JP5776274B2 - Composite semipermeable membrane and method for producing the same - Google Patents

Description

  The present invention relates to a composite semipermeable membrane excellent in durability against oxidizing agents, separation performance, and stability during continuous operation, and a method for producing the same.

  As a reverse osmosis membrane used as a water treatment separation membrane that prevents the permeation of dissolved components such as salt, a separation functional layer that provides different membrane separation performance by providing different materials on a microporous support membrane Composite semipermeable membranes are becoming mainstream. Among them, a membrane using polyamide as a separation functional layer as in Patent Document 1 exhibits high desalting performance and water permeability. However, the composite semipermeable membrane using such a polyamide has an amide bond in the main chain, so that the chemical resistance against the oxidizing agent is still insufficient, and it is treated with chlorine, hydrogen peroxide, etc. used for membrane sterilization. As a result, it is known that the desalting performance and the selective separation performance deteriorate significantly.

  Patent Document 2 is disclosed as a technique for imparting chemical resistance to a separation functional layer of a membrane. Chemical resistance is provided by having a separation functional layer formed by polymerizing and condensing a highly chemical-resistant silane compound and an ethylenically unsaturated compound that is versatile in film forming technology and has a wide range of raw material options. It is stated that it will be. This separation functional layer has chemical durability against oxidation conditions, but its removal rate is lower than that of a polyamide membrane, and the increase in water permeability due to continuous water flow operation is larger than that of a polyamide membrane. The problem is inferior stability during continuous operation.

  In addition, the techniques of Patent Documents 3 and 4 are disclosed as water treatment films having a chemical-resistant silane compound on the surface. Although the technique of patent document 3 is a technique which apply | coats a polymer emulsion to a nonwoven fabric, the hole diameter of the film | membrane formed is about several hundred nm. Considering that the hydration radius of general ions is 1 nm or less, this technique cannot achieve the purpose of blocking salt permeation. The technique of Patent Document 4 is a technique for imparting hydrophilicity to the film surface by coating with a silane compound. Even this technique failed to achieve the purpose of blocking salt permeation.

US Pat. No. 4,277,344 International Publication No. 2010/029985 JP 2000-24471 A US Patent Application Publication No. 2010/0230351

  An object of the present invention is to obtain a composite semipermeable membrane having high durability against an oxidant and having high separation performance and stability during continuous water flow operation.

  A compound having two or more reactive groups having an ethylenically unsaturated group can crosslink between polymer chains. Therefore, as a means of reducing and homogenizing the pore size, the removal rate is improved by crosslinking with a compound having two or more reactive groups having an ethylenically unsaturated group, and at the same time the strength of the separation functional layer is increased. Thus, the inventors have conceived of realizing high durability that is not found in the conventional siloxane compound-containing composite semipermeable membrane, and have reached the following invention.

  (1) A compound (A) comprising a separation functional layer formed on a microporous support membrane, wherein the separation functional layer has a reactive group having an ethylenically unsaturated group and a hydrolyzable group bonded to a silicon atom. A compound other than the compound (A), which has one reactive group having an ethylenically unsaturated group and is a compound other than the compound (B) and the compound (A) having an acidic group, which is ethylenically unsaturated. Condensation of hydrolyzable groups possessed by compound (A), compound (A), compound (B), and compound (C) from compound (C) having two or more reactive groups having a group A composite semipermeable membrane formed by polymerization of ethylenically unsaturated groups.

(2) The composite semipermeable membrane according to (1), wherein the compound (A) is a compound represented by the following general formula (a).
Si (R ¹ ) _m (R ² ) _n (R ³ ) _4-mn— General formula (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 a hydrogen atom, Represents an alkyl group or a hydroxy group, and m and n are positive integers satisfying m + n ≦ 4, and each of R ¹ , R ² and R ³ is identical when two or more functional groups are bonded to a silicon atom. It may or may not be.)
(3) The composite semipermeable membrane according to the above 1 or 2, wherein the compound (C) has three or more reactive groups having an ethylenically unsaturated group.

