KR20200076283A - reverse osmosis membrane and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a reverse osmosis membrane and a manufacturing method thereof. More particularly, the present invention relates to a reverse osmosis membrane and a manufacturing method thereof. The reverse osmosis membrane is excellent in interlayer bonding in a separator and minimizes the reduction in the durability in the membrane during the reverse washing while maintaining an equal flow rate compared to a conventional reverse osmosis membrane, thereby improving cleaning effects. In addition, it is possible to extend the life of a high pressure membrane, maximize the cumulative amount of treatment, and reduce maintenance costs.

Description

Reverse osmosis membrane and manufacturing method thereof

The present invention relates to a reverse osmosis membrane and a method for manufacturing the same, and more specifically, while maintaining an equivalent flow rate compared to a conventional reverse osmosis membrane, excellent interlayer bonding in the separation membrane minimizes durability decrease in the membrane during backwashing, thereby improving the cleaning effect and extending the life of the high pressure membrane. And it relates to a highly durable reverse osmosis membrane and a method of manufacturing the same, which can maximize the cumulative treatment quantity and reduce maintenance costs.

Along with the rapid increase in the membrane filtration market worldwide, the development of membrane filtration technology has led to the emergence of numerous membrane manufacturing and membrane construction methods, and research on this is also increasing. These membrane filtration processes include MF (fine filtration, microfiltration), UF (ultrafiltration, ultrafiltration), low pressure membrane filtration processes operated at low pressure, NF (nanofiltration, nanofiltration), and RO (reverse osmosis, reverse). osmosis), and can be classified as a high pressure membrane filtration process operated at high pressure. Recently, interest in a high pressure membrane filtration process is rapidly increasing.

On the other hand, the separation membrane used in the membrane filtration process, such as organic fouling, inorganic fouling (inorganic fouling), particle fouling (particular fouling), bio-fouling (bio-fouling) Occurs and its performance continues to decrease. Therefore, in order to restore the permeability of the reduced membrane to the initial state according to the operating time of the membrane filtration process, chemical cleaning (CIP) is performed through chemicals. Membrane contamination is divided into reversible membrane contamination and irreversible membrane contamination. Reversible membrane contamination is physically cleaned, such as osmosis reverse cleaning, and chemical cleaning is performed on irreversible membrane contamination.

Conventional reverse osmosis membranes frequently peel off the polymer support layer during the osmosis process or osmosis reverse cleaning process, and peeling off the polymer support layer may cause the phenomenon of accelerating the peeling of the active layer, and thus the salt rejection rate and the permeate flow rate of the reverse osmosis membrane are reduced. There is a problem that the life of the membrane is reduced.

Korean Patent Publication No. 10-2018-0107605 (Publication date: 2018.10.02)

The present invention has been devised to solve the above-mentioned problems, and the reverse osmosis membrane of the present invention maintains an equivalent flow rate compared to the existing reverse osmosis membrane, and has excellent interlayer bonding in the separation membrane, thereby minimizing durability reduction in the membrane during backwashing to enhance the cleaning effect and improve the high-pressure membrane. It is an object of the present invention to provide a reverse osmosis membrane and a method for manufacturing the same, which can prolong the life, maximize the cumulative treatment quantity, and reduce maintenance costs.

In addition, the present invention has another object to provide a reverse osmosis membrane module having a salt rejection rate, permeate flow rate, and excellent durability even after osmosis backwashing, including the reverse osmosis membrane according to the present invention.

In order to solve the above problems, the reverse osmosis membrane of the present invention is a reverse osmosis membrane in which a porous support, a polymer support layer, and a hydrophilic select layer are sequentially stacked, and the adhesive force between the porous support and the polymer support layer may be 20 to 1,100 gf.

In a preferred embodiment of the present invention, the adhesive force between the porous support and the polymer support layer may be 500 ~ 1,100gf.

In a preferred embodiment of the present invention, the reverse osmosis membrane of the present invention may satisfy both of the following relations 1 and 2.

[Relationship 1]

150 <B-A <600

[Relationship 2]

0.5 <B/A <8

In relations 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 selection layer.

In a preferred embodiment of the present invention, the polymer support layer is polysulfone-based polymer compound, polyamide-based polymer compound, polyimide-based polymer compound, polyester-based polymer compound, olefin-based polymer compound, polyvinylidene fluoride and polyacrylic It may include one or more selected from the nitrile.

In a preferred embodiment of the present invention, the polymer support layer may include a polysulfone-based polymer compound represented by Formula 1 below.

[Formula 1]

In Chemical Formula 1, R ₁ and R ₂ are each independently -H or a C1 to C5 alkyl group, and n is a rational number satisfying 10 to 1,130.

