CN105008031A - Composite semipermeable membrane - Google Patents

Abstract

The present invention provides a composite semipermeable membrane, which is capable of achieving a high permeate volume and has high desorption properties with respect to membrane-fouling substances. This composite semipermeable membrane is provided with a support membrane comprising a base material and a porous support layer, and a separation function layer provided on the porous support layer. The surface zeta potential (A) of the separation function layer under measurement conditions of pH 6 and 10 mM NaCl is in the range of +-15 mV, and the potential difference between the surface zeta potential (B) of the separation function layer under measurement conditions of pH 6 and 1 mM NaCl and the surface zeta potential (A) is +-10 mV or more.

Description

composite semipermeable membrane

technical field

The invention relates to a composite semi-permeable membrane capable of realizing high water permeation and working stably for a long time. The composite semipermeable membrane obtained by the present invention can be suitably used for desalination of salt water, for example.

Background technique

Regarding the separation of mixtures, there are various techniques for removing substances (such as salts) dissolved in a solvent (such as water). In recent years, the application of the membrane separation method is expanding as a process for saving energy consumption and saving resources. As the membrane used in the membrane separation method, there are microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, and the like. These membranes are used in the case of obtaining drinking water from, for example, seawater, brackish water, water containing harmful substances, etc., or in the production of ultrapure water for industrial use, waste water treatment, recovery of valuables, and the like.

Most of the currently commercially available reverse osmosis membranes and nanofiltration membranes are composite semipermeable membranes, and there are two types of composite semipermeable membranes: a composite semipermeable membrane with a gel layer and an active layer cross-linked by a polymer on the supporting membrane; And a composite semipermeable membrane having an active layer formed by polycondensation of monomers on a support membrane. Among them, a composite semipermeable membrane obtained by coating a support membrane with a separation function layer formed of a cross-linked polyamide is widely used as a separation membrane with a high permeation rate and high selective separation performance. Copolyamides are obtained by polycondensation of polyfunctional amines and polyfunctional acid halides.

For fresh water generators using reverse osmosis membranes, in order to further reduce operating costs, a higher amount of permeated water is required. For such a requirement, a method of contacting a composite semipermeable membrane containing a cross-linked polyamide polymer in the separation active layer with an aqueous solution containing nitrous acid (see Patent Document 1) or a method of contacting an aqueous solution containing chlorine ( See Patent Document 2) and the like.

In addition, one of the problems occurring in a desalination device using a reverse osmosis membrane is fouling caused by membrane fouling substances such as inorganic substances and organic substances. Due to fouling, the permeate water of the reverse osmosis membrane is significantly reduced. As a method of improving this, a method of suppressing fouling by coating polyvinyl alcohol on the surface of the separation functional layer to neutralize the charged state has been proposed (see Patent Document 3), and the like.

In addition, in order to eliminate scaling, it is usually cleaned with a chemical solution such as alkali or acid after a certain period of work. Therefore, in order to be able to work continuously and stably for a long time, the durability of the composite semipermeable membrane to alkali and acid is required, that is, the membrane performance before and after exposure to chemicals changes little. In order to improve the alkali resistance of the composite semipermeable membrane, a method of bringing the composite semipermeable membrane into contact with an aqueous solution having a hydrogen ion concentration of pH 9 to 13 is disclosed (see Patent Document 4). In addition, in order to improve the acid resistance of the composite semipermeable membrane, a method of bringing the composite semipermeable membrane into contact with a cyclic sulfate is disclosed (see Patent Document 5).

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2011-125856

Patent Document 2: Japanese Patent Application Laid-Open No. 63-54905

Patent Document 3: International Publication No. 97/34686

Patent Document 4: Japanese Patent Laid-Open No. 2006-102624

Patent Document 5: Japanese Patent Laid-Open No. 2010-234284

Contents of the invention

Therefore, for the performance required for the reverse osmosis membrane, not only the desalination performance and the amount of permeated water but also long-term stable operation are required. Although the membranes described in Patent Document 1 and Patent Document 2 can increase the amount of permeated water, they have a problem of low fouling resistance. On the other hand, in the membrane described in Patent Document 3, the amount of permeated water may decrease due to coating. In addition, for the composite semipermeable membranes described in Patent Document 4 and Patent Document 5, although the chemical resistance of the composite semipermeable membrane can be obtained, in order to eliminate fouling, high-frequency cleaning with chemical solutions is sometimes required. There is scope for research on sexuality.

The object of the present invention is to provide a composite semipermeable membrane capable of achieving a high water permeation rate and capable of working stably for a long period of time.

In order to achieve the above objects, the present invention has the following constitutions.

(1) A composite semipermeable membrane, which has a supporting membrane comprising a base material and a porous supporting layer, and a separation function layer disposed on the porous supporting layer, wherein,

The surface Zeta potential A of the above-mentioned separation functional layer is within ± 15mV under the measurement conditions of pH 6 and NaCl 10mM,

And, the potential difference between the surface zeta potential B of the above-mentioned separation functional layer and the above-mentioned surface zeta potential A under pH 6, NaCl 1mM measurement conditions is ± 10mV or more.

(2) The composite semipermeable membrane according to (1) above, wherein the root mean square surface roughness of the surface of the separation function layer is 60 nm or more.

(3) The composite semipermeable membrane according to (1) or (2) above, wherein the separation function layer is formed of polyamide obtained by a polymerization reaction of a polyfunctional amine and a polyfunctional acid halide.

(4) The composite semipermeable membrane as described in any one of above-mentioned (1)～(3), wherein, the surface zeta potential C of above-mentioned separation function layer under pH3, NaCl1mM measuring condition and above-mentioned separation function layer at pH10 , The potential difference of the surface Zeta potential D under the measurement conditions of NaCl 1mM is 40mV or less.

(5) the composite semipermeable membrane as described in any one of above-mentioned (1)～(4), wherein, above-mentioned separation functional layer contains amino group and amide group, and the ratio of the molar equivalent of amino group/amide group is 0.2 or more.

(6) The composite semipermeable membrane as described in any one of the above (1) to (5), wherein the above-mentioned separation function layer has an amide group, an azo group and a phenolic hydroxyl group, and the ratio of the phenolic hydroxyl group/amide group The ratio is 0.1 or less.

(7) The composite semipermeable membrane according to any one of (1) to (6) above, wherein the surface of the separation functional layer is coated with a crosslinked polymer.

(8) The composite semipermeable membrane according to (7) above, wherein the crosslinked polymer is a crosslinked product of a hydrophilic compound.

(9) The composite semipermeable membrane according to (7) or (8) above, wherein the crosslinked polymer forms a covalent bond with the surface of the separation functional layer.

(10) The composite semipermeable membrane as described in any one of the above (7) to (9), wherein the composite semipermeable membrane before the surface of the above-mentioned separation function layer is coated by the above-mentioned cross-linked polymer is used at 1.55 The amount of permeated water when filtering an aqueous solution with a pH of 6.5 at 25°C and a NaCl concentration of 2,000 mg/l for 1 hour under pressure conditions of MPa is F1, and the surface of the separation functional layer is coated with the cross-linked polymer. When the amount of permeated water is F2, the value of F2/F1 is 0.80 or more.

(11) The composite semipermeable membrane as described in any one of the above (1) to (10), wherein, at 25° C., an aqueous solution having a pH of 6.5 and a NaCl concentration of 2,000 mg/l is subjected to a pressure of 1.55 MPa The amount of permeated water when filtering for 1 hour is set as F3, then polyoxyethylene (10) octylphenyl ether is added to the above aqueous solution to make the concentration 100mg/l, and the resulting solution is filtered for 1 hour and then the concentration of NaCl When the amount of permeated water when washed with an aqueous solution of 500 mg/l for 1 hour is F4, the value of F4/F3 is 0.85 or more.

The invention can provide a composite semi-permeable membrane capable of realizing high water permeation and working stably for a long time. By using this composite semipermeable membrane, high-quality permeated water can be stably obtained with low energy consumption.

detailed description

1. Composite semipermeable membrane

The composite semipermeable membrane of the present invention has a support membrane including a substrate and a porous support layer, and a polyamide separation functional layer formed on the porous support layer of the support membrane. Composite semipermeable membrane of the present invention is characterized in that, when measuring the surface Zeta potential of separation function layer under the condition of pH6, NaCl 10mM, the surface Zeta potential of separation function layer is controlled within ± 15mV, and it is compared with pH6, NaCl The potential difference between the surface zeta potentials when measured under the condition of 1 mM was ±10 mV or more.

(1-1) Separation of functional layers

The separation function layer is a layer responsible for separating solutes in the composite semipermeable membrane. The composition and thickness of the separation function layer can be set according to the purpose of use of the composite semipermeable membrane.