  (4) A compound other than the compound (A) or the compound (A) in which a reactive group and a hydrolyzable group having an ethylenically unsaturated group are bonded to a silicon atom on a microporous support membrane, Compound (C) having one reactive group having a saturated group and other than compound (B) having an acidic group and compound (A) having two or more reactive groups having an ethylenically unsaturated group ) And polymerizing the condensation of the hydrolyzable group possessed by the compound (A) and the ethylenically unsaturated group possessed by the compound (A), the compound (B) and the compound (C). A method for producing a composite semipermeable membrane to be formed.

  According to the present invention, it is possible to obtain a composite semipermeable membrane having high durability against an oxidant, high separation performance, and stability during continuous operation.

  The composite semipermeable membrane of the present invention includes a separation functional layer having a fluid separation function such as desalting performance and water permeation performance, a microporous support membrane for supporting the functional layer, and these separation functional layer and microporous support. It consists of a base material for supporting the membrane.

  The microporous support membrane according to the present invention gives strength to the composite semipermeable membrane of the present invention as a support membrane of the separation functional layer. The separation functional layer is provided on at least one side of the microporous support membrane. 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.

  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, a separation functional layer with sufficiently few defects on the surface can be formed by a chemical reaction. Further, the obtained composite semipermeable membrane has a high pure water permeation flux, and the structure can be maintained without the separation functional layer falling into the support membrane pores during the pressurization operation.

  Here, the pore diameter of the surface of the microporous support membrane can be calculated from an electron micrograph. This refers to the value obtained by measuring and averaging the diameters of all the pores that can be photographed and observed. 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, it can be determined by differential scanning calorimetry (DSC). The details are described in literature (Ishikiriyama et al., Journal of Colloid 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. If the thickness is small, the strength of the microporous support membrane tends to decrease, and as a result, the strength of the composite semipermeable membrane tends to decrease. 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 preferable thickness of these reinforcing materials is usually 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.

  The thickness of the separation functional layer present 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 200 nm. By making the film thinner, cracks are less likely to occur and a reduction in removal rate 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 is formed on the microporous support membrane by the following reaction. That is, a reactive group having an ethylenically unsaturated group is a compound other than the compound (A) having a reactive group having a ethylenically unsaturated group and a hydrolyzable group directly bonded to a silicon atom, and the compound (A) and having a ethylenically unsaturated group. Hydrolyzability possessed by compound (A), starting from compound (C) having at least two reactive groups having ethylenically unsaturated groups, other than compound (B) having one compound and compound (A) It is a separation functional layer formed by group condensation and polymerization of ethylenically unsaturated groups of the compound (A), the compound (B) and the compound (C). A separation function is realized by a network of siloxane bonds formed by the compound (A), and appropriate water permeability is imparted by the compound (B). The compound (C) crosslinks between the polymer chains to reduce and uniform the pore size, thereby improving the removal rate, and simultaneously increasing the strength of the separation functional layer to achieve high durability.

  First, the compound (A) in which a reactive group having 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, a methacryloxypropyl group, an acryloxypropyl group, and a styryl group are preferable.

  Further, through a process in which the hydrolyzable group directly bonded to the silicon atom is changed to a hydroxyl group, a condensation reaction occurs in which the compounds are bonded to each other through a siloxane bond, resulting in a polymer. 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. As an alkoxy group, a C1-C10 thing is preferable, More preferably, it is a C1-C2 thing. The alkenyloxy group preferably has 2 to 10 carbon atoms, more preferably 2 to 4 carbon atoms, and further preferably 3 carbon atoms. As the carboxy group, those having 2 to 10 carbon atoms are preferable, and those having 2 carbon atoms, that is, an acetoxy group is preferable. Examples of the ketoxime group include a methyl ethyl ketoxime group, a dimethyl ketoxime group, and a diethyl ketoxime group. The aminohydroxy group is one in which an amino group is bonded to a silicon atom via an oxygen atom via oxygen. Examples of such include dimethylaminohydroxy group, diethylaminohydroxy group, and methylethylaminohydroxy group. As the halogen atom, a chlorine atom is preferably employed.

  In forming the separation functional layer, a compound in which a part of the hydrolyzable group is hydrolyzed to have a silanol structure can be used. In addition, two or more compounds having a high molecular weight such that a part of the hydrolyzable group is not hydrolyzed, condensed, or crosslinked can be used.

The compound (A) is preferably represented by the following general formula (a).
Si (R ¹ ) _m (R ² ) _n (R ³ ) _4-mn— General formula (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 is as described above.

