JP2013240781A - Method for producing composite semipermeable membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stable production of a composite semipermeable membrane having few skin layer defects and a high filter rate.SOLUTION: A method is provided for producing a composite semipermeable membrane wherein a skin layer is formed on the surface of a porous substrate. The method comprises an impurity removal step of removing impurities deposited on the surface of the porous substrate, before the skin layer is formed on the surface of the porous substrate.

Description

  The present invention relates to a method for producing a composite semipermeable membrane comprising a skin layer having high separation performance and a porous support for supporting the skin layer. Such a composite semipermeable membrane can be used in various ways mainly depending on the performance and application of the skin layer such as RO membrane, NF membrane, MF membrane, UF membrane, and FO membrane. For example, composite semipermeable membranes are suitable for the production of ultrapure water, brine or seawater desalination, and are also included in contamination due to pollution such as dye wastewater and electrodeposition paint wastewater. It can be used for wastewater treatment, such as removing and collecting contaminated sources or effective substances. Moreover, it can be used for advanced treatments such as concentration of active ingredients in food applications and removal of harmful components in water purification and sewage applications.

  As a method for producing a composite semipermeable membrane, many methods for forming a skin layer made of polyamide by interfacial polymerization of a polyfunctional amine and a polyfunctional acid halide on a porous support have been proposed.

  For example, Patent Documents 1 and 2 propose a manufacturing method for obtaining a high-performance polyamide composite semipermeable membrane.

  However, in recent years, with the increase in demand for polyamide-based composite semipermeable membranes for treating wastewater, brine, seawater, and the like, higher quality and larger amounts of composite semipermeable membranes have been demanded. For this purpose, it is necessary to stably and continuously produce a composite semipermeable membrane free from defects (scratches, tears, etc.) in the skin layer.

JP-A-9-192461 JP 2006-130497 A

  An object of the present invention is to provide a method for stably producing a composite semipermeable membrane having few defects in the skin layer and having a high rejection.

  The present invention relates to a method for producing a composite semipermeable membrane in which a skin layer is formed on the surface of a porous support, and before the skin layer is formed on the surface of the porous support, the skin layer is attached to the surface of the porous support. The present invention relates to a method for producing a composite semipermeable membrane, comprising a foreign matter removing step for removing foreign matter that is present.

  If foreign matter is present on the surface of the porous support, a skin layer is formed on the foreign matter, and the foreign matter may cause defects (scratches, tears, etc.) in the skin layer. In addition, when the excess solution is removed by a wiper or the like after applying the skin layer forming solution on the porous support as in the conventional production method, if there is a foreign substance on the surface of the porous support, In some cases, scratches may occur, the skin layer may be torn, or the surplus solution cannot be removed uniformly, resulting in poor surface uniformity of the skin layer. For these reasons, it has been difficult for the conventional production method to stably and continuously produce a composite semipermeable membrane having high separation performance.

  Before the skin layer is formed on the surface of the porous support as in the method for producing a composite semipermeable membrane of the present invention, foreign matters (for example, polymer particles) adhering to the surface of the porous support are removed. By providing the step, the generation of defects in the skin layer can be effectively suppressed, so that a composite semipermeable membrane having a high rejection and a high yield can be stably and continuously produced.

  The foreign matter removing step includes a liquid spraying process on the porous support surface, a wiper, squeegee or brush contact moving process on the porous support surface, a gas spraying process on the porous support surface, or two types thereof. It is preferable to carry out by the above combination.

  In particular, the foreign matter removing step is preferably a step of performing a contact movement process or a gas spraying process after performing a liquid spraying process, or a process of performing a contact movement process after performing a gas spraying process.

  Moreover, it is preferable that the said foreign material removal process is a process of removing the foreign material adhering to the both-sides surface of a porous support body.

  The skin layer includes a polyamide-based resin obtained by polymerizing a polyfunctional amine component and a polyfunctional acid halide component, and before bringing the aqueous amine solution containing the polyfunctional amine component into contact with the surface of the porous support. The foreign matter removing step is preferably performed.

  Moreover, it is preferable to perform the said foreign material removal process within 60 second, before making amine aqueous solution contact the surface of a porous support body.

  The polyfunctional amine component is preferably an alicyclic polyfunctional amine.

