JP2015150544A - Surface treatment agent, surface-treated polyamide reverse osmosis membrane and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment agent for a polyamide reverse osmosis membrane which can effectively suppress fouling on the polyamide reverse osmosis membrane for a long term, does not substantially contain an organic solvent and is environmentally excellent, a surface-treated polyamide reverse osmosis membrane treated with the surface treatment agent and a production method of the same.SOLUTION: A surface treatment agent for a polyamide reverse osmosis membrane is the copolymer having a weight average molecular weight of 5,000-150,000 of a monomer composition including a monomer expressed by formula (1) of 10-80 mol% and a cationic (meth)acrylamide of 20-90 mol%. The surface of a surface-treated polyamide reverse osmosis membrane is treated with the surface treatment agent. A production method of the surface-treated polyamide reverse osmosis membrane includes a surface treatment step.

Description

  The present invention relates to a surface treatment agent effective for suppressing fouling of a polyamide reverse osmosis membrane, a surface-treated polyamide reverse osmosis membrane surface-treated with the surface treatment agent, and a method for producing the same.

Recently, filtration membranes such as microfiltration, ultrafiltration, and reverse osmosis have been used in many industrial fields such as drinking water production, water and sewage treatment, and wastewater treatment.
Among such filtration membranes, reverse osmosis membranes are used for desalination of seawater, production of pure water, and the like. Polyamide is generally used as the material for the reverse osmosis membrane, but it has a problem that it easily fouls.
Fouling is a causative substance called foulant contained in raw water, for example, poorly soluble components, proteins, high molecular solutes such as polysaccharides, colloids, micro solids, microorganisms, etc., adhere to the membrane and reduce the permeation flow rate. This phenomenon is known as the main cause of film deterioration.
As a countermeasure against such fouling, there is a method of periodically removing a foulant by washing the filtration membrane by a method of periodically flowing a water flow called a surfactant or backwashing in a reverse direction. In addition, a method using a pretreatment agent for suppressing fouling has been studied. Although these methods have a certain effect as a method for suppressing fouling, they have not been sufficiently effective for fouling caused by proteins and microorganisms. In addition, the pretreatment agent has a problem that it must be used continuously.

As a method having a relatively high effect on fouling caused by such proteins and microorganisms, a method of adsorbing a material capable of suppressing adsorption of foulants such as proteins and microorganisms on the surface of the reverse osmosis membrane is known. As a material capable of suppressing adsorption of foulants such as proteins and microorganisms, for example, a polymer containing a monomer having a phosphorylcholine-like group as a structural unit is known (Patent Document 1, etc.). Patent Documents 1 and 2 disclose reverse osmosis membranes in which a polymer containing a monomer having a phosphorylcholine-like group as a constituent unit is adsorbed. Furthermore, Patent Document 3 discloses an antifouling agent containing a polymer containing a monomer having a phosphorylcholine-like group as a structural unit.
As a method for suppressing fouling of a polyamide reverse osmosis membrane using a copolymer containing a monomer having a phosphorylcholine-like group as a structural unit, a copolymer obtained by polymerizing a phosphorylcholine-like group-containing monomer and an organosilicon-containing monomer is used. There is a method in which the coalescence is dissolved in a solution containing an organic solvent, and a reverse osmosis membrane is immersed in this solution and adsorbed. However, the method using a solution containing such an organic solvent requires a process and equipment for post-processing the organic solvent, and is environmentally problematic.

JP-A-3-39309 JP-A-5-177119 JP 2006-239636 A

  An object of the present invention is to provide a surface for a polyamide reverse osmosis membrane that can effectively suppress fouling of a polyamide reverse osmosis membrane over a long period of time and that is substantially free from organic solvents and environmentally superior. It is to provide a treatment agent. Furthermore, it is providing the surface treatment polyamide reverse osmosis membrane processed with this surface treating agent, and its manufacturing method.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by treating the surface of the polyamide reverse osmosis membrane with a specific polymer, and have completed the present invention.

（式中、Ｒ¹は水素原子又はメチル基を示し、Ｒ²及びＲ³はそれぞれ独立に炭素数１〜４のアルキレン基を示し、Ｒ⁴、Ｒ⁵及びＲ⁶はそれぞれ独立に炭素数１〜４のアルキル基を示す。） That is, according to the present invention, the monomer composition containing 10 to 80 mol% of the monomer represented by the formula (1) and 20 to 90 mol% of cationic (meth) acrylamide has a weight average molecular weight of 5,000 to 5,000. A surface treatment agent for a polyamide reverse osmosis membrane, which is a 150,000 copolymer, is provided. Further, it preferably contains water and is in the form of an aqueous solution.