R ² is a hydrolyzable group, and these are as described above. The number of carbon atoms of the alkyl group to be R ³ is preferably 1 or more and 10 or less, and more preferably 1 or 2.

  As the hydrolyzable group, an alkoxy group is preferably used in forming the separation functional layer because the reaction solution has a viscosity and pot life suitable for film formation.

  Such compounds include vinyltrimethoxysilane, vinyltriethoxysilane, styryltrimethoxysilane, methacryloxypropylmethyldimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropyltriethoxysilane. And acryloxypropyltrimethoxysilane.

  In addition to the compound (A), a reactive group having an ethylenically unsaturated group is not included, but a compound having a hydrolyzable group can also be used. Such a compound is defined as “m ≧ 1” in the general formula (a), but a compound in which m is zero in the general formula (a) is exemplified. Examples of such include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, and methyltriethoxysilane.

  Next, the compound (B) which is a compound other than the compound (A), has one reactive group having an ethylenically unsaturated group, and has an acidic 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. The compound (B) is an alkali-soluble compound having an acidic 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.

  Preferred acids are carboxylic acid, phosphonic acid, phosphoric acid and sulfonic acid, and these acid structures may exist in any form of acid form, ester compound, and metal salt. These compounds (B) having an ethylenically unsaturated group may contain two or more acidic groups, and among them, compounds containing one or two acidic groups are preferable.

  Among the compounds having an ethylenically unsaturated group (B), examples of the compound having a carboxylic acid group include maleic acid, maleic anhydride, acrylic acid, methacrylic acid, 2- (hydroxymethyl) acrylic acid, 4- ( Mention may be made of (meth) acryloyloxyethyl trimellitic acid and the corresponding anhydride, 10-methacryloyloxydecylmalonic acid, N- (2-hydroxy-3-methacryloyloxypropyl) -N-phenylglycine and 4-vinylbenzoic acid.

  Among the compounds (B) having an ethylenically unsaturated group, compounds having a phosphonic acid group include vinylphosphonic acid, 4-vinylphenylphosphonic acid, 4-vinylbenzylphosphonic acid, and 2-methacryloyloxyethylphosphonic acid. 2-methacrylamidoethylphosphonic acid, 4-methacrylamido-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.

  Among the compounds (B) having an ethylenically unsaturated group, the phosphoric acid ester compounds include 2-methacryloyloxypropyl monohydrogen phosphate, 2-methacryloyloxypropyl dihydrogen phosphate, 2-methacryloyloxyethyl mono Hydrogen phosphate and 2-methacryloyloxyethyl dihydrogen phosphate, 2-methacryloyloxyethyl-phenyl-hydrogen phosphate, 10-methacryloyloxydecyl-dihydrogen phosphate, mono- (1-acryloyl-piperidine-4-phosphate) Yl) -ester, 6- (methacrylamide) hexyl dihydrogen phosphate.

  Among the compounds (B) having an ethylenically unsaturated group, examples of the compound having a sulfonic acid group include vinylsulfonic acid, 4-vinylphenylsulfonic acid, and 3- (methacrylamide) propylsulfonic acid.

  In the present invention, it is important to add the compound (C) having two or more reactive groups having an ethylenically unsaturated group. Compound (C) improves the removal rate by cross-linking between the polymer chains formed by compound (A) and compound (B) to reduce and make the pore diameter uniform, and at the same time, increases the strength of the separation functional layer. As a result, the composite semipermeable membrane of the present invention achieves high durability not found in conventional siloxane compound-containing composite semipermeable membranes.

The compound (C) is a compound other than the compound (A) and is not particularly limited as long as it is a compound represented by the following general formula (b).
L (R) _n ... General formula (b)
(R represents any one of a vinyl group, an acryl group, and a methacryl group. L represents an arbitrary atomic group. N is a positive integer of 2 or more.)
R is an unsaturated group responsible for polymerization, and L is a linker connecting them. Examples of L include linear alkyl groups, branched alkyl groups, fluoroalkyl groups and derivatives thereof, oligooxyethylene and derivatives thereof, polyhydric alcohol derivatives, polycarboxylic acid derivatives, sugar derivatives, alkylamines and derivatives thereof, phosphorus Examples include acid derivatives, benzene derivatives, cyclohexane derivatives, imidazole derivatives, pyridine derivatives, triazine derivatives, hexahydrotriazine derivatives, cyanuric acid derivatives, isocyanuric acid derivatives, boroxine derivatives, trisilazane derivatives, and cyclotetrasiloxane derivatives.

