Reverse osmosis membrane and preparation method thereof

Abstract

The present invention relates to a reverse osmosis membrane and a method for preparing the same, and more specifically, to a high-durability reverse osmosis membrane and a method for preparing the same, that is, maintaining the same flux as the existing reverse osmosis membrane, having excellent interlayer bonding in the separation membrane, thereby minimizing the decrease in durability within the membrane during backwashing, thereby increasing the cleaning effect, extending the service life of the high-pressure membrane, maximizing the cumulative processing quantity, and reducing maintenance costs.

Description

Technical Field

[0001] The present invention relates to a reverse osmosis membrane and a method for preparing the same, and more specifically, to a high-durability reverse osmosis membrane and a method for preparing the same, that is, maintaining the same flux as the existing reverse osmosis membrane, having excellent interlayer bonding in the separation membrane, thereby minimizing the decrease in durability within the membrane during backwashing, thereby increasing the cleaning effect, extending the service life of the high-pressure membrane, maximizing the cumulative processing quantity, and reducing maintenance costs. Background Art

[0002] As the membrane filtration market grows rapidly worldwide, along with the development of membrane filtration technology, many membrane manufacturers and technicians have emerged, and research on this has also increased. These membrane filtration processes can be divided into low-pressure membrane filtration processes such as microfiltration (MF) and ultrafiltration (UF) that operate at low pressure, and high-pressure membrane filtration processes such as nanofiltration (NF) and reverse osmosis (RO) that operate at high pressure. Recently, interest in high-pressure membrane filtration processes is rapidly increasing.

[0003] On the other hand, the separation membrane used in the membrane filtration process is subject to organic fouling, inorganic fouling, particular fouling, bio-fouling, etc. as it is used, and therefore, its performance continues to decline. Therefore, chemical cleaning (CIP, cleaning in place) is performed using chemicals to restore the permeability of the separation membrane that has decreased as the membrane filtration process has run for a long time to its initial state. Membrane fouling is divided into reversible membrane fouling and irreversible membrane fouling. Physical cleaning such as osmotic backwashing is performed on reversible membrane fouling, and chemical cleaning is performed on irreversible membrane fouling.

[0004] In existing reverse osmosis membranes, the polymer support layer often peels off during the osmosis process or osmotic backwash process. The peeling of the polymer support layer promotes the peeling of the active layer, thereby reducing the salt rejection rate and permeation flux of the reverse osmosis membrane, resulting in a shortened service life of the membrane. Summary of the invention

[0005] Technical issues

[0006] The present invention is developed to solve the above-mentioned problems. The purpose of the present invention is to provide the following reverse osmosis membrane and its preparation method, that is, the reverse osmosis membrane of the present invention maintains the same flux as the existing reverse osmosis membrane, and has excellent interlayer bonding in the separation membrane, so that the durability reduction in the membrane during backwashing is minimized, thereby increasing the cleaning effect, extending the service life of the high-pressure membrane, maximizing the cumulative processing quantity, and reducing maintenance costs.

[0007] And, another object of the present invention is to provide a reverse osmosis membrane module including the reverse osmosis membrane according to the present invention, thereby having a salt rejection rate, a permeate flux, and excellent durability even after osmotic backwashing.

[0008] Solutions to the problem

[0009] In order to solve the above problems, the reverse osmosis membrane of the present invention is formed by sequentially stacking a porous support body, a polymer support layer and a hydrophilic selective layer.

[0010] In a preferred embodiment of the present invention, the porous support may include copolyester fibers obtained by polycondensing an ester compound prepared by esterifying an acid component including 0.1 mol % to 7 mol % of isophthalic acid (IPA) and a diol component.

[0011] In a preferred embodiment of the present invention, the adhesion between the porous support and the polymer support layer can be 20 gf / mm 2 Up to 1100gf / mm 2 .

[0012] In a preferred embodiment of the present invention, the adhesion between the porous support and the polymer support layer can be 500 gf / mm 2 Up to 1100gf / mm 2 .

[0013] In a preferred embodiment of the present invention, the reverse osmosis membrane of the present invention can satisfy the following equations 1 and 2.

[0014] [Equation 1]

[0015] 150 <B-A<600

[0016] [Equation 2]

[0017] 0.5

[0018] In the above equations 1 and 2, A represents the adhesion force between the porous support and the polymer support layer, and B represents the adhesion force between the polymer support layer and the hydrophilic selective layer.

[0019] ​In a preferred embodiment of the present invention, the polymer support layer may include at least one selected from polysulfone polymer compounds, polyamide polymer compounds, polyimide polymer compounds, polyester polymer compounds, olefin polymer compounds, polyvinylidene fluoride and polyacrylonitrile.

[0020] In a preferred embodiment of the present invention, the polymer support layer may include a polysulfone polymer compound represented by the following Chemical Formula 1:

[0021] [Chemical formula 1]

[0022]

[0023] In the above Chemical Formula 1, R1 and R2 are each independently -H or a C1-C5 alkyl group, and n is a rational number satisfying 10 to 1130.

[0024] In a preferred embodiment of the present invention, the polymer support layer may have a thickness of 30 μm to 90 μm.

[0025] In a preferred embodiment of the present invention, the hydrophilic selective layer may include at least one selected from the group consisting of polyamide polymer compounds, polypiperazine polymer compounds, polyphenylenediamine polymer compounds, polychlorophenylenediamine polymer compounds and polybenzidine polymer compounds.

[0026] In a preferred embodiment of the present invention, the porous support may be a fabric.

[0027] In a preferred embodiment of the present invention, the porous support may have a thickness of 2 cc / cm 2 · Air permeability above 1000 sec and average pore size from 1 μm to 600 μm.

[0028] In a preferred embodiment of the present invention, the porous support may have a thickness of 20 μm to 150 μm.

[0029] In a preferred embodiment of the present invention, the hydrophilic selective layer may have a thickness of 0.1 μm to 1 μm.

[0030] On the other hand, the method for preparing a reverse osmosis membrane of the present invention may include: a first step of preparing a polymer solution comprising a polymer support layer forming composition and a solvent; a second step of forming a polymer support layer by casting the polymer solution on one or both sides of a porous support; a third step of drying the porous support having the polymer support layer formed thereon; and a fourth step of forming a hydrophilic selective layer on one side of the polymer support layer.

