JP2016007593A - Composite semipermeable membrane and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite semipermeable membrane excellent in water permeability and in salt blocking rate.SOLUTION: A composite semipermeable membrane, which comprises a microporous support film and a separation function layer formed on the microporous support film, is characterized in that the separation function layer contains a compound formed by at least two chemical reactions of a polymerization reaction via ethylenic unsaturated groups included in (A) a silicon compound having a silicon atom, a reactive group having an ethylenic unsaturated group directly coupled with the silicon atom, and a hydrolyzable group directly coupled with the silicon atom, and (B) a compound having an ethylenic unsaturated group, other than the (A) compound, and a condensation reaction of the hydrolyzable group of the silicon compound included in the (A) compound, and the separation function layer contains a covalent bond of the hydrolyzable group of the (A) compound with a hydroxyl group contained in (C) a saccharide compound.

Description

  The present invention relates to a composite semipermeable membrane excellent in water permeability and salt rejection and a method for producing the same.

  As a water treatment separation membrane that prevents permeation of dissolved components such as salt, a composite semipermeable membrane comprising a microporous support layer and a separation functional layer thereon is known. Most of the composite semipermeable membranes marketed so far include a layer made of polyamide formed by interfacial polymerization on a microporous support membrane as a separation functional layer.

  However, since the composite semipermeable membrane having a polyamide layer has an amide bond in the main chain, the resistance to an oxidizing agent is insufficient. In particular, it is known that the salt removal performance is significantly reduced by exposure to chlorine or hydrogen peroxide used as a disinfectant.

  From such a background, a film made of a new material has been studied. As an example of imparting high durability against an oxidizing agent to a separation functional layer of a membrane, there is an invention described in Patent Document 1. By having a separation functional layer formed by polymerizing an ethylenically unsaturated compound with high chemical resistance and versatility of film forming technology and a wide range of raw material selection, resistance to oxidizing agents is achieved. It is stated that it will be granted. On the other hand, the properties required for water treatment separation membranes include high separation performance having both a salt rejection and water permeability in addition to chemical resistance. As a film having a silane compound, there is a gas separation film formed by condensing chitosan and a silane compound as in Non-Patent Document 1, but since the film thickness is as extremely thick as 40 μm, it is essential to use it as a water treatment film. Difficult.

International Publication No. 2010/029985

Kariduraganavar, three others, 'Journal of Membrane Science', 441, 2013, p. 83-92

  An object of the present invention is to provide a composite semipermeable membrane having a better balance between salt rejection and water permeability than the composite semipermeable membrane described in Patent Document 1, and a method for producing the same.

In order to solve the above problems, this document discloses the following inventions (1) to (4).
(1) A composite semipermeable membrane comprising a microporous support membrane and a separation functional layer formed on the microporous support membrane,
The separation functional layer has at least 2 polymerization reactions via ethylenically unsaturated groups contained in the following compounds (A) and (B), and a condensation reaction of hydrolyzable groups of the silicon compound of the compound (A). Contains a compound formed by a chemical reaction of the species, and
The composite semipermeable membrane in which the separation functional layer contains a covalent bond between a hydrolyzable group of the following compound (A) and a hydroxyl group contained in the following compound (C).
(A) a silicon compound having a silicon atom, a reactive group having an ethylenically unsaturated group directly bonded to the silicon atom, and a hydrolyzable group directly bonded to the silicon atom (B) an ethylenically unsaturated group A compound semipermeable membrane comprising a compound (C) other than the above (A) having a saccharide compound (2) a microporous support membrane and a separation functional layer formed on the microporous support membrane,
In the presence of the above compound (C), the separation functional layer is formed by a polymerization reaction of ethylenically unsaturated groups contained in the above compounds (A) and (B). A composite semipermeable membrane containing a condensate formed by condensing a hydrolyzable group of a compound.
(3) The composite semipermeable membrane according to (1) or (2), wherein the compound (C) is at least one of a monosaccharide, a disaccharide, and a trisaccharide.
(4) The composite semipermeable membrane according to any one of (1) to (3), wherein the compound (B) has an acidic group.

  According to the present invention, the sugar compound is hydrophilized by having a covalent bond with the hydrolyzable group of the silicon compound in the dense cross-linked structure formed by condensation of the hydrolyzable group of the silicon compound, and the salt blocking rate and water permeability are increased. A composite semipermeable membrane having an excellent balance can be obtained.