Specifically, the separation function layer is formed of a cross-linked polyamide obtained by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide. Hereinafter, the separation function layer in the present invention is also referred to as "polyamide separation function layer".

Here, the polyfunctional amine preferably contains at least one component selected from aromatic polyfunctional amines and aliphatic polyfunctional amines.

The so-called aromatic polyfunctional amine is an aromatic amine having two or more amino groups in one molecule, and is not particularly limited, but examples include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, etc. . In addition, as the N-alkylated product thereof, N,N-dimethyl-m-phenylenediamine, N,N-diethyl-m-phenylenediamine, N,N-dimethyl-p-phenylenediamine, N, N-diethyl-p-phenylenediamine, etc. In terms of the stability of performance, m-phenylenediamine or 1,3,5-triaminobenzene is particularly preferable.

In addition, the aliphatic polyfunctional amine is an aliphatic amine having two or more amino groups in one molecule, and piperazine-based amines and derivatives thereof are preferable. For example, piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5-trimethylpiperazine, 2,5- Diethylpiperazine, 2,3,5-triethylpiperazine, 2-n-propylpiperazine, 2,5-di-n-butylpiperazine, ethylenediamine and the like. From the standpoint of stability in performance, piperazine or 2,5-dimethylpiperazine is particularly preferred.

These polyfunctional amines may be used alone or in combination of two or more.

The polyfunctional acid halide is an acid halide having two or more halogenated carbonyl groups in one molecule, and is not particularly limited as long as it can form a polyamide by reacting with the above-mentioned polyfunctional amine. As polyfunctional acid halides, for example, oxalic acid, malonic acid, maleic acid, fumaric acid, glutaric acid, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, Halides of 1,4-cyclohexanedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, etc. Among acid halides, acid chlorides are preferred, and in terms of economy, ease of acquisition, ease of handling, and ease of reactivity, triphenylene, which is an acid halide of 1,3,5-benzenetricarboxylic acid, is particularly preferred. triformyl halide. The above polyfunctional acid halides may be used alone or in combination of two or more.

The inventors of the present application conducted in-depth research and found that the surface zeta potential of the separation functional layer is closely related to the permeate water volume of the composite semipermeable membrane and the desorption of membrane fouling substances attached to the membrane surface.

The so-called Zeta potential is used to evaluate the standard of the net fixed charge on the surface of the ultra-thin film layer, and the Zeta potential on the surface of the thin film layer of the present invention can be passed through the Helmholtz-Stock shown in the following mathematical formula (1) by electric mobility. It can be obtained by the Helmholtz-Smoluchowski formula.

(In the formula (1), U is the electric mobility, ε is the dielectric constant of the solution, and η is the viscosity of the solution. Here, the dielectric constant and the viscosity of the solution use the literature value when measuring the temperature.)

The principle of measurement of zeta potential will be described. In a (aqueous) solution in contact with a material, there is an immobile static layer near the surface due to the influence of the charge on the surface of the material. Zeta potential is the potential relative to the solution which exists at the boundary surface (slip surface) of the stationary layer and the flowing layer of the material.

Here, if the aqueous solution in the quartz glass tank is studied, since the quartz surface is usually negatively charged, positively charged ions and particles gather near the tank surface. On the other hand, there are many negatively charged ions and particles in the center of the tank, and ion distribution occurs in the tank. If an electric field is applied in this state, the distribution of ions is reflected in the tank, and the ions swim at different swimming speeds at positions in the tank (called electroosmotic flow). Since the swimming speed reflects the charge on the surface of the cell, by obtaining the distribution of the swimming speed, the charge on the surface of the cell (surface potential) can be evaluated.

Usually, the determination of Zeta potential can be carried out as follows, that is, using a film sample with a size of 20 mm × 30 mm, the standard particles (which are polystyrene particles (particle diameter) coated with hydroxypropyl cellulose for electrophoresis 520nm)) dispersed in NaCl aqueous solution adjusted to a predetermined concentration for measurement. As a measurement device, for example, an electrophoretic light scattering photometer ELS-8000 manufactured by Otsuka Electronics Co., Ltd. can be used.

For the composite semipermeable membrane of the present invention, it is necessary to control the surface Zeta potential of the separation function layer within ± 15mV (surface Zeta potential A) when measuring under the conditions of pH6, NaCl 10mM, and measure under the conditions of NaCl 1mM (surface zeta potential B) and the potential difference between surface zeta potential A is ±10mV or more.

The polyamide separation functional layer contains unreacted amino groups and carboxyl groups derived from polyfunctional amines and polyfunctional acid halides, and the value of zeta potential changes depending on the degree of dissociation of these functional groups. The zeta potential of the separation functional layer at pH 6 is related to the adsorption of membrane fouling substances. If the zeta potential under the condition of NaCl 10mM is controlled within ±15mV, the interaction between membrane fouling substances and raw materials on the membrane surface can be suppressed. This is because if the zeta potential is controlled within ±15mV, it means that the membrane surface is electrically neutral, and the electrical interaction with the membrane fouling substances with charged groups present in the water can be suppressed. When the zeta potential is ±15 mV or more, the membrane surface is electrically biased, so that electrical interaction with membrane fouling substances having charged groups easily occurs.

On the other hand, if the degree of dissociation of the functional group is high, the desalination performance and the permeated water amount of the composite semipermeable membrane will become high. This is considered to be because the increase in the amount of functional groups in the separation functional layer increases electrostatic repulsion or increases hydrophilicity. In the present invention, by making the potential difference between the Zeta potential A when measured under the condition of NaCl 10mM and the surface Zeta potential B when measured under the condition of NaCl 1mM be ±10mV or more, the membrane fouling substance under the high salt concentration can be satisfied thus. Desorption, but also can meet the high desalination performance, high water permeation. When the potential difference is less than ±10 mV, the amount of permeated water decreases significantly, or the interaction with membrane fouling substances becomes stronger.

The surface zeta potential C of the above-mentioned separation function layer under the measurement conditions of pH 3 and NaCl 1mM, and the potential difference between the surface zeta potential D of the above-mentioned separation function layer under the measurement conditions of pH 10 and NaCl 1mM are related to the performance stability of the composite semipermeable membrane , when the potential difference is 40 mV or less, the detachment of pollutants when cleaning the composite semipermeable membrane is high, so it is preferable, more preferably 25 mV or less.

In order to satisfy the range of the above-mentioned zeta potential, the functional group ratio "(molar equivalent of amino group)/(molar equivalent of amide group)" in the separation functional layer is preferably 0.2 or more, more preferably 0.6 or more. If the ratio of "(molar equivalent of amino group)/(molar equivalent of amide group)" is 0.2 or more, the amount of functional groups in the polyamide separation functional layer is sufficient, so the hydrophilicity of the membrane can be maintained, the permeated water can be increased, and the In addition, a remarkable effect can be obtained on the immobilization of the coating layer to the separation functional layer described later.

The amount of functional groups in the polyamide separation functional layer can be measured, for example, using a ¹³ C solid NMR method. Specifically, the substrate was peeled off from the composite semipermeable membrane to obtain a polyamide separation function layer and a porous support layer, and then the porous support layer was dissolved and removed to obtain a polyamide separation function layer. The obtained polyamide separation functional layer was measured by DD/MAS- ^13C solid state NMR method, and the ratio of each functional group could be calculated from the comparison of the integrated values of the carbon peaks of each functional group or the carbon peaks to which each functional group was bonded.

In addition, the element ratio of the polyamide separation functional layer can be analyzed using, for example, X-ray photoelectron spectroscopy (XPS). Specifically, it can be exemplified by using "Journal of Polymer Science", Vol.26, 559-572 (1988) and "Journal of the Japan Adhesion Society (Journal of the Japan Adhesion Society)", Vol.27, No.4 (1991) determined by X-ray photoelectron spectroscopy (XPS).

As a method of controlling the zeta potential of the separation functional layer, there are methods of controlling the amount of functional groups that the separation functional layer has when forming the separation functional layer; methods of converting the functional groups that the separation functional layer has into other structures; A method of coating (coating) a polymer on the surface of the layer, and the like. These methods may be used alone or in combination of a plurality of methods. However, the method of coating only the polymer is not preferable since the interaction between the separation functional layer and membrane fouling substances can be reduced, but the amount of water permeated through the membrane decreases.

For the method of coating a polymer on the surface of the separation functional layer, it is preferable that the polymer is a hydrophilic compound. By using a hydrophilic compound, it is possible to reduce the decrease in the amount of permeated water of the composite semipermeable membrane caused by the coating treatment. In addition, the aforementioned polymer is also preferably a cross-linked polymer. When the coated polymer is a cross-linked polymer, peeling of the coating layer can be suppressed when the composite semipermeable membrane is continuously used or washed with a chemical solution, and long-term stable performance can be exhibited.

