JP2020138135A - Composite semipermeable membrane - Google Patents

Abstract

To provide a composite semipermeable membrane having both high solute removal performance and high water permeability.SOLUTION: The composite semipermeable membrane has cross-linked polyamide in which a separation functional layer is a polymeric substance composed of polyfunctional amine and polyfunctional acid halide and a compound having fluorine atom, and satisfies the followings (A) and (B): (A) a contact angle of water in air at the separation functional layer side of the composite semipermeable membrane is 70° or more and 100° or less; and (B) ratios of fluorine atom in an element measured in an X-ray photoelectron spectroscopy measurement that is performed by irradiating X-ray from the separation functional layer side of the composite semipermeable membrane is 8% or higher and 15% or lower.SELECTED DRAWING: None

Description

The present invention relates to a composite semipermeable membrane having both high solute removal property and high water permeability. The composite semipermeable membrane obtained by the present invention can be suitably used for, for example, desalination of brine or seawater.

Membranes used for membrane separation of liquid mixtures include microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, etc., and these membranes are beverages from, for example, salt and water containing harmful substances. It is used to obtain water, to produce industrial ultrapure water, to treat wastewater, and to recover valuable resources.

Most of the reverse osmosis membranes and nanofiltration membranes currently on the market are composite semipermeable membranes, and among them, a separation function consisting of a crosslinked aromatic polyamide obtained by a polycondensation reaction between a polyfunctional amine and a polyfunctional acid halide. A composite semipermeable membrane (Patent Document 1) obtained by coating a layer on a microporous support membrane is widely used. It is important for these composite semipermeable membranes to have both high solute removability and water permeability in order to improve the water quality obtained when used and reduce the operating cost.

As a means for improving the solute removability and water permeability of the membrane, a method of forming a separation functional layer of polyamide by interfacial polycondensation and then modifying the separation functional layer is effective from the viewpoint of versatility. As such a modification method, for example, a semitransparent film having a separation functional layer containing a primary amino group is subjected to a reagent that reacts with a primary amino group to produce a diazonium salt or a derivative thereof for 1 second or more and 60 minutes. Within contact (Patent Document 2), Contacting a liquid containing a carboxylic acid and a condensing agent (Patent Document 3), Contacting an organic solvent containing a polyfunctional aromatic amine compound after condensation in the interface (Patent Document 3) 4) etc. are disclosed. However, it is desired to achieve both higher solute removal property and water permeability.

Japanese Unexamined Patent Publication No. 2001-79372 JP-A-2005-177741 JP-A-2010-125439 Special Table 2016-524530

An object of the present invention is to provide a method for producing a composite semipermeable membrane having both high solute removal property and high water permeability.

The present invention for achieving the above object has the following configuration.

A composite semipermeable membrane having a support membrane including a base material and a porous support layer and a separation functional layer provided on the porous support layer, wherein the separation functional layer is a polyfunctional amine and a polyfunctional acid halide. A composite semipermeable membrane having a crosslinked polyamide which is a polymer of the above and a compound having a fluorine atom and satisfying the following (A) and (B).
(A) In the X-ray photoelectron spectroscopy measurement performed by irradiating X-rays from the separation function layer side of the composite semipermeable membrane, the ratio of fluorine atoms in the measured element is 8% or more and 15% or less. ..
(B) The contact angle of water in the air on the separation function layer side of the composite semipermeable membrane is 70 ° or more and 100 ° or less.

When the composite semipermeable membrane of the present invention satisfies the constitutions (A) and (B), fluorine having a low affinity with the solute is arranged on the surface of the separation functional layer, and as a result, the semipermeable membrane of the present invention is: It exhibits excellent solute removal and water permeability.

1. 1. Composite Semipermeable Membrane The composite semipermeable membrane of the present invention may be a support membrane including a base material and a porous support layer, and a crosslinked polyamide provided on the porous support layer (hereinafter, may be simply referred to as “polyamide”. ) And a separation functional layer formed from a compound having a fluorine atom.
(1-1) Separation function layer The separation function layer is a layer that has a solute separation function in the composite semipermeable membrane. The composition and thickness of the separating functional layer are set according to the purpose of use of the composite semipermeable membrane.

Specifically, the separation functional layer contains a crosslinked polyamide and a compound having a fluorine atom.

The crosslinked polyamide is obtained by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide.

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

The aromatic polyfunctional amine is an aromatic amine having two or more amino groups in one molecule, and is not particularly limited, but is limited to meta-phenylenediamine, para-phenylenediamine, and 1,3,5-tri. Aminobenzene and the like are exemplified. Moreover, as the N-alkylated product, N, N-dimethyl metaphenylenediamine, N, N-diethyl metaphenylenediamine, N, N-dimethylpara-phenylenediamine, N, N-diethyl para-phenylenediamine and the like are exemplified. Metaphenylenediamine (hereinafter referred to as m-PDA) or 1,3,5-triaminobenzene is particularly preferable from the viewpoint of stability of performance expression.

The aliphatic polyfunctional amine is an aliphatic amine having two or more amino groups in one molecule, and is preferably a piperazine-based amine or a derivative thereof. For example, piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5-trimethylpiperazine, 2,5-diethylpiperazine, 2,3,5-triethylpiperazine, 2- Examples thereof include n-propylpiperazine, 2,5-di-n-butylpiperazine, and ethylenediamine. Piperazine or 2,5-dimethylpiperazine is particularly preferable because of the stability of performance expression. One of these polyfunctional amines may be used alone, or two or more thereof may be used as a mixture.

The polyfunctional acid halide is an acid halide having two or more carbonyl halide groups in one molecule, and is not particularly limited as long as it gives a polyamide by reaction with the polyfunctional amine. Examples of the polyfunctional acid halide include oxalic acid, malonic acid, maleic acid, fumaric acid, glutaric acid, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. , 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid and other halides can be used. Among the acid halides, acid halides are preferable, and they are acid halides of 1,3,5-benzenetricarboxylic acid from the viewpoints of economy, availability, handling, and reactivity. Trimesic acid chloride (hereinafter referred to as TMC) is preferable. The polyfunctional acid halide may be used alone or as a mixture of two or more.

The above-mentioned polyamide has an amide group derived from a polymerization reaction of a polyfunctional amine and a polyfunctional acid halide, an amino group derived from an unreacted terminal functional group, and a carboxy group. The amount of these functional groups affects the water permeability and the salt removal rate of the composite semipermeable membrane.