  The composite semipermeable membrane of the present invention includes a separation functional layer that separates a solute and a solvent, and a microporous support membrane that gives strength by supporting the separation functional layer.

[1-1. Microporous support membrane]
The microporous support membrane gives strength to the composite semipermeable membrane by supporting the separation functional layer. The separation functional layer is provided on at least one surface of the microporous support membrane.

  A microporous support membrane can be provided on the substrate, and a separation functional layer can be provided on the microporous support membrane. It is also possible to provide a separation functional layer on the substrate and further provide a microporous support membrane on the separation functional layer. Although a plurality of separation functional layers may be provided on the microporous support membrane, it is usually sufficient to have one separation functional layer on one side. In addition, for reasons of membrane support, prevention of clogging, and ensuring water permeability, the layers are generally laminated in order from fine-grained layer to fine-grained, and a microporous support membrane is provided on the substrate. In addition, a structure in which a separation functional layer is further provided on the microporous support membrane is often employed.

  The pore diameter of the surface of the microporous support membrane used in the present invention is preferably in the range of 1 nm to 100 nm. If the pore diameter on the surface of the microporous support membrane is within this range, the obtained composite semipermeable membrane has a high pure water permeation flux, and the separation functional layer does not fall into the support membrane pores during the pressurization operation. The structure can be maintained.

  Here, the pore diameter of the surface of the microporous support membrane can be calculated from an electron micrograph. The surface of the microporous support membrane is photographed with an electron micrograph, the diameters of all the observable pores are measured, and the pore diameter can be obtained by arithmetic averaging. When the pores are not circular, a circle having an area equal to the area of the pores (equivalent circle) can be obtained by an image processing apparatus or the like, and the equivalent circle diameter can be obtained by the method of setting the diameter of the pores. As another means, the pore diameter can be determined by differential scanning calorimetry (DSC) using the principle that water in minute pores has a lower melting point than ordinary water. The details are described in the literature (Ishikiriyama et al., Journal of Colloids and Interface Science, Vol. 171, p103, Academic Press Incorporated (1995)).

  The thickness of the microporous support membrane is preferably in the range of 1 μm to 5 mm, and more preferably in the range of 10 μm to 100 μm. When the thickness is small, the strength of the microporous support membrane is lowered, and as a result, the strength of the composite semipermeable membrane tends to be lowered. On the other hand, when the thickness is large, it becomes difficult to handle when the microporous support membrane and the composite semipermeable membrane obtained therefrom are bent. In order to increase the strength of the composite semipermeable membrane, the microporous support membrane may be reinforced with cloth, nonwoven fabric, paper, or the like. The preferred thickness of these reinforcing materials is 50 μm or more and 150 μm or less.

  The material used for the microporous support membrane is not particularly limited. For example, homopolymers or copolymers such as polysulfone, polyethersulfone, polyamide, polyester, cellulose polymer, vinyl polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide can be used. These polymers can be used alone or blended. Among the above, examples of the cellulose polymer include cellulose acetate and cellulose nitrate. Preferred examples of the vinyl polymer include polyethylene, polypropylene, polyvinyl chloride, polyacrylonitrile and the like. Of these, homopolymers and copolymers such as polysulfone, polyethersulfone, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferable. Furthermore, among these materials, it is particularly preferable to use polysulfone or polyethersulfone which has high chemical stability, mechanical strength and thermal stability and is easy to mold.

[1-2. Separation function layer]
The thickness of the separation functional layer in the composite semipermeable membrane of the present invention is preferably in the range of 5 nm to 500 nm. The lower limit is more preferably 10 nm. More preferably, the upper limit is 400 nm. By making the film thinner, cracks are less likely to occur, and a reduction in removal performance due to defects can be avoided. Further, the separation functional layer thus thinned can improve water permeability.

