KR20140046952A - Reverse osmosis membrane having excellent fouling resistance and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a reverse osmosis complex membrane having excellent fouling resistance and a manufacturing method thereof, and more specifically, to: a reverse osmosis complex membrane which does not require separate physical and chemical preprocessing for preventing the contamination of a separation membrane, and controls the attachment of contaminants in a positive or negative charge for fundamentally preventing a membrane contamination phenomenon, thereby being applied to salty water and high concentration raw water like seawater; and a manufacturing method thereof.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis composite membrane,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis composite membrane having excellent resistance to contamination and a method for producing the reverse osmosis composite membrane, and more particularly, to a reverse osmosis composite membrane having improved pollution resistance against contaminants caused by organic substances, And a manufacturing method thereof.

Generally, the dissociated material can be separated from the solvent using various types of selective membranes. These selective membranes are classified into reverse osmosis membranes, ultrafiltration membranes and microfiltration membranes in order of increasing pore size.

Conventional use of reverse osmosis membranes is a desalination process of semi-saline or seawater, and this desalination process allows a large amount of fresh or pure water that is relatively suitable for industrial, agricultural, or domestic use. The desalination process of semi-brine or seawater using reverse osmosis membrane is a process of literally filtering salts, other dissolved ions or molecules from the brine. By passing the brine through the reverse osmosis membrane, the purified water passes through the membrane, Ions or molecules can not pass through the separator. The osmotic pressure is inevitably generated in the reverse osmosis process, and the higher the concentration of the raw water, the higher the osmotic pressure. Therefore, there are some conditions that reverse osmosis membranes must be equipped for in order to commercially use salt and seawater in large amounts for desalination, one of which has a high salt rejection rate. At least 97% of the salt excretion rate of the reverse osmosis membrane is currently required for commercial application.

One common type of reverse osmosis membrane is a composite membrane consisting of a porous support and a polyamide membrane formed on the porous support. The polyamide thin film is formed by interfacial polymerization of a polyfunctional amine and a polyfunctional acyl halide.

Various attempts have been made in order to increase the permeation flow rate and the salt rejection rate of the polyamide reverse osmosis composite membrane. The attempts have been made to improve the chemical resistance of the membrane in addition to the membrane permeability. Most of these studies are based on the use of various types of additives in solutions used in interfacial polycondensation.

Various research and development have been carried out to improve the performance of polyamide composite membranes, and reverse osmosis membranes having excellent separation performance and permeability and excellent chemical resistance have been proposed. However, the problem of membrane contamination is still a problem to be solved. The contamination of the membrane means that the suspended or adsorbed substance adsorbs or adheres to the membrane surface, resulting in a decrease in the permeation flow rate. At this time, the contamination of the membrane is primarily caused by the combination of the surface of the membrane with the suspended material or the dissolved substance in the solution, which is filtered by hydrophobic bonding and electrostatic attraction. In addition to the first membrane fouling, microbes formed by organic or inorganic substances are adsorbed on the surface of the separation membrane, and a bio-film is formed on the surface of the separation membrane. Such membrane contamination is undesirable because it impairs the permeability of the membrane and therefore requires frequent correction of pressure to obtain permeate at a constant flow rate or requires cleaning if membrane contamination is severe.

Conventionally, a method of re-coating an electrostatically neutral and hydrophilic polymer such as polyvinyl alcohol to improve the resistance to contamination, a composite membrane comprising a cross-linked polyamide surface containing grafted polyalkylene oxide on a support, Various methods such as a method of applying a quantitative determination of a multifunctional epoxy compound composed of at least two epoxy groups to a separator and then crosslinking the multifunctional epoxy compound to obtain a polymer insoluble in water have been attempted. However, they did not improve the pollution performance enough to apply to high concentration of raw water conditions such as salt water as well as sea water.

 Therefore, in order to improve the pollution resistance of the reverse osmosis membrane system, chemical pre-treatment such as physical pretreatment or pH control for removing fine particles or bacteria through filtration, or a combination thereof, is introduced, which not only complicates the filtration process There still remains a problem of contamination of the separation membrane due to organic matter.

In addition, although a method of forming a hydrophobic coating layer by bonding a hydrophobic compound to the surface of a polyamide layer has been hitherto proposed, there is a problem that the available materials are extremely limited and the permeation flow rate is greatly reduced during the coating process.