2 is a photomicrograph showing the dyed state of the membrane surface at a position where the composite semipermeable membrane produced in Example 1 is at a deposition length of 0 m. 4 is a photomicrograph showing the dyed state of the membrane surface at a position where the composite semipermeable membrane produced in Example 1 is at a film forming length of 1000 m. 4 is a photomicrograph showing the dyeing state of the membrane surface at a position where the composite semipermeable membrane produced in Comparative Example 1 has a film formation length of 0 m. 4 is a photomicrograph showing the dyeing state of the membrane surface at a position where the composite semipermeable membrane produced in Comparative Example 1 is at a deposition length of 1000 m.

  Embodiments of the present invention will be described below. The present invention relates to a method for producing a composite semipermeable membrane in which a skin layer is formed on the surface of a porous support, and before the skin layer is formed on the surface of the porous support, the skin layer is attached to the surface of the porous support. And a foreign matter removing step for removing the foreign matter.

  The material for forming the skin layer is not particularly limited, and examples thereof include cellulose acetate, ethyl cellulose, polyether, polyester, and polyamide.

  In the present invention, a skin layer containing a polyamide-based resin obtained by polymerizing a polyfunctional amine component and a polyfunctional acid halogen component is preferable. Hereinafter, the present invention will be described in the case where the skin layer forming material is a polyamide-based resin.

  The polyfunctional amine component is a polyfunctional amine having two or more reactive amino groups, and examples thereof include aromatic, aliphatic, and alicyclic polyfunctional amines.

  Examples of the aromatic polyfunctional amine include m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, and 3,5-diamino. Examples include benzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, N, N′-dimethyl-m-phenylenediamine, 2,4-diaminoanisole, amidole, xylylenediamine and the like.

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

  Examples of the alicyclic polyfunctional amine include 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminomethylpiperazine, and the like. .

  These polyfunctional amines may be used alone or in combination of two or more. The effect of the production method of the present invention is particularly remarkable when a polyamide skin layer containing an alicyclic polyfunctional amine is used. Since the cycloaliphatic polyfunctional amine has a lower reactivity during polymerization than the aromatic polyfunctional amine, it is presumed that there is a high possibility that defects will occur due to the presence of foreign substances. In order to obtain a skin layer having a high salt-inhibiting performance, it is preferable to use an aromatic polyfunctional amine.

  The polyfunctional acid halide component is a polyfunctional acid halide having two or more reactive carbonyl groups.

  Examples of the polyfunctional acid halide include aromatic, aliphatic, and alicyclic polyfunctional acid halides.

  Examples of aromatic polyfunctional acid halides include trimesic acid trichloride, terephthalic acid dichloride, isophthalic acid dichloride, biphenyl dicarboxylic acid dichloride, naphthalene dicarboxylic acid dichloride, benzene trisulfonic acid trichloride, benzene disulfonic acid dichloride, and chlorosulfonylbenzene dicarboxylic acid. An acid dichloride etc. are mentioned.

  Examples of the aliphatic polyfunctional acid halide include propanedicarboxylic acid dichloride, butanedicarboxylic acid dichloride, pentanedicarboxylic acid dichloride, propanetricarboxylic acid trichloride, butanetricarboxylic acid trichloride, pentanetricarboxylic acid trichloride, glutaryl halide, adipoid Examples include luhalides.

  Examples of the alicyclic polyfunctional acid halide include cyclopropane tricarboxylic acid trichloride, cyclobutane tetracarboxylic acid tetrachloride, cyclopentane tricarboxylic acid trichloride, cyclopentane tetracarboxylic acid tetrachloride, cyclohexane tricarboxylic acid trichloride, and tetrahydrofuran. Examples thereof include tetracarboxylic acid tetrachloride, cyclopentane dicarboxylic acid dichloride, cyclobutane dicarboxylic acid dichloride, cyclohexane dicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride.

  These polyfunctional acid halides may be used alone or in combination of two or more. In order to obtain a skin layer having a high salt inhibition performance, it is preferable to use an aromatic polyfunctional acid halide. Moreover, it is preferable to form a crosslinked structure by using a trifunctional or higher polyfunctional acid halide as at least a part of the polyfunctional acid halide component.

  In order to improve the performance of the skin layer containing a polyamide-based resin, a polymer such as polyvinyl alcohol, polyvinyl pyrrolidone, or polyacrylic acid, a polyhydric alcohol such as sorbitol, glycerin, or the like may be copolymerized.