The separation functional layer of the present invention contains a compound formed by at least two kinds of chemical reactions (I) and (II) below, and includes a hydrolyzable group of the compound (A) and the following compound (C). Contains a structure formed by a covalent bond with an included hydroxyl group.
Chemical reaction:
(I) Polymerization reaction via ethylenically unsaturated group contained in the following compounds (A) and (B) (II) Condensation reaction compound of hydrolyzable group of silicon compound of compound (A):
(A) a silicon compound having a silicon atom, an ethylenically unsaturated group directly bonded to the silicon atom, and a hydrolyzable group directly bonded to the silicon atom (B) the (A) having an ethylenically unsaturated group Compound (C) other than ()) For example, the separation functional layer is formed by conducting the condensation reaction (II) of the hydrolyzable group of the silicon compound of compound (A) in the presence of compound (C). May be. That is, the separation functional layer is a silicon compound that the compound (A) has in the presence of the compound (C) as a polymer formed by the polymerization reaction of the ethylenically unsaturated groups contained in the compounds (A) and (B). It may be formed by condensing the hydrolyzable group. Moreover, before performing the polymerization reaction (I), the hydrolyzable group of the silicon compound of the compound (A) and the hydroxyl group of the compound (C) may be covalently bonded in advance.

  By introducing the compound (C) into the siloxane cross-linked structure, the hydrophilicity of the film is improved, and high water permeability that is not found in a conventional siloxane compound-containing composite semipermeable membrane is realized.

  Furthermore, higher water permeability is implement | achieved because a composition contains the compound (B) which has an acidic group.

  First, the silicon compound (A) in which an ethylenically unsaturated group and a hydrolyzable group are directly bonded to a silicon atom will be described.

  The reactive group having an ethylenically unsaturated group is directly bonded to the silicon atom. Examples of such reactive groups include vinyl groups, allyl groups, methacryloxyethyl groups, methacryloxypropyl groups, acryloxyethyl groups, acryloxypropyl groups, and styryl groups. From the viewpoint of polymerizability, the reactive group is preferably a methacryloxypropyl group, an acryloxypropyl group, or a styryl group.

  Examples of the hydrolyzable group include an alkoxy group, an alkenyloxy group, a carboxy group, a ketoxime group, an aminohydroxy group, a halogen atom and an isocyanate group. It is preferable that carbon number of an alkoxy group is 1-10, and it is more preferable that it is 1-2. The alkenyloxy group preferably has 2 to 10 carbon atoms, more preferably 2 to 4 carbon atoms, and still more preferably 3. The number of carbon atoms of the carboxy group is preferably 2 to 10, and more preferably 2. A carboxy group having two carbons is an acetoxy group. Examples of the ketoxime group include a methyl ethyl ketoxime group, a dimethyl ketoxime group, and a diethyl ketoxime group. In the aminohydroxy group, the amino group is bonded to the silicon atom via an oxygen atom via oxygen. Examples of such aminohydroxy groups include dimethylaminohydroxy group, diethylaminohydroxy group, and methylethylaminohydroxy group. As the halogen atom, a chlorine atom is preferably used.

  In the silicon compound, a part of the hydrolyzable group may be hydrolyzed to have a silanol structure. Two or more silicon compounds may have a high molecular weight to such an extent that some of the hydrolyzable groups are not hydrolyzed, condensed and crosslinked.

The silicon compound (A) is preferably represented by the following general formula (a).
Si (R ¹ ) _m (R ² ) _n (R ³ ) _4-mn (a)
(R ¹ represents a reactive group containing an ethylenically unsaturated group. R ² represents an alkoxy group, an alkenyloxy group, a carboxy group, a ketoxime group, a halogen atom or an isocyanate group. R ³ represents H or alkyl. M and n are integers satisfying m + n ≦ 4 and satisfy m ≧ 1 and n ≧ 1 In each of R ¹ , R ² and R ³ , two or more functional groups are bonded to a silicon atom. They may be the same or different.)
R ¹ is a reactive group containing an ethylenically unsaturated group, and its specific structure is as described above. R ² is a hydrolyzable group, and the specific structure is as described above. It is preferable that carbon number of the alkyl group used as R < ³ > is 1-10, and it is more preferable that it is 1-2.

  As the hydrolyzable group, an alkoxy group is preferably used in forming the separation functional layer because the reaction solution has viscosity.

  Examples of the silicon compound (A) include vinyltrimethoxysilane, vinyltriethoxysilane, styryltrimethoxysilane, methacryloxypropylmethyldimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, and methacryloxy. Examples are propyltriethoxysilane and acryloxypropyltrimethoxysilane.

