JP2011083664A - Method of preserving composite semipermeable membrane or membrane element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of preserving a composite semipermeable membrane or a membrane element which causes less deterioration of the membrane performance even in a long preservation. <P>SOLUTION: The method of preserving a composite semipermeable membrane having a skin layer containing a polyamide resin on a porous support which preserves the composite semipermeable membrane with at least the skin layer brought into contact with an aqueous solution containing an alicyclic diamine. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composite semipermeable membrane having a skin layer containing a polyamide resin on a porous support, or a method for preserving a membrane element in which the composite semipermeable membrane is housed in an element container. Such a composite semipermeable membrane or membrane element is suitable for production of ultrapure water, desalination of brine or seawater, etc., and also from contamination that causes pollution such as dyeing wastewater and electrodeposition paint wastewater. It can contribute to the closure of wastewater by removing and recovering contained pollution sources or effective substances. Moreover, it can be used for advanced treatments such as concentration of active ingredients in food applications and removal of harmful components in water purification and sewage applications.

  Currently, many composite semipermeable membranes have been proposed in which a skin layer composed of polyamide obtained by interfacial polymerization of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide is formed on a porous support. (Patent Document 1). There has also been proposed a skin layer made of polyamide obtained by interfacial polymerization of a polyfunctional aromatic amine and a polyfunctional alicyclic acid halide on a porous support (Patent Document 2).

  The composite semipermeable membrane has high salt blocking performance and water permeation performance, but it has been proposed to perform various post-treatments on the produced composite semipermeable membrane for the purpose of further improving the membrane performance.

  For example, for the purpose of providing a composite semipermeable membrane having both practical water permeability and excellent salt-blocking property and oxidation resistance, a method of bringing the produced composite semipermeable membrane into contact with an oxidizing agent aqueous solution has been proposed. (Patent Document 3).

  Moreover, a method of bringing a polyamide active layer into contact with an aqueous polyfunctional tertiary alcohol amine solution has been proposed for the purpose of improving both water permeability and salt rejection to a desired level (Patent Document 4).

  Further, for the purpose of efficiently removing unreacted residues from the liquid separation membrane, the liquid separation membrane is an aqueous solution containing a surfactant, a monovalent or polyhydric alcohol, or a salt of an organic acid and a trialkylamine. There has been proposed a method of bringing it into contact (Patent Document 5).

  Furthermore, a method of immersing the composite membrane in a saccharide solution having a molecular weight of 1000 or less has been proposed for the purpose of preventing a decrease in flow rate (Patent Document 6).

  On the other hand, the composite semipermeable membrane and the membrane element in which the composite semipermeable membrane is housed in an element container are usually stored in a pure water bath after production until before use. There was a problem that the permeation performance (permeation flux) deteriorated.

JP-A-2-187135 JP-A-61-42308 JP 2003-80042 A Special table 2008-505765 gazette JP 2000-24470 A JP 2000-117074 A

  An object of the present invention is to provide a method for preserving a composite semipermeable membrane or membrane element in which membrane performance is unlikely to deteriorate even when stored for a long period of time.

  As a result of intensive studies to achieve the above object, the present inventors have reduced the membrane performance of the composite semipermeable membrane or membrane element even when stored for a long time by adopting the following storage method (deterioration with time). As a result, the present invention has been completed.

  That is, the present invention relates to a method for storing a composite semipermeable membrane having a skin layer containing a polyamide-based resin on a porous support, wherein at least the skin layer is stored in a state in contact with an alicyclic diamine-containing aqueous solution. The present invention relates to a method for storing a composite semipermeable membrane.

  Further, the present invention provides a method for preserving a membrane element in which a composite semipermeable membrane having a skin layer containing a polyamide-based resin on a porous support is housed in an element container, and at least the skin layer is contacted with an alicyclic diamine-containing aqueous solution. It is related with the preservation | save method of the membrane element characterized by preserve | saving in the made state.

  It is not clear why the skin layer can be kept in contact with the alicyclic diamine-containing aqueous solution to suppress the decrease in membrane performance, particularly the permeation flux, but the alicyclic diamine in the aqueous solution is the end of the polyamide. This is probably because the excessive reaction between the functional group and the unreacted polyfunctional amine component was inhibited, and the increase in the density of the skin layer was suppressed.