  The porous support that supports the skin layer is not particularly limited as long as it can support the skin layer, and usually an ultrafiltration membrane having micropores with an average pore diameter of about 10 to 500 mm is preferably used. Examples of the material for forming the porous support include polysulfone, polyarylethersulfone such as polyethersulfone, polyimide, polyvinylidene fluoride, and the like. Polysulfone and polyarylethersulfone are preferably used from the viewpoint of stability. The thickness of such a porous support is usually about 25 to 125 μm, preferably about 40 to 75 μm, but is not necessarily limited thereto. In addition, the porous support may be reinforced with a backing by a woven fabric, a nonwoven fabric or the like.

  In the present invention, before the skin layer is formed on the surface of the porous support, it is necessary to remove foreign matters adhering to the surface of the porous support (foreign matter removing step). In the present invention, the “foreign matter” means an organic or inorganic substance having a maximum width of 50 nm or more, or a substance that adversely affects the formation of a skin layer such as excess moisture or water droplets.

  The means for removing the foreign matter in the foreign matter removing step is not particularly limited as long as the foreign matter attached to the surface of the porous support can be removed, and a known method can be used. Non-contact means such as a liquid spraying process and a gas spraying process, a contact moving process such as a wiper, squeegee or brush on the surface of the porous support and an adhesive process using an adhesive roller. These foreign matter removing means may be used in combination of two or more. For example, a method of performing a contact movement process or a gas spraying process after performing a liquid spraying process, or a method of performing a contact movement process after performing a gas spraying process is preferably used. Can do. In particular, the method of performing the contact movement process or the gas spraying process after the liquid spraying process is particularly preferable because the fixing substance and the water-soluble substance which are foreign matters on the surface of the porous support can be removed.

  The liquid spraying process is not particularly limited as long as the liquid can be deposited on the surface of the porous support and allowed to flow or be removed together with foreign matter. The processing method is not particularly limited, but a shower or spraying method on the surface is preferably used. It is done. Examples of the liquid to be used include liquids that do not cause chemical damage to the surface of the porous support, such as water and alcohol, and it is particularly preferable to use pure water or ultrapure water. In order to completely remove the foreign matter adhering to the surface of the porous support, it is preferable that the injection force is high enough not to destroy the porous support. The amount of spraying is usually about 0.1 to 30 L / (min · m), preferably 1 to 15 L / (min · m), more preferably 5 to 15 L / (min · m). If the spraying amount is too small, the removal of foreign matters is insufficient, and if it is too large, the porous support is easily damaged. The liquid spraying needs to be performed on the entire surface of the porous support, and after spraying, it is preferable to remove the liquid to the extent that it does not adversely affect the formation of the skin layer.

  The gas blowing process is not particularly limited as long as it is a process of blowing off foreign matter using gas, and examples thereof include an air knife that jets gas from a slit or a nozzle. As the gas to be used, air and an inert gas such as nitrogen gas which do not easily damage the surface of the porous support are preferably used. In order to completely remove the foreign matter adhering to the surface of the porous support, it is preferable to blow a gas by bringing the air knife close to the surface of the porous support to a distance of 1 to 5 mm. The jetting speed is preferably 10 to 500 m / sec in the vicinity of the surface, and if the jetting speed is too high, the surface is easily damaged, and more preferably 35 to 100 m / sec.

  In the case of the contact movement treatment, the tool to be used is not particularly limited as long as it can remove foreign matters and hardly damage the surface of the porous support, and examples thereof include a wiper, a squeegee, and a brush. Examples of the wiper include a rubber blade wiper and a plastic plate wiper. Examples of the squeegee include a urethane rubber squeegee. Examples of brushes include natural fiber brushes and artificial fiber brushes. Examples of the material for the rubber blade wiper and squeegee include nitrile rubber, butyl rubber, fluorine rubber, silicon rubber, and urethane rubber. Nitrile rubber or fluorine rubber is preferably used from the viewpoint of wear resistance and chemical resistance. It is done. In order to completely remove the foreign matter adhering to the surface of the porous support, the wiper or the like can be moved in contact with the portion where the porous support is supported by the roll, or the wiper or the like can be contacted. It is necessary to move the wiper or the like in a state where it is stretched to a certain extent. The contact strength of the wiper or the like to the surface of the porous support may be appropriately adjusted from the viewpoint of the foreign matter removal efficiency depending on the conveyance resistance and the contact amount on the surface of the porous support.