On the other hand, bacteria are often present in a natural environment or in aquatic water system, and secrete EPS (extracellular polymeric substances) during growth, reproduction, etc. after adsorption on the surface of the membrane. These materials mainly consist of proteins and polysaccharides, which bind to bacterial cells to form bio-films and irreversibly combine with the surface of the membrane to cause bio-fouling. In the molecule of the protein, an acidic group having a negative charge such as an amino group or a guanidine group and a negative charge having a positive charge and a negative charge like a carboxyl group are mixed and charged according to a functional group bonded to the polysaccharide molecule. In order to improve the pollution resistance against contaminants of organic materials, development of a polyamide composite membrane having resistance to the charged substances has been required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an apparatus and a method for separating and purifying foreign matter, which can be applied not only to salt water but also to raw water of high concentration such as seawater, The present invention also provides a reverse osmosis membrane having improved resistance to contamination and a method for producing the reverse osmosis membrane, which can prevent membrane fouling due to contaminants having a positive or negative charge.

In order to solve the above-described problems,

(1) forming a porous support layer by doping a polymer solution on a nonwoven fabric layer; (2) immersing the porous support layer in an aqueous solution containing a polyfunctional amine, and then contacting the porous support layer with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer; And (3) reacting the polyamide layer with a positively charged amine compound-containing solution to form an antifouling coating layer on the antifouling coating layer.

According to a preferred embodiment of the present invention, the polymer of step (1) may be selected from the group consisting of a polysulfone polymer, a polyamide polymer, a polyimide polymer, a polyester polymer, an olefin polymer, polyvinylidene fluoride, And ronitril. ≪ RTI ID = 0.0 >

According to another preferred embodiment of the present invention, the positively charged amine compound of the step (3) comprises (i) a primary amine, a secondary amine and a tertiary amine functional group, (ii) Amine or secondary amine functionality.

According to another preferred embodiment of the present invention, the positively charged amine compound may be a compound represented by the following general formula (1).

[Chemical Formula 1]

Wherein R ^1, R ² are independently an alkyl group of C _{1 ~ 6,} respectively,

Wherein R ³ and R ⁴ are not present or are an alkyl group having _{1 to 8} carbon atoms,

이며, 적어도 하나의 X는 H가 아니고, 상기 R⁵, R⁶는 각각 독립적으로 존재하지 않거나 C_{1 ~6}의 알킬기이며, 상기 m은 1 내지 1,000의 정수이고, n은 각각 독립적으로 0 내지 100의 정수이다.
Each X is independently H or < RTI ID = 0.0 >

, And not the at least one X is H, wherein R ^5, R ⁶ are not present, each independently is an alkyl group of C _{1 ~ 6,} wherein m is from 1 to a 1,000 integer, n is independently from 0 to 100 and Lt; / RTI >

According to another preferred embodiment of the present invention, the positively charged amine compound may be a branched polyethylenimine having a molecular weight of 1,000 to 70,000 or a derivative thereof.

According to another preferred embodiment of the present invention, the positive-positive amine compound-containing solution may contain 0.03 to 2% by weight of the positive-charge amine compound.

According to another preferred embodiment of the present invention, the step (3) may be carried out for 5 seconds to 10 minutes to a solution containing a positively charged amine compound.

The present invention also relates to a porous support layer; A polyamide layer formed on one surface of the porous support layer; And an anti-fouling coating layer formed by covalently bonding a positively charged amine compound to the surface of the polyamide layer.

According to a preferred embodiment of the present invention, the porous support layer may be formed on the nonwoven fabric layer.

According to another preferred embodiment of the present invention, the porous support layer may be formed of a polysulfone-based polymer, a polyamide-based polymer, a polyimide-based polymer, a polyester-based polymer, an olefin-based polymer, polyvinylidene fluoride and polyacrylonitrile May be any one or more selected from the group consisting of

According to another preferred embodiment of the present invention, the positively charged amine compound comprises (i) a primary amine, a secondary amine and a tertiary amine functional group, (ii) at least two or more primary amines or secondary amines Functional groups.

According to another preferred embodiment of the present invention, the positively charged amine compound may be a compound represented by the following general formula (1).