In addition to the silicon compound (A), it does not have a reactive group having an ethylenically unsaturated group, but a silicon compound having a hydrolyzable group can also be used. Such a silicon compound is preferably represented by the following general formula (b).
Si (R ⁴ ) _p (R ⁵ ) _4-p (b)
(R ⁴ represents an alkoxy group, an alkenyloxy group, a carboxy group, a ketoxime group, a halogen atom or an isocyanate group. R ⁵ represents H or an alkyl group. P is an integer satisfying 1 ≦ p ≦ 4. When two or more functional groups are bonded to a silicon atom in each of R ⁴ and R ^5, they may be the same or different.
Examples of such include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, and methyltriethoxysilane.

  Next, the compound (B) which is a compound other than the compound (A) and has an ethylenically unsaturated group will be described.

  The ethylenically unsaturated group has addition polymerizability. Examples of such compounds include ethylene, propylene, methacrylic acid, acrylic acid, styrene, and derivatives thereof.

  Further, this compound (B) is an alkali-soluble compound having an acid group in order to increase the selective permeability of water and increase the salt rejection when the composite semipermeable membrane is used for separation of an aqueous solution or the like. It is preferable.

  Preferred acid groups include carboxylic acid, phosphonic acid, phosphoric acid and sulfonic acid, and these acid groups may be present in any state of free acid, ester and salt. These compounds having one or more ethylenically unsaturated groups may contain two or more acid groups, and among them, it is preferable to contain 1 to 2 acid groups.

  Among the compounds having a carboxylic acid group among the compounds (B), maleic acid, maleic anhydride, acrylic acid, methacrylic acid, 2- (hydroxymethyl) acrylic acid, 4- (meth) acryloyloxyethyl trimellitic acid and Corresponding anhydrides, 10-methacryloyloxydecylmalonic acid, N- (2-hydroxy-3-methacryloyloxypropyl) -N-phenylglycine, and 4-vinylbenzoic acid are exemplified.

  Among the compounds having a phosphonic acid group among the compounds (B), vinylphosphonic acid, 4-vinylphenylphosphonic acid, 4-vinylbenzylphosphonic acid, 2-methacryloyloxyethylphosphonic acid, 2-methacrylamidoethylphosphonic acid, 4-methacrylamide-4-methyl-phenyl-phosphonic acid, 2- [4- (dihydroxyphosphoryl) -2-oxa-butyl] -acrylic acid, and 2- [2-dihydroxyphosphoryl) -ethoxymethyl] -acrylic acid Examples include -2,4,6-trimethyl-phenyl ester.

  Among the compounds of the compound (B), 2-methacryloyloxypropyl monohydrogen phosphate, 2-methacryloyloxypropyl dihydrogen phosphate, 2-methacryloyloxyethyl monohydrogen phosphate and 2-methacryloyloxyethyl Dihydrogen phosphate, 2-methacryloyloxyethyl-phenyl-hydrogen phosphate, dipentaerythritol-pentamethacryloyloxyphosphate, 10-methacryloyloxydecyl-dihydrogen phosphate, dipentaerythritol pentamethacryloyloxyphosphate, mono-(( 1-acryloyl-piperidin-4-yl) -ester, 6- (methacrylamide) hexyl dihydrogen phosphate, and 1,3-bis- (N-acryloyl-N-propyl-amino) -propan-2-yl - dihydrogen phosphate are exemplified.

  Examples of the compound having a sulfonic acid group among the compounds (B) include vinyl sulfonic acid, 4-vinylphenyl sulfonic acid, and 3- (methacrylamide) propyl sulfonic acid.

  Next, the sugar compound (C) will be described.

  Examples of sugar compounds include monosaccharides such as glucose, mannose, and galactose; oligosaccharides and polysaccharides in which these monosaccharides are configured via glycosidic bonds; and glycosides in which non-saccharides are bonded to hydroxyl groups of these saccharides. Can be given. For example, glucose, mannose, galactose, fucose, rhamnose, arabinose, maltose, trehalose, raffinose, sucrose, cellulose, cyclodextrin and the like can be mentioned. Monosaccharides, disaccharides and trisaccharides are preferably used. These sugars may be used alone or in combination of two or more.

[1-3. Base material]
From the viewpoint of the strength and dimensional stability of the composite semipermeable membrane, the composite semipermeable membrane main body may have a substrate. As the base material, it is preferable to use a fibrous base material in terms of strength, unevenness forming ability and fluid permeability.

