KR101966823B1

KR101966823B1 - Water-treatment membrane and method for manufacturing thereof

Info

Publication number: KR101966823B1
Application number: KR1020150054730A
Authority: KR
Inventors: 박형숙; 박민수; 양세우; 신정규; 이필; 이영주
Original assignee: 주식회사 엘지화학
Priority date: 2015-04-17
Filing date: 2015-04-17
Publication date: 2019-08-13
Also published as: KR20160123904A

Abstract

The present specification relates to a water treatment membrane and a method of manufacturing the same.

Description

WATER-TREATMENT MEMBRANE AND METHOD FOR MANUFACTURING THEREOF}

Due to the recent severe pollution and lack of water in the water environment, the development of new water resources is an urgent challenge. Water pollution research aims to treat high quality living and industrial water, various kinds of domestic sewage and industrial wastewater, and interest in water treatment processes using membranes has advantages of energy saving. In addition, accelerating environmental regulations are expected to accelerate membrane technology. Conventional water treatment processes are difficult to meet the tightening regulations, but the membrane technology is expected to become a leading technology in the future because of the excellent treatment efficiency and stable treatment.

Liquid separation is classified into Micro Filtration, Ultra Filtration, Nano Filtration, Reverse Osmosis, Sedimentation, Active Transport and Electrodialysis depending on the pore of the membrane. The reverse osmosis method refers to a process of desalting using a semipermeable membrane that transmits water but is impermeable to salt. When the high pressure water in which the salt is dissolved flows into one side of the semipermeable membrane, the pure water is removed. Will come out on the other side at low pressure.

In recent years, about 1 billion gal / day of water worldwide has undergone desalination through reverse osmosis, and since the first desalination using reverse osmosis was introduced in the 1930s, many of the The study was conducted. Among them, cellulose-based asymmetric membranes and polyamide-based composite membranes have come to the forefront of commercial success. Cellulose membranes developed in the early stages of reverse osmosis membranes have suffered from several shortcomings due to their narrow operating pH range, their deformation at high temperatures, the high cost of operation using high pressure, and their vulnerability to microorganisms. This is a rarely used trend.

On the other hand, in the polyamide composite membrane, a polysulfone layer is formed on a nonwoven fabric to form a microporous support, and the microporous support is immersed in an aqueous solution of m-phenylenediamine (mPD) to form an mPD layer. Formed, and then immersed or coated in a trimesoyl chloride (hereinafter referred to as TMC) organic solvent to make a polyamide layer by interfacial polymerization by contacting the mPD layer with TMC. By contacting the nonpolar and polar solutions, the polymerization takes place only at the interface to form a very thin polyamide layer. The polyamide-based composite membrane has high stability against pH change, can be operated at low pressure, and has excellent salt rejection rate, compared to existing cellulose-based asymmetric membranes.

Korean public publication 10-2010-0073795

The present specification is to provide a water treatment membrane and its preparation method.

One embodiment of the present specification, a porous support; A polyamide active layer provided on the porous support; And an adhesive film provided on at least a portion of the polyamide active layer,

Provided between the polyamide active layer and the adhesive film, a water treatment separation membrane comprising a structure in which an acrylic acid group and a hydroxyl group are bonded using a carbodiimide-based material.

One embodiment of the present specification, a porous support; A polyamide active layer provided on the porous support; A polyvinyl alcohol (PVA) layer provided on the polyamide active layer; And an adhesive film provided on at least a portion of the polyvinyl alcohol (PVA) layer,

The adhesive film is provided with a substrate and an adhesive layer containing a compound containing an acrylic acid group on the substrate, the hydroxyl group of the polyvinyl alcohol (PVA) layer and the acrylic acid group of the adhesive layer is bonded using a carbodiimide-based material, Provide a water treatment membrane.

One embodiment of the present specification, preparing a laminate comprising a porous support, a polyamide active layer provided on the porous support, and a polyvinyl alcohol (PVA) layer provided on the polyamide active layer;

Preparing an adhesive film having an adhesive layer including a compound including an acrylic acid group, a carbodiimide-based material, and an amine catalyst on a substrate; And

Attaching the adhesive film to at least a portion of the polyvinyl alcohol (PVA) layer such that the adhesive layer is provided close to the polyvinyl alcohol (PVA) layer,

The hydroxyl group of the polyvinyl alcohol (PVA) layer and the acrylic acid group of the adhesive layer are bonded to each other using a carbodiimide-based material.