  Specifically, as the compound (C) where n = 2, ethylene diacrylate, 1,3-bis (acryloyloxy) propane, 1,4-bis (acryloyloxy) butane, 1,5-bis (acryloyloxy) ) Pentane, 1,6-bis (acryloyloxy) hexane, 1,7-bis (acryloyloxy) heptane, 1,8-bis (acryloyloxy) octane, 1,9-bis (acryloyloxy) nonane, 1,10 -Bis (acryloyloxy) decane, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, neopentyl glycol di Acryla Glycerol diacrylate, N, N′-methylenebisacrylamide, N, N ′-(1,2-dihydroxyethylene) bisacrylamide, diethyl 1,4-phenylene diacrylate, bisphenol A diacrylate, ethylene dimethacrylate 1,3-bis (methacryloyloxy) propane, 1,4-bis (methacryloyloxy) butane, 1,5-bis (methacryloyloxy) pentane, 1,6-bis (methacryloyloxy) hexane, 1,7-bis (Methacryloyloxy) heptane, 1,8-bis (methacryloyloxy) octane, 1,9-bis (methacryloyloxy) nonane, 1,10-bis (methacryloyloxy) decane, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate , Triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, propylene glycol dimethacrylate, dipropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, glycerol dimethacrylate, N, N′-methylenebismethacrylamide, N, N '-(1,2-dihydroxyethylene) bismethacrylamide, diethyl 1,4-phenylenedimethacrylate, bisphenol A dimethacrylate, divinyl oxalate, divinyl malonate, divinyl succinate, divinyl glutarate, adipine Divinyl acid, divinyl pimelate, divinyl suberate, divinyl azelate, divinyl sebacate, divinyl phthalate, divinyl isophthalate, divinyl maleate, divinyl terephthalate , Divinylbenzene, 1,5-hexadiene-3,4-diol, diallyl ether, diallyl sulfide, diallyl disulfide, diallylamine, diallyl oxalate, diallyl malonate, diallyl succinate, diallyl glutarate, diallyl adipate, pimelic acid Diallyl, diallyl suberate, diallyl azelate, diallyl sebacate, diallyl phthalate, diallyl isophthalate, diallyl maleate, diallyl terephthalate, diallyldimethylsilane, diallyldiphenylsilane, 1,3-diallyloxy-2-propanol, isocyanuric Examples thereof include diallylpropyl acid, diallyl 1,4-cyclohexanedicarboxylate, bisphenol A diallyl ether, N, N′-diallyltartaric acid diamide, and the like.

  Since the crosslinking effect of the compound (C) is higher when the number of polymerizable functional groups is larger, in general, a compound with n ≧ 3 is preferable to a compound with n = 2. As compound (C) of n ≧ 3, tris (2-acryloyloxyethyl) cyanurate, tris (2-acryloyloxyethyl) isocyanurate, 1,3,5-triacryloyltriazine, 1,3,5-triacryloyl Hexahydro-1,3,5-triazine, trimethylolpropane triacrylate, gallic acid triacrylate, pentaerythritol triacrylate, pyrogallol triacrylate, cyanuric acid tris (2-methacryloyloxyethyl), isocyanuric acid tris ( 2-methacryloyloxyethyl), 1,3,5-trimethacryloyltriazine, 1,3,5-trimethacryloylhexahydro-1,3,5-triazine, trimethylolpropane trimethacrylate, gallic acid trimethacrylate, penta Lithritol trimethacrylate, 2,4,6-trivinylboroxine, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane, 1,2,4-trivinylcyclohexane, pentaerythritol tetra Acrylate, pentaerythritol tetramethacrylate, pyrogallol triacrylate, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, dipentaerythritol hexaacrylate, dipentaerythritol hexa Examples include methacrylate.