(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ each independently represents an alkylene group having 1 to 4 carbon atoms, and R ⁴ , R ⁵ and R ⁶ each independently represents 1 carbon atom) Represents an alkyl group of ˜4.)

  Furthermore, a surface-treated polyamide reverse osmosis membrane whose surface is treated with the surface treatment agent in the form of an aqueous solution, and a production method thereof having the surface treatment step are provided.

The surface treating agent of the present invention contains a copolymer of a monomer composition containing a monomer represented by the above formula (1) and cationic (meth) acrylamide in a predetermined ratio, and is a polyamide reverse osmosis membrane. By effectively modifying the surface of the film, generation of fouling can be effectively suppressed over a long period of time. Further, since it does not substantially contain an organic solvent, it does not require equipment for removing the organic solvent and is safe for the environment.
In the surface-treated polyamide reverse osmosis membrane of the present invention, fouling is highly suppressed, so that it is possible to prevent a decrease in water permeability for a long period. Moreover, the surface treatment polyamide reverse osmosis membrane which can make good water permeability and environmental safety compatible can be manufactured with the manufacturing method of this invention.

It is the schematic of the test apparatus which performed the fouling suppression effect confirmation test in the Example and the comparative example. It is a graph which shows the result of the fouling suppression effect confirmation test in an example and a comparative example.

The present invention will be described in detail below.
The surface treatment agent of the present invention comprises a copolymer of a monomer composition containing a monomer represented by the above formula (1) (hereinafter sometimes abbreviated as monomer (1)) and cationic (meth) acrylamide. By treating the polyamide reverse osmosis membrane in the form of an aqueous solution, which is a surface treatment agent, fouling of the polyamide reverse osmosis membrane can be suppressed.
In the formula (1), R ¹ represents a hydrogen atom or a methyl group. R ² and R ³ each independently represents an alkylene group having 1 to 4 carbon atoms. R ⁴ , R ⁵ and R ⁶ each independently represents an alkyl group having 1 to 4 carbon atoms.

  Examples of the monomer (1) include 2-methacryloyloxyethyl phosphorylcholine (hereinafter abbreviated as MPC), 3-methacryloyloxypropyl phosphorylcholine, 4-methacryloyloxybutylphosphorylcholine, 2-methacryloyloxyethyl-2′-triethylammonio. Examples thereof include ethyl phosphate and 2-methacryloyloxyethyl-2′-tributylammonioethyl phosphate. MPC is preferable from the viewpoint of availability.

Examples of the cationic (meth) acrylamide include acryloylaminopropyltrimethylammonium chloride (hereinafter abbreviated as AAPTAC), methacryloylaminopropyltrimethylammonium chloride (hereinafter abbreviated as MAPTAC), methacryloylaminopropyltrimethylammonium methyl sulfate, and methacryloyl. Examples thereof include aminopropyldimethylbenzylammonium chloride, methacryloylaminopropyldimethylethyl sulfate, methacryloylaminopropyltrimethylammonium p-toluene sulfate, and the like.
AAPTAC and / or MAPTAC are preferable because they are general-purpose products and easily available at low cost.
Here, the cationic (meth) acrylamide means cationic acrylamide, cationic methacrylamide, or both.

The monomer composition for preparing the copolymer of the present invention may contain a monomer other than the essential monomers as long as the effects of the present invention are not impaired. As the usable monomer other than the essential monomers, those capable of radical polymerization are preferable, and examples thereof include (meth) acrylates such as n-butyl methacrylate.
From the viewpoint of the fouling suppression effect, a copolymer consisting essentially of the monomer (1) and the cationic (meth) acrylamide is preferred except for other monomers inevitably mixed.