[0031] In a preferred embodiment of the present invention, the porous support body of the method for preparing the reverse osmosis membrane of the present invention may include copolyester fibers, which are formed by condensing an ester compound prepared by esterifying an acid component containing 0.1 mol % to 7 mol % of isophthalic acid (IPA) and a diol component.

[0032] In a preferred embodiment of the present invention, the adhesion between the porous support and the polymer support layer in the method for preparing the reverse osmosis membrane of the present invention can be 20 gf / mm 2 Up to 1100gf / mm 2 .

[0033] In a preferred embodiment of the present invention, the polymer solution of the method for preparing a reverse osmosis membrane of the present invention may include 15 wt % to 20 wt % of the polymer support layer forming composition relative to the total wt %.

[0034] In a preferred embodiment of the present invention, the polymer support layer forming composition of the reverse osmosis membrane preparation method of the present invention may include one or more selected from polysulfone polymer compounds, polyamide polymer compounds, polyimide polymer compounds, polyester polymer compounds, olefin polymer compounds, polyvinylidene fluoride and polyacrylonitrile.

[0035] In a preferred embodiment of the present invention, the polymer support layer forming composition of the method for preparing a reverse osmosis membrane of the present invention may include a polysulfone polymer compound represented by the following Chemical Formula 1.

[0036] [Chemical formula 1]

[0037]

[0038] In the above Chemical Formula 1, R1 and R2 are each independently -H or a C1-C5 alkyl group, and n is a rational number satisfying 10 to 1130.

[0039] In a preferred embodiment of the present invention, the solvent of the method for preparing a reverse osmosis membrane of the present invention may include one or more selected from N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc).

[0040] In a preferred embodiment of the present invention, the polymer support layer of the method for preparing a reverse osmosis membrane of the present invention may be formed to have a thickness of 30 μm to 90 μm.

[0041] In a preferred embodiment of the present invention, in the method for preparing a reverse osmosis membrane of the present invention, a hydrophilic selective layer can be formed on one side of the porous support layer by coating a solution containing a multifunctional amine on one side of the porous support layer and subjecting the solution containing a halogen compound to interfacial polymerization.

[0042] In a preferred embodiment of the present invention, the hydrophilic selective layer of the method for preparing a reverse osmosis membrane of the present invention may include a polyamide-based polymer compound formed by interfacial polymerization of a solution containing a polyfunctional amine and a solution containing a polyfunctional halogen compound.

[0043] In a preferred embodiment of the present invention, the multifunctional amine in the method for preparing the reverse osmosis membrane of the present invention may include one or more of m-phenylenediamine, p-phenylenediamine, aliphatic primary diamine, alicyclic primary diamine and alicyclic secondary amine.

[0044] In a preferred embodiment of the present invention, the multifunctional halogen compound in the method for preparing the reverse osmosis membrane of the present invention may include at least one of trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride.

[0045] In a preferred embodiment of the present invention, the drying in the third step of the method for preparing a reverse osmosis membrane of the present invention may be performed at a temperature of 110° C. to 170° C. for 1 minute to 5 minutes.

[0046] Furthermore, the reverse osmosis membrane module of the present invention includes the reverse osmosis membrane of the present invention.

[0047] Effects of the Invention

[0048] The reverse osmosis membrane and preparation method of the present invention can maintain the same flux as the existing reverse osmosis membrane, and has excellent interlayer bonding in the separation membrane, thereby preventing the polymer support layer from peeling off during osmotic backwashing, and has excellent membrane durability and service life.

[0049] Furthermore, according to the reverse osmosis membrane and the preparation method thereof of the present invention, not only the reduction value of the desalination rate is low, but also the increase rate of the permeate flux is small.

[0050] Also, the reverse osmosis membrane module including the reverse osmosis membrane of the present invention can maximize the cumulative processing quantity, and thus can minimize the maintenance management cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A reverse osmosis membrane according to an embodiment of the present invention is shown.

[0052] Figure 2 is a cross-sectional SEM photograph of the reverse osmosis membrane prepared according to Example 1.

[0053] Figure 3The figure is an exploded perspective view of a reverse osmosis membrane assembly according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that a person skilled in the art can easily implement the present invention. The present invention can be implemented in a variety of different embodiments and is not limited to the embodiments described in this specification. In order to clearly illustrate the present invention, parts not related to the description are omitted in the accompanying drawings, and the same reference numerals are given to the same or similar structural elements throughout the specification.

[0055] During the operation of the osmosis process or the osmosis backwash process of the existing reverse osmosis membrane, the polymer support layer is often peeled off, and accordingly, the hydrophilic selective layer formed on the polymer support layer is also peeled off, resulting in a significant decrease in the performance of the reverse osmosis membrane.

[0056] In order to solve the above problems, in the reverse osmosis membrane of the present invention, the porous support and the polymer support layer have an adhesion force within a predetermined range, so that the permeation flux reduction can be minimized while having excellent bonding strength.

[0057] In the present invention, "adhesion force" refers to the force of adhesion between two media. For example, the force of mutual adhesion between the porous support and the polymer support layer of the reverse osmosis membrane described in the present invention is called "adhesion force".

[0058] The above-mentioned adhesion force was measured by laminating the reverse osmosis membrane using a texture analyzer. Specifically, after the reverse osmosis membrane was attached to the tape and PET film, the PET film was pulled up in a 180-degree direction at a constant speed to measure the force according to the distance when laminating the separation membrane.

[0059] The reverse osmosis membrane of the present invention is formed by sequentially stacking a porous support, a polymer support layer and a hydrophilic selective layer.

[0060] Specifically, refer to Figure 1 The reverse osmosis membrane 100 of the present invention has a structure in which a porous support 110, a polymer support layer 120 and a hydrophilic selective layer 130 are stacked in sequence.

[0061] First, the porous support 110 of the present invention is not particularly limited as long as it is a material generally used as a support for a reverse osmosis membrane, and preferably, it may be a fabric, and more preferably, it may be a nonwoven fabric.

[0062] Specifically, fabric refers to woven fabric, knitted fabric or non-woven fabric. Woven fabric is woven with warp and weft yarns, so it has longitudinal and transverse directions. The specific directionality of knitted fabrics may vary depending on the weaving method, but in a broad sense, it can have directionality in either the longitudinal and transverse directions. In addition, unlike woven fabrics or knitted fabrics, non-woven fabrics do not have longitudinal and transverse directions.