[Chemical Formula 1]

Wherein R ^1, R ² are independently an alkyl group of C _{1 ~ 6,} respectively,

Wherein R ³ and R ⁴ are not present or are an alkyl group having _{1 to 8} carbon atoms,

이며, 적어도 하나의 X는 H가 아니고, 상기 R⁵, R⁶는 각각 독립적으로 존재하지 않거나 C_{1 ~6}의 알킬기이며, 상기 m은 1 내지 1,000의 정수이고, n은 각각 독립적으로 0 내지 100의 정수이다.
Each X is independently H or < RTI ID = 0.0 >

, And not the at least one X is H, wherein R ^5, R ⁶ are not present, each independently is an alkyl group of C _{1 ~ 6,} wherein m is from 1 to a 1,000 integer, n is independently from 0 to 100 and Lt; / RTI >

According to another preferred embodiment of the present invention, the positively charged amine compound may be a branched polyethyleneimine having a molecular weight of 1,000 to 70,000 or a derivative thereof.

According to another preferred embodiment of the present invention, the antifouling coating layer can simultaneously absorb positive charge and negative charge.

According to another preferred embodiment of the present invention, when the reverse osmosis membrane is permeated in an aqueous solution of 32,000 ppm sodium chloride in an aqueous solution containing 100 ppm of humic acid and 2 ppm of calcium chloride in a cross-flow mode at 25 ° C under a pressure of 225 psi The flow rate reduction rate after 8 hours may be 5.0% or less.

According to another preferred embodiment of the present invention, the thickness of the porous support layer is 30 to 300 μm, the thickness of the polyamide layer is 0.1 to 1 μm, and the thickness of the anti-fouling coating layer is 0.01 to 0.5 μm.

The reverse osmosis membrane having excellent stain resistance of the present invention does not require separate physical and chemical pretreatment for preventing contamination of the separation membrane and can suppress the membrane contamination phenomenon by suppressing the adsorption of a positive charge or a negative charge pollutant, A reverse osmosis membrane having improved resistance to contamination which can be applied even under high concentration of raw water such as seawater, and a method for producing the reverse osmosis membrane can be provided.

1 is a process diagram of the reverse osmosis membrane manufacturing method of the present invention.
2 is a cross-sectional view of a reverse osmosis membrane according to a preferred embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As described above, the conventional polyamide reverse osmosis composite membrane is not sufficiently improved in its contamination performance to be applied to high-concentration raw water such as seawater as well as brine. Therefore, it is necessary to perform physical pretreatment such as removal of fine particles or bacteria through filtration, There is a problem in that a chemical pretreatment process or a combination process thereof has to be introduced and there is a problem in that the improvement of the pollution performance which prevents contamination of the separation membrane due to organic materials having positive or negative charge is insufficient.

(1) forming a porous support layer by doping a polymer solution on a nonwoven fabric layer; (2) immersing the porous support layer in an aqueous solution containing a polyfunctional amine, and then contacting the porous support layer with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer; And (3) reacting the polyamide layer with a positively charged amine compound-containing solution to form a contamination-resistant coating layer. The present invention provides a method of manufacturing a reverse osmosis membrane having improved stain resistance, . This eliminates the need for separate physical and chemical pretreatment to prevent separation membrane contamination. By preventing the adsorption of contaminants with positive or negative charges, membrane contamination can be fundamentally prevented. As a result, not only salt water but also high- A reverse osmosis membrane having improved stain resistance and a method for producing the same can be provided.

 In the step (1), a polymer solution is doped on the nonwoven fabric layer to form a porous support layer. (S1)

The nonwoven fabric layer is not particularly limited as long as it serves as a support of a membrane, but more preferably synthetic fibers selected from the group consisting of polyester, polypropylene, nylon and polyethylene; Or natural fibers including cellulosic fibers; And the nonwoven fabric layer can control the physical properties of the membrane according to porosity and hydrophilicity of the material. The thickness of the nonwoven fabric layer is preferably from 20 to 150 μm, and if it is less than 20 μm, the strength and support of the entire membrane are insufficient. If the thickness is more than 150 μm, the nonwoven fabric layer may cause a decrease in the flow rate.

The solvent for forming the polymer solution is not particularly limited as long as it can dissolve the polymer uniformly without forming precipitates, but is more preferably selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF) Dimethylsulfoxide (DMSO) or dimethylacetamide (DMAc), or the like.

If the temperature is lower than 20 ° C, the polymer may not be dissolved and the membrane may not be produced. If the temperature is higher than 90 ° C, the viscosity of the polymer solution may become too thin, and thus the membrane may be difficult to produce .