In a preferred embodiment of the present invention, the polymer support layer of the present invention may have a thickness of 30 ~ 90㎛.

In a preferred embodiment of the present invention, the hydrophilic selective layer is a polyamide-based polymer compound, a polypiperazine-based polymer compound, a polyphenylene diamine-based polymer compound, a polychlorophenylene diamine-based polymer compound and a polybenzidine-based polymer compound. It may include one or more selected.

In one preferred embodiment of the present invention, the porous support of the present invention may be a pepper.

In a preferred embodiment of the present invention, the porous support of the present invention may include at least one selected from synthetic fibers and cellulose-based natural fibers selected from the group consisting of polyester, polypropylene, nylon and polyethylene.

In a preferred embodiment of the present invention, the porous support of the present invention may have a thickness of 20 ~ 150㎛.

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

On the other hand, the manufacturing method of the reverse osmosis membrane of the present invention is a first step of preparing a polymer solution containing a polymer support layer forming composition and a solvent, and a second step of forming the polymer support layer by casting the polymer solution on one or both surfaces of the porous support. It includes a step and a third step of forming a hydrophilic selective layer on one surface of the polymer support layer, the adhesive force between the porous support and the polymer support layer may be 20 ~ 1,100gf.

In one preferred embodiment of the present invention, the polymer solution of the present invention may include 15 to 20% by weight of the polymer support layer forming composition in the total weight%.

In a preferred embodiment of the present invention, the polymer support layer forming composition of the present invention is a polysulfone-based polymer compound, polyamide-based polymer compound, polyimide-based polymer compound, polyester-based polymer compound, olefin-based polymer compound, polyvinylidene It may include one or more selected from fluoride and polyacrylonitrile.

In one preferred embodiment of the present invention, the polymer support layer-forming composition may include a polysulfone-based polymer compound represented by Formula 1 below.

[Formula 1]

In Chemical Formula 1, R ₁ and R ₂ are each independently -H or a C1 to C5 alkyl group, and n is a rational number satisfying 10 to 1,130.

In one preferred embodiment of the present invention, the solvent is at least one selected from N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO) and dimethylacetamide (DMAc). It may include.

In a preferred embodiment of the present invention, the polymer support layer may be formed to a thickness of 30 ~ 90㎛.

In a preferred embodiment of the present invention, the hydrophilic selective layer may be formed on one surface of the porous support layer by applying a polyfunctional amine-containing solution to one surface of the porous support layer and interfacial polymerization of a solution containing a halogen compound.

In a preferred embodiment of the present invention, the hydrophilic selective layer may include a polyamide-based polymer compound formed by interfacial polymerization of a polyfunctional amine-containing solution and a polyfunctional halogen compound-containing solution.

In one preferred embodiment of the present invention, the polyfunctional amine may include at least one of metaphenylenediamine, paraphenylenediamine, aliphatic primary diamine, cycloaliphatic primary diamine, and cycloaliphatic secondary amine. Can.

In one preferred embodiment of the present invention, the polyfunctional halogen compound may include at least one of trimethoyl chloride, isophthaloyl chloride and terephthaloyl chloride.

Furthermore, the reverse osmosis membrane module of the present invention includes the above-mentioned reverse osmosis membrane.

The reverse osmosis membrane of the present invention and a method for manufacturing the same can maintain a flow rate comparable to that of a conventional reverse osmosis membrane, and have excellent interlayer bonding in the separation membrane, thereby preventing the polymer support layer from peeling during osmosis backwashing, and implementing a reverse osmosis membrane having excellent membrane durability and lifetime.

In addition, the reverse osmosis membrane of the present invention and a method for manufacturing the same have low salt excretion rate reduction and low rate of permeate flow increase.

In addition, the reverse osmosis membrane module including the reverse osmosis membrane of the present invention can maximize the cumulative processing quantity, thereby minimizing maintenance costs.

1 shows a reverse osmosis membrane according to an embodiment of the present invention.
2 is a cross-sectional SEM photograph of the reverse osmosis membrane prepared according to Example 1.
3 is an exploded perspective view of a reverse osmosis membrane module according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. In the drawings, parts not related to the description are omitted in order to clearly describe the present invention, and the same reference numerals are added to the same or similar elements throughout the specification.

In the conventional reverse osmosis membrane, the polymer support layer is frequently peeled during the osmosis process or the osmosis reverse washing process, and accordingly, the hydrophilic selective layer formed on the polymer support layer is also peeled off, causing a problem that the performance of the reverse osmosis membrane is significantly deteriorated.

In order to solve the above-mentioned problems, the reverse osmosis membrane of the present invention has an adhesive strength between the porous support and the polymer support layer, and thus has excellent bonding strength and at the same time, it is possible to minimize the decrease in the permeation flow rate.