A compound having a fluorine atom is a unit compound having a fluorine atom in the molecule. The unit having a "fluorine atom" is specifically a unit having 1 to 10 carbon atoms and containing a functional group having a structure represented by -CF2- or -CF3. Further, the unit may include an ether bond, for example, containing structures such as CF3-O-CF2-, -CF2-O-CF2-, CF2-CH2-O-, -CF (CF3)-. May be good.

As a result of diligent studies, the present inventors reduced the interaction with the solute contained in the raw water and reduced the permeability of the solute by having a compound having a fluorine atom having a low surface free energy in the separation functional layer. I found that.

In the X-ray photoelectron spectroscopy measurement performed by irradiating X-rays from the separation function layer side of the composite semipermeable membrane of the present invention, the ratio of fluorine atoms in the measured element is 8% or more and 15% or less. When the ratio of fluorine atoms is within the above range, excellent solute removability can be exhibited. If the proportion of fluorine atoms is less than 8%, a sufficient effect of improving removability cannot be exhibited, and if it is more than 15%, the water permeability is greatly reduced, which is not practical. More preferably, it is 9% or more and 13% or less.

Further, the contact angle of water in the air on the separation functional layer side of the composite semipermeable membrane of the present invention is 70 ° or more and 100 ° or less. By controlling the contact angle with water within the above range, excellent performance in both water permeability and removability is achieved. The separation function is achieved by designing so that the ratio of fluorine atoms is within the above range and a large number of compounds having fluorine atoms are present on the surface of the separation function layer, and the contact angle with water in the air is within the above range. It is possible to improve the solute removal performance while suppressing the decrease in water permeability in the layer. More preferably, it is 75 ° or more and 95 ° or less.

The separation functional layer of the present invention is not particularly limited as long as it has a crosslinked polyamide and a compound having a fluorine atom, but it is preferable that the crosslinked polyamide and the compound having a fluorine atom are chemically bonded. By being chemically bonded, it is possible to prevent the outflow of the compound having a fluorine atom and maintain high solute removability for a long period of time.

The compound having a fluorine atom is not particularly limited, but when chemically bonded to polyamide, a structure having a functional group capable of forming a chemical bond by reacting with an amino group or an acid halide which is an unreacted terminal functional group of polyamide is preferable. ..

Specifically, perfluoropentanoyl fluoride, perfluorohexanoyl fluoride, perfluoroheptanoyl fluoride, perfluorooxanoyl fluoride, perfluorosuccinoyl fluoride, hexafluoroglutaryl fluoride, octafluoro Adipoil fluoride, perfluoromethoxypropionoyl fluoride, perfluorobutoxyethoxyacetylfluoride, perfluoro-3,6-dioxaoctanedioil difluoride, perfluoro-3,6,9-trioxaundecane Acid fluorides such as dioil difluoride, perfluorohexanoic acid, perfluoroheptanic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoro-3,5,5-trimethylhexanoic acid, perfluoro- 3,7-Dimethyloctanoic acid, perfluorosuccinic acid, perfluoroglutaric acid, perfluoroadipic acid, perfluorosveric acid, perfluoroazelinic acid, perfluorosevacinic acid, perfluoro-3,6-dioxaheptanoic acid, Perfluoro-3,6,9-trioxadecanoic acid, perfluoro-3,6-dioxadecanoic acid, perfluoro-3,6,9-trioxatridecanoic acid, perfluoro-3,6-dioxaoctane- Hexanoic acids such as 1,8-dioic acid, perfluoro-3,6,9-trioxaundecane-1,11-dioic acid, 1H, 1H-trifluoroethanol, 1H, 1H-pentafluoro-propanol, 1H, 1H-perfluoro-1-hexanol, 1H, 1H-perfluoro-1-heptanol, 1H, 1H-perfluoro-1-octanol, 1H, 1H-perfluoro-1-nonanol, 1H, 1H-perfluoro -1-decanol, perfluoro-3,5,5-trimethylhexane-1-ol, perfluoro-3,7-dimethyloctane-1-ol, 1H, 1H, 4H, 4H-perfluoro-1,4- Butanediol, 1H, 1H, 5H, 5H-perfluoro-1,5-pentanediol, 1H, 1H, 6H, 6H-perfluoro-1,6-hexanediol, 1H, 1H, 7H, 7H-perfluoro- 1,7-Heptanediol, 1H, 1H, 8H, 8H-perfluoro-1,8-octanediol, 1H, 1H, 9H, 9H-perfluoro-1,9-nonanediol, 1H, 1H, 10H, 10H-perfluoro-1,10-decanediol, perfluoro-t-butanol, 1H, 1H-perfluoro-3,6-dioxaheptane-1-ol, 1H, 1H-perfluoro -3,6,9-Trioxadecane-1-ol, 1H, 1H-perfluoro-3,6-dioxadecane-1-ol, 1H, 1H-perfluoro-3,6,9-trioxatridecane- 1-ol, 1H, 1H, 8H, 8H-perfluoro-3,6-dioxaoctane-1,8-diol, 1H, 1H, 11H, 11H-perfluoro-3,6,9-trioxaundecane- Alcohols such as 1,11-diol, acid anhydrides such as perfluorosuccinic acid anhydride and perfluoroglutaric acid anhydride, and amines such as 1H, 1H-heptafluorobutylamine and 1H, 1H-tridecafluoroheptylamine. Compounds, Hexafluoroepoxy Propane, 3-Perfluorobutyl-1,2-Epoxy Propane, 3-Perfluorohexyl-1,2-Epoxy Propane, 3- (2,2,3,3-Tetrafluoropropoxy) -1 , 2-Epoxy Propane, 3- (1H, 1H, 5H-Octafluoropentyroxy) -1,2-Epoxy Propane, 3- (1H, 1H, 7H-Dodecafluoroheptyroxy) -1,2-Epoxy Propane , 1,4-Bis (2', 3'-epoxypropyl) -perfluoro-n-butane and other epoxy compounds are exemplified.

These compounds having a fluorine atom are preferably present on the surface of the separation functional layer, and it is preferable that the compound having a fluorine atom is brought into contact with the surface of the crosslinked polyamide formed by interfacial polymerization.

As another preferred embodiment of the present invention, the separating functional layer has a first layer having a crosslinked polyamide which is a polymer of a polyfunctional amine and a polyfunctional acid halide, and a second layer having a hydrophilic polymer. , A form composed of a third layer having a compound having a fluorine atom can also be preferably used. By taking the form of a first layer having a crosslinked polyamide, a second layer having a hydrophilic polymer, and a third layer having a compound having a fluorine atom, the inside of the separation function layer is made hydrophilic and A compound having a fluorine atom can be arranged on the surface, and while suppressing the decrease in water permeability of the separation functional layer, the permeability of the solute can be decreased and the removability can be improved. At this time, it is preferable that the composition of the second layer having a hydrophilic polymer and the composition of the third layer having a compound having a fluorine atom are different.