Preparing a carbodiimide composition comprising a solvent, a carbodiimide-based material, and an amine catalyst;

Preparing an adhesive film having an adhesive layer including a compound including an acrylic acid group on a substrate; And

Attaching an adhesive film to the polyvinyl alcohol (PVA) layer at least a portion of the polyvinyl alcohol (PVA) layer via the carbodiimide composition such that the adhesive layer is provided close to the polyvinyl alcohol (PVA) layer,

The water treatment separation membrane according to one embodiment of the present specification has an advantage in that the adhesion between the water treatment separation membrane and the adhesive film is excellent even after a long time in the water.

The water treatment separation membrane according to one embodiment of the present specification has an advantage that a crack occurrence rate of a region folded by an adhesive film is significantly reduced.

In the method of manufacturing a water treatment membrane according to one embodiment of the present specification, it is possible to manufacture a water treatment membrane having excellent durability through a simple process.

1 illustrates a structure of a water treatment separation membrane according to an exemplary embodiment of the present specification.
2 is a cross-sectional view showing a folded water treatment membrane according to one embodiment of the present specification.
Figure 3 shows the test result of the adhesive strength of the adhesive film according to the water treatment separator prepared according to Example 1.

In this specification, when a member is located "on" another member, this includes not only when a member is in contact with another member but also when another member exists between the two members.

In the present specification, when a part "contains" a certain component, this means that the component may further include other components, except for the case where there is no contrary description.

Because of the nature of the water treatment membrane, it is essential to maintain the adhesion in water because it operates in water. Furthermore, the polyvinyl alcohol (PVA) layer of the water treatment separation membrane has a problem in that the adhesive force with the adhesive film is deteriorated with time due to the property of swelling in water. When the adhesive force between the adhesive film and the water treatment separator is lowered and the adhesive film is separated from the water treatment separator, the adhesive film may cause physical damage to the water treatment separator, which may cause degradation of the performance of the water treatment separator. Therefore, it is necessary to develop a water treatment membrane in which the adhesion between the water treatment membrane and the adhesive film is maintained in water, and the present inventors have developed the following water treatment separator.

Hereinafter, this specification is demonstrated in detail.

The combination of the acrylic acid group and the hydroxyl group may form an ester (-COO-) bond to maintain the adhesion of the adhesive film in water. Specifically, the binding reaction may be a steglich esterification reaction.

The polyvinyl alcohol (PVA) layer may serve to protect the polyamide active layer from external physical and chemical elements as well as to prevent the polyamide active layer from being dried and damaged.

The adhesive film may serve to prevent cracks by physically increasing the physical strength of the water treatment separator when physically processing the shape of the water treatment separator. In addition, the adhesive film may serve to protect the water treatment separation membrane from external physical shocks.

According to one embodiment of the present specification, the adhesive film which is generally used may be used without limitation. Specifically, the adhesive film may be an adhesive film made of plastic.

According to one embodiment of the present specification, the adhesive film is provided with an adhesive layer on one surface, and the adhesive film is provided on the water treatment separator so that the adhesive layer is provided near the water treatment separator.

According to an exemplary embodiment of the present specification, the adhesive layer includes a compound containing an acrylic acid group.

According to an exemplary embodiment of the present specification, the carbodiimide-based material may be represented by a structure such as RN = C = NR ′. In this case, R and R 'may each independently be a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic ring group, or a substituted or unsubstituted aliphatic ring group.

Specifically, according to one embodiment of the present specification, the carbodiimide-based material may be DCC (Dicyclohexylcarbodiimide) or DIC (N, N'-diisopropylcarbodiimide).

According to an exemplary embodiment of the present specification, the carbodiimide-based material may form a bond of an acrylic acid group and a hydroxy group by an amine catalyst.

The amine catalyst may promote the reaction of the carbodiimide-based material to form a bond of a hydroxy group and an acrylic acid group in a short time.

According to an exemplary embodiment of the present specification, the amine catalyst may be dimethylami nopyridine (DMAP).