The polymer forming the polymer solution is not particularly limited as long as it is capable of forming a reverse osmosis membrane, but it is more preferably a polysulfone-based polymer including a polysulfone or polyethersulfone, a polyamide-based polymer, a polyimide-based polymer, An olefin-based polymer such as a polyester-based polymer or a polypropylene, a polybenzimidazole polymer, polyvinylidene fluoride or polyacrylonitrile, and the like.

The polymer solution may preferably contain 7 to 35% by weight of the polymer. If the content of the polymeric substance is less than 7% by weight, the strength is lowered and the solution viscosity is low. Thus, the film is difficult to manufacture and has a problem. When it exceeds 35% by weight, the concentration of the polymer solution is too high.

In the step (2), the porous support layer is immersed in an aqueous solution containing a polyfunctional amine, and then contacted with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer. (S2)

 Specifically, the polyfunctional amine may be a polyamine having two or three amine functional groups per monomer, and may include a primary amine or a secondary amine. As the polyamines, aromatic primary diamine is used as the metaphenylenediamine, paraphenylenediamine, orthophenyldiamine and the substituent. As another example, aliphatic primary diamine and cycloaliphatic primary diamine such as cyclohexenediamine , Cycloaliphatic secondary amines such as piperazine, and aromatic secondary amines. More preferably, the polyfunctional amine is selected from the group consisting of metaphenylenediamine, and the concentration thereof is preferably in the form of an aqueous solution containing 0.5 to 10 wt% of metaphenylenediamine, more preferably 1 to 4 wt% % May be contained.

Upon forming the polyamide layer of the present invention, the polyfunctional amine-containing aqueous solution may be applied onto the porous support for 0.1 to 10 minutes, more preferably for 0.5 to 1 minute.

The material which reacts with the polyfunctional amine used in forming the polyamide layer of the present invention is a polyfunctional acid halide, that is, a polyfunctional acyl halide. Preferably, it may be used alone or in a mixed form of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, and the like. At this time, the use of the mixed form is most preferable in terms of the salt removal rate. The polyfunctional acyl halide may 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 It is preferable to use a cyclic hydrocarbon having 5 to 7 carbon atoms. The polyfunctional acyl halide-containing solution preferably dissolves 0.01 to 2% by weight, more preferably 0.05 to 0.3% by weight, of the polyfunctional acyl halide in the aliphatic hydrocarbon solvent.

 In the step (3), a positively charged amine compound-containing solution is reacted with the polyamide layer to form an antifouling coating layer. (S3)

 The antifouling coating layer of the present invention is formed by forming a covalent bond through a polymerization reaction to form an amide bond between the primary amino group or the secondary amino group of the positively charged amine compound and the residual acid halide compound of the polyamide layer, Containing solution to form a polyamide layer, drying the membrane for 1 to 3 minutes, and then bringing the resulting membrane into contact with an aqueous solution containing a positively charged amine compound to perform a polymerization reaction with the reaction residual multifunctional acid halide compound.

Upon formation of the stain resistant coating layer, a solution containing a positively charged amine compound is contacted by impregnation or spraying at a temperature of from room temperature to 95 캜 for 5 seconds to 10 minutes, more preferably for 20 seconds to 4 minutes, A stain resistant coating layer can be formed.

At this time, the positively charged amine compound-containing solution may contain 0.03 to 2.0 wt% of the positively charged amine compound. If the amount of the positively charged amine compound is less than 0.03 wt%, the effect of improving the stain resistance is insufficient. If the amount of the positively charged amine compound is more than 2.0 wt%, the permeation flow rate sharply decreases and the commercial required properties of the polyamide composite membrane may not be satisfied.

 The positively charged amine compound of the present invention specifically includes (i) a primary amine, a secondary amine, and a tertiary amine functional group, and (ii) at least two or more primary amine or secondary amine functional groups .

 After the formation of the polyamide layer, the residual acid halide and the primary or secondary amine group may form a covalent bond through a polymerization reaction. Herein, the positively charged amine compound should include a reactive group that directly forms a covalent bond, and the reactive group may mean a compound containing at least two or more primary amines or secondary amines.

The contaminant-resistant coating thus formed simultaneously adsorbs the negative charge of the carbonyl group (-C (= O) -) and the positive charge of the primary amine, the secondary amine and the tertiary amine, thus preventing the adsorption of the charged contaminants can do. At this time, in the case where a primary amine and a secondary amine as well as a tertiary amine are contained, it is possible to more effectively improve stain resistance due to negative charge and positively charged contaminants (see Examples 4 and 5).