The hydrophilic compound of the present invention preferably has at least one reactive group that reacts with a functional group on the membrane surface. The reactive group may be any reactive group as long as it can form a covalent bond with the functional group on the film surface. For example, as the reactive group bonded to the acid halide on the film surface, hydroxyl group, amino group, Epoxy etc. Examples of specific hydrophilic compounds include polyvinyl alcohol, partially saponified polyvinyl acetate, polyethyleneimine, polyallylamine, polyepiaminohydrin, and amine-modified polyglycol. Chlorohydrin, polyoxyethylene dipropylamine, copolymers using monomers containing amino groups or hydroxyl groups, partially saponified products of copolymers of vinyl acetate and methacrylate, vinyl acetate and 2-methacryloyloxy Partial saponification of ethyl ethyl phosphorylcholine copolymer, etc. They can be used alone or in combination. Among them, it is preferable to use a primary amino compound or a secondary amino compound or a polymer having a hydroxyl group from the viewpoint of reactivity and the performance of the resulting film. When the amino group reacts with the acid halide, the cross-linked polyamide separation functional layer forms an amide bond with the hydrophilic compound, and when the hydroxyl group reacts with the acid halide, the cross-linked polyamide separation function layer and the hydrophilic compound form ester bonds.

In addition, it is also preferable that the hydrophilic compound having at least one reactive group that reacts with the functional group on the membrane surface also has a hydrophilic group that does not react with the functional group on the membrane surface. Examples of the hydrophilic group include ether group, amide group, ester group, tertiary amino group, quaternary ammonium group, cyano group, nitro group, alkoxy group, carboxyl group, carbonyl group, ketone group, alkoxycarbonyl group, amide group, Cyano, formyl, mercapto, imino, alkylthio, sulfinyl, sulfonyl, sulfonic acid, nitroso, phosphoric acid, phosphorylcholine, etc. Electroneutral hydrophilic groups such as ether groups, amide groups, and ester groups are particularly preferable. In addition, an amphoteric charged polymer containing positively charged groups and negatively charged groups in equal amounts is also preferable from the viewpoint of controlling the Zeta potential of the present invention.

By making such a hydrophilic compound having at least one reactive group that reacts with a functional group on the surface of the membrane react with a functional group on the surface of the crosslinkable polyamide separation functional layer to form a covalent bond, the hydrophilic compound is immobilized on the membrane surface. The membrane surface is thus able to exhibit long-term stable properties compared to the case of adsorption alone.

The functional groups present in the above separation functional layer can be converted into different functional groups by appropriately selected chemical reactions. For example, an aromatic amino group can undergo a diazonium coupling reaction via an aromatic diazonium salt by using dinitrogen tetroxide, nitrous acid, nitric acid, sodium bisulfite, sodium hypochlorite, etc. as a reagent. In addition, an amino group can also be converted into an azo group by a reaction of an amino group with a nitroso compound or the like. The zeta potential of the above-mentioned separation functional layer can be controlled by changing the concentration of the reaction reagent, temperature and time during the reaction. In addition, when the functional group is converted, since the amount of the functional group before the reaction also affects the Zeta potential of the obtained separation functional layer, the Zeta potential of the separation functional layer can also be controlled by the following method: by making the porous A method in which the thickness of the support layer is thin to reduce the remaining amount of unreacted substances during production; a method in which a compound having a functional group is removed by washing with hot water after forming a separation functional layer, and the like.

When the separation functional layer is brought into contact with a reagent (which reacts with an amino group or a carboxyl group), the yellowness index of the separation functional layer is preferably 15 to 50, more preferably 20 to 45. The yellowness index varies depending on the amount of the azo compound and the azo group in the separation functional layer, and within the above range, the stability of the zeta potential and the hydrophilic compound of the present invention can be obtained. If the yellow index of the separation functional layer is less than 15, the amount of the azo compound in the separation functional layer is small, so the zeta potential of the present invention cannot be obtained. If the yellowness index exceeds 50, the amount of azo compound is large, so the amount of permeated water becomes low.

The azo compound is an organic compound having an azo group (-N=N-), and is generated and retained in the separation function layer when the separation function layer is brought into contact with a reagent (which reacts with an amino group or a carboxyl group).

The so-called yellowness index, as stipulated in Japanese Industrial Standard JIS K7373 (2006), is the degree to which the color tone of a polymer deviates from colorless or white to yellow, and is expressed in the form of a positive value.

The yellow index of the separation functional layer can be measured by a color meter. For example, in the case of measuring the yellowness index in a composite semipermeable membrane provided with a separation function layer on a support membrane, the reflection measurement method is simple. In addition, it can also be measured by placing the composite semipermeable membrane on a glass plate with the separation function layer facing down, dissolving and removing the supporting membrane with a solvent that only dissolves the supporting membrane, and measuring the remaining amount of the membrane by a permeation measurement method. Separation of functional layer samples on a glass plate. In addition, when placing a composite semipermeable membrane on a glass plate, it is preferable to peel off the base material of a supporting membrane beforehand. As a colorimeter, SM Color Computer SM-7 manufactured by SugaTest Instruments Co., Ltd. can be used.

In the present invention, by making the polyamide separation functional layer have amide groups, azo groups, and phenolic hydroxyl groups, and making the ratio of phenolic hydroxyl groups/amide groups 0.10 or less, the amount of permeated water after contact with acids and alkalis can be obtained. It is a composite semipermeable membrane with low change in fouling property and high chemical resistance, so it is preferred. The phenolic hydroxyl group is protonated or deprotonated with the change of solution pH, so the charge state of the polyamide chain constituting the separation functional layer changes, and the higher order structure of the polyamide chain changes, resulting in the amount of desalination, Salt removal performance may vary. Although there is no phenolic hydroxyl group in the cross-linked aromatic polyamide formed by the interfacial polycondensation of polyfunctional aromatic amines and polyfunctional acid halides, in the post-treatment after interfacial polycondensation, it is combined with dinitrogen tetroxide, nitrous acid, Nitric acid, sodium bisulfite, sodium hypochlorite and other reagents react, thereby converting aromatic amino groups into aromatic diazonium salts. Thereafter, by contacting with water, a conversion reaction of an aromatic diazonium salt to a phenolic hydroxyl group occurs. In addition, a phenolic hydroxyl group that does not exist in the crosslinked aromatic polyamide immediately after interfacial polycondensation can also be introduced by a diazo coupling reaction in which an aromatic diazonium salt is reacted with a phenol.

In addition, although the lower limit of the ratio of phenolic hydroxyl group/amide group is not specifically limited, For example, this ratio may be 0.005 or more, or may be 0.01 or more.

In the composite semipermeable membrane of the present invention, by making aromatic diazonium salt (which is produced by post-treatment of cross-linked aromatic polyamide) and aromatic compound with electron-donating group, or carbon with proton with high acidity The hydrogen acid reaction can make the diazo coupling reaction take place preferentially, and suppress the generation of phenolic hydroxyl formed by the reaction with water. The electron donating group includes, for example, a hydroxyl group, an amino group, and an alkoxy group. However, as mentioned above, it is not preferable to use a phenolic compound having a hydroxyl group. In consideration of water solubility, it is preferable to use a compound having an aromatic amino group.

The root mean square surface roughness (Rms) of the separation functional layer is preferably 60 nm or more. By making the root mean square surface roughness 60 nm or more, the surface area of the separation function layer becomes large, and the amount of permeated water becomes high. On the other hand, when the thickness of the coating layer and the root mean square surface roughness are less than 60 nm, the amount of permeated water decreases significantly.

The root mean square surface roughness of the separation functional layer can be controlled by the monomer concentration, temperature when the separation functional layer is formed by interfacial polycondensation. For example, when the temperature at the time of interfacial polycondensation is low, the root mean square surface roughness becomes small, and when the temperature is high, the root mean square surface roughness becomes large. In addition, when a polymer is applied to the surface of the separation functional layer, the root mean square surface roughness becomes smaller as the applied layer becomes thicker.

It should be noted that the root mean square surface roughness can be measured by an atomic force microscope (AFM). The root mean square surface roughness is the square root of a value obtained by averaging the squares of the deviations from the reference plane to the specified plane. Here, the measurement surface refers to the surface on which all measurement data are displayed, the specified surface is the surface to be measured for roughness, and refers to a specific part of the measurement surface specified by a jig, and the reference surface refers to the average height of the specified surface. When the value is Z0, the plane represented by Z=Z0. For the AFM, NanoScope IIIa manufactured by Digital Instruments can be used, for example.

(1-2) Support film

The support membrane is used to impart strength to the polyamide separation functional layer having separation performance, and itself does not substantially have separation performance for ions or the like. The support membrane is formed from a substrate and a porous support layer.