The hydrophilic polymer is a polymer that dissolves 0.5 g or more in 1 L of water under the condition of 25 ° C. Specifically, maleic acid, maleic anhydride, acrylic acid, methacrylic acid, itaconic acid, 2- (hydroxymethyl) acrylic acid, 4- (meth) acryloyloxyethyl trimerito, which are monomers having an ethylenically unsaturated group. Acids and corresponding anhydrides, 10-methacryloyloxydecylmalonic acid, N- (2-hydroxy-3-methacryloyloxypropyl) -N-phenylglycine and 4-vinylbenzoic acid, vinylphosphonic acid, 4-vinylphenylphosphonic acid , 4-Vinylbenzylphosphonic acid, 2-methacryloyloxyethylphosphonic acid, 2-methacrylamide ethylphosphonic acid, 4-methacrylamide-4-methyl-phenyl-phosphonic acid, 2- [4- (dihydroxyphosphoryl) -2- Oxa-butyl] -acrylic acid and 2- [2-dihydroxyphosphoryl) -ethoxymethyl] -acrylic acid-2,4,6-trimethyl-phenyl ester, 2-methacryloyloxypropyl monohydrogen phosphate and 2-methacryloyloxypropyl Dihydrogen Phosphonate, 2-methacryloyloxyethyl monohydrogen phosphate and 2-methacryloyloxyethyl dihydrogen phosphate, 2-methacryloyloxyethyl-phenyl-hydrogen phosphate, dipentaerytritor-pentamethacryloyloxyphosphate, 10-methacryloyloxy Decyl-dihydrogen phosphate, dipentaerytritor pentamethacryloyloxyphosphate, mono-phosphate (1-acryloyl-piperidin-4-yl) -ester, 6- (methacrylamide) hexyldihydrogen phosphate and 1,3-bis- (N-acryloyl-N-propyl-amino) -propan-2-yl-dihydrogen phosphate, vinyl sulfonic acid, 4-vinylphenyl sulfonic acid or 3- (methacrylamide) propyl sulfonic acid, vinyl pyroridone, vinyl alcohol, acetic acid Monomeric weight selected from vinyl, ethylene glycol, propylene glycol, hydroxyethyl (meth) acrylate, polyethylene glycol (meth) acrylate, allylamine, diallylamine, 2-aminoethyl (meth) acrylate, 2-aminoethyl (meth) acrylamide, etc. Examples include coalesced or copolymers consisting of a plurality of monomers. Examples of the polymer of the monomer having no ethylenically unsaturated group include polyethylene glycol, polypropylene glycol, polyglycerin, and polyethyleneimine.

The weight average molecular weight of the hydrophilic polymer is preferably 2,000 or more and 1,500,000 or less. When the weight average molecular weight is 2,000 or more, a sufficient layer of hydrated water can be provided, and when it is 1,500,000 or less, the increase in resistance of water permeating the separation functional layer is suppressed. , High permeation flow velocity can be maintained. It is more preferably 3,000 to 1,200,000, still more preferably 5,000 to 1,000,000.

The third layer having a compound having a fluorine atom may be a compound having a fluorine atom alone, or another compound may be present as long as the above-mentioned ratio of fluorine atoms and the contact angle with water in the air are satisfied. Good.

"The composition of the second layer and the third layer are different" means that the compounds forming the third layer, which is the outermost surface of the separation functional layer, and the second layer, which is the inner layer, are different. That is, by forming the third layer using the second layer having a hydrophilic polymer and the compound having a fluorine atom, the proportion of fluorine atoms in the inner layer is low and the proportion of fluorine atoms on the outermost surface is high. Can be. When the element composition in the depth direction of the separation function layer is measured by Rutherford backscattering, the proportion of fluorine atoms is high near the surface and low in the inner layer.

The above configuration is achieved by forming a first layer, a crosslinked polyamide, a second layer, a hydrophilic polymer layer, and a third layer, a compound layer containing a fluorine atom, in this order. it can. When a hydrophilic polymer and a compound containing a fluorine atom are mixed or bonded and brought into contact with the surface of the crosslinked polyamide which is the first layer at the same time, and the second layer and the third layer have the same composition, solute removability It is not preferable because the improvement effect cannot be sufficiently obtained.

(1-2) Support Membrane The support membrane is for giving strength to the separation functional layer, and itself does not substantially have the separation performance of ions and the like. The support film is composed of a base material and a porous support layer.

The size and distribution of the pores in the support membrane are not particularly limited, but for example, they have uniform and fine pores or gradually large fine pores from the surface on which the separation function layer is formed to the other surface and are separated. A support film having a micropore size of 0.1 nm or more and 100 nm or less on the surface on the side where the functional layer is formed is preferable.

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

Examples of the base material include a fabric made of at least one selected from polyester and aromatic polyamide. It is particularly preferred to use polyester, which is mechanically and thermally stable.

As the cloth used as the base material, a long fiber non-woven fabric or a short fiber non-woven fabric can be preferably used. When a solution of a polymer polymer is cast on a base material, it strikes through due to over-penetration, the base material and the porous support layer are peeled off, and the film is non-uniform due to fluffing of the base material. A long-fiber non-woven fabric can be more preferably used because it is required to have excellent film-forming properties so as not to cause defects such as conversion and pinholes.

Examples of the long-fiber non-woven fabric include long-fiber non-woven fabrics composed of thermoplastic continuous filaments. Since the base material is made of a long-fiber non-woven fabric, it is possible to suppress the non-uniformity of the polymer solution caused by fluffing when the short-fiber non-woven fabric is used and the film defects. Further, in the step of continuously forming a composite semipermeable membrane, tension is applied in the film forming direction of the base material, so that it is preferable to use a long fiber non-woven fabric having excellent dimensional stability as the base material.

In particular, since the fibers arranged on the opposite side of the porous support layer of the base material are oriented longitudinally with respect to the film forming direction, the strength of the base material can be maintained and film tearing can be prevented. preferable. Here, the longitudinal orientation means that the orientation direction of the fibers is parallel to the film forming direction. On the contrary, when the orientation direction of the fibers is perpendicular to the film formation direction, it is called lateral orientation.