 Thus, the positively charged amine compound of the present invention can be preferably represented by the following formula (1).

[Chemical Formula 1]

Wherein R ^1, R ² are each repeating unit may be each independently an alkyl group having 1 to 6 carbon atoms, wherein R ^3, R ⁴ is not present or may be an alkyl group of C _{1 ~ 8.} The absence of R ³ or R ⁴ may mean that the N or R ^{1 at the} end of the repeat unit is directly connected to the primary amine.

이며, 적어도 하나의 X는 H가 아닐 수 있다. X가 H이면 X와 결합된 N은 2차 아민이며, X가

이면 3차 아민이 되는데, 반복 단위 중 적어도 하나의 X는 H가 아니라는 것은 3차 아민을 적어도 하나 포함하는 것을 의미할 수 있다. 상기 R⁵ 는 반복 단위마다 각각 독립적으로 존재하지 않거나 C_{1 ~6}의 알킬기일 수 있으며, R⁶도 각각 독립적으로 존재하지 않거나 C_{1 ~6}의 알킬기일 수 있다. R⁵ 또는 R⁶가 존재하지 않는 때에는 알킬기 없이 N과 N이 결합될 수 있다. 또한, 상기 m은 1 내지 1,000의 정수이고, n은 각각 독립적으로, 0 내지 100의 정수일 수 있다.
X is independently for each repeating unit H or

, And at least one X may not be H. When X is H, N bonded to X is a secondary amine and X is

If at least one X of the repeating units is not H, it may mean that at least one tertiary amine is contained. Wherein R ⁵ may be in each repeating unit, each exists independently or alkyl group of C _{1 ~ ^6,} R ₆ is also not present, each independently may be an alkyl group of C _{1 ~ 6.} When R < ⁵ > or R < ⁶ > is absent, N and N may be bonded without an alkyl group. M is an integer of 1 to 1,000, and n may be independently an integer of 0 to 100.

Examples of the positively charged amine compound of the present invention include branched polyethyleneimines having a molecular weight of 1,000 to 70,000.

In addition, the present invention thus fabricated has a porous support layer; A polyamide layer formed on one surface of the porous support layer; And an anti-fouling coating layer formed by covalently bonding a positively charged amine compound to the surface of the polyamide layer.

FIG. 1 is a cross-sectional view of a reverse osmosis membrane according to a preferred embodiment of the present invention. Referring to FIG. 1, the reverse osmosis membrane 200 according to an embodiment of the present invention includes a nonwoven fabric layer 210, A polyamide layer 230 formed on the porous support layer 220 and an anti-fouling coating layer 240 formed on the polyamide layer 230. The anti-

The nonwoven fabric layer 210 may be omitted, but the nonwoven fabric layer 210 may be formed as shown in FIG. The nonwoven fabric layer 210 is not particularly limited as long as it serves as a support for the membrane, but more preferably synthetic fibers selected from the group consisting of polyester, polypropylene, nylon and polyethylene; Or natural fibers including cellulosic fibers; And the nonwoven fabric layer can control the physical properties of the membrane according to porosity and hydrophilicity of the material.

The thickness of the nonwoven fabric layer 210 of the present invention is preferably 20 to 150 占 퐉. If the thickness is less than 20 占 퐉, the strength and support of the entire membrane may be insufficient.

 The porous support layer 220 that can be formed on the nonwoven fabric layer 210 is not particularly limited as long as it can form a reverse osmosis membrane. However, in consideration of mechanical strength, it is preferable to use a polymer having a weight average molecular weight in the range of 65,000 to 150,000 And preferred examples thereof include polysulfone-based polymers including polysulfone or polyethersulfone, polyamide-based polymers, polyimide-based polymers, polyester-based polymers, olefin-based polymers such as polypropylene, polybenzimidazole polymers, poly Vinylidene fluoride or polyacrylonitrile, or the like, alone or in combination.

The thickness of the porous support layer 220 may be in the range of 30 to 300 μm. If the thickness is less than 30 μm, there may be a problem of reduction in flow rate and durability due to compaction. If the thickness is more than 300 μm, There may be a problem. The pore size of the porous support layer 220 is preferably 1 to 500 nm.