  It can often be proved that the compound (C) is contained in the constituent components of the composite semipermeable membrane by peeling and analyzing the separation functional layer on the surface. For example, when R is an acryl group or a methacryl group, the separation functional layer may be hydrolyzed using hot alkali, and then the low molecular weight component may be separated and subjected to NMR measurement, mass spectrometry, or the like.

  Examples of methods for forming the separation functional layer include a step of applying a reaction solution containing the compound (A), the compound (B) and the compound (C), a step of removing the solvent, and an ethylenically unsaturated group. The polymerization step and the hydrolyzable group condensation step are performed in this order. In the step of polymerizing an ethylenically unsaturated group, condensation of hydrolyzable groups may occur simultaneously.

  First, the reaction liquid containing the compound (A), the compound (B) and the compound (C) is brought into contact with the microporous support membrane. Such a reaction solution is usually a solution containing a solvent. However, such a solvent does not destroy the microporous support membrane, and is added as necessary to compound (A), compound (B) and compound (C). There is no particular limitation as long as it dissolves the polymerization initiator. To this reaction solution, 1 to 10 molar equivalents, preferably 1 to 5 molar equivalents of water, together with an inorganic acid or an organic acid, is added with respect to the number of moles of the compound (A). Thus, it is preferable 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 an alcohol organic solvent, 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 50% by weight to 99% by weight and more preferably 80% by weight to 99% by weight with respect to 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.

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

  When immersed, the contact time between the microporous support membrane and the reaction 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 reaction solution is brought into contact with the microporous support membrane, it is preferable to sufficiently drain the liquid so that no droplets remain on 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. Liquid draining can be performed by holding the microporous support membrane in contact with the reaction liquid in the vertical direction to allow the excess reaction liquid to flow down naturally or by blowing air such as nitrogen from an air nozzle to forcibly drain the liquid. Or the like can be used. In addition, after draining, the membrane surface can be dried to remove a part of the solvent in the reaction solution.

  The step of condensing the hydrolyzable group of the compound is carried out by subjecting the reaction solution to contact with the microporous support membrane and then performing a 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. The reaction temperature is preferably 150 ° C. or lower, and more preferably 120 ° 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.

  As a polymerization method of the ethylenically unsaturated group of the compound (A), the compound (B) and the compound (C), it can be carried out by heat treatment, electromagnetic wave irradiation, electron beam irradiation and plasma irradiation. Here, electromagnetic waves include 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, ultraviolet irradiation is more preferable from the viewpoint of simplicity. When the polymerization is actually performed using ultraviolet rays, these light sources do not need to selectively generate only light in this wavelength range, and any light source that includes 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 the ultraviolet thin film formation property is particularly high. 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.

  Next, when this is heat-treated at about 100 to 200 ° C. for about 10 minutes to 3 hours, a polycondensation reaction occurs, and the composite semipermeable membrane of the present invention in which a separation functional layer is formed on the surface of the microporous support membrane can be obtained. it can. Although the heating temperature depends on the material of the microporous support membrane, if it is too high, dissolution occurs and the pores of the microporous support membrane are blocked, resulting in a decrease in the amount of water produced in the composite semipermeable membrane. On the other hand, if it is too low, the polycondensation reaction becomes insufficient, and the removal rate decreases due to elution of the functional layer.

  In the above production method, the polymerization step of the ethylenically unsaturated group may be performed before or after the polycondensation step with the hydrolyzable group. Moreover, you may perform a polycondensation reaction and a polymerization reaction simultaneously.

  The composite semipermeable membrane thus obtained can be used as it is, but before use, it is preferable to hydrophilize the surface of the membrane with, for example, an alcohol-containing aqueous solution or an alkaline aqueous solution.