The carbodiimide-based material serves to maintain adhesion between the water treatment separator and the adhesive film, and in particular, even when the polyvinyl alcohol (PVA) layer is swelled in water. It plays a role in maintaining

Specifically, the hydroxyl group (-OH) of the polyvinyl alcohol (PVA) layer and the acrylic acid group of the adhesive film form a strong bond through the carbodiimide-based material, so that the polyvinyl alcohol (PVA) layer is dissolved and removed. Even if it is possible to maintain the bond between the polyamide active layer and the adhesive film.

According to one embodiment of the present specification, the water treatment separation membrane may be used as a single sheet form by folding two layers or two or more layers. In this case, since there is a risk that cracking may occur in the folding region of the water treatment separation membrane, the adhesive film may be provided in the folding region to prevent cracking. In addition, the adhesive film has a strong bond with the polyvinyl alcohol (PVA) layer or the polyamide active layer by the bonding structure of the acrylic acid group and the hydroxyl group through the carbodiimide-based material, specifically, the strong bond even to the end of the adhesive film The state is maintained to minimize the damage of the water treatment membrane to prevent performance degradation.

1 illustrates a structure of a water treatment separation membrane according to an exemplary embodiment of the present specification.

2 is a cross-sectional view showing a folded water treatment membrane according to one embodiment of the present specification.

According to FIG. 1, an adhesive film 201 is provided on the water treatment separation membrane 101, a folding area 301 of the water treatment separation membrane is indicated by a dotted line, and the water treatment separation membrane 101 and the adhesive film 201 are bonded to each other. The representation of the chemical structure is omitted. Further, a cross section of the water treatment separation membrane of FIG. 1 is shown in FIG. 2. 2 is spaced apart for convenience of separation of the water treatment separation membrane 101 and the adhesive film 201.

According to an exemplary embodiment of the present specification, the step of attaching the adhesive film, after applying the carbodiimide composition on at least a portion of the polyvinyl alcohol (PVA) layer, the area on which the carbodiimide composition is applied The adhesive layer may be attached to the adhesive film to be provided close to the polyvinyl alcohol (PVA) layer.

In addition, according to one embodiment of the present specification, the step of attaching the adhesive film, after applying the carbodiimide composition to at least a portion on the adhesive layer, so that the adhesive layer is provided close to the polyvinyl alcohol (PVA) layer. It may be to attach the adhesive film.

According to one embodiment of the present specification, after attaching the adhesive film, the method may further include folding the water treatment separator so that the region to which the adhesive film is bonded is folded.

According to an exemplary embodiment of the present specification, the content of the carbodiimide-based material may be 0.05% or more and 1% or less with respect to the mole number of the acrylic acid group of the adhesive film.

According to an exemplary embodiment of the present specification, the content of the carbodiimide-based material is 1% by volume or more and 15% by volume or less with respect to the carbodiimide composition, the method of manufacturing a water treatment membrane.

When the carbodiimide-based material is in the above content range, the adhesive force in the water of the adhesive film may be maintained strongly. If the carbodiimide-based material is less than the content range, there is a problem that the adhesion strength in the adhesive film is not sufficiently secured. In addition, when the content range of the carbodiimide-based material exceeds the above range, a problem may occur causing gelation of the adhesive layer.

According to an exemplary embodiment of the present specification, the content of the amine catalyst may be 0.1 times or more and 0.5 times or less with respect to the number of moles of the carbodiimide-based material.

According to one embodiment of the present specification, the thickness of the adhesive layer may be 10 μm or more and 50 μm or less. Specifically, according to one embodiment of the present specification, the adhesive layer may have a thickness of 20 μm or more and 30 μm or less.

When the thickness of the adhesive layer is in the above range, it is possible to secure the maximum adhesion strength in the adhesive film.

According to one embodiment of the present specification, the carbodiimide composition may be interposed with a thickness of 1 μm or more and 10 μm or less.

When the carbodiimide composition is applied to the surface of the adhesive layer, even a small amount of coating may exhibit high underwater adhesion.

According to one embodiment of the present specification, the solvent of the carbodiimide composition may apply an organic solvent generally used in the art.

The adhesive film is provided with an adhesive layer on one surface of the substrate and the substrate, and may be to attach the surface provided with the adhesive layer toward the adhesive target member. According to one embodiment of the present specification, the adhesive layer may have viscoelasticity with fluidity at room temperature.