The size of the pores of the support membrane and the distribution of the pores are not particularly limited, but the following support membranes are preferred: for example, have uniform and minute pores, or have micropores that gradually increase from the surface on which the separation functional layer is formed to the other surface. , and form a support membrane in which the size of micropores on the surface of the separation functional layer is 0.1 nm to 100 nm.

The support film can be obtained by, for example, casting a high molecular polymer on the base material to form a porous support layer on the base material. The material used for the support film and its shape are not particularly limited.

As the base material, a fabric made of at least one selected from polyester and aramid can be exemplified. In particular, polyesters with high mechanical and thermal stability are preferably used.

As the fabric used for the base material, long-fiber nonwoven fabrics and short-fiber nonwoven fabrics can be preferably used. Long-fiber nonwoven fabrics can be more preferably used from the point of view of requiring excellent film-forming properties that do not cause the disadvantage of excessive permeation when casting a high-molecular polymer solution on a substrate. On the other hand, through the back surface, the base material and the porous support layer are peeled off, or defects such as unevenness of the film and pinholes occur due to fluffing of the base material. Examples of the long-fiber nonwoven fabric include long-fiber nonwoven fabrics made of thermoplastic continuous filaments, and the like. By forming the base material from a long-fiber nonwoven fabric, it is possible to suppress non-uniformity during casting of a polymer solution and film defects due to fluff that occurs when using a short-fiber nonwoven fabric. In addition, it is also preferable to use a long-fiber nonwoven fabric excellent in dimensional stability as the substrate from the viewpoint of applying tension in the film-forming direction of the substrate during the continuous film-forming step of the composite semipermeable membrane. In particular, by orienting the fibers disposed on the opposite side of the substrate to the porous support layer in the longitudinal direction with respect to the film-forming direction, it is possible to maintain the strength of the substrate and prevent the film from breaking, which is preferable. Here, the longitudinal orientation means that the orientation direction of the fibers is parallel or nearly parallel to the film-forming direction. On the contrary, the case where the orientation direction of fibers is at right angles to the film forming direction, or close to right angles is called transverse orientation.

As the degree of fiber orientation of the nonwoven fabric base material, the degree of orientation of the fibers on the side opposite to the porous support layer is preferably in the range of 0° to 25°. Here, the degree of fiber orientation is an index indicating the direction of the fibers of the nonwoven fabric substrate constituting the support film, and refers to a direction at right angles to the film-forming direction when the film-forming direction during continuous film-forming is 0°. , that is, when the width direction of the nonwoven fabric substrate is 90°, the average angle of the fibers constituting the nonwoven fabric substrate. Therefore, the closer the degree of fiber orientation is to 0°, the more longitudinally oriented the fiber orientation is, and the closer the fiber orientation is to 90°, the more transversely oriented.

A heating step is included in the manufacturing process of the composite semipermeable membrane or the manufacturing process of the element, however, the shrinkage phenomenon of the supporting membrane or the composite semipermeable membrane may be caused by heating. Especially in continuous film formation, since tension is not applied in the width direction, it tends to shrink in the width direction. Since the shrinkage of the supporting membrane or the composite semipermeable membrane causes problems such as dimensional stability, a substrate having a small rate of thermal dimensional change is desired as the substrate.

In the non-woven fabric base material, when the difference in the degree of orientation between the fibers arranged on the side opposite to the porous support layer and the fibers arranged on the porous support layer side is 10° to 90°, the width caused by heat can be suppressed. A change of direction is preferred.

The air permeability of the substrate is preferably 2.0 cc/cm ² /sec or higher. When the air permeability is within this range, the permeation water rate of the composite semipermeable membrane increases. This is considered to be because: in the process of forming the support film, when the high molecular polymer is cast on the base material and immersed in the coagulation bath, since the replacement rate of the non-solvent from the base material side becomes faster, the inside of the porous support layer The structural change affects the amount of monomer retained and the diffusion rate in the subsequent step of forming the separation functional layer.

The air permeability can be measured with a Frazier type tester based on JIS L1096 (2010). For example, a substrate having a size of 200 mm×200 mm is cut out as a sample. Install this sample on a Fraser-type testing machine, adjust the suction fan and air hole so that the pressure of the inclined type barometer becomes 125Pa, and the pressure displayed by the vertical type barometer at this time and the type of air hole used can be obtained. To calculate the amount of air passing through the substrate, that is, the air permeability. As the Fraser type testing machine, KES-F8-AP1 made by KATO TECHCO., LTD. can be used.

In addition, the thickness of the substrate is preferably in the range of 10 μm to 200 μm, and more preferably in the range of 30 μm to 120 μm.

The support membrane in the present invention has a base material and a porous support layer, has substantially no separation performance for ions, etc., and is used to impart strength to a separation functional layer having substantially separation performance.

For the raw material of the porous support layer, the following materials can be used alone or in combination: polysulfone, polyethersulfone, polyamide, polyester, cellulose-based polymer, vinyl polymer, polyphenylene sulfide Ether, polyphenylene sulfide sulfone, polyphenylene sulfone, polyphenylene ether and other homopolymers or copolymers. Here, as the cellulosic polymer, cellulose acetate, nitrocellulose, etc. can be used, and as the vinyl polymer, polyethylene, polypropylene, polyvinyl chloride, polyacrylonitrile, etc. can be used. Among them, homopolymers or copolymers such as polysulfone, polyamide, polyester, cellulose acetate, nitrocellulose, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferable. More preferably, cellulose acetate, polysulfone, polyphenylene sulfide sulfone, or polyphenylene sulfone are used. Furthermore, among these raw materials, polysulfone has high chemical stability, mechanical stability, and high thermal stability, and is easy to form. Typically polysulfone can be used.

Specifically, use of polysulfone composed of a repeating unit represented by the following chemical formula is preferable since it is easy to control the pore diameter of the support membrane and has high dimensional stability.

For example, by casting the N,N-dimethylformamide (DMF) solution of the above-mentioned polysulfone to a certain thickness on densely woven polyester cloth or polyester non-woven fabric, and then wet coagulating it in water, Thereby, a supporting membrane having micropores with a diameter of several tens of nm or less in most of the surface can be obtained.

The thickness of the supporting membrane affects the strength of the obtained composite semipermeable membrane and the packing density when it is made into a device. In order to obtain sufficient mechanical strength and packing density, the thickness of the supporting film is preferably in the range of 30 μm to 300 μm, more preferably in the range of 100 μm to 220 μm.

The morphology of the porous support layer can be observed with a scanning electron microscope, a transmission electron microscope, or an atomic force microscope. For example, when observing using a scanning electron microscope, the porous support layer is peeled off from the substrate, and then cut by freeze fracture to prepare a sample for cross-sectional observation. Thinly coat platinum, platinum-palladium or ruthenium tetrachloride (preferably ruthenium tetrachloride) on the sample, and use a high-resolution field emission scanning electron microscope (UHR-FE- SEM) for observation. As a high-resolution field emission scanning electron microscope, Hitachi, Ltd. S-900 electron microscope etc. can be used.

The support film used in the present invention can be selected from various commercially available materials such as "Milliporefilter VSWP" (trade name) manufactured by Millipore Corporation or "Ultrafilter UK10" (trade name) manufactured by Toyo Filter Paper Co., Ltd., or can be selected according to "Office of Saline Water Research and Development Progress Report", No. 359 (1968) described in the method and so on.

The thickness of the porous support layer is preferably in the range of 20 μm or more and 100 μm or less. By making the thickness of the porous support layer more than 20 μm, good pressure resistance can be obtained, and a uniform support film without defects can be obtained simultaneously, therefore, the composite semipermeable membrane with such a porous support layer can show good properties. Salt removal performance. If the thickness of the porous support layer exceeds 100 μm, the remaining amount of unreacted substances during production increases, thereby reducing the amount of permeated water and reducing chemical resistance.

It should be noted that the thickness of the base material and the thickness of the composite semipermeable membrane can be measured by a digital thickness gauge. In addition, since the thickness of the separation functional layer is very thin compared with the support membrane, the thickness of the composite semipermeable membrane can be regarded as the thickness of the support membrane. Therefore, the thickness of the porous support layer can be easily calculated by measuring the thickness of the composite semipermeable membrane with a digital thickness gauge and subtracting the thickness of the substrate from the thickness of the composite semipermeable membrane. As a digital thickness gauge, PEACOCK of Ozaki Seisakusho Co., Ltd., etc. can be used. In the case of using a digital thickness gauge, the thickness at 20 positions was measured, and the average value was calculated.