  The present invention will be described more specifically with reference to the following 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 the following equation (c), the initial performance of the membrane permeation flux of the composite semipermeable membrane is the following equation (d), and the pure water permeability coefficient is the following equation ( e) The solute permeability coefficient is calculated by the following formula (f), and the pure water permeability coefficient change rate is calculated by the following formula (g).
NaCl removal rate (%) = {(NaCl concentration of the feed solution−NaCl concentration of the permeate) / NaCl concentration of the feed solution} × 100 Formula (c)
Membrane permeation flux (m ³ / m ² / day) = (Amount of permeate per day) / (Membrane area) Formula (d)
Pure water permeability coefficient (m ³ / m ² / sec / Pa) = (membrane permeation flux) / (pressure difference on both sides of the membrane−osmotic pressure difference on both sides of the membrane × solute reflection coefficient) Equation (e)
Solute permeability coefficient (m / sec) = (solute flux through membrane− (1−solute reflection coefficient) × average concentration on both sides of membrane × membrane flux) / (membrane surface concentration−membrane permeate concentration) Formula (f)
Change rate of pure water permeability coefficient (day ⁻¹ ) = (pure water permeability coefficient after passing water−pure water permeability coefficient before passing water) / (pure water permeability coefficient before passing water × water passing time) Expression (G)
Example 1
A 15.7% by weight dimethylformamide solution of polysulfone was cast on a polyethylene terephthalate nonwoven fabric to a thickness of 200 μm at room temperature (25 ° C.), and immediately immersed in pure water and left for 5 minutes to form a microporous support membrane. Produced. The microporous support membrane thus obtained had a surface pore size of 21 nm and a thickness of 150 μm.

In a 65 wt% aqueous solution of isopropyl alcohol, 3-acryloxypropyltrimethoxysilane corresponding to compound (A) is 94 mM, sodium 4-vinylphenylsulfonate corresponding to compound (B) is 66 mM, and compound (C) is The corresponding 1,4-bisacryloyloxybutane was dissolved at a concentration of 10 mM and the photopolymerization initiator 2,2-dimethoxy-2-phenylacetophenone was dissolved at a concentration of 8.5 mM. The microporous support membrane was brought into contact with this solution for 1 minute, and nitrogen was blown from an air nozzle to remove excess solution from the surface of the support membrane to form a layer of the solution on the microporous support membrane. Next, using a UV irradiation apparatus TOSCURE (registered trademark) 752 manufactured by Harrison Toshiba Lighting Co., which can irradiate 365 nm ultraviolet rays, the irradiation intensity is set to 20 mW / cm ² , and ultraviolet rays are irradiated for 15 minutes to make the separation functional layer microporous. A composite semipermeable membrane formed on the surface of the support membrane was prepared.

  Next, the obtained composite semipermeable membrane is held in a hot air dryer at 120 ° C. for 3 hours to condense the compound (A), and a dry composite semipermeable membrane having a separation functional layer on the microporous support membrane is obtained. Obtained. Thereafter, the dried composite semipermeable membrane was hydrophilized by immersing it in a 10% by weight isopropyl alcohol aqueous solution for 10 minutes. 500 ppm saline adjusted to pH 6.5 was supplied to the composite semipermeable membrane thus obtained under the conditions of 0.75 MPa and 25 ° C., and pressure membrane filtration operation was performed. The results shown in Table 1 were obtained by measuring the quality of the permeated water and the feed water after time.

  In addition, the pressure membrane filtration operation was continued, and the performance evaluation was similarly performed 23 hours after the start of the operation. Table 1 also shows the NaCl removal rate of the membrane calculated from the equation (c) and the pure water permeability coefficient change rate calculated from the equation (g) using the performance 3 hours and 23 hours after the start of water flow.

(Example 2)
A composite semipermeable membrane was prepared in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with 1,6-bisacryloyloxyhexane. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

(Example 3)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with 1,4-bismethacryloyloxybutane. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

Example 4
A composite semipermeable membrane was produced in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with tetraethylene glycol diacrylate. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

(Example 5)
A composite semipermeable membrane was prepared in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with N, N′-methylenebisacrylamide. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

(Example 6)
The compound semi-permeable as in Example 1, except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with N, N ′-(1,2-dihydroxyethylene) bisacrylamide. A membrane was prepared. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

(Example 7)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with pentaerythritol triacrylate. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

(Example 8)
A composite semipermeable membrane was prepared in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with tris (2-acryloyloxyethyl) isocyanurate. The obtained composite semipermeable membrane was evaluated in the same manner as in Example 1, and the results shown in Table 1 were obtained.