[0063] When the fabric is a woven fabric, the desired physical properties of the porous support 110, such as porosity, pore size, strength and permeability, etc., can be adjusted by adjusting the fiber type, fineness, density of the warp and weft yarns, and the structure of the woven fabric.

[0064] In addition, when the fabric is a knitted fabric, the desired physical properties of the porous support 110, such as porosity, pore size, strength and permeability, can be adjusted by adjusting the fiber type, fineness, structure, machine gauge, needle density, etc. contained in the knitted fabric.

[0065] Furthermore, when the fabric is a nonwoven fabric, the desired physical properties of the porous support 110, such as porosity, pore size, strength and permeability, can be adjusted by adjusting the type, fineness, fiber length, basis weight, density, etc. of the fibers contained in the nonwoven fabric.

[0066] On the other hand, the material of the porous support 110 of the present invention can generally be used as a porous support for a reverse osmosis membrane, and the porous support of the present invention may include copolyester fibers, which are prepared by polycondensing an ester compound prepared by esterifying an acid component containing 0.1 mol% to 7 mol%, preferably 0.1 mol% to 4.5 mol%, more preferably 0.2 mol% to 1.0 mol% of isophthalic acid (IPA) and a diol component. At this time, when the isophthalic acid content in the acid component is greater than 7 mol%, it may become a cause of flux reduction.

[0067] On the other hand, the acid component of the porous support may include carboxylic acid in addition to isophthalic acid, and the carboxylic acid may include one or more selected from aromatic polycarboxylic acids having 6 to 14 carbon atoms and aliphatic polycarboxylic acids having 2 to 16 carbon atoms.

[0068] The aromatic polycarboxylic acid having 6 to 14 carbon atoms of the present invention may include one or more selected from terephthalic acid, dimethyl terephthalate and dimethyl isophthalate, and the aliphatic polycarboxylic acid having 2 to 16 carbon atoms of the present invention may include one or more selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, citric acid, pimelic acid, azelaic acid, sebacic acid, nonanoic acid, decanoic acid, dodecanoic acid and hexadecanoic acid.

[0069] Furthermore, the diol component of the porous support may include one or more selected from ethylene glycol, diethylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 3-methyl-1,5-pentanediol, 1,4-butanediol, 1,6-hexanediol, propylene glycol, trimethylethylene glycol, tetramethylethylene glycol, pentamethylethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, undecamethylene glycol, dodecamethylene glycol and tridecamethylene glycol.

[0070] Furthermore, in the porous support 110 of the present invention, the physical properties of the membrane can be adjusted according to the porosity and hydrophilicity. As a non-limiting example, the porous support 110 of the present invention may have a 2cc / cm 2 ·Sec or more air permeability, preferably 2cc / cm 2 sec to 20cc / cm 2 The average pore size of the porous support 110 may be 1 μm to 600 μm, preferably 5 μm to 300 μm. If the air permeability and average pore size conditions of the porous support 110 are met, the smooth inflow of water and the water permeability can be improved.

[0071] The porous support 110 may be made of a nonwoven fabric having a multilayer structure with a double structure based on coarse fibers and a back layer using fine fibers. In addition, the porous support 110 is made of polymers having different melting points, and the porous support 110 may be arranged around the high melting point polymer with a low melting point polymer having a melting point 5°C to 140°C lower than that of the high melting point polymer.

[0072] Furthermore, the thickness of the porous support 110 may be 20 μm to 150 μm, preferably 50 μm to 120 μm, and more preferably 70 μm to 110 μm. If the thickness is less than 20 μm, the strength of the entire film will be reduced. If the thickness is greater than 150 μm, it may cause a reduction in flux.

[0073] Secondly, the polymer support layer 120 of the present invention is a general microporous support layer, and its type is not particularly limited, but generally speaking, its size should be large enough to allow the permeation water to penetrate, and should not be large enough to interfere with the crosslinking of the ultra-thin film formed thereon. In this case, the pore size of the porous support layer is preferably 1nm to 500nm. When the pore size exceeds 500nm, after the film is formed, the ultra-thin film is recessed into the pore size, so it may be difficult to achieve the desired flat sheet structure.

[0074] The polymer support layer 120 of the present invention may include one or more selected from polysulfone polymer compounds, polyamide polymer compounds, polyimide polymer compounds, polyester polymer compounds, olefin polymer compounds, polyvinylidene fluoride and polyacrylonitrile. Preferably, it may include a polysulfone polymer compound, and more preferably, it may include a polysulfone polymer compound represented by the following chemical formula 1.

[0075] [Chemical formula 1]

[0076]

[0077] In the above Chemical Formula 1, R1 and R2 are each independently -H or a C1-C5 alkyl group. Preferably, R1 and R2 are each independently a C1-C3 alkyl group.

[0078] Furthermore, in the above Chemical Formula 1, n is a rational number satisfying 10 to 1130, and preferably, n is a rational number satisfying 140 to 340.

[0079] Furthermore, the polymer support layer 120 of the present invention may have a thickness of 30 μm to 90 μm, preferably, may have a thickness of 35 μm to 60 μm, and more preferably, may have a thickness of 55 μm to 60 μm. If the above thickness is less than 30 μm, the bonding force between the polymer support layer 120 and the porous support body 110 may not be performed at an ideal level, and the polymer support layer 120 may be peeled off from the porous support body 110 after backwashing. If the above thickness is greater than 90 μm, the permeation flux of the reverse osmosis membrane may be reduced.

[0080] Finally, as the hydrophilic selective layer 130 of the present invention, any material that can be generally used as a hydrophilic selective layer of a reverse osmosis membrane can be used without restriction. Preferably, it can include at least one selected from polyamide polymer compounds, polypiperazine polymer compounds, polyphenylenediamine polymer compounds, polychlorophenylenediamine polymer compounds and polybenzidine polymer compounds, and more preferably, it can include a polyamide polymer compound.

[0081] Furthermore, the hydrophilic selective layer 130 of the present invention may have a thickness of 0.1 μm to 1 μm, preferably 0.1 μm to 0.5 μm. If the thickness is less than 0.1 μm, the desalination capacity may be reduced. If the thickness is greater than 1 μm, the permeation flux of the reverse osmosis membrane may be reduced.