In the present invention, the term "adhesive force" means the sticking force between two media. For example, the force that adheres to each other between the porous support of the reverse osmosis membrane and the polymer support layer described in the present invention is referred to as "adhesive force".

The adhesion was measured by a method of laminating a reverse osmosis membrane using a material analyzer. Specifically, after attaching the reverse osmosis membrane to the tape and the PET film, the PET film can be pulled up in a 180 degree direction at a constant speed to measure the force according to the distance when the separation membrane is laminated.

In the reverse osmosis membrane of the present invention, a porous support, a polymer support layer, and a hydrophilic selection layer are sequentially stacked.

Specifically, referring to FIG. 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 selection layer 130 are sequentially stacked.

First, the porous support 110 of the present invention is not particularly limited as long as it usually serves as a support of the reverse osmosis membrane, but may be preferably a fabric, more preferably a nonwoven fabric.

Specifically, the fabric refers to a fabric, a knitted fabric, or a non-woven fabric, and the fabric has a directionality as it is woven with warp and weft yarns, and a knitted fabric may have a specific directionality depending on the knitting method, but in a broad sense, in either direction Can have a directionality of In addition, the nonwoven fabric has no vertical and horizontal orientation, unlike fabrics or knitted fabrics.

If the fabric is a fabric, it is possible to control the properties of porosity, pore size, strength, permeability, etc. of the desired porous support 110 by adjusting the type of fiber, fineness, density of the weft yarn, the tissue of the fabric, etc. Can.

In addition, when the fabric is knitted, it is possible to control the properties of porosity, pore size, strength, permeability, etc. of the desired porous support 110 by adjusting the type, fineness, tissue, gauge, cut, etc. of fibers included in the knitted fabric. .

In addition, when the fabric is a non-woven fabric, the type, fineness, fiber length, basis weight, density, etc. of fibers included in the non-woven fabric can be adjusted to control physical properties such as porosity, pore size, strength, and permeability of the desired porous support 110. .

On the other hand, the material of the porous support 110 of the present invention can usually serve as a porous support of a reverse osmosis membrane, and can be used without limitation as long as it is used for a porous support of a conventional reverse osmosis membrane. As a non-limiting example, a synthetic fiber selected from the group consisting of polyester, polypropylene, nylon, and polyethylene or a natural fiber including cellulose may be included, and preferably polyester synthetic fiber. It includes.

Furthermore, the porous support 110 of the present invention can be adjusted according to the porosity and hydrophilicity of the membrane. As a non-limiting example of this, the porous support 110 of the present invention may have an air permeability of 2 cc/cm ² ㆍsec or more, and preferably may have an air permeability of 2 to 20 cc/cm ² ㆍsec, , The average pore size of the porous support 110 may be 1 to 600㎛, preferably 5 to 300㎛. If the air permeability of the porous support 110 and the pore size of the average pore are satisfied, it is possible to increase the smooth inflow of water and water permeability.

In addition, the thickness of the porous support 110 may be 20 ~ 150㎛, preferably 50 ~ 120㎛, more preferably 70 ~ 110㎛, if the thickness is less than 20㎛, the strength of the entire film may be lowered If it exceeds 150 μm, it may cause a decrease in flow rate.

Next, the polymer support layer 120 of the present invention is a general microporous support layer, and the type is not particularly limited, but should be large enough to allow permeate to pass through, and is large enough to prevent crosslinking of the ultra-thin film formed thereon. Should not. At this time, the pore size of the porous support layer is preferably 1 to 500 nm, and if it exceeds 500 nm, the ultra-thin film after the formation of the thin film is recessed into the pore, it may be difficult to achieve the required flat sheet structure.

The polymer support layer 110 of the present invention is selected from polysulfone-based polymer compounds, polyamide-based polymer compounds, polyimide-based polymer compounds, polyester-based polymer compounds, olefin-based polymer compounds, polyvinylidene fluoride and polyacrylonitrile It may include one or more, preferably may include a polysulfone-based polymer compound, more preferably may include a polysulfone-based polymer compound represented by the following formula (1).

[Formula 1]

In Chemical Formula 1, R ₁ and R ₂ are each independently -H or a C1 to C5 alkyl group, preferably a C1 to C3 alkyl group.

In addition, in Chemical Formula 1, n is a rational number satisfying 10 to 1,130, and preferably a rational number satisfying 140 to 340.

In addition, the polymer support layer 120 of the present invention may have a thickness of 30 ~ 90㎛, preferably a thickness of 35 ~ 60㎛, more preferably 55 ~ 60㎛, if the thickness is less than 30㎛ Since the bonding force between the polymer support layer 120 and the porous support 110 is not expressed at a desired level, the polymer support layer 120 may be peeled from the porous support 110 after backwashing, and when the thickness exceeds 90 μm, the reverse osmosis membrane The permeate flow rate may decrease.