  As a base material, both a long fiber nonwoven fabric and a short fiber nonwoven fabric can be used preferably. In particular, long-fiber nonwoven fabrics have excellent film-forming properties, so that when a polymer solution is cast, the solution penetrates through excessive penetration, the porous support membrane peels off, and the substrate It is possible to prevent the film from becoming non-uniform due to fluffing and the like, and the occurrence of defects such as pinholes. Furthermore, since the base material is made of a long-fiber non-woven fabric composed of thermoplastic continuous filaments, non-uniformity and film defects caused by fiber fluffing when a polymer solution is cast compared to a short-fiber non-woven fabric are generated. Can be suppressed. Furthermore, since the composite semipermeable membrane is subjected to tension in the film forming direction when continuously formed, it is preferable to use a long fiber nonwoven fabric having excellent dimensional stability as a base material.

[2. Production method]
The composite semipermeable membrane described above can be manufactured by a manufacturing method including a step of forming a separation functional layer on a microporous support membrane.

The step of forming the separation functional layer on the microporous support membrane is
(i) polymerizing compounds (A) and (B) via an ethylenically unsaturated group;
(ii) applying a reaction solution containing the compounds (A) and (B) or a polymer solution thereof on the microporous support membrane;
(iii) a step of condensing hydrolyzable groups possessed by the compound (A) and forming a covalent bond by a condensation reaction with a hydroxyl group contained in the compound (C);
It is.
In addition, the compound (C) may be included in the steps (i) and (ii). Furthermore, the steps (i), (ii), and (iii) do not have to be performed in this order, and may be performed simultaneously.

  Below, the manufacturing process of the isolation | separation functional layer is demonstrated more concretely.

  First, the compounds (A) and (B) or the compounds (A), (B) and (C) are dissolved in a solvent, and a polymerization reaction is performed via an ethylenically unsaturated group. As such a solvent, compounds (A) and (B) or compounds (A), (B) and (C), and a polymerization initiator which is added as necessary, do not destroy the microporous support membrane. If it melt | dissolves, it will not specifically limit.

  It is preferable to add 1 to 1000 times the amount of water with respect to the number of moles of the compound (A) to the reaction solution together with an inorganic acid or an organic acid to promote hydrolysis of the compound (A).

  As the solvent for the reaction solution, water, an alcohol-based organic solvent, an ether-based organic solvent, a ketone-based organic solvent, and a mixture thereof are preferable. For example, as alcohol-based organic solvents, methanol, ethoxymethanol, ethanol, propanol, butanol, amyl alcohol, cyclohexanol, methylcyclohexanol, ethylene glycol monomethyl ether (2-methoxyethanol), ethylene glycol monoacetate, diethylene glycol monomethyl ether, Examples include diethylene glycol monoacetate, propylene glycol monoethyl ether, propylene glycol monoacetate, dipropylene glycol monoethyl ether, and methoxybutanol. Examples of ether organic solvents include methylal, diethyl ether, dipropyl ether, dibutyl ether, diamyl ether, diethyl acetal, dihexyl ether, trioxane, dioxane and the like. As ketone organic solvents, acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl cyclohexyl ketone, diethyl ketone, ethyl butyl ketone, trimethylnonanone, acetonitrile acetone, dimethyl oxide, phorone, cyclohexanone, dye Acetone alcohol etc. are mentioned.

  The amount of the solvent added is preferably from 50% by weight to 99% by weight, more preferably from 80% by weight to 99% by weight, based on the total weight of the reaction solution. If the amount of the solvent added is too large, defects tend to occur in the membrane, and if it is too small, the water permeability of the resulting composite semipermeable membrane tends to be low.

  As a polymerization method of the ethylenically unsaturated group contained in the compound (A) and the compound (B), heat treatment, electromagnetic wave irradiation, electron beam irradiation, and plasma irradiation can be performed. Here, the electromagnetic wave includes infrared rays, ultraviolet rays, X-rays, γ rays and the like. The polymerization method may be appropriately selected as appropriate, but polymerization by electromagnetic wave irradiation is preferred from the viewpoint of running cost, productivity and the like. Among electromagnetic waves, infrared irradiation and ultraviolet irradiation are more preferable from the viewpoint of simplicity. When the polymerization is actually performed using infrared rays or ultraviolet rays, these light sources do not need to selectively generate only light in this wavelength range, and any light source containing electromagnetic waves in these wavelength ranges may be used. However, from the viewpoint of ease of shortening the polymerization time and controlling the polymerization conditions, it is preferable that the intensity of these electromagnetic waves is higher than electromagnetic waves in other wavelength regions.