[0082] On the other hand, the adhesion between the porous support and the polymer support layer of the reverse osmosis membrane of the present invention can be 20 gf / mm 2 Up to 1100gf / mm 2 , preferably, it can be 500gf / mm 2From 0 to 1100 gf / mm 2 , more preferably, it can be 800 gf / mm 2 to 900 gf / mm2, even more preferably, it can be 840 gf / mm 2 to 900 gf / mm 2 , if it exceeds the above adhesion range, it may lead to problems such as an increase in the reduction value of the desalination rate and the increase rate of the permeation flux and a decrease in durability.

[0083] Moreover, the adhesion between the polymer support layer and the hydrophilic selective layer of the reverse osmosis membrane of the present invention can be 500 gf / mm 2 to 1600 gf / mm 2 , preferably, it can be 800 gf / mm 2 to 1500 gf / mm 2 , more preferably, it can be 1100 gf / mm 2 to 1400 gf / mm 2 , even more preferably, it can be 1200 gf / mm 2 to 1350 gf / mm 2 , if it exceeds the above adhesion range, it may lead to problems such as an increase in the reduction value of the desalination rate and the increase rate of the permeation flux and a decrease in durability.

[0084] Moreover, the reverse osmosis membrane of the present invention can satisfy the following relational expressions 1 and 2.

[0085] [Relational expression 1]

[0086] 150 < B - A < 600, preferably, 250 < B - A < 550, more preferably, 300 < B - A < 500, even more preferably, 350 < B - A < 450, even more preferably, 375 < B - A < 425

[0087] [Relational expression 2]

[0088] 0.5 < B / A < 8, preferably, 1.0 < B / A < 4, more preferably, 1.1 < B / A < 2, even more preferably, 1.3 < B / A < 1.6, even more preferably, 1.4 < B / A < 1.56

[0089] In the above relational expressions 1 and 2, A represents the adhesion between the porous support and the polymer support layer, and B represents the adhesion between the polymer support layer and the hydrophilic selective layer.

[0090] If the above relational expressions 1 and 2 are not satisfied, it may lead to problems such as a high reduction value of the desalination rate and an increase in the increase rate of the permeation flux.

[0091] Furthermore, after backwashing at a pressure of 3 bar, the reverse osmosis membrane of the present invention can satisfy the following conditions (a) and (b) for a 2000 ppm sodium chloride aqueous solution at a temperature of 25° C. and a pressure of 225 psi, thereby confirming that the reverse osmosis membrane of the present invention has excellent durability.

[0092] (a) Change in desalination rate below 10%

[0093] (b) Permeation flux change rate below 15%

[0094] In another aspect, the present invention includes a reverse osmosis membrane module comprising the reverse osmosis membrane as described above.

[0095] The structure of the reverse osmosis membrane assembly of the present invention can be the structure of the reverse osmosis membrane assembly conventionally used in the field to which the present invention belongs. As a non-limiting example, the reverse osmosis membrane can be spirally wound on a porous water-permeable outflow pipe together with a spacer for forming a flow path, and end caps can be included for the shape stability of the separation membrane wound on both ends of the wound membrane.

[0096] Figure 3 The figure is an exploded perspective view of a reverse osmosis membrane assembly according to an embodiment of the present invention.

[0097] The size and shape of the pressure shell may be unlimited within the acceptable range of the reverse osmosis membrane assembly. Preferably, the plurality of filter assemblies are spirally wound, so that the shape thereof may be cylindrical. However, the shape of the pressure shell is not limited thereto. As the material of the pressure shell, any material commonly used for the pressure shell of the reverse osmosis membrane assembly in the art may be used without limitation.

[0098] Reference Figure 3 In the reverse osmosis separation membrane module 1000, a plurality of filter components are spirally wound around the outflow pipe 1400. The cross-sectional diameter of the reverse osmosis membrane component may vary according to the diameter of the outflow pipe, the number and thickness of the osmotic membrane assembly, and the like.

[0099] The outflow pipe 1400 has a plurality of holes, and the fluid flowing through the outflow pipe 1400 flows into the reverse osmosis membrane 1100 of the filter assembly through the holes. Specifically, of the two solutions A and B with different concentrations, the A solution flows to the inside of the pressure shell and the outside of the reverse osmosis membrane 1100 of the filter assembly, and the B solution flows from the outflow pipe 1400 through the holes to the inside of the reverse osmosis membrane 1100 of the filter assembly. Thus, the two solutions A and B with different concentrations are located inside and outside the reverse osmosis membrane 1100 of the filter assembly, thereby generating osmotic pressure. However, the above two solutions A and B may be as Figure 3 Although the two solutions A and B are shown to be injected in the same direction, this is just an example, and differently from this, the two solutions A and B may be injected in different directions according to the purpose.

[0100] Between the plurality of filter modules of the reverse osmosis membrane module, an internal spacer 1200 may be included between the external spacer 1300 and the reverse osmosis membrane. The external spacer 1300 and the internal spacer 1200 are flow paths for water to flow in, and can form a flow path for fluid, such as solution A, to flow smoothly between different filter modules.

[0101] As the material, shape and size of the spacer and the end cap, the structure of the spacer and the end cap commonly used in the reverse osmosis membrane assembly in the art can be adopted, so a specific description will be omitted. The reverse osmosis membrane wound as described above can be accommodated in a shell, and the material, size and shape of the shell can also be the material, size and shape of the shell conventionally used in the reverse osmosis membrane assembly in the art. And, the reverse osmosis membrane wound as described above can be wrapped with fiber reinforced plastics (fiber reinforced plastics, FRP) instead of being wrapped by the shell.

[0102] Furthermore, the method for producing a reverse osmosis membrane of the present invention includes the first step to the fourth step.

[0103] First, in the first step of the method for producing a reverse osmosis membrane of the present invention, a polymer solution including a polymer support layer forming composition and a solvent may be prepared.

[0104] At this time, relative to the total weight % of the polymer solution, the content of the polymer support layer forming composition can be 15 wt % to 20 wt %, preferably, 17 wt % to 20 wt %, more preferably, 17.1 wt % to 17.8 wt %, and further preferably, 17.2 wt % to 17.4 wt %. If the content of the above-mentioned polymer support layer forming composition is less than 15 wt %, the polymer support layer of the reverse osmosis membrane will be peeled off after backwashing. If the content of the above-mentioned polymer support layer forming composition is greater than 20 wt %, the permeation flux and salt rejection rate of the reverse osmosis membrane will decrease, etc., and it may be difficult to achieve the purpose of the present invention.

