2) N, N-di-n was further added to a hexane solution.
A composite semipermeable membrane was obtained in the same manner as in Example 1 except that 0.5% by weight of -butylformamide was added. Table 1 shows the evaluation results.
Shown in Example 3 A composite semipermeable membrane was obtained in the same manner as in Example 2 except that 5.0% by weight of ε-caprolactam was added instead of N-methylpyrrolidone. Table 1 shows the evaluation results. Example 4 A composite semipermeable membrane was obtained in the same manner as in Example 3 except that ethyl caprylate and N, N-di-n-butylformamide were not added. Table 1 shows the evaluation results. Example 5 A composite semipermeable membrane was obtained in the same manner as in Example 1 except that 1% by weight of caprylic acid was added instead of ethyl caprylate. Table 1 shows the evaluation results. (Example 6) N, N-di-n was further added to the hexane solution.
A composite semipermeable membrane was obtained in the same manner as in Example 4, except that 0.5% by weight of -butylformamide was added. Table 1 shows the evaluation results.
Shown in Example 7 A composite semipermeable membrane was obtained in the same manner as in Example 4 except that 0.5% by weight of N-methylpyrrolidone was further added to the hexane solution. Table 1 shows the evaluation results. (Example 8) A composite semipermeable membrane was obtained in the same manner as in Example 2 except that a decane solution was used instead of the hexane solution. Table 1 shows the evaluation results. Example 9 A composite semipermeable membrane was obtained in the same manner as in Example 4 except that ε-caprolactam was not added. Table 1 shows the evaluation results. (Comparative Example 1) A composite semipermeable membrane was obtained in the same manner as in Example 4, except that ε-caprolactam was not used, the reaction time was 10 minutes, and the filtration treatment with an ultrafiltration membrane was not performed. Table 1 shows the evaluation results.

[0057]

[Table 1]

[0058]

According to the present invention, the thickness of the separation function layer is set to T.
(Μm) and the actual length L of the surface of the separation function layer per 1 μm length of the porous support membrane, T and L are L / T ≧ 5.
Since the relationship of 0 is satisfied, the surface area of the separation function layer is sufficiently large with respect to the thickness of the separation function layer, and the permeation flux and rejection of the composite separation membrane can be increased.

When the separation functional layer contains a crosslinked polyamide, the permeation flux and the rejection can be further increased, and a separation membrane having excellent durability can be obtained.

Further, in forming the separation function layer by interfacial polycondensation by contacting a polyfunctional amine aqueous solution and a polyfunctional acid chloride organic solvent solution on a porous support membrane, the aqueous solution and the organic solvent are used. When a solution having a circumscribed circle equivalent diameter of 10 μm or more and a suspension substance of 5,000 or less per 100 μl is used as the solution, the thickness of the separation function layer can be reduced and formed uniformly, and Thus, a composite semipermeable membrane having few pinholes and further improved permeation flux and rejection can be obtained.

In this case, by performing the interfacial polycondensation in the presence of an ester group, an ether group, a sulfonic acid group, a hydroxyl group, a carboxyl group, and an acylation catalyst, the reaction can be easily controlled and the reaction rate can be reduced. Since it can be increased, the productivity of the composite semipermeable membrane can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cross section of a composite semipermeable membrane according to an embodiment of the present invention.

[Explanation of symbols]

 1: porous support membrane 2: separation functional layer

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4D006 GA03 HA01 HA21 HA41 HA61 JA02C JA52Z KE05R KE06R MA01 MA03 MA07 MA08 MA09 MA22 MA31 MB02 MB06 MB11 MB16 MC11 MC17 MC18 MC22 MC23 MC27 MC36 MC39 MC46 MC48 MC48X MC54 MC56 MC62 MC62X MC71 MC74 MC75 MC75X MC77 MC78X NA04 NA10 NA41 NA44 NA46 NA62 NA64 PA01 PB02 PB06 PB12 PB13 PC02 PC12 PC17 PC21 PC31 PC54

Claims (5)

[Claims] 1. A separation function layer provided on a porous support membrane, wherein the thickness of the separation function layer is T (μm), and the actual separation function layer surface per 1 μm length of the porous support membrane is Length is L
A composite semipermeable membrane, characterized in that T and L satisfy the following formula when defined as (μm): L / T ≧ 50 2. The composite semipermeable membrane according to claim 1, wherein the separation functional layer contains a crosslinked polyamide. 3. A method for forming a separation functional layer on a porous support membrane by interfacial polycondensation by bringing an aqueous solution of a polyfunctional amine into contact with an organic solvent solution of a polyfunctional acid chloride on the porous support membrane. 3. The composite semipermeable membrane according to claim 1, wherein the aqueous solution and the organic solvent solution are solutions in which the number of suspended substances having a circumscribed circle equivalent diameter of 10 μm or more is 5,000 or less per 100 μl. Manufacturing method. 4. The method according to claim 3, wherein the interfacial polycondensation is performed in the presence of a compound containing at least one functional group selected from the group consisting of an ester group, an ether group, a sulfonic acid group, a hydroxyl group and a carboxyl group. A method for producing a composite semipermeable membrane. 5. The method for producing a composite semipermeable membrane according to claim 3, wherein the interfacial polycondensation is performed in the presence of an acylation catalyst.