It should be noted that, when the thickness of the substrate or the thickness of the composite semipermeable membrane is difficult to measure with a thickness gauge, it can be measured using a scanning electron microscope. For one sample, the thickness was obtained by measuring the thickness from electron micrographs observed in cross-sections at five arbitrary positions, and calculating the average value.

2. Manufacturing method

Next, a method for producing the above-mentioned composite semipermeable membrane will be described. The production method includes a step of forming a support membrane and a step of forming a separation function layer.

(2-1) Formation process of supporting film

The step of forming the supporting film includes a step of coating a polymer solution on a substrate, and a step of immersing the substrate coated with the solution in a coagulation bath to coagulate the polymer.

In the step of coating the polymer solution on the substrate, the polymer solution is prepared by dissolving the polymer that is a component of the porous support layer in a good solvent for the polymer.

The temperature of the polymer solution when applying the polymer solution is preferably in the range of 10°C to 60°C when polysulfone is used as the polymer. When the temperature of the polymer solution is within this range, the polymer solution does not precipitate, and the polymer solution solidifies after fully impregnating the interfibers of the substrate. As a result, the porous support layer is firmly bonded to the base material due to the anchor effect, and a good support film can be obtained. It should be noted that the preferred temperature range of the polymer solution can be appropriately adjusted according to the type of polymer used, desired solution viscosity, and the like.

The time from coating the polymer solution on the substrate to immersing in the coagulation bath is preferably in the range of 0.1 to 5 seconds. If the time until immersion in the coagulation bath is within this range, the polymer-containing organic solvent solution is sufficiently impregnated to interfibers of the substrate, and then cured. In addition, the preferable range of time until immersion in a coagulation bath can be adjusted suitably according to the kind of polymer solution to be used, desired solution viscosity, etc.

As the coagulation bath, water is generally used, but any coagulation bath may be used as long as it does not dissolve the polymer that is a component of the porous support layer. Depending on the composition of the coagulation bath, the membrane morphology of the obtained support membrane will change, and the composite semipermeable membrane thus obtained will also change. The temperature of the coagulation bath is preferably -20°C to 100°C, more preferably 10°C to 50°C. If the temperature of the coagulation bath is higher than the above range, the vibration of the surface of the coagulation bath due to thermal motion becomes severe, and the smoothness of the film surface after film formation tends to decrease. Conversely, if the temperature is too low, the solidification rate will be slowed down and the film-forming properties will be lowered.

Next, in order to remove the solvent remaining in the membrane, the support membrane obtained as described above was washed with hot water. The temperature of the hot water at this time is preferably 40°C to 100°C, more preferably 60°C to 95°C. Within this range, the degree of shrinkage of the support film does not increase, and the amount of permeated water is good. On the contrary, if the temperature is too low, the cleaning effect will be small.

(2-2) Step of forming the separation functional layer

Next, the formation process of the separation functional layer constituting the composite semipermeable membrane will be described. In the forming step of the polyamide separation function layer, the polyamide separation function layer is formed by performing interfacial polycondensation on the surface of the support membrane using an aqueous solution containing the polyfunctional amine and an organic solvent solution containing the polyfunctional acid halide.

As the organic solvent for dissolving the polyfunctional acid halide, any solvent can be used as long as it is immiscible with water, does not damage the support film, and does not inhibit the formation reaction of the crosslinked polyamide. Typical examples include liquid hydrocarbons and halogenated hydrocarbons such as trichlorotrifluoroethane. Considering the substances that do not destroy the ozone layer, the ease of obtaining, the ease of handling, and the safety of handling, hexane, heptane, octane, nonane, decane, undecane, and dodecane are preferably used. , tridecane, tetradecane, heptadecane, hexadecane, cyclooctane, ethylcyclohexane, 1-octene, 1-decene and other single substances or their mixtures.

In the multifunctional amine aqueous solution or the organic solvent solution containing the multifunctional acid halide, as long as the reaction between the two components is not hindered, an acylation catalyst, a polar solvent, an acid-binding agent, a surfactant, an anti-acid compounds such as oxidants.

In order to perform interfacial polycondensation on the support membrane, first, the surface of the support membrane is coated with an aqueous solution of polyfunctional amine. Here, the concentration of the aqueous solution containing a polyfunctional amine is preferably from 0.1% by weight to 20% by weight, more preferably from 0.5% by weight to 15% by weight.

As a method of coating the surface of the support membrane with an aqueous solution of polyfunctional amine, as long as the surface of the support membrane can be uniformly and continuously coated by the aqueous solution, it can be applied by a known coating method (for example, applying an aqueous solution to the surface of the support membrane). method, the method of immersing the support film in an aqueous solution, etc.). The contact time between the support film and the polyfunctional amine aqueous solution is preferably in the range of 5 seconds to 10 minutes, and more preferably in the range of 10 seconds to 3 minutes. Next, the excessively applied aqueous solution is preferably removed by a liquid drainage step. As a method of liquid drainage, there is, for example, a method of keeping the membrane surface in a vertical direction and allowing the liquid to flow down naturally. After draining, the membrane surface can also be dried to remove all or part of the water in the aqueous solution.

Thereafter, an organic solvent solution containing the above polyfunctional acid halide is coated on the support film coated with a polyfunctional amine aqueous solution, and a separation functional layer of a crosslinked polyamide is formed by interfacial polycondensation. The time for interfacial polycondensation is preferably from 0.1 second to 3 minutes, and more preferably from 0.1 second to 1 minute.

The concentration of the polyfunctional acid halide in the organic solvent solution is not particularly limited, but if it is too low, there may be a defect that the formation of the active layer, that is, the separation function layer is insufficient, and if it is too high, it is disadvantageous in terms of cost. Therefore, it is preferably about 0.01% by weight or more and 1.0% by weight or less.

Next, the organic solvent solution after the reaction is preferably removed in a liquid drainage step. Regarding the removal of the organic solvent, for example, a method of holding the film in a vertical direction and allowing the excess organic solvent to flow down naturally to remove it can be used. In this case, the time for holding in the vertical direction is preferably in the range of 1 minute to 5 minutes, and more preferably in the range of 1 minute to 3 minutes. If the holding time is more than 1 minute, it is easy to obtain a separation function layer having the target function, and if it is less than 3 minutes, the generation of defects caused by excessive drying of the organic solvent can be suppressed, so performance degradation can be suppressed.

For the composite semipermeable membrane obtained by the above method, the solute barrier performance of the composite semipermeable membrane can be further improved by further implementing a process of washing with hot water in the range of 25°C to 90°C for 1 minute to 60 minutes , Through the water. However, when the temperature of the hot water is too high, the chemical resistance will decrease if it is rapidly cooled after the hot water washing treatment. Therefore, hot water washing is preferably performed in the range of 25°C to 60°C. In addition, when the hot water washing treatment is performed at a high temperature of more than 60° C. to 90° C. or lower, it is preferable to perform gradual cooling after the hot water washing treatment. For example, there is a method of cooling to room temperature by bringing it into contact with low-temperature hot water step by step.

In addition, in the step of washing with hot water, acid or alcohol may be contained in the hot water. By containing acid or alcohol, the formation of hydrogen bonds in the separation functional layer can be more easily controlled. Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, organic acids such as citric acid, and oxalic acid. The acid concentration is preferably adjusted to pH 2 or lower, more preferably pH 1 or lower. Examples of the alcohol include monohydric alcohols such as methanol, ethanol, and isopropanol, and polyhydric alcohols such as ethylene glycol and glycerin. The concentration of alcohol is preferably 10 to 100% by weight, more preferably 10 to 50% by weight.

In the case of controlling the Zeta potential of the separation functional layer by converting the functional group of the separation functional layer, next, the above separation functional layer is reacted with a reagent (which reacts with the unreacted functional group contained in the separation functional layer) )touch. The reaction reagent is not particularly limited, and examples thereof include aqueous solutions of nitrous acid and its salts, nitrosyl compounds, and the like that react with primary amino groups in the separation functional layer to form diazonium salts or derivatives thereof. Since aqueous solutions of nitrous acid and nitrosyl compounds tend to generate gas and decompose, it is preferable to gradually generate nitrous acid, for example, by reacting nitrite with an acidic solution. Usually, nitrite reacts with hydrogen ions to generate nitrous acid (HNO ₂ ), which can be efficiently generated when the pH of the aqueous solution is 7 or lower, preferably pH 5 or lower, more preferably pH 4 or lower. Among them, an aqueous solution of sodium nitrite reacted with hydrochloric acid or sulfuric acid in an aqueous solution is particularly preferable in view of the simplicity of handling.

The concentration of nitrous acid or nitrite in the reagent that reacts with the above-mentioned primary amino group to form a diazonium salt or a derivative thereof is preferably in the range of 0.01 to 1% by weight. When the concentration is 0.01% by weight or more, a sufficient effect is easily obtained, and when the concentration of nitrous acid or nitrite is 1% by weight or less, handling of the solution becomes easy.