The polyamide layer 230 formed on the porous support layer 220 may be formed by interfacial polymerization after being immersed in an aqueous solution containing a polyfunctional amine and then contacting an organic solution containing a polyfunctional acid halide compound. The thickness of the polyamide layer 230 may range from 0.1 to 1 μm. If the thickness of the polyamide layer 230 is less than 0.1 μm, the salt removing ability is deteriorated to fail to serve as a selective layer. If the thickness is more than 1 μm, There is a problem that the flow rate is lowered.

 The anti-staining coating layer 240 formed by covalently bonding a positively charged amine compound to the surface of the polyamide layer 230 may be formed by a polymerization reaction between a primary amino group or a secondary amino group of the positively charged amine compound and a residual acid halide compound of the polyamide layer To form a covalent bond.

The positively charged amine compound specifically includes (i) a primary amine, a secondary amine and a tertiary amine functional group, and (ii) at least two or more primary amine or secondary amine functional groups.

After the formation of the polyamide layer, the residual acid halide and the primary or secondary amine group may form a covalent bond through a polymerization reaction. The positively charged amine compound should contain a reactive group that directly forms a covalent bond, and the reactive group refers to a compound containing at least two or more primary amines or secondary amines.

The thus formed contamination-resistant coating layer can simultaneously absorb positive charge and negative charge. Specifically, since the negative charge of the carbonyl group (-C (= O) -) and the positive charge of the primary amine, the secondary amine and the tertiary amine group are simultaneously applied, it prevents the adsorption of the negative charge or the positively charged contaminant You can. At this time, in the case where a primary amine and a secondary amine as well as a tertiary amine are contained, it is possible to more effectively improve stain resistance due to negative charge and positively charged contaminants (see Examples 4 and 5).

Thus, the positively charged amine compound of the present invention can be preferably represented by the following formula (1).

[Chemical Formula 1]

Wherein R ^1, R ² are each repeating unit may be each independently an alkyl group having 1 to 6 carbon atoms, wherein R ^3, R ⁴ is not present or may be an alkyl group of C _{1 ~ 8.} The absence of R ³ or R ⁴ may mean that the N or R ^{1 at the} end of the repeat unit is directly connected to the primary amine.

이며, 적어도 하나의 X는 H가 아닐 수 있다. X가 H이면 X와 결합된 N은 2차 아민이며, X가

이면 3차 아민이 되는데, 반복 단위 중 적어도 하나의 X는 H가 아니라는 것은 3차 아민을 적어도 하나 포함하는 것을 의미할 수 있다. 상기 R⁵ 는 반복 단위마다 각각 독립적으로 존재하지 않거나 C_{1 ~6}의 알킬기일 수 있으며, R⁶도 각각 독립적으로 존재하지 않거나 C_{1 ~6}의 알킬기일 수 있다. R⁵ 또는 R⁶가 존재하지 않는 때에는 알킬기 없이 N과 N이 결합될 수 있다. 또한, 상기 m은 1 내지 1,000의 정수이고, n은 각각 독립적으로, 0 내지 100의 정수일 수 있다.
X is independently for each repeating unit, H or

, And at least one X may not be H. When X is H, N bonded to X is a secondary amine and X is

If at least one X of the repeating units is not H, it may mean that at least one tertiary amine is contained. Wherein R ⁵ may be in each repeating unit, each exists independently or alkyl group of C _{1 ~ ^6,} R ₆ is also not present, each independently may be an alkyl group of C _{1 ~ 6.} When R < ⁵ > or R < ⁶ > is absent, N and N may be bonded without an alkyl group. M is an integer of 1 to 1,000, and n may be independently an integer of 0 to 100.

 Examples of the positively charged amine compound of the present invention include branched polyethyleneimines having a molecular weight of 1,000 to 70,000.

 The thickness of the antifouling coating layer 240 is preferably from 0.01 to 0.5 μm. If the thickness of the antifouling coating layer 240 is less than 0.01 μm, the effect of improving stain resistance is insufficient. If the thickness is more than 0.5 μm, the permeation flow rate is excessively decreased, Can be.

The reverse osmosis membrane can remarkably improve the stain resistance of the reverse osmosis membrane compared to a conventional polyamide reverse osmosis membrane under conditions of 25 ° C., 800 psi, pH 8.0 and high concentration of water at a concentration of 32,000 ppm. When the aqueous solution containing 100 ppm of humic acid and 2 ppm of calcium chloride in a 32,000 ppm sodium chloride aqueous solution is permeated in a cross-flow mode at 25 ° C and 800 psi pressure, the rate of decrease in flow rate after 8 hours may be 5.0% or less.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples should not be construed as limiting the scope of the present invention, and should be construed to facilitate understanding of the present invention.