As for the fiber orientation of the non-woven fabric base material, it is preferable that the fiber orientation on the side opposite to the porous support layer is 0 ° or more and 25 ° or less. Here, the fiber orientation is an index indicating the orientation of the fibers of the non-woven fabric base material constituting the support film, and the film-forming direction when continuous film-forming is set to 0 °, and the direction perpendicular to the film-forming direction, that is, the non-woven fabric. It refers to the average angle of the fibers constituting the non-woven fabric base material when the width direction of the base material is 90 °. Therefore, the closer the fiber orientation is to 0 °, the longer the vertical orientation, and the closer to 90 °, the more the horizontal orientation.

The manufacturing process of the composite semipermeable membrane and the manufacturing process of the element include a heating step, and a phenomenon occurs in which the support membrane or the composite semipermeable membrane shrinks due to 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 support membrane or the composite semipermeable membrane causes problems in dimensional stability and the like, a base material having a small thermal dimensional change rate is desired.

When the orientation difference between the fibers arranged on the opposite side of the porous support layer and the fibers arranged on the porous support layer side in the non-woven fabric base material is 10 ° or more and 90 ° or less, the change in the width direction due to heat Can be suppressed, which is preferable.

The air permeability of the base material is preferably 2.0 cc / cm ² / sec or more. When the air permeability is in this range, the amount of water permeated by the composite semipermeable membrane becomes high. This is a step of forming a support film, when a polymer polymer is cast on a base material and immersed in a coagulation bath, the non-solvent replacement rate from the base material side is increased, so that the porous support layer is formed. This is thought to be because the internal structure of the polymer changes, which 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 by a Frazier type tester based on JIS L1096 (2010). For example, a base material is cut out to a size of 200 mm × 200 mm and used as a sample. This sample was attached to the Frazier type tester, the suction fan and air holes were adjusted so that the inclined barometer had a pressure of 125 Pa, and the pressure indicated by the vertical barometer at this time and the type of air holes used were used as the basis. The amount of air passing through the material, that is, the air permeability, can be calculated. As the Frazier type testing machine, KES-F8-AP1 manufactured by Kato Tech Co., Ltd. can be used.

The thickness of the base material is preferably in the range of 10 μm or more and 200 μm or less, and more preferably in the range of 30 μm or more and 120 μm or less.

The material of the porous support layer is a homopolymer or copolymer such as polysulfone, polyether sulfone, polyamide, polyester, cellulose polymer, vinyl polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide, alone or blended. Can be used. Here, as the cellulosic polymer, cellulose acetate, cellulose nitrate and the like can be used, and as the vinyl polymer, polyethylene, polypropylene, polyvinyl chloride, polyacrylonitrile and the like can be used. Of these, homopolymers or copolymers such as polysulfone, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferable. More preferably, cellulose acetate, polysulfone, polyphenylene sulfide sulfone, or polyphenylene sulfide can be mentioned, and among these materials, polysulfone has high chemical, mechanical, and thermal stability and is easy to mold. Can be used in general.

Specifically, it is preferable to use polysulfone composed of repeating units shown in the following chemical formula because the pore size of the support membrane can be easily controlled and the dimensional stability is high.

For example, a solution of the above polysulfone in N, N-dimethylformamide (hereinafter referred to as DMF) is cast on a densely woven polyester cloth or polyester non-woven fabric to a certain thickness, and the solution is wet-coagulated in water. A support film having fine pores having a diameter of several tens of nm or less can be obtained on most of the surface.

The thickness of the above-mentioned support membrane affects the strength of the obtained composite semipermeable membrane and the packing density when it is used as an element. The thickness of the support film is preferably in the range of 30 μm or more and 300 μm or less, and more preferably in the range of 100 μm or more and 220 μm or less in order to obtain sufficient mechanical strength and packing density.

The morphology of the porous support layer can be observed with a scanning electron microscope, a transmission electron microscope, and an atomic force microscope. For example, when observing with a scanning electron microscope, the porous support layer is peeled off from the base material and then cut by a freeze-cutting method to prepare a sample for cross-sectional observation. This sample is lightly coated with platinum or platinum-palladium or ruthenium tetrachloride, preferably ruthenium tetrachloride, and observed with a high resolution field emission scanning electron microscope (UHR-FE-SEM) at an accelerating voltage of 3 to 15 kV. As the high-resolution field emission scanning electron microscope, an S-900 type electron microscope manufactured by Hitachi, Ltd. can be used.

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

The thickness of the porous support layer is preferably in the range of 20 μm or more and 100 μm or less. When the thickness of the porous support layer is 20 μm or more, good pressure resistance can be obtained and a uniform support film without defects can be obtained. Therefore, a composite semipermeable membrane provided with such a porous support layer. Can show good salt removal performance. When the thickness of the porous support layer exceeds 100 μm, the residual amount of unreacted substances during production increases, which reduces the amount of permeated water and the chemical resistance.

The thickness of the base material and the thickness of the composite semipermeable membrane can be measured by a digital thickness gauge. Further, since the thickness of the separation functional layer is very thin as 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 base material from the thickness of the composite semipermeable membrane. As the digital thickness gauge, PEACOCK of Ozaki Seisakusho Co., Ltd. can be used. When using a digital thickness gauge, the thickness is measured at 20 points and the average value is calculated.

If it is difficult to measure the thickness of the base material or the thickness of the composite semipermeable membrane with a thickness gauge, it may be measured with a scanning electron microscope. The thickness of one sample is obtained by measuring the thickness from electron micrographs of cross-sectional observations at arbitrary five points and calculating the average value.
2. 2. Manufacturing Method Next, a manufacturing method of the composite semipermeable membrane will be described. The manufacturing method includes a step of forming a support film and a step of forming a separation functional layer.
(2-1) Support film forming step The support film forming step includes a step of applying a polymer solution to a base material and a step of immersing the base material to which the solution is applied in a coagulation bath to coagulate the polymer. ..

In the step of applying the polymer solution to the base material, the polymer solution is prepared by dissolving the polymer, which is a component of the porous support layer, in a good solvent of the polymer.

When polysulfone is used as the polymer, the temperature of the polymer solution at the time of applying the polymer solution is preferably 10 ° C. or higher and 60 ° C. or lower. When the temperature of the polymer solution is within this range, the polymer does not precipitate, and the polymer solution is sufficiently impregnated between the fibers of the base material and then solidified. 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. The preferable temperature range of the polymer solution can be appropriately adjusted depending on the type of polymer used, the desired solution viscosity, and the like.

The time from applying the polymer solution on the substrate to immersing it in the coagulation bath is preferably 0.1 seconds or more and 5 seconds or less. If the time until immersion in the coagulation bath is within this range, the organic solvent solution containing the polymer is sufficiently impregnated between the fibers of the base material and then solidified. The preferable range of the time until immersion in the coagulation bath can be appropriately adjusted depending on the type of the polymer solution to be used, the desired solution viscosity, and the like.