Finally, the hydrophilic selective layer 130 of the present invention can be used without limitation as long as it can be used as a hydrophilic selective layer of a reverse osmosis membrane, but is preferably a polyamide-based polymer compound, polypiperazine-based polymer compound, polyphenyl It may include at least one selected from a ren diamine-based polymer compound, a polychlorophenylene diamine-based polymer compound and a polybenzidine-based polymer compound, more preferably a polyamide-based polymer compound.

In addition, the hydrophilic selective layer 130 of the present invention may have a thickness of 0.1 to 1 μm, preferably a thickness of 0.1 to 0.5 μm, and if the thickness is less than 0.1 μm, the salt removal ability may be reduced, 1 If it exceeds µm, the permeate flow rate of the reverse osmosis membrane may decrease.

Meanwhile, the reverse osmosis membrane of the present invention may have an adhesive strength between a porous support and a polymer support layer of 20 to 1,100 gf, preferably 500 to 1,100 gf, more preferably 500 to 810 gf, and even more preferably 550 to 650 gf, if the If it is out of the range of adhesion, there may be a problem that the salt exclusion ratio decreases and the rate of increase in permeate flow increases, and durability decreases.

In addition, the reverse osmosis membrane of the present invention may satisfy both of the following relations 1 and 2.

[Relationship 1]

150 <B-A <600, preferably 250 <B-A <550, more preferably 300 <B-A <500

[Relationship 2]

0.5 <B/A <8, preferably 1 <B/A <2.5, more preferably 1.2 <B/A <1.5

In relations 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 selection layer.

If both of the relations 1 and 2 are not satisfied, there is a problem that the salt excretion rate decrease value is high and the permeate flow rate increase rate increases.

Furthermore, the reverse osmosis membrane of the present invention can be backwashed at a pressure of 3 bar, and satisfy the following conditions (a) and (b) for an aqueous solution of 2,000 ppm sodium chloride at a temperature of 25° C. and a pressure of 225 psi. It can be seen that the reverse osmosis membrane has excellent durability.

(a) 10% or less salt removal rate change rate

(b) Rate of change in permeate flow of 15% or less

Meanwhile, the present invention includes a reverse osmosis membrane module including the aforementioned reverse osmosis membrane.

The configuration of the reverse osmosis membrane module of the present invention may adopt a configuration of a reverse osmosis module commonly used in the art, and as a non-limiting example, the reverse osmosis membrane is wound around a porous permeate outlet tube together with a spacer for the purpose of forming a flow path. It can be wound with and may include an end cap for the shape stability of the separation membrane wound at both ends of the wound membrane.

3 is an exploded perspective view of a reverse osmosis membrane module according to an embodiment of the present invention.

The size and shape of the pressure case may not be limited within a range in which the reverse osmosis membrane module is acceptable, but preferably, the shape may be cylindrical because a plurality of filter assemblies are wound in a spiral shape. However, the shape of the pressure case is not limited to this. The material of the pressure case may be used without limitation in the case of a pressure case material that is commonly used in a reverse osmosis membrane module in the art.

Referring to FIG. 3, the reverse osmosis membrane module 1000 includes a plurality of filter assemblies wound around the outlet tube 1400 in a spiral wound shape, wherein the cross-section diameter of the reverse osmosis membrane module is the diameter of the outlet tube and the number of osmosis membrane assemblies. , May vary depending on the thickness.

The outlet pipe 1400 is formed with a plurality of holes, and the fluid flowing through the outlet pipe 1400 flows into the reverse osmosis membrane 1100 of the filter assembly through the hole. Specifically, of the two solutions A and B having different concentrations, the A solution flows inside the pressure case and outside the reverse osmosis membrane 1100 of the filter assembly, and the B solution flows through the hole in the outlet pipe 1400 through the hole in the reverse osmosis membrane 1100 of the filter assembly. It flows inside. Through this, two solutions (A, B) having different concentrations are located inside and outside the reverse osmosis membrane 1100 of the filter assembly, whereby osmotic pressure is generated and acts. However, the two solutions A and B may be injected in the same direction as in FIG. 3, but this is an example, differently, the solutions A and B may be injected in different directions according to purposes.

The reverse osmosis membrane module may include an outer spacer 1300 between a plurality of filter assemblies and an inner spacer 1200 between reverse osmosis membranes. The outer spacer 1300 and the inner spacer 1200 are influent flow paths, and may form a flow path through which fluids flowing between different filter assemblies, for example, A solutions, can flow smoothly.