  When the skin layer contains a polyamide-based resin obtained by polymerizing a polyfunctional amine component and a polyfunctional acid halide component, the foreign matter removing step involves contacting the aqueous amine solution containing the polyfunctional amine component with the surface of the porous support. However, it is preferably performed within 60 seconds before the aqueous amine solution is brought into contact with the surface of the porous support in order to prevent reattachment of foreign matters from the outside after the foreign matter removing step. More preferably, it is within 30 seconds, and particularly preferably within 15 seconds.

  The foreign matter removing step needs to be performed on the surface of the porous support in contact with the aqueous amine solution, but is preferably performed on both surfaces of the porous support. Thereby, when winding in roll shape, or when contacting with a conveyance roll, it can suppress that a foreign material adheres to the surface.

  In the present invention, after the foreign matter removing step, an aqueous solution coating layer comprising an aqueous amine solution containing a polyfunctional amine component is formed on the surface of the porous support, and then an organic solution containing the polyfunctional acid halide component and the aqueous solution coating layer are formed. It is preferable to form a skin layer by bringing the polymer into contact with each other for interfacial polymerization. The details of the conditions of such interfacial polymerization method are described in JP-A-58-24303, JP-A-1-180208 and the like, and those known techniques can be appropriately employed.

  In the interfacial polymerization method, the concentration of the polyfunctional amine component in the aqueous amine solution is not particularly limited, but is preferably 0.1 to 5% by weight, more preferably 0.5 to 2% by weight. When the concentration of the polyfunctional amine component is less than 0.1% by weight, defects such as pinholes are likely to occur in the skin layer, and the salt blocking performance tends to decrease. On the other hand, when the concentration of the polyfunctional amine component exceeds 5% by weight, the polyfunctional amine component is likely to penetrate into the porous support, or the film thickness becomes too thick to increase the permeation resistance and increase the permeation flow. The bundle tends to decrease.

  The concentration of the polyfunctional acid halide component in the organic solution is not particularly limited, but is preferably 0.01 to 5% by weight, and more preferably 0.05 to 3% by weight. If the concentration of the polyfunctional acid halide component is less than 0.01% by weight, the unreacted polyfunctional amine component tends to remain, or defects such as pinholes are likely to occur in the skin layer, resulting in a decrease in salt blocking performance. Tend to. On the other hand, when the concentration of the polyfunctional acid halide component exceeds 5% by weight, the unreacted polyfunctional acid halide component tends to remain, or the film thickness becomes too thick to increase the permeation resistance, thereby increasing the permeation flux. It tends to decrease.

  The organic solvent used in the organic solution is not particularly limited as long as it has low solubility in water, does not deteriorate the porous support, and dissolves the polyfunctional acid halide component. For example, cyclohexane, heptane, octane And saturated hydrocarbons such as nonane, and halogen-substituted hydrocarbons such as 1,1,2-trichlorotrifluoroethane. Preferred is a saturated hydrocarbon having a boiling point of 300 ° C. or lower, more preferably a boiling point of 200 ° C. or lower.

Various additives can be added to the amine aqueous solution and the organic solution for the purpose of facilitating film formation and improving the performance of the resulting composite semipermeable membrane. Examples of the additive include surfactants such as sodium dodecylbenzenesulfonate, sodium dodecylsulfate, and sodium laurylsulfate, sodium hydroxide that removes hydrogen halide generated by polymerization, trisodium phosphate, and triethylamine. And basic compounds, acylation catalysts, compounds having a solubility parameter of 8 to 14 (cal / cm ³ ) ^1/2 described in JP-A-8-224452, and the like.

  The time from the application of the aqueous amine solution to the application of the organic solution on the porous support depends on the composition of the aqueous amine solution, the viscosity, and the pore size of the surface layer of the porous support, but is 15 seconds or less. It is preferable that there is, more preferably 5 seconds or less. When the application interval of the solution exceeds 15 seconds, the aqueous amine solution may penetrate and diffuse deep inside the porous support, and a large amount of unreacted polyfunctional amine component may remain in the porous support. . In addition, after coating the said amine aqueous solution on the said porous support body, you may remove excess amine aqueous solution.