Water is usually used as the coagulation bath, but any one that does not dissolve the polymer that is a component of the porous support layer may be used. The membrane morphology of the support membrane obtained by the composition of the coagulation bath changes, and the composite semipermeable membrane obtained thereby also changes. The temperature of the coagulation bath is preferably −20 ° C. or higher and 100 ° C. or lower, more preferably 10 ° C. or higher and 50 ° C. or lower. When the temperature of the coagulation bath is within this range, the vibration of the coagulation bath surface due to thermal motion does not become intense, and the smoothness of the film surface after film formation is maintained. If the temperature is within this range, the solidification rate is appropriate and the film forming property is good.

Next, the support film thus obtained is washed with hot water in order to remove the solvent remaining in the film. The temperature of the hot water at this time is preferably 40 ° C. or higher and 100 ° C. or lower, and more preferably 60 ° C. or higher and 95 ° C. or lower. Within this range, the degree of contraction of the support membrane does not increase, and the amount of permeated water is good. Further, if the temperature is within this range, the cleaning effect is sufficient.
(2-2) Separation Function Layer Formation Step Next, a separation function layer forming step constituting the composite semipermeable membrane will be described. The step of forming the separation functional layer of the present invention is
(A) A step of forming a crosslinked polyamide by performing interfacial polycondensation on the surface of a support membrane using an aqueous solution containing a polyfunctional amine and an organic solvent solution containing a polyfunctional acid halide.
(B) The step includes contacting the polyamide obtained in (a) above with a compound having a fluorine atom. In addition, the process of forming the separation functional layer further
(C) The step of bringing the hydrophilic polymer into contact with the polyamide obtained in (a) above,
May be further included. The step (b) may be after the step (a). Further, the step (c) is preferably performed between the steps (a) and (b).

In the above step (a), a layer containing a polyamide as a main component is formed, and in a subsequent step (b), a layer containing a compound having a fluorine atom as a main component is formed on the surface of the polyamide. Since it is considered that the compound having a fluorine atom hardly passes through the crosslinked polyamide which substantially carries out the separation function, a layer containing the compound having a fluorine atom as a main component is formed on the surface of the polyamide. More preferably, the step (b) is a step of introducing a compound having a crosslinked polyamide and a fluorine atom by a covalent bond. On the other hand, the step (c) is a step of forming a layer containing a hydrophilic polymer as a main component, and the step (c) is performed before the step (b) to be a first step containing a polyamide as a main component. Layer, a second layer containing a hydrophilic polymer as a main component, and a third layer containing a compound having a fluorine atom as a main component are formed, and the hydrophilic polymer and the separation functional layer are formed inside the separation functional layer. By introducing a compound having a fluorine atom on the surface, it is possible to improve the removal performance while suppressing the decrease in water permeability.

In step (a), the organic solvent that dissolves the polyfunctional acid halide is immiscible with water, does not destroy the support membrane, and does not inhibit the reaction for forming the crosslinked polyamide. Any of these may be used. Typical examples include liquid hydrocarbons and halogenated hydrocarbons such as trichlorotrifluoroethane. Considering that it is a substance that does not destroy the ozone layer, its availability, ease of handling, and safety in handling, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, heptadecane, hexadecane, and cyclooctane , Ethylcyclohexane, 1-octene, 1-decane and the like alone or mixtures thereof are preferably used.

In an organic solvent solution containing a polyfunctional amine aqueous solution or a polyfunctional acid halide, an acylation catalyst, a polar solvent, an acid trapping agent, and surface activity are required as long as they do not interfere with the reaction between the two components. It may contain a compound such as an agent or an antioxidant.

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

As a method of coating the surface of the support film with the polyfunctional amine aqueous solution, the surface of the support film may be uniformly and continuously coated with the aqueous solution, and a known coating means, for example, an aqueous solution is coated on the surface of the support film. It may be carried out by a method, a method of immersing the support film in an aqueous solution, or the like. The contact time between the support membrane and the polyfunctional amine aqueous solution is preferably in the range of 5 seconds or more and 10 minutes or less, and more preferably in the range of 10 seconds or more and 3 minutes or less. Next, it is preferable to remove the excessively applied aqueous solution by a liquid draining step. As a method of draining the liquid, for example, there is a method of holding the film surface in the vertical direction and allowing it to flow naturally. After draining the liquid, the membrane surface may be dried to remove all or part of the aqueous solution of water.

Then, an organic solvent solution containing the above-mentioned polyfunctional acid halide is applied to a support film coated with a polyfunctional amine aqueous solution, and a crosslinked polyamide is formed by interfacial polycondensation. The time for performing the interfacial polycondensation is preferably 0.1 seconds or more and 3 minutes or less, and more preferably 0.1 seconds or more and 1 minute or less.

The concentration of the polyfunctional acid halide in the organic solvent solution is not particularly limited, but if it is too low, the formation of the polyamide as the active layer may be insufficient, which may be a drawback, and if it is too high, it is disadvantageous in terms of cost. , 0.01% by weight or more and 1.0% by weight or less is preferable.

Next, it is preferable to remove the organic solvent solution after the reaction by a draining step. For the removal of the organic solvent, for example, a method of grasping the membrane in the vertical direction and allowing the excess organic solvent to flow down naturally can be used. In this case, the time for gripping in the vertical direction is preferably 1 minute or more and 5 minutes or less, and more preferably 1 minute or more and 3 minutes or less. When the gripping time is 1 minute or more, it is easy to obtain a polyamide having a desired function, and when it is 3 minutes or less, the occurrence of defects due to overdrying of an organic solvent can be suppressed, so that performance deterioration can be suppressed. ..

Next, the polyamide obtained by the above method is washed with hot water for 1 minute or more and 60 minutes or less within the range of 25 ° C. or higher and 90 ° C. or lower to prevent the solute of the composite semipermeable membrane and the amount of permeated water. Can be further improved. However, if the temperature of the hot water is too high, the chemical resistance will decrease if it is cooled rapidly after the hot water cleaning treatment. Therefore, hot water washing is preferably performed in the range of 25 ° C. or higher and 60 ° C. or lower. Further, when the hot water washing treatment is performed at a high temperature of 61 ° C. or higher and 90 ° C. or lower, it is preferable to cool the hot water gently after the hot water washing treatment. For example, there is a method of gradually contacting with hot water having a low temperature to cool it to room temperature.