Content of the monomer (1) in a monomer composition is 10-80 mol%. That is, the constituent ratio of the monomer (1) -derived part (corresponding part) in the copolymer is 10 to 80 mol%. In the following description, the monomer-derived part in the copolymer and the constituent ratio thereof will be indicated by the monomer name for convenience. The monomer (1) in the copolymer is preferably 30 mol% or more and 70 mol% or less.
The cationic (meth) acrylamide in the copolymer is 20 to 90 mol%, preferably 30 mol% or more and 70 mol% or less.
When the constituent ratio of the monomer (1) in the copolymer exceeds 80 mol% and the constituent ratio of the cationic (meth) acrylamide is less than 20 mol%, the cationic property that interacts with the polyamide reverse osmosis membrane ( The proportion of (meth) acrylamide becomes small, the interaction with the polyamide reverse osmosis membrane becomes insufficient, and the fouling suppressing effect may be lowered. When the constituent ratio of the monomer (1) is less than 10 mol% and the constituent ratio of the cationic (meth) acrylamide exceeds 90 mol%, there is a possibility that a sufficient fouling suppressing effect is not exhibited.
Here, the interaction between the cationic (meth) acrylamide and the polyamide reverse osmosis membrane means that the cationic (meth) acrylamide site is adsorbed on the surface of the polyamide reverse osmosis membrane by electrostatic interaction.

  The molecular weight of the copolymer used in the present invention needs to be a molecular weight that dissolves in water used as a solvent for the surface treatment agent. The molecular weight is 5,000 to 150,000, preferably 10,000 to 100,000, in terms of weight average molecular weight calculated by gel permeation chromatography (GPC) using standard polyethylene glycol. When the molecular weight is less than 5,000, the resulting copolymer may be difficult to adsorb on the surface of the polyamide reverse osmosis membrane. When the molecular weight is 150,000 or more, the copolymer may be dissolved in water as a solvent. Therefore, there is a possibility that the polyamide reverse osmosis membrane cannot be adsorbed.

As a polymerization method of the copolymer according to the present invention, known methods such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization and the like can be used. For example, the monomer composition is used in a solvent in the presence of an initiator. A polymerization reaction method can be employed.
The solvent used in the polymerization reaction may be any solvent that dissolves the monomer composition, and examples thereof include water, methanol, ethanol, propanol, dimethylformamide, tetrahydrofuran, chloroform, and the like. Good.
Any initiator can be used as the initiator used in the polymerization reaction. For example, in the case of radical polymerization, an aliphatic azo compound or an organic peroxide can be used.

  When the polymerization solvent is water, the copolymer obtained by the polymerization reaction can be used as it is as a surface treatment agent by adjusting the concentration of the copolymer after purification. If the solvent is an organic solvent, the surface treatment agent can be obtained by isolating the copolymer by reprecipitation with acetone or filtering and then dissolving it in water and adjusting the concentration of the copolymer. .

  When a polyamide reverse osmosis membrane is treated with the surface treatment agent of the present invention, the surface treatment agent is preferably in the form of an aqueous solution, and the concentration of the copolymer in the aqueous solution is preferably 0.001 to 10% by mass. More preferably, the content is 0.01 to 1% by mass. If the amount is less than 0.001% by mass, the fouling suppressing effect may not be exhibited. If the amount exceeds 10% by mass, the pores of the polyamide reverse osmosis membrane may be blocked and sufficient filtered water may not be obtained. is there.

  As water used for the solvent for a surface treating agent of the present invention, pure water, purified water, or the like can be used.

  The polyamide reverse osmosis membrane may be subjected to other surface treatment such as coating with an antibacterial agent. Examples of the antibacterial agent include surfactants such as benzalkonium chloride, and metal antibacterial agents composed of inorganic compounds such as copper, silver, and tin.

The surface-treated polyamide reverse osmosis membrane which is surface-treated with the surface treatment agent of the present invention is produced by carrying out the following steps.
(1) Surface treatment step: A polyamide reverse osmosis membrane is set in a filtration device, and the surface treatment agent is passed through the surface at 5 to 35 ° C., 0.05 to 30 atm, and a flow rate of 3 to 100 mL / min for 1 to 30 minutes. Process to process. At this time, the surface treatment agent is preferably an aqueous solution of 0.001 to 10% by mass, more preferably 0.01 to 1% by mass.
(2) Washing step: A step of washing the polyamide reverse osmosis membrane after the surface treatment with pure water.
In addition, about a process (1), the method of immersing a polyamide reverse osmosis membrane in a surface treating agent, or the method of spray-coating a surface treating agent on a polyamide reverse osmosis membrane is also employable.

Hereinafter, although an example and a comparative example explain the present invention still in detail, the present invention is not limited to these.
Table 1 shows the composition and properties of each copolymer and homopolymer used in each Example and Comparative Example.