According to one embodiment of the present specification, the substrate may use a general substrate film used in the art, and is not particularly limited. Examples include polyolefins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymers, ethylene- (meth) acrylic acid copolymers, polyesters such as polyurethanes, polyethylene terephthalates, polyethylene naphthalates, polycarbonates, polyether ether ketones, Polyimide, polyetherimide, polyamide, polyvinyl chloride, polyvinylidene chloride, paper, metal and the like.

According to one embodiment of the present specification, as the porous support, a coating layer of a polymer material may be used on a nonwoven fabric. Examples of the polymer material include polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyether ether ketone, polypropylene, polymethylpentene, polymethyl chloride and polyvinylidene fluorine. Ride or the like may be used, but is not necessarily limited thereto. Specifically, polysulfone may be used as the polymer material.

According to one embodiment of the present specification, the polyamide active layer may be formed through interfacial polymerization of an aqueous solution containing an amine compound and an organic solution containing an acyl halide compound. Specifically, the polyamide active layer comprises the steps of forming an aqueous layer including an amine compound on the porous support; And an organic solution including an acyl halide compound and an organic solvent on the aqueous solution layer including the amine compound, to form a polyamide active layer.

Upon contact of the aqueous solution layer containing the amine compound with the organic solution, an amine compound and an acyl halide compound coated on the surface react with each other to generate polyamide by adsorption on the microporous support to form a thin film. In the contact method, the polyamide active layer may be formed through a method such as dipping, spraying or coating.

According to one embodiment of the present specification, a method of forming an aqueous solution layer including an amine compound on the porous support is not particularly limited, and any method capable of forming an aqueous solution layer on the support may be used without limitation. Specifically, the method of forming the aqueous solution layer containing an amine compound on the porous support may be sprayed, applied, immersed, dripping and the like.

At this time, the aqueous solution layer may be further subjected to the step of removing the aqueous solution containing the excess amine compound as necessary. The aqueous solution layer formed on the porous support may be unevenly distributed when there are too many aqueous solutions present on the support. When the aqueous solution is unevenly distributed, a non-uniform polyamide active layer may be formed by subsequent interfacial polymerization. have. Therefore, it is preferable to remove excess aqueous solution after forming an aqueous solution layer on the said support body. The removal of the excess aqueous solution is not particularly limited, but may be performed using, for example, a sponge, air knife, nitrogen gas blowing, natural drying, or a compression roll.

According to an exemplary embodiment of the present specification, the amine compound in the aqueous solution containing the amine compound is not limited if the amine compound used in the water treatment separation membrane manufacturing, to give a specific example, m-phenylenediamine, p -Phenylenediamine, 1,3,6-benzenetriamine, 4-chloro-1,3-phenylenediamine, 6-chloro-1,3-phenylenediamine, 3-chloro-1,4-phenylene diamine Or a mixture thereof.

According to an exemplary embodiment of the present specification, the acyl halide compound is not limited thereto, but may be, for example, an aromatic compound having 2 to 3 carboxylic acid halides, such as trimezoyl chloride, isophthaloyl chloride and At least one mixture selected from the group of compounds consisting of terephthaloyl chloride.

According to an exemplary embodiment of the present specification, the organic solvent is an aliphatic hydrocarbon solvent, for example, a hydrophobic liquid which is not mixed with freons and water such as hexane, cyclohexane, heptane and alkanes having 5 to 12 carbon atoms, for example. For example, alkanes having 5 to 12 carbon atoms and mixtures thereof, such as IsoPar (Exxon), ISOL-C (SK Chem), ISOL-G (Exxon), and the like may be used, but are not limited thereto.

According to one embodiment of the present specification, the water treatment separation membrane may be used as a micro filtration membrane, an ultra filtration membrane, an ultra filtration membrane, a nano filtration membrane, a reverse osmosis membrane, or a reverse osmosis membrane. Can be used.

One embodiment of the present invention provides a water treatment module including at least one or more of the aforementioned water treatment separation membrane.

A specific kind of the water treatment module is not particularly limited, and examples thereof include a plate & frame module, a tubular module, a hollow & fiber module or a spiral wound module. In addition, as long as the water treatment module includes the water treatment separation membrane according to one embodiment of the present specification described above, other configurations and manufacturing methods are not particularly limited, and general means known in the art may be employed without limitation. have.