  Electromagnetic waves can be generated from halogen lamps, xenon lamps, UV lamps, excimer lamps, metal halide lamps, rare gas fluorescent lamps, mercury lamps, and the like. The energy of the electromagnetic wave is not particularly limited as long as it can be polymerized, but in particular, high-efficiency, low-wavelength ultraviolet rays have high film-forming properties. Such ultraviolet rays can be generated by a low-pressure mercury lamp or an excimer laser lamp. The thickness and form of the separation functional layer according to the present invention may vary greatly depending on the respective polymerization conditions. If polymerization is performed using electromagnetic waves, the thickness and shape of the separation functional layers vary greatly depending on the wavelength of electromagnetic waves, the intensity, the distance to the irradiated object, and the processing time. Sometimes. Therefore, these conditions need to be optimized as appropriate.

  For the purpose of increasing the polymerization rate, it is preferable to add a polymerization initiator, a polymerization accelerator or the like during the formation of the separation functional layer. Here, the polymerization initiator and the polymerization accelerator are not particularly limited, and are appropriately selected according to the structure of the compound to be used, the polymerization technique, and the like.

  The polymerization initiator is exemplified below. As an initiator for polymerization by electromagnetic waves, benzoin ether, dialkylbenzyl ketal, dialkoxyacetophenone, acylphosphine oxide or bisacylphosphine oxide, α-diketone (for example, 9,10-phenanthrenequinone), diacetylquinone, furylquinone, anisylquinone, 4,4′-dichlorobenzylquinone and 4,4′-dialkoxybenzylquinone, and camphorquinone are exemplified. Initiators for thermal polymerization include azo compounds (eg, 2,2′-azobis (isobutyronitrile) (AIBN) or azobis- (4-cyanovaleric acid), or peroxides (eg, dibenzoyl peroxide). , Dilauroyl peroxide, tert-butyl peroctanoate, tert-butyl perbenzoate or di- (tert-butyl) peroxide), aromatic diazonium salts, bissulfonium salts, aromatic iodonium salts, aromatic sulfonium salts, Examples include potassium sulfate, ammonium persulfate, alkyllithium, cumylpotassium, sodium naphthalene, distyryl dianion, and benzopinacol and 2,2'-dialkylbenzopinacol are particularly preferred as initiators for radical polymerization.

  Peroxides and α-diketones are preferably used in combination with aromatic amines to accelerate initiation. This combination is also called a redox system. Examples of such systems include benzoyl peroxide or camphorquinone and amines (eg, N, N-dimethyl-p-toluidine, N, N-dihydroxyethyl-p-toluidine, ethyl p-dimethyl-aminobenzoate). Ester or a derivative thereof). Furthermore, a system containing a peroxide in combination with ascorbic acid, barbiturate or sulfinic acid as a reducing agent is also preferred.

  The contact between the polymer solution and the microporous support membrane is preferably performed uniformly and continuously on the surface of the microporous support membrane. Specifically, for example, a method of coating the polymer solution on the microporous support film using a coating apparatus such as a spin coater, a wire bar, a flow coater, a die coater, a roll coater, or a spray. Furthermore, the method of immersing a microporous support membrane in a polymer solution can be mentioned.

  When immersed, the contact time between the microporous support membrane and the polymer solution is preferably in the range of 0.5 minutes to 10 minutes, and more preferably in the range of 1 minute to 3 minutes. After the polymer solution is brought into contact with the microporous support membrane, it is preferable to sufficiently drain the liquid so that droplets do not remain in the membrane. By sufficiently draining the liquid, it is possible to prevent the remaining portion of the liquid droplet from becoming a film defect after the film is formed and deteriorating the film performance. The liquid draining method includes a method in which the microporous support membrane after contact with the polymer solution is vertically gripped and the excess polymer solution is allowed to flow down naturally, or air such as nitrogen is blown from an air nozzle to force A method of draining can be used. After draining, the membrane surface can be dried to remove part of the solvent content of the polymer solution.