The material, shape, and size of the spacer and the end cap may adopt the configuration of the spacer and the end cap commonly used in the reverse osmosis membrane module in the art, so detailed description thereof will be omitted. The reverse osmosis membrane wound as described above may be housed in an outer case, and the material, size, and shape of the outer case may also be the material, size, and shape of the outer case commonly used in the reverse osmosis module in the art. In addition, the reverse osmosis membrane wound as described above may be wrapped using fiber reinforced plastics (FRP) rather than the outer case.

Furthermore, the method for manufacturing a reverse osmosis membrane of the present invention includes first to third steps.

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

At this time, the polymer solution is 15 to 20% by weight, preferably 17 to 20% by weight, more preferably 17.1 to 17.8% by weight, even more preferably 17.2 to 17.4% by weight of the polymer support layer forming composition of the total weight% It may include, if, less than 15% by weight, after backwashing, the polymer support layer of the reverse osmosis membrane may be peeled off, and if it exceeds 20% by weight, the permeate flow rate and salt rejection rate of the reverse osmosis membrane may be reduced, etc. It can be difficult to achieve the object of the invention.

In addition, the polymer support layer forming composition of the present invention is a polysulfone-based polymer compound, polyamide-based polymer compound, polyimide-based polymer compound, polyester-based polymer compound, olefin-based polymer compound, polyvinylidene fluoride and polyacrylonitrile It may include one or more selected, preferably may include a polysulfone-based polymer compound, more preferably may include a polysulfone-based polymer compound represented by the following formula (1).

[Formula 1]

In Chemical Formula 1, R ₁ and R ₂ are each independently -H or a C1 to C5 alkyl group, preferably a C1 to C3 alkyl group.

In addition, in Chemical Formula 1, n is a rational number satisfying 10 to 1,130, and preferably a rational number satisfying 130 to 340.

In addition, the solvent of the present invention can be used without limitation as long as it is a solvent capable of dissolving the polymer support layer forming composition, preferably N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc) may include one or more selected from, and more preferably, may include dimethylformamide (DMF).

In addition, the solvent of the present invention includes 80 to 85% by weight, preferably 80 to 83% by weight, more preferably 82.2 to 83% by weight, even more preferably 82.6 to 83% by weight of the total weight% of the polymer solution. If the solvent is included in less than 80% by weight, the viscosity of the polymer solution may be excessively increased to make film formation difficult. If it exceeds 85% by weight, the strength of the reverse osmosis membrane is lowered or the viscosity of the polymer solution is very low, resulting in a film formation. It can be difficult.

In addition, when preparing a polymer solution by mixing a polymer support layer forming composition and a solvent, the temperature of the solvent may be 20 to 90°C, and if the temperature of the solvent is less than 20°C, the polymer support layer forming composition may not be dissolved, If it exceeds 90 ℃, the viscosity of the polymer solution is lowered, it may be difficult to form a polymer support layer of the desired thickness.

Next, in the second step of the method of manufacturing the reverse osmosis membrane of the present invention, the polymer solution prepared in the first step may be cast on one side or both sides, preferably one side of the porous support to form a polymer support layer.

The method of forming the polymer support layer in the second step can be used without limitation as long as it is a processing method of a conventional polymer solution used in forming the polymer support layer in the art, and the method of casting the polymer solution is a coating known in the art such as slot coating. Laws may apply. After casting the polymer solution on the porous support, the polymer support layer may be formed by removing the solvent contained in the polymer solution, and the method of removing the solvent may use a phase inversion method that replaces a solvent and a non-solvent. As the non-solvent may be at least one selected from water, ethanol and methanol, but may vary depending on the composition of the solvent.

In addition, the polymer support layer was formed on one or both sides of the porous support by removing the solvent contained in the polymer solution, and the thickness of the polymer support layer formed to realize excellent durability of the polymer support layer without lowering the permeate flow rate and salt rejection rate of the reverse osmosis membrane. The thickness may be 30 ~ 90㎛, preferably 35 ~ 60㎛, more preferably 55 ~ 60㎛, if the thickness is less than 30㎛, the binding force between the polymer support layer and the porous support is expressed at a desired level If not, the polymer support layer may be peeled from the porous support after backwashing, and if the thickness exceeds 90㎛, the permeate flow rate of the reverse osmosis membrane may be reduced.

Finally, in the third step of the method of manufacturing the reverse osmosis membrane of the present invention, a hydrophilic selective layer may be formed on one surface of the polymer support layer formed in the second step.

Specifically, the hydrophilic selective layer can be used without limitation as long as it can be used as a hydrophilic selective layer of a reverse osmosis membrane in the art, but is preferably a polyamide-based polymer compound, polypiperazine-based polymer compound, polyphenylene diamine-based A polymer compound, a polychlorophenylene diamine-based polymer compound, and a polybenzidine-based polymer compound may include one or more selected from the group, and more preferably, a polyamide-based polymer compound.