Further, in the above-mentioned step of washing with hot water, acid or alcohol may be contained in the hot water. The inclusion of an acid or alcohol makes it easier to control the formation of hydrogen bonds in the polyamide. Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, and organic acids such as citric acid and oxalic acid. The acid concentration is preferably adjusted to pH 2 or less, and more preferably pH 1 or less. Examples of the alcohol include monohydric alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, and polyhydric alcohols such as ethylene glycol and glycerin. The concentration of alcohol is preferably 10% by weight or more and 100% by weight or less, and more preferably 10% by weight or more and 50% by weight or less.

In step (b), a compound having a fluorine atom is introduced into the surface of the polyamide. As described above, when introduced by a weak bond or interaction, it is easily desorbed by washing with a chemical solution or the like, so that it is preferably introduced by a covalent bond.

The structure, type, etc. of the compound having a fluorine atom to be introduced are as described above.

As this step, a method of bringing a solution containing a compound having a fluorine atom into contact with the surface of the polyamide is preferably used. At this time, the functional group on the surface of the polyamide and the functional group contained in the compound having a fluorine atom can form a covalent bond by a reaction. The method of contacting the separation functional layer with the solution containing the compound having a fluorine atom is not particularly limited. For example, the entire composite semipermeable membrane may be immersed in the solution containing the compound having a fluorine atom, or the fluorine atom may be immersed. A solution containing the compound having a compound may be sprayed on the surface of the composite semipermeable membrane, and the method is not limited as long as the polyamide and the compound having a fluorine atom come into contact with each other.

The compound having a fluorine atom to be brought into contact with the surface of the polyamide may be used alone or in combination of several kinds.

The compound having a fluorine atom is preferably used as a solution having a weight concentration of 100 ppm or more and 10,000 ppm or less. When the concentration of the compound having a fluorine atom is 100 ppm or more, a layer of the compound having a fluorine atom can be sufficiently formed on the polyamide. On the other hand, if it exceeds 10,000 ppm, the layer of the compound having a fluorine atom becomes thick, so that the amount of water produced decreases. It is more preferably 200 ppm or more and 7,000 ppm or less, and further preferably 500 ppm or more and 5,000 ppm or less.

Further, other compounds can be mixed with the solution of the compound having a fluorine atom, if necessary. For example, when a compound having a fluorine atom having a carboxy group is used and reacted with an amino group on the surface of polyamide to form an amide bond, or when a compound having a fluorine atom having a hydroxy group is used and reacted with a carboxy group on the surface of polyamide. A condensing agent may be added when forming an ester bond. The condensing agent refers to a compound that activates a carboxy group and proceeds with a condensation reaction with an amino group or a hydroxy group. Compounds capable of activating the carboxy group in water include 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride and 1,3-bis (2,2-dimethyl-1,3-dioxolan-4-). Examples thereof include ylmethyl) carbodiimide and 4- (4,6-dimethoxy-1,3,5-triazine-2-yl) -4-methylmorpholinium chloride (hereinafter referred to as DMT-MM). Among these compounds, DMT-MM is particularly preferably used because of its stability during the condensation reaction and low toxicity of by-products after the condensation reaction.

The concentration of the condensing agent in the solution containing the compound having a fluorine atom and the condensing agent is not particularly limited as long as it is higher than the concentration of the carboxy group to be activated, and a sufficient effect can be obtained for condensation with the reactive group.

In step (c), a hydrophilic polymer is introduced into the polyamide surface. Like the compound having a fluorine atom, the hydrophilic polymer is easily desorbed by chemical washing or the like when introduced by a weak bond or interaction, so that it is preferably introduced by a covalent bond.

The structure, type, etc. of the hydrophilic polymer to be introduced are as described above.

As this step, a method of bringing an aqueous solution containing a hydrophilic polymer into contact with the surface of the polyamide is preferably used. At this time, the functional group on the surface of the polyamide and the functional group contained in the hydrophilic polymer can form a covalent bond by a reaction. The method of bringing the aqueous solution containing the hydrophilic polymer into contact with the separation functional layer is not particularly limited. For example, the entire composite semipermeable membrane may be immersed in the aqueous solution containing the hydrophilic polymer, or the hydrophilic polymer may be used. The aqueous solution containing the mixture may be sprayed on the surface of the composite semipermeable membrane, and the method is not limited as long as the polyamide and the hydrophilic polymer come into contact with each other.

The hydrophilic polymer to be brought into contact with the surface of the polyamide may be used alone or in combination of several kinds.

The hydrophilic polymer is preferably used as an aqueous solution having a weight concentration of 10 ppm or more and 10,000 ppm or less. When the concentration of the hydrophilic polymer is 10 ppm or more, a layer of the hydrophilic polymer can be sufficiently formed on the polyamide. On the other hand, if it exceeds 10,000 ppm, the layer of the hydrophilic polymer becomes thick, so that the amount of water produced decreases. It is more preferably 20 ppm or more and 7,000 ppm or less, and further preferably 50 ppm or more and 5,000 ppm or less.

Further, other compounds can be mixed with the aqueous solution of the hydrophilic polymer, if necessary. For example, when a hydrophilic polymer having a carboxy group is used and reacted with an amino group on the surface of the polyamide to form an amide bond, or when a hydrophilic polymer having an amino group is used and reacted with a carboxy group on the surface of the polyamide. A condensing agent may be added when forming the ester bond. As the condensing agent, the above-mentioned one can be preferably used.

The pH of the aqueous solution containing the hydrophilic polymer and the condensing agent is preferably 2 or more and 12 or less. By setting the pH of the aqueous solution within the above range, deterioration of the membrane due to acid or alkali can be suppressed, and the salt removal performance of the composite semipermeable membrane can be maintained. Further, when the hydrophilic polymer has many acidic groups such as carboxy groups, the frequency of contact between the polyamide and the hydrophilic polymer decreases due to the load electric force generated by the dissociation of the carboxy groups in the polyamide, so that pH 6 is more preferable. Hereinafter, the pH is more preferably 5 or less. On the other hand, when the hydrophilic polymer contains a large amount of basic groups such as amino groups, the pH is more preferably 9 or more, still more preferably 10 or more in order to improve the nucleophilicity of the amino groups.

As other compounds, alkaline metal compounds such as sodium carbonate, sodium hydroxide, and sodium phosphate may be added in order to promote the reaction between the polyamide surface and the hydrophilic polymer. Further, in order to remove the organic solvent immiscible with water, the monomers such as polyfunctional acid halides and polyfunctional amine compounds, and the oligomers generated by the reaction of these monomers remaining in the polyamide, dodecyl sulfate It is also preferable to add a surfactant such as sodium or sodium benzenesulfonate.
3. 3. Utilization of Composite Semipermeable Membrane The composite semipermeable membrane of the present invention has a large number of holes together with a raw water flow path material such as a plastic net, a permeation water flow path material such as a tricot, and a film for increasing pressure resistance as required. Is wound around a tubular water collecting pipe, and is suitably used as a spiral type composite semipermeable membrane element. Further, the elements can be connected in series or in parallel to form a composite semipermeable membrane module housed in a pressure vessel.