  At this time, when the compound (C) is not added during the polymerization reaction, the compound (C) is added to the polymer solution before the contact between the microporous support membrane and the polymer solution. Even when added during the polymerization reaction, a saccharide compound which is the same as or different from the already added compound (C) may be added.

  The step of condensing the hydrolyzable group of the polymer is performed by bringing the polymer solution into contact with the microporous support membrane, followed by heat treatment. The heating temperature at this time is required to be lower than the temperature at which the microporous support membrane melts and the performance as a separation membrane decreases. In order to allow the condensation reaction to proceed rapidly, it is usually preferred to heat at 0 ° C. or higher, more preferably 20 ° C. or higher. Further, the reaction temperature is preferably 150 ° C. or lower, and more preferably 100 ° C. or lower. If the reaction temperature is 0 ° C. or higher, the hydrolysis and condensation reaction proceed rapidly, and if it is 150 ° C. or lower, the hydrolysis and condensation reaction are easily controlled. Further, by adding a catalyst that promotes hydrolysis or condensation, the reaction can proceed even at a lower temperature. Furthermore, in the present invention, the heating condition and the humidity condition are selected so that the separation functional layer has pores, and the condensation reaction is appropriately performed.

  From the IR measurement of the separation functional layer produced by the above method, it can be proved that the hydroxyl group of the compound (C) and the hydrolyzable group of the silicon compound of the compound (A) have a covalent bond. There are many cases. In addition, even if the produced composite semipermeable membrane is brought into contact with a solution containing the compound (C) as described in the patent document (Japanese Patent Laid-Open No. 2012-135757), the existence of such a covalent bond is not confirmed. Therefore, it is essential to add the compound (C) before the step of condensing the hydrolyzable group of the polymer.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereby.

  In the following examples, the initial performance of the NaCl removal rate of the composite semipermeable membrane is calculated by the following formula (I), and the initial performance of the membrane permeation flux of the composite semipermeable membrane is calculated by the following formula (II). is there.

NaCl removal rate (%) = {(NaCl concentration in the feed solution−NaCl concentration in the permeate) / NaCl concentration in the feed solution} × 100 Formula (I)
Membrane flow velocity of solution (m ³ / m ² / day) = (Amount of permeate per day) / (Membrane area) Formula (II)
Example 1
A 15.7 wt% dimethylformamide solution of polysulfone was cast on a polyethylene terephthalate nonwoven fabric to a thickness of 200 μm at room temperature. After casting, the substrate was immediately immersed in pure water and allowed to stand for 5 minutes to prepare a microporous support membrane. 80 mM sodium 4-vinylphenylene sulfonate corresponding to compound (B) is dissolved in water, and 2-hydroxy-4 '-(2-hydroxyethoxy) -2-methylpropiophenone is dissolved at a concentration of 4 mM as a photopolymerization initiator. I let you. After adjusting the pH of the aqueous solution to 3 with 1M hydrochloric acid, 3-acryloxypropyltrimethoxysilane corresponding to the compound (A) was dissolved at a concentration of 80 mM and stirred for 30 minutes to prepare a film forming solution.

The irradiation intensity when using a UV irradiation device (TOSCURE (registered trademark) 752) manufactured by Toshiba Harrison Co., Ltd. and a UV integrated light meter (UNIMETER UIT-250) manufactured by USHIO ELECTRIC CO., LTD. Was 13.4 mW / cm ² for this solution. Then, ultraviolet rays were irradiated for 60 minutes to prepare a polymer aqueous solution.

  Trehalose dihydrate corresponding to the compound (C) is dissolved in the obtained polymer aqueous solution at a concentration of 5 mM, the microporous support membrane is brought into contact with the aqueous solution for 1 minute, and a spin coater (Opticoat) manufactured by Mikasa Co., Ltd. is used. An excess solution was removed from the surface of the support membrane by MS-A200) to prepare a composite semipermeable membrane having a separation functional layer on the microporous support membrane.