Meanwhile, the water treatment module according to one embodiment of the present specification has excellent salt removal rate and permeation flow rate, and has excellent chemical stability, and thus may be usefully used for water treatment devices such as household / industrial water purification devices, sewage treatment devices, seawater treatment devices, and the like. have.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the embodiments according to the present disclosure may be modified in various other forms, and the scope of the present specification is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present specification to those skilled in the art.

Preparation Example-Preparation of Acrylic Resin

n-butyl acrylate (BA): acrylate resin containing acrylic acid (AA) in a weight ratio of 95: 5, 150 parts by weight of ethyl acetate as a solvent based on 100 parts by weight of the acrylate resin And, based on 100 parts by weight of the acrylate resin was prepared a composition comprising 0.05 parts by weight of dodecanethiol. Subsequently, after substitution with nitrogen in an atmosphere of 67 ° C., azobisisobutyronitrile (AIBN) as an initiator was added to the composition at 0.04 parts by weight based on 100 parts by weight of the acrylate resin. Then, after the reaction for 5 hours, it was diluted with ethyl acetate to prepare an acrylic resin.

The weight-average molecular weight of the acrylic resin thus prepared was 650,000, the total solid content was 39%, the polydispersity index was 4.5, and the viscosity was Viscosity. Was 1800 cps.

Example 1

The composition was prepared by adding 0.15% of DCC and 0.4 times of DMAP to DMAP with respect to the number of moles of acrylic acid to the acrylic resin prepared according to the above preparation. A 25 μm thick adhesive layer was formed. And the release film was provided on the adhesion layer, and the adhesive film was manufactured.

The adhesive film prepared as described above was cut to a width of 25 mm and the release film was removed to attach to a laminate including a polyvinyl alcohol (PVA) layer provided on the polyamide active layer to prepare a water treatment separation membrane.

Example 2

DCC content was adjusted to 0.075% with respect to the number of moles of acrylic acid, except that it was adjusted to DMAP 0.4 times the number of moles of DCC, a water treatment separation membrane was prepared as in Example 1.

Example 3

The composition was prepared by adding an acrylic resin prepared according to the preparation example to an ethyl acetate solvent. The composition was applied to a PET substrate with a thickness of 25 μm, and then dried to form a 25 μm thick adhesive layer. And the release film was provided on the adhesion layer, and the adhesive film was manufactured.

The adhesive film prepared as described above was cut to a width of 25 mm, and the release film was removed to obtain an adhesive layer. After applying a composition comprising 10% DCC and 0.4 times the number of DCC moles per mole of acrylic acid at a thickness of 10 μm or less on the surface of the adhesive layer, the adhesive film was provided on the polyamide active layer. A water treatment separation membrane was prepared by adhering to a laminate including a vinyl alcohol (PVA) layer.

Comparative Example 1

The adhesive film prepared as described above was cut to a width of 25 mm, and the release film was removed to attach to a laminate including a polyvinyl alcohol (PVA) layer provided on the polyamide active layer to prepare a water treatment separation membrane.

Comparative Example 2

DCC content was adjusted to 0.015% with respect to the number of moles of acrylic acid, except that it was adjusted to DMAP 0.4 times the number of moles of DCC, a water treatment separation membrane was prepared as in Example 1.

The water treatment separator prepared according to the above example was left in water at 55 ° C. for 5 minutes after attaching the adhesive film, respectively. As a result of peeling the adhesive film and the laminate and testing the adhesion of the adhesive film in water, the adhesive film of the water treatment separation membrane according to Comparative Examples 1 to 2 was peeled off with very little force without damaging the polyamide active layer. On the contrary, the adhesive film of the water treatment separation membrane according to the embodiment took a lot of force during peeling, and after peeling, it was confirmed that a part of the adhesive layer remained in the polyamide active layer or the adhesive strength was such that the polyamide layer was destroyed.

Figure 3 shows the test result of the adhesive strength of the adhesive film according to the water treatment separator prepared according to Example 1. Specifically, FIG. 3 shows that the polyamide layer on the bottom surface is peeled off while the adhesive film is peeled off. That is, it can be determined that the adhesive strength in water of the adhesive film of the water treatment separator according to Example 1 is very excellent.