Example 9
A composite semipermeable membrane was produced in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with pentaerythritol tetraacrylate. 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 produced in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of 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 produced in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with 4-hydroxybutyl acrylate. 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 3)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that 1,4-bisacryloyloxybutane of the compound (C) used in Example 1 was replaced with p-methylstyrene. 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, it turns out that the composite semipermeable membrane shown by Examples 1-9 has a high salt removal rate compared with the composite semipermeable membrane obtained by Comparative Examples 1-3. Moreover, when comparing the pure water permeability coefficient change rate after passing water, the composite semipermeable membranes shown in Examples 1 to 9 are more effective than the composite semipermeable membranes obtained in Comparative Examples 1 to 3. It can be seen that the change is small. Further, in the general formula (b), the pure water permeability coefficient change rate is small in the order of Example 9 where n = 4, Examples 7 and 8 where n = 3, and Examples 1-6 where n = 2. I understand that.

  From the above, the addition of compound (C) is effective in improving the solute removal rate and stability during continuous operation.

  The composite semipermeable membrane of the present invention includes solid-liquid separation, liquid separation, filtration, purification, concentration, sludge treatment, seawater desalination, drinking water production, pure water production, waste water reuse, waste water volume reduction, valuable material recovery, etc. Available in the field of water treatment.

Claims (3)

A separation functional layer is formed on a microporous support membrane, and the separation functional layer comprises a compound (A), a compound (A) in which a reactive group having an ethylenically unsaturated group and a hydrolyzable group are bonded to a silicon atom. A compound other than A) which has one reactive group having an ethylenically unsaturated group, and which is a compound other than compound (B) and compound (A) having an acidic group and has an ethylenically unsaturated group Using the compound (C) having two or more reactive groups as a raw material, the condensation of the hydrolyzable group possessed by the compound (A), and the ethylenic defect possessed by the compound (A), the compound (B) and the compound (C). all SANYO formed by the polymerization of unsaturated groups,
Compound (A) is a compound represented by the following general formula (a),
Si (R ¹ ) _m (R ² ) _n (R ³ ) _4-mn— General formula (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 a hydrogen atom, Represents an alkyl group or a hydroxy group, and m and n are positive integers satisfying m + n ≦ 4, and each of R ¹ , R ² and R ³ is identical when two or more functional groups are bonded to a silicon atom. It may or may not be.)
The compound (B) has a structure selected from ethylene, propylene, methacrylic acid, acrylic acid, styrene and derivatives thereof as the ethylenically unsaturated group, and as the acidic group, carboxylic acid, phosphonic acid, phosphoric acid and Having a structure selected from sulfonic acids,
Compound (C) is a compound represented by the general formula (b).

L (R) _n ... General formula (b)
(R represents any one of a vinyl group, an acryl group, and a methacryl group. L represents an arbitrary atomic group. N is a positive integer of 2 or more.)
Composite semipermeable membrane. The composite semipermeable membrane according to claim 1, wherein the compound (C) has three or more reactive groups having an ethylenically unsaturated group. Compound (A) in which reactive group and hydrolyzable group having ethylenically unsaturated group are bonded to silicon atom on microporous support membrane, compound other than compound (A) and having ethylenically unsaturated group A compound (C) having one or more reactive groups, a compound (B) having an acidic group and a compound other than the compound (A) and having two or more reactive groups having an ethylenically unsaturated group is applied. And the condensation of the hydrolyzable group possessed by the compound (A), and the formation of the separation functional layer by polymerizing the ethylenically unsaturated groups possessed by the compound (A), the compound (B) and the compound (C). A method for producing a semipermeable membrane ,
Compound (A) is a compound represented by the following general formula (a),
Si (R ¹ ) _m (R ² ) _n (R ³ ) _4-mn— General formula (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 a hydrogen atom, Represents an alkyl group or a hydroxy group, and m and n are positive integers satisfying m + n ≦ 4, and each of R ¹ , R ² and R ³ is identical when two or more functional groups are bonded to a silicon atom. It may or may not be.)
The compound (B) has a structure selected from ethylene, propylene, methacrylic acid, acrylic acid, styrene and derivatives thereof as the ethylenically unsaturated group, and as the acidic group, carboxylic acid, phosphonic acid, phosphoric acid and Having a structure selected from sulfonic acids,
Compound (C) is a compound represented by the general formula (b).

L (R) _n ... General formula (b)
(R represents any one of a vinyl group, an acryl group, and a methacryl group. L represents an arbitrary atomic group. N is a positive integer of 2 or more.)
A method for producing a composite semipermeable membrane.