[0105] Furthermore, the polymer support layer forming composition of the present invention may include one or more selected from polysulfone polymer compounds, polyamide polymer compounds, polyimide polymer compounds, polyester polymer compounds, olefin polymer compounds, polyvinylidene fluoride and polyacrylonitrile, preferably, may include a polysulfone polymer compound, more preferably, may include a polysulfone polymer compound represented by the following Chemical Formula 1.

[0106] [Chemical formula 1]

[0107]

[0108] In the above Chemical Formula 1, R1 and R2 are each independently -H or a C1-C5 alkyl group. Preferably, R1 and R2 are each independently a C1-C3 alkyl group.

[0109] Furthermore, in the above Chemical Formula 1, n is a rational number satisfying 10 to 1130, and preferably, n is a rational number satisfying 130 to 340.

[0110] Furthermore, as the solvent of the present invention, any solvent that can dissolve the polymer support layer forming composition can be used without restriction. Preferably, it can include one or more selected from N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc), and more preferably, it can include dimethylformamide (DMF).

[0111] Furthermore, the content of the solvent in the present invention can be 80 wt % to 85 wt % relative to the total weight % of the polymer solution, preferably, it can be 80 wt % to 83 wt %, further preferably, it can be 82.2 wt % to 83 wt %, further preferably, it can be 82.6 wt % to 83 wt %. If the content of the solvent is less than 80 wt %, the viscosity of the polymer solution may increase excessively, making it difficult to form a membrane. If the content of the solvent is greater than 85 wt %, the strength of the reverse osmosis membrane will decrease, or the viscosity of the polymer solution may be very low, making it difficult to form a membrane.

[0112] Furthermore, when preparing a polymer solution by mixing a polymer support layer forming composition and a solvent, the temperature of the solvent can be 20°C to 90°C. If the temperature of the solvent is less than 20°C, the polymer support layer forming composition may not be dissolved. If the temperature of the solvent is greater than 90°C, the viscosity of the polymer solution decreases, and thus it may be difficult to form a polymer support layer of a desired thickness.

[0113] Next, in the second step of the method for preparing a reverse osmosis membrane of the present invention, the polymer support layer may be formed by casting the polymer solution prepared in the first step on one or both sides of the porous support, preferably on one side of the porous support.

[0114] As a method for forming a polymer support layer in the second step, any conventional polymer solution treatment method that can be used in the art to form a polymer support layer can be used without restriction. As a method for casting a polymer solution, a coating method known in the art, such as slit coating, etc., can be used. After the polymer solution is cast on the porous support, the solvent contained in the polymer solution is removed, thereby forming a polymer support layer. As a method for removing the solvent, a phase inversion method of replacing a solvent and a non-solvent is used. Specifically, the non-solvent can be at least one selected from water, ethanol and methanol, but can be different depending on the composition of the solvent.

[0115] Furthermore, a polymer support layer is formed on one or both sides of the porous support by removing the solvent contained in the polymer solution. In order to prevent the permeation flux and desalination rate of the reverse osmosis membrane from decreasing and to achieve excellent durability of the polymer support layer, the thickness of the formed polymer support layer may be 30 μm to 90 μm, preferably 35 μm to 60 μm, and more preferably 55 μm to 60 μm. If the thickness is less than 30 μm, the bonding force between the polymer support layer and the porous support may not be expressed at an ideal level, and the polymer support layer may be peeled off from the porous support after backwashing. If the above thickness is greater than 90 μm, the permeation flux of the reverse osmosis membrane may be reduced.

[0116] The porous support in the second step is not limited as long as it is a support generally used for a reverse osmosis membrane, but the porous support may preferably be a fabric, more preferably a nonwoven fabric.

[0117] In addition, the material of the porous support in the second step can generally be used as a porous support for a reverse osmosis membrane, and the porous support of the present invention may include copolyester fibers, which are obtained by polycondensing an ester compound prepared by esterifying an acid component containing 0.1 mol% to 7 mol%, preferably 0.1 mol% to 4.5 mol%, more preferably 0.2 mol% to 1.0 mol% of isophthalic acid (IPA) and a diol component. At this time, when the isophthalic acid content in the acid component is greater than 7 mol%, it may become a cause of flux reduction.

[0118] Furthermore, in the porous support of the second step, the physical properties of the membrane can be adjusted according to the porosity and hydrophilicity. As a non-limiting example, the porous support 110 of the present invention may have a porosity of 2 cc / cm 2 ·Sec or more air permeability, preferably 2cc / cm 2 sec to 20cc / cm 2The average pore size of the porous support may be 1 μm to 600 μm, preferably 5 μm to 300 μm. If the air permeability and average pore size conditions of the porous support are met, the smooth inflow of water and the water permeability can be improved.

[0119] And, the porous support of the second step can be made of a nonwoven fabric having a multilayer structure with a double structure based on coarse fibers and a back layer using fine fibers. In addition, the porous support is made of polymers with different melting points, and the porous support can arrange a low melting point polymer having a melting point 5°C to 140°C lower than the melting point of the above-mentioned high melting point polymer around the high melting point polymer.

[0120] Next, in the third step of the method for preparing a reverse osmosis membrane of the present invention, the porous support having the polymer support layer formed thereon may be dried.

[0121] At this time, drying can be carried out at a temperature of 110°C to 170°C, preferably 120°C to 150°C, more preferably 120°C to 135°C, for 1 minute to 5 minutes, preferably 2 minutes to 4 minutes. If the temperature is less than 110°C, adhesion problems may occur, and if the temperature exceeds 170°C, water permeability problems may occur.

[0122] Finally, in the fourth step of the method for preparing a reverse osmosis membrane of the present invention, a hydrophilic selective layer may be formed on one side of the polymer support layer formed in the second step.

[0123] Specifically, as the material of the hydrophilic selective layer, any material that can be commonly used as a hydrophilic selective layer of a reverse osmosis membrane in the art can be used without restriction, but preferably, it can include one or more selected from polyamide polymer compounds, polypiperazine polymer compounds, polyphenylenediamine polymer compounds, polychlorophenylenediamine polymer compounds and polybenzidine polymer compounds, and more preferably, it can include a polyamide polymer compound.