  In the present invention, after contacting the aqueous solution coating layer composed of an aqueous amine solution with the organic solution, the excess organic solution on the porous support is removed, and the formed film on the porous support is dried by heating at 70 ° C. or higher. It is preferable to form a skin layer. By heat-treating the formed film, its mechanical strength, heat resistance, etc. can be increased. The heating temperature is more preferably 70 to 200 ° C, particularly preferably 100 to 150 ° C. The heating time is preferably about 30 seconds to 10 minutes, more preferably about 40 seconds to 7 minutes.

  The thickness of the skin layer formed on the porous support is not particularly limited, but is usually about 0.05 to 2 μm, preferably 0.1 to 1 μm.

  The composite semipermeable membrane of the present invention is not limited in its shape. That is, any conceivable membrane shape such as a flat membrane shape or a spiral element shape is possible. Moreover, in order to improve the salt-blocking property, water permeability, oxidation resistance, etc. of the composite semipermeable membrane, various conventionally known treatments may be performed.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[Measurement and evaluation method]
(Measurement of MgSO ₄ rejection)
The produced sample was set in a cell for flat membrane evaluation. An aqueous solution containing 0.2% by weight of MgSO ₄ and adjusted to pH 6.5 with NaOH is brought into contact with the membrane by applying a differential pressure of 0.9 MPa between the supply side and the permeation side of the membrane at 25 ° C. For 30 minutes. The conductivity of the permeated water obtained by this operation was measured, and the MgSO ₄ rejection (%) was calculated. The MgSO ₄ rejection was calculated in advance using the correlation (calibration curve) between the MgSO ₄ concentration and aqueous solution conductivity in advance.
MgSO ₄ rejection (%) = {1- (MgSO ₄ concentration in the permeate [mg / L]) / (MgSO ₄ concentration in the feed [mg / L])} × 100

(Evaluation of membrane staining)
The produced sample was set in a cell for flat membrane evaluation. An aqueous solution containing 1% by weight of basic violet dye is brought into contact with the membrane by applying a differential pressure of 1.5 MPa on the supply side and permeation side of the membrane at 25 ° C., and the aqueous solution is allowed to permeate for 10 minutes, and the dye adheres to the membrane surface. I let you.

Example 1
While continuously feeding a porous support body (UF membrane having a polysulfone porous layer formed on a nonwoven fabric) wound in a roll shape, 10 L / (min · m) of pure water was applied to both surfaces of the porous support body for 1 second. Immediately after spraying, a fluororubber blade wiper (type A hardness: 50) was brought into contact with the skin layer forming surface of the porous support to remove foreign matters (foreign matter removing step). Here, an appropriate amount of a sample (10 mm × 10 mm) was cut from the porous support in the width direction, and the number of fine particles having a size of 50 nm or more was counted visually using a microscope, and the average value was obtained. The results are shown in Table 1.
Thereafter, an aqueous amine solution containing 1.2% by weight of piperazine was applied to the surface of the remaining porous support, and then an excess aqueous amine solution was removed to form an aqueous solution coating layer. Next, an isooctane solution containing 0.9% by weight of trimesic acid chloride was applied to the surface of the aqueous solution coating layer. Thereafter, the excess solution was removed, and further kept in a hot air dryer at 120 ° C. for 3 minutes to form a skin layer containing a polyamide-based resin on the porous support to obtain a composite semipermeable membrane. Three samples each having a size of φ75 mm were cut out from the initial (film formation 0 to 1 m) and composite semipermeable membrane at a film formation position of 1000 m at this time, and the MgSO ₄ blocking rate was measured using the samples. The average value of the results is shown in Table 1.

Example 2
In the foreign matter removing step of Example 1, 10 L / (min · m) pure water was sprayed on both surfaces of the porous support for 1 second, and then air at a wind speed of 40 m / s was sprayed on both surfaces of the porous support for 1 second. A composite semipermeable membrane was prepared in the same manner as in Example 1 except that the foreign matters were removed, and the MgSO ₄ blocking rate was measured. The average value of the results is shown in Table 1.