≪ Example 1 >

A dimethylformamide solution containing 18% by weight of polysulfone was cast on a polyester nonwoven fabric to a thickness of about 125 ± 10 μm and immediately thereafter immersed in distilled water at 25 ° C. for phase transformation. Thereafter, a nonwoven reinforced polysulfone porous substrate Was sufficiently washed with water to replace the solvent and water in the substrate and stored in pure water at room temperature. Thereafter, after immersing in an aqueous solution containing m-phenylenediamine at a concentration of 3.0% by weight for 1 minute, the water layer on the surface was removed by a pressing method. The substrate was immersed in an organic solution containing 0.07% by weight of trimethoyl chloride and 0.1% by weight of isophthaloyl chloride for 1 minute, followed by naturally polymerizing at room temperature (25 ° C.) for 1 minute and 30 seconds, .

Immediately after the formation of the polyamide layer, a polyethyleneimine having a molecular weight of 1,200 was immersed in an aqueous solution containing 0.01 wt% for 2 minutes and then immersed in a 0.2 wt% sodium carbonate solution for 2 hours to remove unreacted residues To prepare a polyamide composite reverse osmosis membrane having both ionic coating layers.

≪ Example 2 >

Immediately after the formation of the polyamide layer, it was prepared in the same manner as in Example 1, except that it was immersed in an aqueous solution containing 0.05 wt% of polyethylenimine having a molecular weight of 1,200.

≪ Example 3 >

Was prepared in the same manner as in Example 1, except that the polyamide layer was immersed in an aqueous solution containing 0.1 wt% of polyethylenimine having a molecular weight of 1,200 immediately after formation of the polyamide layer.

<Example 4>

Immediately after the formation of the polyamide layer, a polyethylenimine having a molecular weight of 1,200 was immersed in an aqueous solution containing 0.05% by weight of polyethylenimine.

&Lt; Example 5 >

Immediately after the formation of the polyamide layer, a polyethylenimine having a molecular weight of 1,200 was immersed in an aqueous solution containing 0.1% by weight of polyethylenimine.

&Lt; Comparative Example 1 &

The procedure of Example 1 was repeated except that the unreacted residues were removed immediately after the polyamide layer was formed and then immersed in a polyethyleneimine aqueous solution to form a stain resistant coating layer.

&Lt; Comparative Example 2 &

The procedure of Example 1 was repeated except that the polyamide layer was immersed in an aqueous solution of 0.05% by weight of 1-amino-3- (2,2,3,3-tetrafluoropropoxy) -2-propanol immediately after formation of the polyamide layer .

<Experimental Example>

The reverse osmosis composite membranes prepared according to Examples 1 to 7 and Comparative Examples 1 and 2 were subjected to cross flow mode at 25 ° C and 800 psi pressure using a 32,000 ppm sodium chloride aqueous solution at a flow rate and a salt rejection rate in a cross- And the initial basic properties were confirmed.

Then, to evaluate the pollution resistance, an aqueous solution containing 10 ppm of humic acid and 2 ppm of calcium chloride was added to a 32,000 ppm sodium chloride aqueous solution, and the flow rate reduction rate after 8 hours was measured.

division Flow rate (GFD) Salt exclusion rate (%) Flow rate reduction (%) Example 1 0.01% branched PEI 18.43 99.59 6.12 Example 2 0.05% branched PEI 15.59 99.68 3.21 Example 3 0.1% branched PEI 13.21 99.75 1.09 Example 4 0.05% linear PEI 16.32 99.61 5.72 Example 5 0.1% linear PEI 14.17 99.69 4.03 Comparative Example 1 - 20.22 99.23 8.25 Comparative Example 2 0.05% ATFP 15.07 99.59 5.94

 As can be seen from the above Table 1, the flow rate reduction rate of Examples 1 to 5 was smaller than that of Comparative Example 1 in which the contamination-resistant coating layer was not formed, and the stain resistance was improved.

Specifically, Examples 2 and 3, which used 0.05 wt.% And 0.1 wt.%, Respectively, were superior to Example 1 using 0.01 wt.% Branched PEI. Examples 4 and 5 of linear PEI containing no tertiary amine It is found that the effect is less than that of Examples 2 and 3 including tertiary amine. In addition, it can be seen that the flow rate reduction rate in Example 2 using the same type of branched PEI of 0.05 weight% was significantly reduced as compared with Comparative Example 2 in which a hydrophobic compound was combined to form a coating layer.