Example 1-1
<Manufacture of surface treatment agent 1>
(1) Copolymer 1; Synthesis of MPC / AAPTAC = 70/30 (molar ratio) 36.92 g of MPC (manufactured by NOF Corporation), 11.08 g of AAPTAC (manufactured by MRC Unitech Co., Ltd.) and 190.00 g of water It put into a 500 mL four necked flask, and nitrogen was blown in for 30 minutes. Next, a solution composed of 0.36 g of 2,2′-azobis (2-methylpropionamidine) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.) and 2.00 g of water was added, and 70 ° C. And stirred for 2 hours, and then cooled to room temperature to obtain a copolymer solution. Subsequently, the copolymer solution was placed in a dialysis membrane (fractionated molecular weight 3500) and immersed in water for purification, whereby a copolymer 1 was obtained.
(2) Measurement of molecular weight of copolymer 1 The weight average molecular weight of the copolymer 1 converted by standard polyethylene glycol by GPC was 73,000. The method for measuring the weight average molecular weight of copolymer 1 is shown below.
(Molecular weight measurement method)
The aqueous copolymer solution is diluted with 20 mM phosphate buffer (pH 7.4) to 1.0 w / v%, and this solution is filtered through a 0.45 μm membrane filter to obtain a test solution. The weight average molecular weight is determined by GPC. Measured and calculated. The measurement conditions for GPC analysis are as follows.
(GPC analysis measurement conditions)
Column: TSKgel PWXL-CP (manufactured by Tosoh Corporation), elution solvent: 20 mM phosphate buffer (pH 7.4), standard substance: polyethylene glycol (manufactured by Polymer Laboratories Ltd.), detection; differential refractometer RI-8020 (Tosoh Corporation) (Manufactured by company), flow rate: 0.5 mL / min, sample solution usage: 10 μL, column temperature: 45 ° C.
(3) Preparation of surface treatment agent 1 Copolymer 1 was dissolved in water so that the concentration thereof was 0.1% by mass to prepare surface treatment agent 1.

Example 1-2
<Manufacture of surface treatment agent 2>
Except having changed the usage-amount of MPC to 28.24g and the usage-amount of AAPTAC to 19.76g, it implemented the synthesis | combination of the copolymer 2, and the measurement of the weight average molecular weight similarly to Example 1-1, Subsequently, surface treating agent 2 was prepared using copolymer 2.

Example 1-3
<Manufacture of surface treatment agent 3>
Except having changed the usage-amount of MPC to 12.15g and the usage-amount of AAPTAC to 34.03g, it implemented the synthesis | combination of the copolymer 3, and the measurement of the weight average molecular weight similarly to Example 1-1, Subsequently, surface treating agent 3 was prepared using copolymer 3.

Example 1-4
<Manufacture of surface treatment agent 4>
(1) Copolymer 4; Synthesis of MPC / MAPTAC = 50/50 (molar ratio) 27.47 g of MPC, 20.54 g of MAPTAC (manufactured by MRC Unitech Co., Ltd.) and 166 g of water were placed in a 500 mL four-necked flask, 30 Nitrogen was blown for a minute. Next, a solution composed of 0.36 g of 2,2′-azobis (2-methylpropionamidine) dihydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.) and 2.00 g of water was added, After stirring and polymerizing for 2 hours, the mixture was cooled to room temperature to obtain a copolymer solution. Subsequently, the copolymer solution was put in a dialysis membrane (fractionated molecular weight 3500) and immersed in water for purification to obtain a copolymer 4.
(2) Measurement of molecular weight of copolymer 4 The weight average molecular weight of copolymer 4 was measured in the same manner as in Example 1-1.
(3) Preparation of surface treatment agent 4 Surface treatment agent 4 was prepared using copolymer 4 in the same manner as in Example 1-1.

Comparative Example 1-1
<Manufacture of surface treatment agent 5>
(1) Copolymer 5: Synthesis of MPC / butyl methacrylate (BMA) = 30/70 (molar ratio) MPC 8.0 g, BMA (manufactured by Wako Pure Chemical Industries, Ltd.) 9.0 g, and ethanol 153 g in four-necked 300 mL Nitrogen was bubbled through the flask for 30 minutes. Next, 0.06 g of perbutyl-ND (registered trademark) (manufactured by NOF Corporation) is added, and after stirring and polymerization at 60 ° C. for 3 hours, the mixture is cooled to room temperature and purified by reprecipitation with acetone. A polymer 5 was obtained.
(2) Molecular weight measurement of the copolymer 5 The weight average molecular weight of the copolymer 5 was measured like Example 1-1.
(3) Preparation of surface treatment agent 5 Surface treatment agent 5 was prepared using copolymer 5 in the same manner as in Example 1-1.