[0124] The method of forming the hydrophilic selective layer may differ according to the type of material included in the selected hydrophilic selective layer, but the method may be a conventional hydrophilic selective layer forming method according to the type of material.

[0125] For example, the hydrophilic selective layer can be formed on one side of the porous support layer by applying a solution containing a polyfunctional amine to one side of the porous support layer and subjecting the solution containing a halogen compound to interfacial polymerization.

[0126] As a specific example, the hydrophilic selective layer may include a polyamide-based polymer compound formed by interfacial polymerization of a solution containing a polyfunctional amine and a solution containing a polyfunctional halogen compound.

[0127] Specifically, a porous support having a polymer support layer formed on one or both surfaces is immersed in a solution containing a polyfunctional amine and then immersed in a solution containing a polyfunctional halogen compound to perform interfacial polymerization, thereby forming a hydrophilic selective layer containing a polyamide polymer compound.

[0128] The polyfunctional amine is a substance having 2 to 3 amine functional groups per monomer, and may be a polyamine including primary or secondary amines. In this case, m-phenylenediamine, p-phenylenediamine, o-phenylenediamine and aromatic primary diamines may be used as the polyamines, and aromatic primary diamines may be used as the substituents. As another example, aliphatic primary diamines, alicyclic primary diamines such as cyclohexanediamine, alicyclic secondary amines such as piperazine, and aromatic secondary amines may be used. More preferably, m-phenylenediamine may be used among the polyfunctional amines, and at this time, the concentration is preferably in the form of an aqueous solution containing 0.5 wt % to 10 wt % of m-phenylenediamine, more preferably 1 wt % to 4 wt % of m-phenylenediamine, and further preferably 1.5 wt % to 2.5 wt % of m-phenylenediamine, thereby having the ability to exhibit a more improved permeation flux.

[0129] Furthermore, when the porous support having the polymer support layer formed on one or both sides is immersed in the solution containing the multifunctional amine, the immersion time may be 0.1 to 10 minutes, more preferably, 0.5 to 1 minute.

[0130] And, preferably, the polyfunctional halogen compound may include a polyfunctional acyl halide, and more preferably, may include at least one selected from trimesoyl chloride, isophthaloyl chloride, 5-methoxy-1,3-isophthaloyl chloride, and terephthaloyl chloride.

[0131] The polyfunctional acyl halide can be dissolved in an aliphatic hydrocarbon solvent in an amount of 0.01 wt % to 2 wt %, and in this case, the aliphatic hydrocarbon solvent can be mixed with a normal alkane having 5 to 12 carbon atoms and a structural isomer of a saturated or unsaturated hydrocarbon having 8 carbon atoms, or a cyclic hydrocarbon having 5 to 7 carbon atoms can be used. Preferably, the solution containing the polyfunctional acyl halide can be prepared by dissolving 0.01 wt % to 2 wt % of the polyfunctional acyl halide in the aliphatic hydrocarbon solvent, and more preferably, can be prepared by dissolving 0.05 wt % to 0.3 wt % of the polyfunctional acyl halide in the aliphatic hydrocarbon solvent.

[0132] At this time, interfacial polymerization can be performed by immersing the porous support having the polymer support layer formed on one or both sides in the solution containing the polyfunctional halogen compound for 0.1 to 10 minutes, more preferably, 0.5 to 1 minute.

[0133] On the other hand, the hydrophilic selective layer formed through the third step of the preparation method of the reverse osmosis membrane of the present invention may have a thickness of 0.1 μm to 1 μm, preferably, it may have a thickness of 0.1 μm to 0.5 μm. If the above thickness is less than 0.1 μm, the desalination ability may decrease. If the above thickness is greater than 1 μm, the permeation flux of the reverse osmosis membrane may decrease.

[0134] Furthermore, the adhesion force between the porous support and the polymer support layer of the reverse osmosis membrane prepared by the preparation method of the reverse osmosis membrane of the present invention may be 20 gf / mm 2 to 1100 gf / mm 2 , preferably, it may be 500 gf / mm 2 to 1100 gf / mm 2 , more preferably, it may be 800 gf / mm 2 to 900 gf / mm 2 , further preferably, it may be 840 gf / mm 2 to 900 gf / mm 2 , if it exceeds the above range of adhesion force, it may cause problems such as an increase in the reduction value of the desalination rate and the increase rate of the permeation flux and a decrease in durability.

[0135] Moreover, the adhesion force between the polymer support layer and the hydrophilic selective layer of the reverse osmosis membrane prepared by the preparation method of the reverse osmosis membrane of the present invention may be 500 gf / mm 2 to 1600 gf / mm 2 , preferably, it may be 800 gf / mm 2 to 1500 gf / mm 2 , more preferably, it may be 1100 gf / mm 2 to 1400 gf / mm 2 , further preferably, it may be 1200 gf / mm 2 to 1350 gf / mm 2 , if it exceeds the above range of adhesion force, it may cause problems such as an increase in the reduction value of the desalination rate and the increase rate of the permeation flux and a decrease in durability.

[0136] Moreover, all the reverse osmosis membranes prepared by the preparation method of the reverse osmosis membrane of the present invention can satisfy the following relational expressions 1 and 2.

[0137] [Relational expression 1]

[0138] 150 < B - A < 600, preferably, 250 < B - A < 550, more preferably, 300 < B - A < 500, further preferably, 350 < B - A < 450, further preferably, 375 < B - A < 425

[0139] [Relational expression 2]

[0140] 0.5

[0141] In the above equations 1 and 2, A represents the adhesion force between the porous support and the polymer support layer, and B represents the adhesion force between the polymer support layer and the hydrophilic selective layer.

[0142] If neither of the above equations 1 and 2 is satisfied, it may lead to a high reduction in the desalination rate and an increased permeate flux increase rate.

[0143] The present invention has been described above with examples as the center, but this is only an example and does not limit the examples of the present invention. A person skilled in the art of the present invention should understand that the present invention can be subjected to various deformations and applications not illustrated in the above description within the scope of the essential characteristics of the present invention. For example, the various structural elements specifically shown in the examples of the present invention can be changed to implement the invention. Moreover, the differences related to such deformations and applications should be interpreted as belonging to the scope of the present invention specified in the scope of the invention claims.