Claims (16)

(1) forming a porous support layer by doping a polymer solution on a nonwoven fabric layer;
(2) immersing the porous support layer in an aqueous solution containing a polyfunctional amine, and then contacting the porous support layer with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer; And
(3) reacting the polyamide layer with a positively charged amine compound-containing solution to form a contamination-resistant coating layer.
The method according to claim 1,
The polymer of step (1) may be any one selected from the group consisting of a polysulfone-based polymer, a polyamide-based polymer, a polyimide-based polymer, a polyester-based polymer, an olefin-based polymer, polyvinylidene fluoride, and polyacrylonitrile By weight based on the total weight of the reverse osmosis membrane.
The method according to claim 1,
The positively charged amine compound in the step (3)
(i) comprises primary, secondary, and tertiary amine functional groups,
(ii) at least two or more primary amine or secondary amine functional groups.
The method according to claim 1,
Wherein the positively charged amine compound is a compound represented by the following general formula (1).
[Chemical Formula 1]

Wherein R ^1, R ² are independently an alkyl group of C _{1 ~ 6,} respectively,
Wherein R ³ and R ⁴ are not present or are an alkyl group having _{1 to 8} carbon atoms,
Each X is independently H or &lt; RTI ID = 0.0 &gt;

, And not the at least one X is H, wherein R ^5, R ⁶ are not present, each independently is an alkyl group of C _{1 ~ 6,} wherein m is from 1 to a 1,000 integer, n is independently from 0 to 100 and Lt; / RTI &gt;
The method according to claim 1,
Wherein the positively charged amine compound is a branched polyethylenimine having a molecular weight of 1,000 to 70,000 or a derivative thereof.
The method according to claim 1,
Wherein the positively charged amine compound-containing solution contains 0.03 to 2% by weight of a positively charged amine compound.
The method according to claim 1,
Wherein the step (3) comprises contacting the positively charged amine compound-containing solution for 5 seconds to 10 minutes.
A porous support layer;
A polyamide layer formed on one surface of the porous support layer; And
And an anti-fouling coating layer formed by covalent bonding of a positively charged amine compound on the surface of the polyamide layer.
9. The method of claim 8,
Wherein the porous support layer is formed on the nonwoven fabric layer.
9. The method of claim 8,
Wherein the porous support layer is at least one selected from the group consisting of a polysulfone-based polymer, a polyamide-based polymer, a polyimide-based polymer, a polyester-based polymer, an olefin-based polymer, polyvinylidene fluoride, and polyacrylonitrile Reverse osmosis membrane with improved stain resistance.
9. The method of claim 8,
The positively charged amine compound
(i) comprises primary, secondary, and tertiary amine functional groups,
(ii) at least two primary amine or secondary amine functional groups.
9. The method of claim 8,
Wherein the positively charged amine compound is a compound represented by the following general formula (1).
[Chemical Formula 1]

Wherein R ^1, R ² are independently an alkyl group of C _{1 ~ 6,} respectively,
Wherein R ³ and R ⁴ are not present or are an alkyl group having _{1 to 8} carbon atoms,
Each X is independently H or &lt; RTI ID = 0.0 &gt;

At least one X is not H, each of R ⁵ and R ⁶ is independently absent or is an alkyl group having _{1 to 6} carbon atoms, m is an integer of 1 to 1,000, n is independently 0, Lt; / RTI &gt;
9. The method of claim 8,
Wherein the positively charged amine compound is a branched polyethyleneimine having a molecular weight of 1,000 to 70,000 or a derivative thereof.
9. The method of claim 8,
Wherein the anti-fouling coating layer has a positive charge and a negative charge at the same time.
9. The method of claim 8,
The reverse osmosis membrane has a flow rate reduction rate of 5.0% or less after 8 hours when an aqueous solution containing 100 ppm of humic acid and 2 ppm of calcium chloride is passed through a 32,000 ppm sodium chloride aqueous solution in a cross-flow mode at 25 ° C. and 800 psi pressure. The reverse osmosis membrane having improved stain resistance.
9. The method of claim 8,
Wherein the porous support layer has a thickness of 30 to 300 占 퐉, the polyamide layer has a thickness of 0.1 to 1 占 퐉, and the stainproof coating layer has a thickness of 0.01 to 0.5 占 퐉.

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