Comparative Example 1-2
<Manufacture of surface treatment agent 6>
(1) Homopolymer 1; Synthesis of MPC Homopolymer (Homopolymer) 20 g of MPC and 180 g of water were placed in a 300 mL four-necked flask, and nitrogen was blown for 30 minutes. Next, 0.9 g of Parroyl SA (registered trademark) (manufactured by NOF Corporation) was added and subjected to stirring polymerization at 70 ° C. for 6 hours, and then cooled to room temperature to obtain a polymer solution. Subsequently, the copolymer solution was placed in a dialysis membrane (fractionated molecular weight 3500) and immersed in water for purification to obtain a homopolymer 1.
(2) Molecular weight measurement of homopolymer 1 The weight average molecular weight of the homopolymer 1 was measured in the same manner as in Example 1-1.
(3) Preparation of surface treatment agent 6 Surface treatment agent 6 was prepared in the same manner as in Example 1-1 using homopolymer 1.

  The surface treatment agent prepared in each Example 1 and each Comparative Example 1 was used to treat the surface of the polyamide reverse osmosis membrane, and the fouling suppression effect was measured for each surface-treated polyamide reverse osmosis membrane. Details will be described below.

Example 2-1
<Manufacture of surface-treated polyamide reverse osmosis membrane 1 (hereinafter abbreviated as treatment membrane 1)>
(1) Surface treatment process In the flat membrane test apparatus shown in FIG. 1, as a polyamide reverse osmosis membrane (hereinafter, an untreated polyamide reverse osmosis membrane is referred to as an RO membrane), a reverse osmosis membrane SU700 (membrane surface area) manufactured by Toray Industries, Inc. 40 cm ² ) was set. Subsequently, the surface treatment agent 1 was continuously supplied for 15 minutes at a cross flow method, a pressure of 7.5 atm, 25 ° C., and a flow rate of 50 mL / min.
(2) Washing step After the surface treatment agent 1 was flowed, the membrane was washed with water by continuously flowing pure water through the flat membrane test apparatus for 15 minutes, whereby a treated membrane 1 was obtained.

Next, the presence of MPC on the surface of the treatment film 1 was confirmed as follows.
<X-ray photoelectron spectroscopy measurement (XPS measurement)>
The treatment film 1 was cut into an appropriate size with a cutter and then attached to a sample table using a double-sided carbon tape. Then, the presence or absence of the phosphorus element contained in MPC was qualitatively analyzed about the processing film 1 using XPS measuring apparatus JPS-9200 (made by JEOL Ltd.). The XPS measurement conditions are as follows. As a result of XPS measurement, phosphorus element was detected in the treatment film 1 and it was confirmed that MPC was present.
(XPS measurement conditions) X-ray source: MgKa, X-ray output: 100 W.

The fouling suppression effect of the treatment film 1 was measured as follows.
<Fouling suppression test>
A fouling suppression test was performed on a bovine serum albumin-containing solution, which is a kind of protein. An outline of the fouling suppression test is shown in FIG.
Specifically, a solution (foulant stock solution 1) in which bovine serum albumin (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in “treated membrane 1” 2 to a concentration of 100 ppm is a cross flow method, pressure 7.5 atm, flow rate 50 mL. The solution was sent and passed at a rate of 48 minutes per minute. At this time, the volume w (L) of the filtered water 3 is measured immediately after the start of measurement and every predetermined time (measurement time; 0.1 hr to 48 hr shown in Table 2), and the absolute water permeability (L / m) according to the following formula 1. ² / h / atm) was calculated. The absolute water permeability immediately after the start of measurement was 250 (L / m ² / h / atm). Then, the relative water permeation amount obtained by dividing the absolute water permeation amount at each measurement time by the absolute water permeation amount immediately after the start of the measurement was calculated. Table 2 and FIG. 2 show changes in the relative water permeability of each measurement time by the treatment membrane 1.

（数式１中、ｗはろ過水体積（Ｌ）、ｐは入口圧力（ａｔｍ）、ｔはろ過水回収時間（ｈ）、Ｓはポリアミド逆浸透膜の膜表面積（ｍ²）を示す。）

(Wherein, w is the filtrate volume (L), p is the inlet pressure (atm), t is the filtrate recovery time (h), and S is the membrane surface area (m ² ) of the polyamide reverse osmosis membrane.