  By holding the obtained composite semipermeable membrane in a hot air dryer at 120 ° C. for 2 hours, the condensation reaction of the hydrolyzable group of the silicon compound of the compound (A) and the sharing with the hydroxyl group of the compound (C) A bond formation reaction was performed to obtain a dry composite semipermeable membrane having a separation functional layer made of 3-acryloxypropyltrimethoxysilane, sodium 4-vinylphenylenesulfonate, and trehalose on a microporous support membrane. Thereafter, the dried composite semipermeable membrane was immersed in a 10% by weight isopropyl alcohol aqueous solution for 10 minutes to make it hydrophilic, and then washed in a 500 mg / L saline solution at 80 ° C. for 15 minutes. The composite semipermeable membrane thus obtained was supplied with 500 mg / L saline adjusted to pH 6.5 under the conditions of 0.75 MPa and 25 ° C., and pressure membrane filtration operation was performed. Table 1 shows the NaCl removal rate and the membrane water production amount calculated from the formulas (I) and (II) by measuring the quality of the permeated water and the feed water and the amount of permeated water after 3 hours.

(Examples 2 to 4)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that trehalose dihydrate corresponding to the compound (C) used in Example 1 was replaced with the compounds shown in Table 1. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

(Comparative Example 1)
A composite semipermeable membrane was prepared in the same manner as in Example 1 except that trehalose dihydrate corresponding to the compound (C) used in Example 1 was not added. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

(Comparative Example 2)
A composite semipermeable membrane was prepared in the same manner as in Comparative Example 1 except that the dry composite membrane was immersed in a 10 wt% isopropyl alcohol aqueous solution for 10 minutes in Comparative Example 1 for 2 minutes before being immersed in a 5 wt% trehalose aqueous solution. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

  From Table 1, the composite semipermeable membranes obtained in Examples 1 to 4 have high water permeability while maintaining the same salt rejection as compared with the composite semipermeable membranes obtained in Comparative Examples 1 and 2. It can be seen that the separation performance is higher.

A separation functional layer obtained by bringing the aqueous polymer solution produced by the same operation as in Example 1 and Comparative Example 1 into contact with a polyethylene terephthalate film and holding it in a hot air dryer at 120 ° C. for 2 hours A separation functional layer obtained by the same method as in Comparative Example 1 is used for the separation functional layer obtained by IR measurement using a FT-IR measurement device (Nicolet AVATAR 360) manufactured by Fisher Scientific. It was confirmed that there was an absorption of 1080 cm ⁻¹ , which is not present. This indicates the presence of Si—O—C bonds. Further, the separation functional layer obtained by immersing the separation functional layer obtained in the same manner as in Comparative Example 1 in a 12 wt% trehalose aqueous solution for 2 minutes did not show an absorption of 1080 cm ⁻¹ .

The composite semipermeable membrane of the present invention can be used for water such as solid-liquid separation, liquid separation, filtration, purification, concentration, sludge treatment, seawater desalination, drinking water production, pure production, wastewater reuse, wastewater diluting, and valuable resource recovery. Can be used in the processing field.

Claims (4)

A composite semipermeable membrane comprising a microporous support membrane and a separation functional layer formed on the microporous support membrane,
The separation functional layer has at least 2 polymerization reactions via ethylenically unsaturated groups contained in the following compounds (A) and (B), and a condensation reaction of hydrolyzable groups of the silicon compound of the compound (A). Contains a compound formed by a chemical reaction of the species, and
The composite semipermeable membrane in which the separation functional layer contains a covalent bond between a hydrolyzable group of the following compound (A) and a hydroxyl group contained in the following compound (C).

(A) a silicon compound having a silicon atom, a reactive group having an ethylenically unsaturated group directly bonded to the silicon atom, and a hydrolyzable group directly bonded to the silicon atom (B) an ethylenically unsaturated group Compounds other than (A) having (C) sugar compounds
A composite semipermeable membrane comprising a microporous support membrane and a separation functional layer formed on the microporous support membrane,
In the presence of the following compound (C), the compound (A) has a polymer formed by the polymerization reaction of the ethylenically unsaturated groups contained in the following compounds (A) and (B). A composite semipermeable membrane containing a condensate formed by condensing a hydrolyzable group of a silicon compound.
(A) a silicon compound having a silicon atom, a reactive group having an ethylenically unsaturated group directly bonded to the silicon atom, and a hydrolyzable group directly bonded to the silicon atom (B) an ethylenically unsaturated group Compound (C) other than the above (A) having a sugar compound
The composite semipermeable membrane according to claim 1 or 2, wherein the compound (C) is at least one of a monosaccharide, a disaccharide, and a trisaccharide.
The composite semipermeable membrane according to any one of claims 1 to 3, wherein the compound (B) has an acidic group.