In addition, the above-mentioned composite semipermeable membrane, its elements, and modules can be combined with a pump for supplying raw water to them, a device for pretreating the raw water, and the like to form a fluid separation device. By using this separation device, raw water can be separated into permeated water such as drinking water and concentrated water that has not permeated the membrane, and water suitable for the purpose can be obtained.

The higher the operating pressure of the fluid separator, the higher the salt removal rate, but the energy required for operation also increases, and considering the durability of the composite semipermeable membrane, water to be treated is applied to the composite semipermeable membrane. The operating pressure for permeation is preferably 0.1 MPa or more and 10 MPa or less. The salt removal rate decreases as the supply water temperature increases, but the membrane permeation flux also decreases as the temperature decreases, so 5 ° C or higher and 45 ° C or lower are preferable. Further, when the pH of the supply water becomes high, in the case of supply water having a high salt concentration such as seawater, scales such as magnesium may be generated, and there is a concern that the membrane may be deteriorated due to high pH operation. It is preferable to operate in.

Examples of the raw water treated by the composite semipermeable membrane according to the present invention include liquid mixtures containing 500 mg / L to 100 g / L of TDS (Total Dissolved Solids) such as seawater, brackish water, and wastewater. .. Generally, TDS refers to the total amount of dissolved solids and is expressed as "mass ÷ volume" or "weight ratio". According to the definition, it can be calculated from the weight of the residue obtained by evaporating the solution filtered through the 0.45 micron filter at a temperature of 39.5 to 40.5 ° C., but more simply from the practical salinity (S). Convert.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.
(NaCl removal rate)
Evaluation water adjusted to a temperature of 25 ° C., pH 7 and a sodium chloride concentration of 32,000 ppm was supplied to the composite semipermeable membrane at an operating pressure of 5.5 MPa to perform a membrane filtration treatment. The electric conductivity of the supplied water and the permeated water was measured with an electric conductivity meter manufactured by Toa Denpa Kogyo Co., Ltd. to obtain the respective practical salt content, that is, the NaCl concentration. The NaCl removal rate was calculated based on the NaCl concentration thus obtained and the following formula.

NaCl removal rate (%) = 100 × {1- (NaCl concentration in permeated water / NaCl concentration in feed water)}
(Boron removal rate)
In the test of the previous section, the boron concentration in the supplied water and the permeated water was analyzed by an ICP emission spectrometer and calculated from the following formula.

Boron removal rate (%) = 100 × {1- (boron concentration in permeated water / boron concentration in feed water)
}
(Amount of permeated water)
In the test of the previous section, the amount of water permeated through the membrane of the supplied water (Aqueous NaCl solution) was measured, and the value converted to the amount of water permeated per day (cubic meter) per square meter of the membrane surface was converted into the permeated membrane flux (m ³ / m ² / day). ).
(Water contact angle measurement)
The composite semipermeable membrane was vacuum-dried at 40 ° C. for 12 hours, and the bubble contact angle adhering to the separation membrane functional layer was measured using a contact angle measuring device (DM-301 manufactured by Kyowa Interface Science Co., Ltd.). The measurement was carried out at N = 3 times for those having 0.5 to 2.0 μL of water droplets. At this time, the water droplets were supplied using a syringe needle. The water contact angles of the composite semipermeable membranes prepared in each Comparative Example and Example were the values shown in Table 1.
(X-ray photoelectron spectroscopy)
X-ray photoelectron spectroscopy can be performed by the following procedure. The obtained composite semipermeable membrane was dried at room temperature and under vacuum, and the composition of the elements detected in the range of 0 eV or more and 1400 eV or less was analyzed by wide scan analysis by X-ray photoelectron spectroscopy. Using the X-ray photoelectron spectroscopy measuring device SSX-100 manufactured by SSI of the United States, aluminum Kα1 line and Kα2 line (1486.6 eV) were measured as excitation X-rays, the X-ray output was 10 kV 20 mV, and the photoelectron escape angle was 30 °. , The measurement at different film positions was repeated three times, and the average value was taken as the measured value.
(Preparation of composite semipermeable membrane)
(Comparative Example 1)
A 15.0 wt% DMF solution of polysulfone (PSf) was cast on a polyester non-woven fabric (breathability 2.0 cc / cm ² / sec) made of long fibers under the condition of 25 ° C., and immediately immersed in pure water. By leaving it to stand for 5 minutes, a support film having a porous support layer having a thickness of 40 μm was prepared.