101: water treatment membrane
201: adhesive film
301: folding area

Claims

delete

Porous support; A polyamide active layer provided on the porous support; A polyvinyl alcohol (PVA) layer provided on the polyamide active layer; And an adhesive film provided on at least a portion of the polyvinyl alcohol (PVA) layer,
The adhesive film is provided with a substrate and an adhesive layer containing a compound containing an acrylic acid group on the substrate,
The hydroxyl group of the polyvinyl alcohol (PVA) layer and the acrylic acid group of the adhesive layer are bonded using a carbodiimide-based material,
The carbodiimide-based material is a water treatment separation membrane to form a bond of an acrylic acid group and a hydroxyl group with an amine catalyst.

delete

The method according to claim 2,
The water treatment separation membrane is a water treatment separation membrane is a region provided with the adhesive film is folded.

Preparing a laminate comprising a porous support, a polyamide active layer provided on the porous support, and a polyvinyl alcohol (PVA) layer provided on the polyamide active layer;
Preparing an adhesive film having an adhesive layer including a compound including an acrylic acid group, a carbodiimide-based material, and an amine catalyst on a substrate; And
Attaching the adhesive film to at least a portion of the polyvinyl alcohol (PVA) layer such that the adhesive layer is provided close to the polyvinyl alcohol (PVA) layer,
The hydroxyl group of the polyvinyl alcohol (PVA) layer and the acrylic acid group of the adhesive layer are bonded using a carbodiimide-based material,
The carbodiimide-based material is a method of manufacturing a water treatment separation membrane to form a bond of an acrylic acid group and a hydroxyl group with an amine catalyst.

Preparing a laminate comprising a porous support, a polyamide active layer provided on the porous support, and a polyvinyl alcohol (PVA) layer provided on the polyamide active layer;
Preparing a carbodiimide composition comprising a solvent, a carbodiimide-based material, and an amine catalyst;
Preparing an adhesive film having an adhesive layer including a compound including an acrylic acid group on a substrate; And
Attaching an adhesive film to the polyvinyl alcohol (PVA) layer at least a portion of the polyvinyl alcohol (PVA) layer via the carbodiimide composition such that the adhesive layer is provided close to the polyvinyl alcohol (PVA) layer,
The hydroxyl group of the polyvinyl alcohol (PVA) layer and the acrylic acid group of the adhesive layer are bonded using a carbodiimide-based material,
The carbodiimide-based material is a method of manufacturing a water treatment separation membrane to form a bond of an acrylic acid group and a hydroxyl group with an amine catalyst.

The method according to claim 6,
The attaching of the adhesive film may include applying the carbodiimide composition to at least a portion of the polyvinyl alcohol (PVA) layer, and then attaching the carbodiimide composition to the area where the carbodiimide composition is applied. Attaching the adhesive film so as to be provided close to the layer, the method of producing a water treatment separation membrane.

The method according to claim 6,
The attaching of the adhesive film may include applying the carbodiimide composition to at least a portion of the adhesive layer, and then attaching the adhesive film so that the adhesive layer is provided near the polyvinyl alcohol (PVA) layer. Manufacturing method.

The method according to claim 5 or 6,
After the step of attaching the adhesive film, further comprising the step of folding the water treatment separator so that the region to which the adhesive film is bonded, the manufacturing method of the water treatment separator.

The method according to claim 5,
The content of the carbodiimide-based material is 0.05% or more and 1% or less with respect to the number of moles of the acrylic acid group of the adhesive film, the method of producing a water treatment separation membrane.

The method according to claim 6,
The content of the carbodiimide-based material is 1% by volume or more and 15% by volume or less with respect to the carbodiimide composition.

The method according to claim 5 or 6,
The amount of the amine catalyst is 0.1 to 0.5 times the mole of the carbodiimide-based material, the method of producing a water treatment separation membrane.

The method according to claim 5,
The thickness of the said adhesive layer is 10 micrometers or more and 50 micrometers or less, The manufacturing method of the water treatment separation membrane.

The method according to claim 6,
The carbodiimide composition is a method of producing a water treatment separation membrane that is interposed in a thickness of 1 ㎛ or more and 10 ㎛ or less.