Example 3
In the foreign matter removing step of Example 1, after the air of 40 m / s was blown on both surfaces of the porous support for 1 second, the foreign matter was removed by treatment with a rubber blade wiper as in Example 1. A composite semipermeable membrane was prepared in the same manner as in Example 1, and the MgSO ₄ rejection was measured. The average value of the results is shown in Table 1.

Example 4
In the foreign matter removing step of Example 1, the same method as in Example 1 was applied except that the foreign matter was removed by continuously applying air blowing at a wind speed of 40 m / s for 1 second on both surfaces of the porous support. A composite semipermeable membrane was prepared, and the MgSO ₄ rejection was measured. The average value of the results is shown in Table 1.

Example 5
In the foreign matter removing step of Example 1, after removing the foreign matter by spraying 10 L / (min · m) of pure water on both surfaces of the porous support for 1 second, the porous support was tilted to remove excess water. Except for this, a composite semipermeable membrane was prepared in the same manner as in Example 1, and the MgSO ₄ rejection was measured. The average value of the results is shown in Table 1.

Example 6
In the foreign matter removing step of Example 1, after removing the foreign matter by spraying 1 L / (min · m) of pure water for 1 second on both surfaces of the porous support, the porous support was tilted to remove excess water. Except for this, a composite semipermeable membrane was prepared in the same manner as in Example 1, and the MgSO ₄ rejection was measured. The average value of the results is shown in Table 1.

Example 7
In the foreign matter removing step of Example 1, 0.5 L / (min · m) pure water was sprayed on both surfaces of the porous support for 1 second to remove the foreign matter, and then the porous support was tilted to remove excess water. A composite semipermeable membrane was prepared in the same manner as in Example 1 except that it was removed, and the MgSO ₄ blocking rate was measured. The average value of the results is shown in Table 1.

Comparative Example 1
A composite semipermeable membrane was prepared in the same manner as in Example 1 except that the foreign matter removing step in Example 1 was not performed, and the MgSO ₄ blocking rate was measured. The average value of the results is shown in Table 1.

As is apparent from Table 1, the composite semipermeable membranes of Examples 1 to 7 have 10 or less fine particles, and even when continuously produced at 1000 m, the MgSO ₄ blocking rate is stable at 99% or more, and the skin It can be seen that there are almost no defects on the surface of the layer. Furthermore, it can be seen that by reducing the number of fine particles to 5 or less, a decrease in the MgSO ₄ blocking rate can be remarkably suppressed even at 1000 m production. On the other hand, the composite semipermeable membrane of Comparative Example 1 has a greatly reduced MgSO ₄ blocking rate when 1000 m is continuously produced, and there is a concern that the yield may be reduced.

Claims (8)

In the method for producing a composite semipermeable membrane having a skin layer formed on the surface of the porous support, the foreign matter adhering to the surface of the porous support before the skin layer is formed on the surface of the porous support. The manufacturing method of the composite semipermeable membrane characterized by including the foreign substance removal process of removing. The foreign matter removing step includes a liquid spraying process on the porous support surface, a wiper, squeegee or brush contact moving process on the porous support surface, a gas spraying process on the porous support surface, or two types thereof. 2. The method for producing a composite semipermeable membrane according to claim 1, wherein the method is performed in combination. The method for producing a composite semipermeable membrane according to claim 2, wherein the foreign matter removing step is a step of performing a contact movement process or a gas spraying process after a liquid spraying process. The method for producing a composite semipermeable membrane according to claim 2, wherein the foreign matter removing step is a step of performing a contact movement process after performing a gas blowing process. The method for producing a composite semipermeable membrane according to any one of claims 1 to 4, wherein the foreign matter removing step is a step of removing foreign matter adhering to both side surfaces of the porous support. The skin layer includes a polyamide-based resin obtained by polymerizing a polyfunctional amine component and a polyfunctional acid halide component, and before bringing the aqueous amine solution containing the polyfunctional amine component into contact with the surface of the porous support. The method for producing a composite semipermeable membrane according to any one of claims 1 to 5, wherein the foreign matter removing step is performed. The method for producing a composite semipermeable membrane according to claim 6, wherein the foreign matter removing step is performed within 60 seconds before bringing the aqueous amine solution into contact with the surface of the porous support. The method for producing a composite semipermeable membrane according to claim 6 or 7, wherein the polyfunctional amine component is an alicyclic polyfunctional amine.

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