Example 2-2 to Example 2-4
In the same manner as in Example 2-1, each of the RO membranes was treated with surface treatment agents 2 to 4 to produce surface treated polyamide reverse osmosis membranes 2 to 4 (hereinafter referred to as treatment membranes 2 to 4, respectively). . Subsequently, as in Example 2-1, it was confirmed by XPS measurement that MPC was present in the treatment films 2 to 4. Further, a fouling suppression test was conducted in the same manner as in Example 2-1. The absolute water permeation amount immediately after the start of the measurement is 240 (L / m ² / h / atm) for the treatment film ² , 270 (L / m ² / h / atm) for the treatment film 3, and 260 (L / m for the treatment film 4). / M ² / h / atm). Changes in the relative water permeability are shown in Table 2 and FIG.

Comparative Example 2-1 to Comparative Example 2-2
In the same manner as in Example 2-1, the RO membranes were treated with the surface treatment agents 5 and 6, respectively, to produce surface-treated polyamide reverse osmosis membranes 5 and 6 (hereinafter referred to as treatment membranes 5 and 6, respectively). . Subsequently, as in Example 2-1, it was confirmed by XPS measurement that MPC was present in the treatment films 5 and 6. Further, a fouling suppression test was conducted in the same manner as in Example 2-1. The absolute water permeability immediately after the start of measurement was 265 (L / m ² / h / atm). Changes in the relative water permeability are shown in Table 2 and FIG.

Comparative Example 2-3
A fouling suppression test was conducted in the same manner as in Example 2-1, except that an RO membrane that was not surface-treated with a surface treatment agent was used. The absolute water permeability immediately after the start of measurement was 280 (L / m ² / h / atm). Changes in the relative water permeability are shown in Table 2 and FIG.

From the results shown in Table 2 and FIG. 2, the relative water permeation amount was higher in any of the examples than in any of the comparative examples. The fact that the relative water permeability is kept high indicates that it is resistant to fouling. That is, the treated membranes 1 to 4 which are surface-treated polyamide reverse osmosis membranes surface-treated with the surface treating agents 1 to 4 have a remarkable fouling suppressing effect as compared with the RO membrane of Comparative Example 2-3. Admitted.
In addition, while the treatment films 1 to 4 maintained a high relative water permeability, the treatment films 5 and 6 surface-treated with the surface treatment agent 5 or 6 as a comparative example gradually decreased in the water permeability. It was. Thus, each surface treatment comprising a copolymer of a monomer composition having MPC as an example of the monomer represented by the formula (1) but not having cationic (meth) acrylamide, and a homopolymer of MPC. It can be seen that the surface treatment agent of each example, which is an embodiment of the present invention, is superior in the fouling suppressing effect as compared with the agent.

1: Foulant stock solution 2: Surface-treated polyamide reverse osmosis membrane (treated membranes 1-6) or RO membrane 3: Filtered water

Claims (5)

A copolymer having a weight average molecular weight of 5,000 to 150,000, which is a monomer composition containing 10 to 80 mol% of the monomer represented by formula (1) and 20 to 90 mol% of cationic (meth) acrylamide. is there,
Surface treatment agent for polyamide reverse osmosis membranes.

(1)
(Wherein R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ each independently represents an alkylene group having 1 to 4 carbon atoms, and R ⁴ , R ⁵ and R ⁶ each independently represents 1 carbon atom) Represents an alkyl group of ˜4.) The monomer represented by the formula (1) is 2-methacryloyloxyethyl phosphorylcholine, and the cationic (meth) acrylamide is acryloylaminopropyltrimethylammonium chloride, methacryloylaminopropyltrimethylammonium chloride, or both.
The surface treating agent for polyamide reverse osmosis membranes according to claim 1. Further containing water, an aqueous solution of the copolymer.
The surface treating agent for polyamide reverse osmosis membranes according to claim 1 or 2. The surface was treated with the surface treatment agent according to claim 3,
Surface treated polyamide reverse osmosis membrane. The surface treatment agent according to claim 3 is subjected to a surface treatment on a polyamide reverse osmosis membrane, and the surface of the polyamide reverse osmosis membrane after the surface treatment is washed with pure water.
A method for producing a surface-treated polyamide reverse osmosis membrane.

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