Next, after immersing this support membrane in a 2.8% by weight m-PDA aqueous solution, the excess aqueous solution was removed, and the n-decane solution dissolved so as to have a TMC of 0.14% by weight was made porous. It was applied so that the surface of the support layer was completely wet. Next, in order to remove the excess solution from the membrane, the membrane was vertically drained, blown with air at 25 ° C. for drying, and then washed with pure water at 80 ° C. When the membrane performance of the composite semipermeable membrane thus obtained was measured, it was the value shown in Table 1.
(Comparative Example 2)
The composite semipermeable membrane obtained in Comparative Example 1 was brought into contact with a solution prepared to have 1H, 1H-heptafluorobutylamine at 1500 ppm for 1 hour at 25 ° C., and air was blown at 25 ° C. to dry it using a blower. Then, it was washed with water to obtain a composite semipermeable membrane of Comparative Example 2. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 3)
The composite semipermeable membrane obtained in Comparative Example 1 is brought into contact with a solution prepared by adjusting 1H, 1H-tridecafluoroheptylamine to 30000 ppm at 25 ° C. for 1 hour, and dried by blowing air at 25 ° C. using a blower. After that, it was washed with water to obtain a composite semipermeable membrane of Comparative Example 3. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 4)
The composite semipermeable membrane obtained in Comparative Example 1 is brought into contact with a solution adjusted to have perfluorohexanoic acid at 6000 ppm, polyacrylic acid at 400 ppm, and DMT-MM at 12000 ppm for 1 hour at 25 ° C., and then washed with water. Then, the composite semipermeable membrane of Comparative Example 4 was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 5)
JEFFAMINE (ED-2003) manufactured by Huntsman Co., Ltd. was dissolved in water, perfluorobutoxyethoxyacetylfluoride was added so as to have the same molar ratio, and the mixture was stirred at 25 ° C. for 1 hour to obtain a reaction solution A. The composite semipermeable membrane obtained in Comparative Example 1 was brought into contact with a solution prepared by adjusting the reaction solution A to a polymer weight of 10000 ppm at 25 ° C. for 1 hour, washed with water, and the composite semipermeable membrane of Comparative Example 5 was washed. Got When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 6)
Polyethylenimine (Mw70,000) 2500 ppm and perfluoro-3,6,9-trioxaundecane-1,11-dioic acid 5000 ppm were dissolved in water and added to DMT-MM 5000 ppm for 1 hour at 25 ° C. The mixture was stirred to obtain a reaction solution B. DMT-MM was added to the reaction solution B at a concentration of 1000 ppm, and the composite semipermeable membrane obtained in Comparative Example 1 was contacted at 25 ° C. for 1 hour, washed with water, and the composite semipermeable membrane of Comparative Example 6 was washed. Got When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 7)
The composite semipermeable membrane obtained in Comparative Example 1 was brought into contact with a solution adjusted so that polyacrylic acid was 150 ppm and DMT-MM was 1500 ppm at 25 ° C. for 1 hour, and then washed with water, and the composite of Comparative Example 7 was combined. A semipermeable membrane was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 8)
The composite semipermeable membrane obtained in Comparative Example 1 was contacted with a solution adjusted to have polyethyleneimine at 100 ppm and DMT-MM at 1500 ppm at 25 ° C. for 1 hour, washed with water, and the composite semipermeable membrane of Comparative Example 8 was washed. A semipermeable membrane was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 9)
The composite semipermeable membrane obtained in Comparative Example 7 was contacted with a solution adjusted to have 1H, 1H-heptafluorobutylamine at 1000 ppm and DMT-MM at 3000 ppm for 1 hour at 25 ° C., washed with water, and compared. The composite semipermeable membrane of Example 9 was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Comparative Example 10)
The composite semipermeable membrane obtained in Comparative Example 7 was contacted with a solution adjusted to have 1H, 1H-tridecafluoroheptylamine at 8000 ppm and DMT-MM at 10000 ppm for 1 hour at 25 ° C., and then washed with water. , A composite semipermeable membrane of Comparative Example 10 was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 1)
The composite semipermeable membrane obtained in Comparative Example 1 was brought into contact with a solution prepared to have 1H, 1H-heptafluorobutylamine at 3000 ppm for 1 hour at 25 ° C., and air was blown at 25 ° C. to dry it using a blower. After that, it was washed with water to obtain a composite semipermeable membrane of Example 1. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 2)
The composite semipermeable membrane obtained in Comparative Example 1 is brought into contact with a solution prepared by adjusting 1H, 1H-tridecafluoroheptylamine to 6000 ppm at 25 ° C. for 1 hour, and dried by blowing air at 25 ° C. using a blower. After that, it was washed with water to obtain a composite semipermeable membrane of Example 2. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 3)
The composite semipermeable membrane obtained in Comparative Example 1 is brought into contact with a solution prepared by adjusting 1H, 1H-tridecafluoroheptylamine to 20000 ppm at 25 ° C. for 1 hour, and dried by blowing air at 25 ° C. using a blower. After that, it was washed with water to obtain a composite semipermeable membrane of Example 3. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 4)
The composite semipermeable membrane obtained in Comparative Example 7 was contacted with a solution adjusted to have 1H, 1H-heptafluorobutylamine at 2000 ppm and DMT-MM at 5000 ppm for 1 hour at 25 ° C., washed with water, and carried out. The composite semipermeable membrane of Example 4 was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 5)
The composite semipermeable membrane obtained in Comparative Example 7 was contacted with a solution adjusted to have 1H, 1H-tridecafluoroheptylamine at 5000 ppm and DMT-MM at 10000 ppm for 1 hour at 25 ° C., and then washed with water. , A composite semipermeable membrane of Example 5 was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 6)
The composite semipermeable membrane obtained in Comparative Example 7 was contacted with a solution adjusted to 1H, 1H-tridecafluoroheptylamine at 10000 ppm and DMT-MM at 20000 ppm for 1 hour at 25 ° C., and then washed with water. , A composite semipermeable membrane of Example 6 was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 7)
The composite semipermeable membrane obtained in Comparative Example 7 was added to a solution prepared so that 1H, 1H-perfluoro-3,6,9-trioxadecane-1-ol was 8000 ppm and DMT-MM was 15000 ppm. After contacting at ° C. for 1 hour, the mixture was washed with water to obtain a composite semipermeable membrane of Example 7. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.
(Example 8)
The composite semipermeable membrane obtained in Comparative Example 8 was brought into contact with a solution adjusted to have perfluorohexanoic acid at 5000 ppm and DMT-MM at 10000 ppm at 25 ° C. for 1 hour, and then washed with water. A composite semipermeable membrane was obtained. When the obtained composite semipermeable membrane was evaluated, the membrane performance was the value shown in Table 1.

As described above, the composite semipermeable membrane of the present invention can achieve both high removability and water permeability.

By using the composite semipermeable membrane of the present invention, raw water can be separated into permeated water such as drinking water and concentrated water that has not permeated the membrane to obtain water suitable for the purpose. The composite semipermeable membrane of the present invention can be particularly preferably used for desalination of brine or seawater.

Claims (4)

A composite semipermeable membrane having a support membrane including a base material and a porous support layer and a separation functional layer provided on the porous support layer, wherein the separation functional layer is a polyfunctional amine and a polyfunctional acid halide. A composite semipermeable membrane having a crosslinked polyamide which is a polymer of the above and a compound having a fluorine atom and satisfying the following (A) and (B).
(A) The contact angle of water in air on the separation function layer side of the composite semipermeable membrane is 70 ° or more and 100 ° or less.
(B) In the X-ray photoelectron spectroscopy measurement performed by irradiating X-rays from the separation function layer side of the composite semipermeable membrane, the ratio of fluorine atoms in the measured element is 8% or more and 15% or less. .. The composite semipermeable membrane according to claim 1, wherein the compound having a fluorine atom is chemically bonded to the crosslinked polyamide. The separation functional layer has a first layer having a crosslinked polyamide which is a polymer of a polyfunctional amine and a polyfunctional acid halide, a second layer having a hydrophilic polymer, and a compound having a fluorine atom. The composite semipermeable membrane according to claim 1, wherein the composite semipermeable membrane is composed of three layers. The composite semipermeable membrane according to claim 3, wherein the second layer having a hydrophilic polymer and the third layer having a compound having a fluorine atom have different compositions.