The temperature of the aqueous nitrous acid solution is preferably 15°C to 45°C. If the temperature of the solution is lower than 15°C, the reaction will take time, and if it is higher than 45°C, the decomposition of nitrous acid will be rapid and the operation will be difficult.

The contact time with the aqueous nitrous acid solution may be the time required for the formation of the diazonium salt and/or its derivatives, and the treatment can be performed in a short time at a high concentration, but a long time is required at a low concentration. Therefore, for the solution of the above concentration, the contact time is preferably within 10 minutes, more preferably within 3 minutes. In addition, the method of contacting is not particularly limited, and a solution of the reagent may be applied, or the composite semipermeable membrane may be immersed in the solution of the reagent. As the solvent for dissolving the reagent, any solvent can be used as long as the reagent can be dissolved and the composite semipermeable membrane is not corroded. In addition, the solution may contain a surfactant, an acidic compound, a basic compound, and the like as long as the reaction between the primary amino group and the reagent is not hindered.

Part of the diazonium salt or its derivative produced by the contact reacts with water to convert into a phenolic hydroxyl group. In addition, it also reacts with an aromatic ring in a material forming a support membrane or a separation functional layer, or an aromatic ring of a compound contained in a separation functional layer to form an azo group.

Next, the composite semipermeable membrane on which the diazonium salt or derivative thereof has been produced may be further brought into contact with a reagent that reacts with the diazonium salt or derivative thereof. Reagents used here include chloride ions, bromide ions, cyanide ions, iodide ions, fluoroboric acid, hypophosphorous acid, sodium bisulfite, sulfite ions, aromatic amines, phenols, hydrogen sulfide, and thiocyanate Acid etc.

For example, halogen can be introduced by reacting with copper (I) chloride, copper (I) bromide, potassium iodide, or the like. In addition, by contacting with aromatic amines and phenols, a diazo coupling reaction occurs, and aromatics can be introduced into the membrane surface. It should be noted that these reagents may be used alone, or in admixture of multiple species, or may be contacted with different reagents multiple times. Among these reagents, a reagent that causes a diazo coupling reaction effectively functions to increase the boron removal rate of the composite semipermeable membrane, and therefore is particularly preferably used. This is considered to be because, through the diazo coupling reaction, the substituent introduced instead of the amino group is bulkier, and the effect of clogging the pores existing in the separation functional layer can be obtained.

Examples of the reagent causing the diazo coupling reaction include compounds having an electron-rich aromatic ring or heteroaromatic ring. Examples of the compound having an electron-rich aromatic ring or heteroaromatic ring include aromatic amine derivatives, heteroaromatic amine derivatives, phenol derivatives, and hydroxyheteroaromatic ring derivatives. Specific examples of the above compounds include, for example, aniline, methoxyaniline bonded to a benzene ring in an arbitrary positional relationship of ortho, meta, or para, and methoxyaniline in which two amino groups are positioned in an ortho, meta, or para position. Phenylenediamine bonded to the benzene ring in any positional relationship, amino phenol, 1,3,5-triaminobenzene, 1, 2,4-triaminobenzene, 3,5-diaminobenzoic acid, 3-aminobenzylamine, 4-aminobenzylamine, p-aminobenzenesulfonic acid, 3,3'-dihydroxybenzidine, 1-amino Naphthalene, 2-aminonaphthalene, 1-amino-2-naphthol-4-sulfonic acid, 2-amino-8-naphthol-6-sulfonic acid, 2-amino-5-naphthol-7-sulfonic acid, or Its N-alkylate and its salts, phenol, ortho, meta or para cresol, catechol, resorcinol, hydroquinone, phloroglucinol, pyroglucinol, pyrogallol Phenol, tyrosine, 1-naphthol, 2-naphthol and their salts, etc.

The concentration and time of these reagents reacting with the diazonium salt or its derivatives can be appropriately adjusted in order to obtain the desired effect. The contact temperature is preferably 10 to 90°C, more preferably 20 to 60°C. When the contact temperature is lower than 10°C, the reaction is difficult to proceed, and the desired effect cannot be obtained. Sometimes it is converted into a phenolic hydroxyl group by the reaction with water. When the temperature is higher than 90°C, the polymer sometimes shrinks and the amount of permeated water decreases. In addition, the concentration of the reagent is preferably 0.01 to 10% by weight, more preferably 0.05 to 1% by weight. When the concentration is less than 0.01% by weight, the reaction with the diazonium salt or its derivative may take a long time, and when the concentration exceeds 10% by weight, it may be difficult to control the reaction with the diazonium salt or its derivative.

Next, the step of providing a hydrophilic compound on the separation functional layer will be described. The hydrophilic compound is formed by coating a solution containing a compound having a hydrophilic group on the separation functional layer and then heating it.

A hydrophilic compound may be used individually or in mixture of several types. The hydrophilic compound is preferably used in the form of a solution having a weight concentration of 10 ppm to 1%. If the concentration of the hydrophilic compound is less than 10 ppm, the coating of the separation function layer will be insufficient and the membrane fouling substances will adhere significantly, so it will be difficult to desorb the membrane fouling substances during cleaning. If it is greater than 1%, the coating layer becomes thicker, and surface zeta potential A (which reflects the potential of the outermost surface of the membrane) and surface zeta potential B (which is considered to be less affected by free ions in water and reflects the potential of the separation function layer) cannot be realized. ) The potential difference is ±10mV or more.

As the solvent used in the solution containing the above-mentioned hydrophilic compound, water, lower alcohols, halogenated hydrocarbons, acetone, acetonitrile and the like are preferably used. These may be used individually by 1 type, and may mix and use 2 or more types.

Other compounds can be mixed in the solution as needed. For example, in order to promote the reaction, basic metal compounds such as sodium carbonate, sodium hydroxide, and sodium phosphate can be added, and in order to remove the remaining solvent that is immiscible with water, the reaction product of free polyfunctional acid halides and amine compounds, It is also preferable to add surfactants such as sodium lauryl sulfate and sodium benzenesulfonate.

The method of crosslinking the hydrophilic compound is not particularly limited, but thermal crosslinking is preferred. As a heating method at the time of thermal crosslinking, the method of blowing hot air can be used, for example. The heating temperature at this time is preferably in the range of 30 to 150°C, more preferably in the range of 30 to 130°C, and more preferably in the range of 60 to 100°C. When the heating temperature is lower than 30°C, sufficient heating cannot be performed, and the crosslinking reaction rate tends to decrease, and when it exceeds 150°C, side reactions tend to proceed. In addition, when thermal crosslinking is performed at a temperature exceeding 150° C., the thermal shrinkage of the composite semipermeable membrane may increase, and the amount of permeated water tends to decrease.

A crosslinking agent is preferably used for crosslinking of the hydrophilic compound. As a crosslinking agent, the aldehyde etc. which have at least 2 functional groups in 1 molecule, such as the said acid or base, glyoxal, or glutaraldehyde, etc. are mentioned, for example. Particularly preferably, the raw material of the cross-linked polymer is polyvinyl alcohol, the cross-linking agent is glutaraldehyde, and the cross-linked polymer contains a reactant of polyvinyl alcohol and glutaraldehyde.

The added concentration of the crosslinking agent is preferably within a range of 0.01 to 5.0% by weight, more preferably within a range of 0.01 to 1.0% by weight, and even more preferably within a range of 0.01 to 0.5% by weight. If the concentration is lower than 0.01% by weight, the crosslinking density becomes low, and the water insolubility of the crosslinked polymer tends to become insufficient; Furthermore, the speed of the crosslinking reaction becomes faster, gelation tends to occur, and uniform coating tends to be difficult. The reaction time of the crosslinking reaction is preferably 10 seconds to 3 minutes. If it is less than 10 seconds, the reaction may not proceed sufficiently, and if it exceeds 3 minutes, it may be difficult to adjust to the zeta potential of the present invention.

Here, even if the composite semipermeable membrane of the present invention is coated with a crosslinked polymer, it is preferable that the amount of permeated water hardly decrease before and after coating. That is, when a composite semipermeable membrane before the surface of the separation functional layer is coated with a cross-linked polymer is used to filter an aqueous solution of 25°C, pH 6.5, and a NaCl concentration of 2,000 mg/l for 1 hour under a pressure of 1.55 MPa When the amount of water permeated is F1, and the amount of water permeated after the surface of the separation functional layer is coated with the crosslinked polymer is F2, the value of F2/F1 is preferably 0.80 or more. More preferably, it is 0.90 or more. By using such a composite semipermeable membrane, it is possible to provide the surface of the membrane with high desorption properties for membrane fouling substances without significantly reducing the permeated water amount of the membrane.