The method for forming the hydrophilic selective layer may be different depending on the type of material included in the selected hydrophilic selective layer, but the method may be based on a conventional method for forming a hydrophilic selective layer according to the type of material.

As an example, the hydrophilic selective layer may be formed on one surface of the porous support layer by applying a polyfunctional amine-containing solution to one surface of the porous support layer and interfacial polymerization of the halogen compound-containing solution.

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

Specifically, a porous support having a polymer support layer formed on one or both surfaces is immersed in a solution containing a multifunctional amine, and then immersed in a solution containing a multifunctional halogen compound to undergo interfacial polymerization to form a hydrophilic selective layer containing a polyamide-based polymer compound. Can.

The polyfunctional amine is a material having 2 to 3 amine functional groups per monomer and may be a primary amine or a polyamine containing a secondary amine. At this time, as the polyamine, aromatic primary diamines may be used as metaphenylenediamine, paraphenylenediamine, orthophenyldiamine, and substituents, and as another example, cycloaliphatic such as aliphatic primary diamine and cyclohexenediamine Primary diamines, cycloaliphatic secondary amines such as piperazine, aromatic secondary amines, and the like can be used. More preferably, it is possible to use metaphenylenediamine among polyfunctional amines, wherein the concentration is preferably an aqueous solution form containing 0.5 to 10% by weight of metaphenylenediamine, and more preferably, metaphenylenediamine 1 To 4% by weight, more preferably 1.5 to 2.5% by weight may be included, and through this there is an advantage that can express a more improved permeate flow.

In addition, when immersing a porous support having a polymer support layer on one side or both sides in a solution containing a multifunctional amine, the immersion time may be 0.1 to 10 minutes, more preferably 0.5 to 1 minute.

In addition, the polyfunctional halogen compound may preferably include a polyfunctional acyl halide, more preferably trimethoylchloride, isophthaloylchloride, 5-methoxy-1,3-isophthaloylchloride and terephthalo It may include at least one or more selected from monochloride.

The polyfunctional acyl halide can be dissolved in an aliphatic hydrocarbon solvent in an amount of 0.01 to 2% by weight, wherein the aliphatic hydrocarbon solvent is a mixture of n-alkanes having 5 to 12 carbon atoms and structural isomers of saturated or unsaturated hydrocarbons having 8 carbon atoms or carbon atoms. Five to seven ring hydrocarbons can be used. Preferably, the polyfunctional acyl halide-containing solution may be dissolved in an aliphatic hydrocarbon solvent at 0.01 to 2% by weight of polyfunctional acyl halide, more preferably 0.05 to 0.3% by weight.

At this time, the interfacial polymerization may be performed by immersing a porous support having a polymer support layer on one side or both sides immersed in a solution containing a multifunctional halogen compound in a solution containing a multifunctional halogen compound for 0.1 to 10 minutes, more preferably 0.5 to 1 minute. have.

On the other hand, the thickness of the hydrophilic selective layer formed through the third step of the method of manufacturing a reverse osmosis membrane of the present invention may be 0.1 to 1 μm, preferably 0.1 to 0.5 μm, and if the thickness is less than 0.1 μm, salt removal capability This may be lowered, and if it exceeds 1 μm, the permeate flow rate of the reverse osmosis membrane may be lowered.

Furthermore, the reverse osmosis membrane produced through the method of preparing the reverse osmosis membrane of the present invention has an adhesive strength between the porous support and the polymer support layer of 20 to 1,100 gf, preferably 500 to 1,100 gf, more preferably 500 to 810 gf, even more preferably 550 It may be ~ 650gf, if out of the range of the adhesive force, there is a problem that the salt exclusion rate decreases and the rate of increase in the permeate flow rate increases, and durability decreases.

In addition, the reverse osmosis membrane prepared through the method of manufacturing the reverse osmosis membrane of the present invention may satisfy both of the following relations 1 and 2.

[Relationship 1]

150 <B-A <600, preferably 250 <B-A <550, more preferably 300 <B-A <500

[Relationship 2]

0.5 <B/A <8, preferably 1 <B/A <2.5, more preferably 1.2 <B/A <1.5

In relations 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 selection layer.

If both of the relations 1 and 2 are not satisfied, there is a problem that the salt excretion rate decrease value is high and the permeate flow rate increase rate increases.

In the above, the present invention has been mainly described with reference to embodiments, but this is merely an example and does not limit the embodiments of the present invention, and those having ordinary knowledge in the field to which the embodiments of the present invention pertain may provide essential characteristics of the present invention. It will be appreciated that various modifications and applications not illustrated above are possible without departing from the scope. For example, each component specifically shown in the embodiment of the present invention can be implemented by modification. And differences related to these modifications and applications should be construed as being included in the scope of the invention defined in the appended claims.