[0144] Comparative Example 1: Preparation of reverse osmosis membrane

[0145] (1) A polymer solution is prepared by mixing a polysulfone-based polymer compound represented by the following Chemical Formula 1-1 and dimethylformamide (DMF) as a solvent.

[0146] At this time, a polymer solution was prepared by mixing 17.3 wt % of a polysulfone-based polymer compound represented by the following Chemical Formula 1-1 and 82.7 wt % of dimethylformamide (DMF) with respect to the total wt %.

[0147] [Chemical formula 1-1]

[0148]

[0149] In the above chemical formula 1-1, R1 and R2 are methyl groups, and n is 235.

[0150] (2) A nonwoven fabric (polyester synthetic fiber, thickness: 90 μm) was prepared as a porous support, and the prepared polymer solution was cast on one side of the prepared nonwoven fabric at 25° C. for 3 minutes to form a polymer support layer with an average thickness of 57.5 μm.

[0151] ​(3) The porous support having the polymer support layer formed thereon was immersed in an aqueous solution containing 2.0 wt% of m-phenylenediamine for 1 minute, the surface moisture was removed by compression, and the porous support was immersed in an organic solution containing 0.1 wt% of phthaloyl chloride for 1 minute to perform interfacial polymerization. Thereafter, the porous support was naturally dried at room temperature (25° C.) for 1 minute and 30 seconds, and a hydrophilic selective layer composed of a polyamide polymer compound having an average thickness of 0.3 μm was formed on one side of the polymer support layer.

[0152] (4) Then, in order to remove unreacted residues, the porous support having the hydrophilic selective layer and the polymer support layer formed thereon was immersed in a solution containing 0.2 wt % of sodium carbonate for 2 hours to prepare a reverse osmosis membrane.

[0153] Comparative Examples 2 to 12: Preparation of Reverse Osmosis Membranes

[0154] A reverse osmosis membrane was prepared in the same manner as in Comparative Example 1. However, when preparing the polymer solution, the mixing ratio of the polysulfone-based polymer compound represented by the above Chemical Formula 1-1 and dimethylformamide (DMF) as a solvent was changed as shown in Table 1 below.

[0155] Furthermore, reverse osmosis membranes were prepared by changing the thickness of the formed polymer support layer as shown in Table 1 below.

[0156] Example 1: Preparation of reverse osmosis membrane

[0157] (1) A polymer solution is prepared by mixing a polysulfone-based polymer compound represented by the following Chemical Formula 1-1 and dimethylformamide (DMF) as a solvent.

[0158] At this time, a polymer solution was prepared by mixing 17.3 wt % of a polysulfone-based polymer compound represented by the following Chemical Formula 1-1 and 82.7 wt % of dimethylformamide (DMF) with respect to the total wt %.

[0159] [Chemical formula 1-1]

[0160]

[0161] In the above Chemical Formula 1-1, R1 and R2 are methyl groups, and n is 2-35.

[0162] (2) A nonwoven fabric (polyester synthetic fiber, thickness: 90 μm) containing 0.3 mol % of isophthalic acid (IPA) as a porous support was prepared, and the prepared polymer solution was cast on one side of the prepared nonwoven fabric at a temperature of 25°C for 3 minutes to form a polymer support layer with an average thickness of 57.5 μm.

[0163] (3) The porous support having the polymer support layer formed thereon was dried at 130° C. for 2 minutes.

[0164] (4) After drying, the porous support having the polymer support layer formed thereon was immersed in an aqueous solution containing 2.0 wt% of m-phenylenediamine for 1 minute, the surface moisture was removed by compression, and the porous support was immersed in an organic solution containing 0.1 wt% of phthaloyl chloride for 1 minute to perform interfacial polymerization. Thereafter, the porous support was naturally dried at room temperature (25° C.) for 1 minute and 30 seconds, and a hydrophilic selective layer composed of a polyamide polymer compound having an average thickness of 0.3 μm was formed on one side of the polymer support layer.

[0165] (5) Then, in order to remove unreacted residues, the porous support having the hydrophilic selective layer and the polymer support layer formed thereon was immersed in a solution containing 0.2 wt % of sodium carbonate for 2 hours to prepare a reverse osmosis membrane.

[0166] Example 2: Preparation of reverse osmosis membrane

[0167] A reverse osmosis membrane was prepared in the same manner as in Example 1, except that drying was performed at 150° C. for 2 minutes in step (3).

[0168] Example 3: Preparation of reverse osmosis membrane

[0169] A reverse osmosis membrane was prepared in the same manner as in Example 1, except that a nonwoven fabric (polyester synthetic fiber, thickness: 90 μm) containing 2.0 mol % of isophthalic acid (IPA) as a porous support was used instead of a nonwoven fabric containing 0.3 mol % of isophthalic acid (IPA) as a porous support.

[0170] Example 4: Preparation of reverse osmosis membrane

[0171] A reverse osmosis membrane was prepared in the same manner as in Example 1, except that a nonwoven fabric (polyester synthetic fiber, thickness: 90 μm) containing 4.0 mol % of isophthalic acid (IPA) as a porous support was used instead of a nonwoven fabric containing 0.3 mol % of isophthalic acid (IPA) as a porous support.

[0172] Example 5: Preparation of reverse osmosis membrane

[0173] A reverse osmosis membrane was prepared in the same manner as in Example 1, except that a nonwoven fabric (polyester synthetic fiber, thickness: 90 μm) containing 6.0 mol % of isophthalic acid (IPA) as a porous support was used instead of a nonwoven fabric containing 0.3 mol % of isophthalic acid (IPA) as a porous support.

[0174] Experimental Example 1

[0175] In order to evaluate the peeling stability of the reverse osmosis membranes prepared in Examples 1 to 5 and Comparative Examples 1 to 12, adhesion evaluation was performed before the initial performance evaluation of the reverse osmosis membranes. The results are shown in Tables 1 and 3.

[0176] The above-mentioned adhesion force was measured by laminating the reverse osmosis membrane using a texture analyzer. Specifically, after the reverse osmosis membrane was attached to the tape and PET film, the PET film was pulled up in a 180-degree direction at a constant speed to measure the force according to the distance when laminating the separation membrane.