3. Utilization of composite semipermeable membrane

The composite semipermeable membrane of the present invention is wound together with a raw water flow path material such as plastic mesh, a permeated water flow path material such as tricot, and a film for improving pressure resistance if necessary. The surrounding of the cylindrical water collecting pipe with many holes can be suitably used as a spiral composite semi-permeable membrane element. In addition, the elements can also be connected in series or in parallel and accommodated in a pressure vessel to form a composite semipermeable membrane module.

In addition, the above-mentioned composite semipermeable membrane, or its elements and modules can be combined with a pump for supplying raw water to them, a device for pre-treating the raw water, etc., to constitute a fluid separation device. By using this separator, raw water can be separated into permeated water such as drinking water and concentrated water that does not permeate the membrane, thereby obtaining water that meets the purpose.

By using the composite semipermeable membrane of the present invention, for example, the operating pressure is in the range of 0.1 to 3 MPa, more preferably in such a low-pressure region in the range of 0.1 to 1.5 MPa, the composite semipermeable membrane can be used to maintain a high permeable water amount, Fluid separation element. In order to be able to reduce the operating pressure, the capacity of the pump etc. used can be reduced, power consumption can be suppressed, and the cost of desalination can be realized. If the operating pressure is lower than 0.1 MPa, the amount of permeated water tends to decrease, and if it exceeds 3 MPa, the power consumption of pumps and the like increases, and membrane clogging due to fouling tends to occur.

For the composite semipermeable membrane of the present invention, it is preferable to use a sodium chloride aqueous solution with a pH of 6.5 and a concentration of 2,000 mg/l to filter for 1 hour at 25°C and an operating pressure of 1.0 MPa. The water volume is 0.5~3m ³ /m ² /d. Such a composite semipermeable membrane can be produced, for example, by appropriately selecting the aforementioned production method. By setting the permeation rate of water in the range of 0.5 to 3 m ³ /m ² /d, the occurrence of scaling can be moderately suppressed and desalination can be stably performed.

Sewage treated with the composite semipermeable membrane of the present invention may contain hardly biodegradable organic substances such as surfactants that are not decomposed at all by biological treatment. If the existing composite semipermeable membrane is used for treatment, the surfactant is adsorbed on the surface of the membrane, and the amount of permeated water decreases. However, the composite semipermeable membrane of the present invention can exhibit stable performance due to its high water permeation and high desorption of membrane fouling substances.

Here, the composite semipermeable membrane of the present invention has high desorption properties for membrane fouling substances. That is, at 25°C, the amount of permeated water when an aqueous solution with a pH of 6.5 and a NaCl concentration of 2,000 mg/l is filtered at a pressure of 1.55 MPa for 1 hour is set as F3, and then polyoxyethylene (10) is added to the aqueous solution. The value of F4/F3 when the concentration of octylphenyl ether is 100 mg/l, and the permeated water when the obtained solution is filtered for 1 hour and then washed with an aqueous solution having a NaCl concentration of 500 mg/l for 1 hour is F4 Preferably it is 0.85 or more. More preferably, it is 0.90 or more. By using such a composite semipermeable membrane, even when fouling or the like occurs on the surface of the membrane, the effect of inhibiting the interaction between the membrane and the pollutant can be obtained by washing with an aqueous solution having a NaCl concentration of 500 mg/l or more. Easily desorbs. Therefore, it can work stably for a long time even if it is used for high-level treatment of sewage.

It should be noted that, when the surface of the separation function layer of the composite semipermeable membrane of the present invention is coated with a crosslinked polymer, the above-mentioned permeated water amount F3 is the same as the aforementioned permeated water amount F2.

Example

Examples are given below to illustrate the present invention, but the present invention is not limited by these Examples.

(NaCl removal rate)

The evaluation water adjusted to a temperature of 25° C., a pH of 7, and a sodium chloride concentration of 2,000 ppm was supplied to the composite semipermeable membrane under the conditions of an operating pressure of 1.55 MPa to perform membrane filtration treatment. The electrical conductivity of the supplied water and the permeated water were measured with a conductivity meter manufactured by Toa Denpa Kogyo Co., Ltd. to obtain the respective practical salinity, that is, the NaCl concentration. Based on the NaCl concentration thus obtained and the following formula, the NaCl removal rate was calculated.

NaCl removal rate (%)=100×{1-(NaCl concentration in permeate water/NaCl concentration in feed water)}

(through rate)

In the test of the preceding paragraph, the membrane permeation water volume of the supplied water (NaCl aqueous solution) was measured, and the value converted into the water permeation volume (cubic meters) of 1 day per 1 square meter of membrane surface was used as the membrane permeation flux (m ³ /m ² /d).

It should be noted that, in the evaluation of permeated water during membrane formation, when the surface of the separation function layer is coated with a cross-linked polymer, the composite semipermeable membrane before coating is used under the pressure condition of 1.55MPa to 25°C. , pH 6.5, and NaCl concentration of 2,000 mg/l aqueous solution filtered for 1 hour, the permeated water amount was F1, and the permeated water amount after being coated with the cross-linked polymer was F2, and the value of F2/F1 was calculated.

In the evaluation of the amount of permeated water after cleaning, the amount of permeated water obtained when an aqueous solution with a pH of 6.5 and a NaCl concentration of 2,000 mg/l was filtered at 25°C for 1 hour at a pressure of 1.55 MPa was defined as F3, and then Add polyoxyethylene (10) octyl phenyl ether to a concentration of 100 mg/l, and filter the resulting solution for 1 hour, and then wash with an aqueous solution having a NaCl concentration of 500 mg/l for 1 hour. Let the amount of permeated water be F4 , Calculate the value of F4/F3.

(thickness of porous support layer)

The thickness of the base material before the formation of the porous support layer and the thickness of the composite semipermeable membrane after completion were measured with a PEACOCK digital thickness gauge manufactured by Ozaki Seisakusho Co., Ltd., and the difference was defined as the thickness of the porous support layer. About the thickness of the base material and the thickness of the composite semipermeable membrane, 20 points were measured in each width direction, and the average value was calculated.

Porous support layer thickness (μm) = support film thickness (μm) - substrate thickness (μm)

(Zeta potential)

The composite semipermeable membrane was cleaned with ultrapure water, and it was set in the flat sample tank in such a way that the separation function layer of the composite semipermeable membrane was in contact with the monitoring particle solution, and the electrophoretic light scattering photometer (ELS -8000) for measurement. As the monitor particle solution, a measurement solution in which monitor particles of polystyrene latex were dispersed in NaCl aqueous solution adjusted to pH 6, pH 10, or pH 3 was used.

Use each measuring solution to measure the surface Zeta potential A (pH6, NaCl 10mM), the surface Zeta potential B (pH6, NaCl 1mM), the surface Zeta potential C (pH3, NaCl 1mM), and the surface Zeta potential D (pH10 , NaCl 1mM).

(functional group amount)

With regard to the amount of functional groups in the polyamide separation functional layer, the base material is peeled off from the composite semipermeable membrane to obtain a polyamide separation functional layer and a porous support layer, and the porous support layer is dissolved and removed with dichloromethane to obtain a polyamide separation function layer. functional layer. The obtained polyamide separation functional layer was measured by the DD/MAS- ^13C solid NMR method, and the amount of each functional group was calculated from the comparison of the integrated values of the carbon peaks of each functional group or the carbon peaks to which each functional group was bonded.

(rms surface roughness)

The composite semi-permeable membrane was cleaned with ultrapure water, and the air-dried composite semi-permeable membrane was cut out to a 1 cm square and pasted on a glass slide with double-sided tape, using an atomic force microscope (Nanoscope IIIa: Digital Instruments company), in the knocking mode ( The root mean square surface roughness (RMS) of the separation functional layer was measured under tapping mode). Veeco Instruments NCHV-1 was used as a cantilever, and the measurement was carried out at normal temperature and pressure. The scanning speed is 1Hz, and the number of sampling points is a square of 512 pixels. Analysis software uses Gwyddion. For the measurement results, one-dimensional baseline correction (slope correction) was performed on both the X-axis and the Y-axis.

(air permeability)

Based on JIS L1096 (2010), air permeability was measured using a Fraser type tester. Cut out the base material to a size of 200mm×200mm, and install it on a Fraser-type testing machine, adjust the suction fan and air hole so that the inclined-type barometer becomes a pressure of 125Pa, from the pressure shown by the vertical-type barometer at this time The air permeability is obtained from the type of air holes used. The Fraser type testing machine used KES-F8-AP1 manufactured by KATO TECH CO., LTD.