Example 1: Preparation of reverse osmosis membrane

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

In this case, the polymer solution was prepared by mixing 17.3% by weight of a polysulfone-based polymer compound represented by the following Chemical Formula 1-1, and 82.7% by weight of dimethylformamide (DMF) in total weight%.

[Formula 1-1]

In Chemical Formula 1-1, R ₁ and R ₂ are methyl groups, and n is 235.

(2) As a porous support, a nonwoven fabric (polyester-based synthetic fiber, thickness: 90 µm) was prepared, and the polymer solution prepared on one side of the prepared nonwoven fabric was cast for 3 minutes at a temperature of 25° C. to an average thickness of 57.5 µm. A polymer support layer was formed.

(3) The porous support having a polymer support layer was immersed in an aqueous solution containing 2.0% by weight of metaphenylenediamine for 1 minute, and after removing the water on the surface by a pressing method, it contained 0.1% by weight of 0.1% by weight of trimezoyl chloride. It was immersed in an organic solution for 1 minute to perform interfacial polymerization. Thereafter, the mixture was naturally dried at room temperature (25° C.) for 1 minute and 30 seconds to form a hydrophilic selective layer composed of a polyamide-based polymer compound having an average thickness of 0.3 μm on one surface of the polymer support layer.

(4) Then, to remove unreacted residues, a porous support having a hydrophilic selective layer and a polymer support layer was immersed in a solution containing 0.2% by weight of sodium carbonate for 2 hours to prepare a reverse osmosis membrane.

Examples 2 to 12: Preparation of reverse osmosis membrane

(1) A reverse osmosis membrane was prepared in the same manner as in Example 1.

However, when preparing the polymer solution, as shown in Table 1 below, the mixing ratio of the polysulfone-based polymer compound represented by Chemical Formula 1-1 and dimethylformamide (DMF), which is a solvent, was changed.

In addition, a reverse osmosis membrane was prepared by varying the thickness of the polymer support layer formed as described in Table 1 below.

Experimental Example 1

In order to evaluate the peeling stability of the reverse osmosis membrane prepared in Example, the adhesive strength was evaluated prior to the initial performance evaluation of the reverse osmosis membrane and is shown in Table 1 below.

The adhesive force was measured by a method of laminating a reverse osmosis membrane using a material analyzer. Specifically, after attaching the reverse osmosis membrane to the tape and the 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 the separation membrane was laminated.

Experimental Example 2

After evaluating the initial performance of the reverse osmosis membrane prepared in Example, in order to evaluate the peeling stability of the reverse osmosis membrane, the performance after backwashing of the reverse osmosis membrane was evaluated and shown in Table 2 below.

The initial performance evaluation of the reverse osmosis membrane was measured by measuring the flow rate of water produced on the opposite side of the reverse osmosis membrane by adding 2,000 ppm of sodium chloride aqueous solution (25°C, 225 psi) onto the hydrophilic selective layer of the reverse osmosis membrane, and converting it into a unit area and a flow rate per unit pressure. .

The salt exclusion rate was determined through the following equation 1 by measuring the ionic conductivity value (TDS: Total Dissolved Solids) of the product water.

[Calculation formula 1]

Salt elimination rate (%)={1-(conductivity value of production water/conductivity value of raw water)}Х 100

In addition, the performance evaluation after backwashing of the reverse osmosis membrane was operated for 20 minutes at a pressure of 3 bar (43.5 psi), and then the flow rate and salt rejection rate were remeasured.

Referring to Table 1 and Table 2, Examples 8 to 12 having a low polymer support layer thickness have a significantly reduced salt rejection rate after backwashing, and the permeate flow rate is significantly increased. do.

In addition, it was confirmed that the reverse osmosis membranes prepared in Example 1 among the reverse osmosis membranes prepared in Examples 1 to 7 had the lowest salt excretion rate reduction and the lowest permeate flow rate increase.

Experimental Example 3

A cross-sectional SEM image of the reverse osmosis membrane prepared in Example 1 showing the most excellent effect was performed.