[0177] Experimental Example 2

[0178] After evaluating the initial performance of the reverse osmosis membranes prepared in Examples 1 to 5 and Comparative Examples 1 to 12, in order to evaluate the peeling stability of the reverse osmosis membranes, the performance was evaluated after backwashing the reverse osmosis membranes. The results are shown in Tables 2 and 4.

[0179] The initial performance evaluation of the reverse osmosis membrane was performed by dropping a 2,000 ppm sodium chloride aqueous solution (25°C, 225 psi) onto the hydrophilic selective layer, measuring the flux of water produced on the opposite side of the reverse osmosis membrane, and then converting it to flux per unit area and per unit pressure.

[0180] The ionic conductivity value (Total Dissolved Solids, TDS) of the produced water was measured, and the desalination rate was calculated by the following formula 1.

[0181] [Calculation formula 1] Methoxy

[0182] Desalination rate (%) = {1-(conductivity of production water / conductivity of raw water)} × 100

[0183] Furthermore, as for the performance evaluation of the reverse osmosis membrane after backwashing, the flux and salt rejection were re-measured after operating at a pressure of 3 bar (43.5 psi) for 20 minutes.

[0184] Table 1

[0185]

[0186]

[0187] Table 2

[0188]

[0189] Referring to Tables 1 and 2 above, in the case of Comparative Examples 8 to 12 where the polymer support layer thickness was relatively low, the salt rejection rate significantly decreased and the permeate flux significantly increased after backwashing, thereby indicating that the polymer support layer was stripped during backwashing.

[0190] Furthermore, it was confirmed that among the reverse osmosis membranes prepared in Comparative Examples 1 to 7, the reverse osmosis membrane prepared in Comparative Example 1 had the lowest reduction in salt rejection and the smallest increase in permeate flux.

[0191] Table 3

[0192]

[0193]

[0194] Table 4

[0195]

[0196] Referring to Tables 1 to 4 above, compared with Comparative Example 1, the reduction value of the salt rejection rate and the increase rate of the permeate flux of Example 1 are lower, thereby it can be judged that the exfoliation stability of the polymer support layer is significantly excellent.

[0197] Furthermore, it was confirmed that among the reverse osmosis membranes prepared in Examples 1 to 5, the reverse osmosis membrane prepared in Example 1 had the lowest reduction in salt rejection and the smallest increase in permeate flux.

[0198] Experimental Example 3

[0199] A cross-sectional SEM image of the reverse osmosis membrane prepared in Example 1 showing the best effect was taken.

[0200] Figure 2 is a cross-sectional SEM image of the reverse osmosis membrane prepared in Example 1, with reference to Figure 2 It can be confirmed that the polymer support layer is formed on the upper surface and inside of the porous support, so that it can be judged that the bonding force between the polymer support and the porous support is excellent. Since the polymer support layer is formed flat, the peeling stability of the polymer support layer is excellent, so it is judged that a reverse osmosis membrane with improved durability can be achieved.

[0201] Simple modifications and variations may be easily made by those skilled in the art and are intended to fall within the scope of the appended claims.

[0202] Industrial Applicability

[0203] The present invention relates to a reverse osmosis membrane and a method for preparing the same, and more particularly to a high-durability reverse osmosis membrane and a method for preparing the same, which maintains the same flux as the existing reverse osmosis membrane and has excellent interlayer bonding in the separation membrane, thereby minimizing the decrease in durability within the membrane during backwashing, thereby increasing the cleaning effect, extending the service life of the high-pressure membrane, maximizing the cumulative processing amount, and reducing the maintenance cost.

Claims

1. A reverse osmosis membrane, which is formed by sequentially stacking a porous support, a polymer support layer and a hydrophilic selective layer, wherein the reverse osmosis membrane is characterized in that: The porous support includes copolyester fibers obtained by polycondensing an ester compound prepared by subjecting an acid component containing 0.1 mol % to 7 mol % of isophthalic acid and a diol component to an esterification reaction. The adhesion between the porous support and the polymer support layer is 500 gf / mm 2 Up to 1100gf / mm 2 ; The above reverse osmosis membranes all satisfy the following equations 1 and 2: [Equation 1] 250 <B-A<500 [Equation 2] 1.1 In the above equations 1 and 2, A represents the adhesion force between the porous support and the polymer support layer, and B represents the adhesion force between the polymer support layer and the hydrophilic selective layer; The polymer support layer has a thickness of 30 μm to 90 μm.

2. The reverse osmosis membrane according to claim 1, characterized in that The polymer support layer includes a polysulfone polymer compound represented by the following chemical formula 1: [Chemical formula 1] In the above Chemical Formula 1, R1 and R2 are each independently -H or a C1-C5 alkyl group, and n is a rational number satisfying 10 to 1130. include:

3. A method for preparing a reverse osmosis membrane, characterized in that: The first step is to prepare a polymer solution comprising a polymer support layer forming composition and a solvent; The second step is to form a polymer support layer by pouring the polymer solution on one side or both sides of the porous support; The third step is drying the porous support having the polymer support layer formed thereon; and The fourth step is to form a hydrophilic selective layer on one side of the polymer support layer; The porous support includes copolyester fibers obtained by polycondensing an ester compound prepared by subjecting an acid component containing 0.1 mol % to 7 mol % of isophthalic acid and a diol component to an esterification reaction. The above reverse osmosis membranes all satisfy the following equations 1 and 2: The adhesion between the porous support and the polymer support layer is 500 gf / mm 2 Up to 1100gf / mm 2 ; [Equation 1] 250 <B-A<500 [Equation 2] 1.1 In the above equations 1 and 2, A represents the adhesion force between the porous support and the polymer support layer, and B represents the adhesion force between the polymer support layer and the hydrophilic selective layer; The polymer support layer has a thickness of 30 μm to 90 μm.

4. The method for preparing a reverse osmosis membrane according to claim 3, characterized in that: The polymer support layer forming composition includes a polysulfone polymer compound represented by the following Chemical Formula 1: [Chemical formula 1] In the above Chemical Formula 1, R1 and R2 are each independently -H or a C1-C5 alkyl group, and n is a rational number satisfying 10 to 1130.

5. The method for preparing a reverse osmosis membrane according to claim 3, characterized in that: The drying in the above third step is performed at a temperature of 110° C. to 170° C. for 1 minute to 5 minutes. The invention comprises the reverse osmosis membrane according to any one of claims 1 to 2. ​ 6. A reverse osmosis membrane assembly, characterized in that: ​

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