(Production of composite semipermeable membrane)

(comparative example 1)

A 15.0% by weight solution of polysulfone in dimethylformamide (DMF) was cast at room temperature (25°C) on a nonwoven fabric made of polyester fibers (air permeability: 1.0cc/ ^cm2 /sec) produced by the papermaking method , and immediately immersed in pure water for 5 minutes to prepare a support membrane with a porous support layer having a thickness of 40 μm.

Next, the supporting membrane was dipped in an aqueous solution containing 3.5% by weight of m-phenylenediamine, then the excess aqueous solution was removed, and the solution (which was prepared in n-decyl diamine) was further coated in such a manner that the surface of the porous supporting layer could be completely wetted. Trimellitic acid halide was dissolved in alkane so as to make it 0.14% by weight). Next, in order to remove excess solution from the film, the film was vertically drained, and air at 20° C. was blown with a blower to dry it. Then, it was washed with pure water at 40° C. to obtain a composite semipermeable membrane. The composite semipermeable membrane thus obtained was evaluated, and the membrane properties were the values shown in Table 1.

(Example 1)

The composite semipermeable membrane obtained in Comparative Example 1 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree 88%, weight average molecular weight 2,000) and 0.2% by weight of glutaraldehyde for 1 minute. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 30 seconds with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(Example 2)

The composite semipermeable membrane obtained in Comparative Example 1 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree 88%, weight average molecular weight 2,000) and 0.2% by weight of glutaraldehyde for 1 minute. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 1 minute with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(comparative example 2)

The composite semipermeable membrane obtained in Comparative Example 1 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree: 88%, weight average molecular weight: 2,000) and 0.2% by weight of glutaraldehyde for 2 minutes. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 4 minutes with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(comparative example 3)

The composite semipermeable membrane obtained in Comparative Example 1 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree: 99%, average polymerization degree: 500) for 2 minutes. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 4 minutes with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(comparative example 4)

The composite semipermeable membrane obtained in Comparative Example 1 was treated at 30° C. for 1 minute with a 0.3 wt % sodium nitrite aqueous solution adjusted to pH 3 with sulfuric acid. After the composite semipermeable membrane was taken out from the nitrous acid aqueous solution, it was washed with pure water at 20° C. to obtain a composite semipermeable membrane. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(Example 3)

The composite semipermeable membrane obtained in Comparative Example 4 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree 88%, weight average molecular weight 2,000) and 0.2% by weight of glutaraldehyde for 1 minute. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 45 seconds with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(Example 4)

The composite semipermeable membrane obtained in Comparative Example 4 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree: 88%, weight average molecular weight: 2,000) and 0.2% by weight of glutaraldehyde for 1 minute. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 1 minute with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(comparative example 5)

The composite semipermeable membrane obtained in Comparative Example 4 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree: 88%, weight average molecular weight: 2,000) and 0.2% by weight of glutaraldehyde for 2 minutes. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 3 minutes with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(Example 5)

The composite semipermeable membrane obtained in Comparative Example 4 was immersed in an 80° C. aqueous solution containing 1% by weight of polyvinyl alcohol (saponification degree: 88%, weight average molecular weight: 2,000) for 2 minutes. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 1 minute with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(comparative example 6)

The composite semipermeable membrane obtained in Comparative Example 1 was treated at 30° C. for 1 minute with a 0.4 wt % sodium nitrite aqueous solution adjusted to pH 3 with sulfuric acid. After taking out the composite semipermeable membrane from the nitrous acid aqueous solution, it was immersed in 0.1% aniline aqueous solution at 30 degreeC for 1 minute. Next, it was immersed in 0.1 weight% sodium sulfite aqueous solution for 2 minutes. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(Example 6)

The composite semipermeable membrane obtained in Comparative Example 6 was immersed for 1 minute in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree: 88%, weight average molecular weight: 2,000) and 0.2% by weight of glutaraldehyde. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 30 seconds with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(Example 7)

The composite semipermeable membrane obtained in Comparative Example 6 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree: 88%, weight average molecular weight: 2,000) and 0.2% by weight of glutaraldehyde for 1 minute. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 30 seconds with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

(comparative example 7)

The composite semipermeable membrane obtained in Comparative Example 6 was immersed in an aqueous solution containing 0.5% by weight of polyvinyl alcohol (saponification degree: 88%, weight average molecular weight: 2,000) and 0.2% by weight of glutaraldehyde for 2 minutes. An aqueous solution obtained by adding hydrochloric acid as an acid catalyst to an aqueous solution so that the concentration of the hydrochloric acid becomes 0.1 mol/liter. After being held vertically for 1 minute to remove excess liquid, dry at 90° C. for 3 minutes with a hot air dryer to obtain a composite semipermeable membrane in which the separation function layer is coated with polyvinyl alcohol. The composite semipermeable membrane was subjected to hydrophilization treatment by immersing in a 10% isopropanol aqueous solution for 10 minutes before evaluation. The composite semipermeable membrane thus obtained was evaluated, and as a result, the membrane properties were the values shown in Table 1.

As above, the composite semipermeable membrane of the present invention has a high permeable water volume and high desorption of membrane fouling substances, and can maintain stable performance for a long time.

【Table 1】

Although the present invention has been described in detail with reference to specific embodiments, it is obvious for those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application claims priority based on Japanese Patent Application (Japanese Patent Application No. 2013-39605) filed on February 28, 2013 and Japanese Patent Application (Japanese Patent Application No. 2013-39648) filed on February 28, 2013. Incorporated herein by reference.

Industrial availability

Using the composite semi-permeable membrane of the present invention, raw water can be separated into permeated water such as drinking water and concentrated water not permeated through the membrane, so that target water can be obtained. The composite semipermeable membrane of the present invention can be particularly suitable for desalination of salt water or seawater.

Claims (11)

1. a composite semipermeable membrane, it has the support membrane comprising base material and porous supporting course and the separating. functional layer be arranged on described porous supporting course, wherein,

The surperficial Zeta potential A of described separating. functional layer under pH6, NaCl 10mM condition determination within ± 15mV,

Further, the potential difference of the surperficial Zeta potential B of described separating. functional layer under pH6, NaCl 1mM condition determination and described surperficial Zeta potential A is ± more than 10mV.

2. composite semipermeable membrane as claimed in claim 1, wherein, the rms surface roughness on the surface of described separating. functional layer is more than 60nm.

3. composite semipermeable membrane as claimed in claim 1 or 2, wherein, described separating. functional layer is formed by polyamide, and described polyamide is obtained by the polymerisation of polyfunctional amine and multifunctional etheride.

4. the composite semipermeable membrane according to any one of claims 1 to 3, wherein, the potential difference of the surperficial Zeta potential C of described separating. functional layer under pH3, NaCl 1mM condition determination and the surperficial Zeta potential D of described separating. functional layer under pH10, NaCl 1mM condition determination is below 40mV.

5. the composite semipermeable membrane according to any one of Claims 1 to 4, wherein, described separating. functional layer contains amino and amide groups, and the ratio of the molar equivalent of the molar equivalent/amide groups of amino is more than 0.2.

6. the composite semipermeable membrane according to any one of Claims 1 to 5, wherein, described separating. functional layer has amide groups, azo group and phenolic hydroxyl, and the ratio of phenolic hydroxyl/amide groups is less than 0.1.

7. the composite semipermeable membrane according to any one of claim 1 ~ 6, wherein, the surface of described separating. functional layer is crosslinked polymer and is coated to.

8. composite semipermeable membrane as claimed in claim 7, wherein, described cross-linked polymer is the cross-linking agent of hydrophilic compounds.

9. composite semipermeable membrane as claimed in claim 7 or 8, wherein, the surface of described cross-linked polymer and described separating. functional layer forms covalent bond.

10. the composite semipermeable membrane according to any one of claim 7 ~ 9, wherein, composite semipermeable membrane before being coated to using the surface of described separating. functional layer by described cross-linked polymer, under the pressure condition of 1.55MPa to 25 DEG C, pH6.5, NaCl concentration is 2, the aqueous solution of 000mg/l filter 1 little constantly be set to F1 through the water yield, after the surface of described separating. functional layer is coated to by described cross-linked polymer be set to F2 through the water yield time, the value of F2/F1 is more than 0.80.

11. composite semipermeable membranes according to any one of claim 1 ~ 10, wherein, in 25 DEG C, by with the pressure of 1.55MPa to pH6.5, NaCl concentration for 2, the aqueous solution of 000mg/l filter 1 little constantly be set to F3 through the water yield, then in the described aqueous solution, add polyoxyethylene (10) octyl phenyl ether and make its concentration become 100mg/l, by after 1 hour is filtered to the solution of gained with NaCl concentration be the aqueous cleaning 1 of 500mg/l little constantly be set to F4 through the water yield time, the value of F4/F3 is more than 0.85.