FIG. 2 is a cross-sectional SEM image of the reverse osmosis membrane prepared in Example 1, and referring to FIG. 2, it can be seen that the polymer support layer is formed over the upper surface and the inside of the porous support, and through this, the bonding strength with the porous support is excellent. It is judged that the polymer support layer is formed flat, and the peeling stability of the polymer support layer is excellent, so that it is possible to realize a reverse osmosis membrane with improved durability.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (19)

In a reverse osmosis membrane in which a porous support, a polymer support layer and a hydrophilic select layer are sequentially stacked,
Reverse osmosis membrane, characterized in that the adhesive force between the porous support and the polymer support layer is 20 ~ 1,100gf.
According to claim 1,
Reverse osmosis membrane, characterized in that the adhesive force between the porous support and the polymer support layer is 500 ~ 1,100gf.
According to claim 2,
The reverse osmosis membrane is a reverse osmosis membrane, characterized in that satisfies both of the following relations 1 and 2.
[Relational Formula 1]
150 <B-A <600
[Relationship 2]
0.5 <B/A <8
In relations 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 selection layer.
According to claim 1,
The polymer support layer includes at least one selected from polysulfone-based polymer compounds, polyamide-based polymer compounds, polyimide-based polymer compounds, polyester-based polymer compounds, olefin-based polymer compounds, polyvinylidene fluoride and polyacrylonitrile. Reverse osmosis membrane, characterized in that.
According to claim 1,
The polymer support layer is a reverse osmosis membrane, characterized in that it comprises a polysulfone-based polymer compound represented by the following formula (1).
[Formula 1]

In Chemical Formula 1, R ₁ and R ₂ are each independently -H or a C1 to C5 alkyl group, and n is a rational number satisfying 10 to 1,130.
According to claim 1,
The polymer support layer is a reverse osmosis membrane, characterized in that it has a thickness of 30 ~ 90㎛.
According to claim 1,
The hydrophilic selective layer is characterized in that it comprises at least one selected from polyamide-based polymer compounds, polypiperazine-based polymer compounds, polyphenylene diamine-based polymer compounds, polychlorophenylene diamine-based polymer compounds and polybenzidine-based polymer compounds Reverse osmosis membrane.
According to claim 1,
The porous support is a reverse osmosis membrane, characterized in that the fabric.
According to claim 1,
The porous support is a reverse osmosis membrane, characterized in that it comprises at least one selected from synthetic fibers and cellulose-based natural fibers selected from the group consisting of polyester, polypropylene, nylon and polyethylene.
According to claim 1,
The porous support has a thickness of 20 ~ 150㎛,
The hydrophilic selective layer is a reverse osmosis membrane, characterized in that it has a thickness of 0.1 ~ 1㎛.
A first step of preparing a polymer solution comprising a polymer support layer forming composition and a solvent;
A second step of forming the polymer support layer by casting the polymer solution on one side or both sides of the porous support; And
A third step of forming a hydrophilic selective layer on one surface of the polymer support layer; Including,
The method of manufacturing a reverse osmosis membrane, characterized in that the adhesive force between the porous support and the polymer support layer is 20 to 1,100gf.
The method of claim 11,
The polymer solution is a method for producing a reverse osmosis membrane, comprising 15 to 20% by weight of the polymer support layer forming composition in the total weight%.
The method of claim 11,
The polymer support layer forming composition is at least one selected from polysulfone-based polymer compounds, polyamide-based polymer compounds, polyimide-based polymer compounds, polyester-based polymer compounds, olefin-based polymer compounds, polyvinylidene fluoride and polyacrylonitrile. Method of producing a reverse osmosis membrane comprising a.
The method of claim 13,
The polymer support layer forming composition is a method for producing a reverse osmosis membrane comprising a polysulfone-based polymer compound represented by the following formula (1).
[Formula 1]

In Chemical Formula 1, R ₁ and R ₂ are each independently -H or a C1 to C5 alkyl group, and n is a rational number satisfying 10 to 1,130.
The method of claim 11,
The solvent of the reverse osmosis membrane, characterized in that it comprises at least one selected from N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc) Manufacturing method.
The method of claim 11,
The polymer support layer is a method of manufacturing a reverse osmosis membrane, characterized in that formed to a thickness of 30 ~ 90㎛.
The method of claim 11,
The hydrophilic selective layer is a method of manufacturing a reverse osmosis membrane characterized in that a polyfunctional amine-containing solution is applied to one surface of the porous support layer, and a halogen compound-containing solution is interfacially polymerized to form on one surface of the porous support layer.
The method of claim 17,
The hydrophilic selective layer includes a polyamide-based polymer compound formed by interfacial polymerization of a polyfunctional amine-containing solution and a polyfunctional halogen compound-containing solution,
The polyfunctional amine includes at least one of metaphenylenediamine, paraphenylenediamine, aliphatic primary diamine, cycloaliphatic primary diamine, and cycloaliphatic secondary amine,
The polyfunctional halogen compound is trimethoyl chloride, isophthaloyl chloride and terephthaloyl chloride method for producing a reverse osmosis membrane, characterized in that it comprises at least one of.
The reverse osmosis membrane module comprising the reverse osmosis membrane according to any one of claims 1 to 10.

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