  The alicyclic diamine is preferably a bis-type alicyclic diamine, and particularly preferably bis (4-aminocyclohexyl) methane. When a bis-type alicyclic diamine, particularly bis (4-aminocyclohexyl) methane, is used, a decrease in permeation flux can be more effectively suppressed.

  The concentration of the alicyclic diamine in the alicyclic diamine-containing aqueous solution is preferably 10 ppm to 1500 ppm. If the concentration of the alicyclic diamine is too low, it is difficult to suppress a decrease in the permeation flux. On the other hand, if the concentration is too high, the alicyclic diamine tends to adhere to the skin layer and the permeation flux tends to decrease. .

  When the porous support is an epoxy resin porous body, the effect of suppressing the decrease in permeation flux after long-term storage is remarkable. The reason for this is not clear, but the alicyclic diamine in the aqueous solution inhibited the excessive reaction between the terminal functional group of the epoxy resin and the unreacted polyfunctional amine component, and the increase in the density of the porous epoxy resin was suppressed. it is conceivable that.

  In particular, when the composite semipermeable membrane in which the porous support is a porous epoxy resin is stored in contact with an aqueous solution containing a bis-type alicyclic diamine, particularly bis (4-aminocyclohexyl) methane. Surprisingly, the permeation flux tends to be higher than before storage.

  When the polyfunctional amine component that is a raw material component of the polyamide-based resin is an aromatic polyfunctional amine, the effect of suppressing the decrease in permeation flux after long-term storage is remarkable. This is probably because the alicyclic diamine in the aqueous solution inhibited the excessive reaction of the unreacted aromatic polyfunctional amine, thereby suppressing the decrease in the permeation flux.

  Embodiments of the present invention will be described below. The composite semipermeable membrane of the present invention has a skin layer containing a polyamide-based resin on a porous support. The said composite semipermeable membrane can be manufactured by forming the skin layer containing the polyamide-type resin formed by making a polyfunctional amine component and a polyfunctional acid halide component react on the surface of a porous support body.

  The polyfunctional amine component is a polyfunctional amine having two or more reactive amino groups, and examples thereof include aromatic, aliphatic and alicyclic polyfunctional amines.

  Examples of the aromatic polyfunctional amine include m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, and 3,5-diamino. Examples include benzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, N, N′-dimethyl-m-phenylenediamine, 2,4-diaminoanisole, amidole, xylylenediamine and the like.

  Examples of the aliphatic polyfunctional amine include ethylenediamine, propylenediamine, tris (2-aminoethyl) amine, N-phenyl-ethylenediamine, and the like.

  Examples of the alicyclic polyfunctional amine include 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminomethylpiperazine, and the like. .

  These polyfunctional amines may be used alone or in combination of two or more. In order to obtain a skin layer having a high salt inhibition performance, it is preferable to use an aromatic polyfunctional amine.

  The polyfunctional acid halide component is a polyfunctional acid halide having two or more reactive carbonyl groups.

  Examples of the polyfunctional acid halide include aromatic, aliphatic and alicyclic polyfunctional acid halides.

  Examples of the aromatic polyfunctional acid halide include trimesic acid trichloride, terephthalic acid dichloride, isophthalic acid dichloride, biphenyldicarboxylic acid dichloride, naphthalene dicarboxylic acid dichloride, benzenetrisulfonic acid trichloride, benzenedisulfonic acid dichloride, chlorosulfonylbenzene dicarboxylic acid. An acid dichloride etc. are mentioned.

  Examples of the aliphatic polyfunctional acid halide include propanedicarboxylic acid dichloride, butanedicarboxylic acid dichloride, pentanedicarboxylic acid dichloride, propanetricarboxylic acid trichloride, butanetricarboxylic acid trichloride, pentanetricarboxylic acid trichloride, glutaryl halide, adipoid Examples include luhalides.

  Examples of the alicyclic polyfunctional acid halide include cyclopropanetricarboxylic acid trichloride, cyclobutanetetracarboxylic acid tetrachloride, cyclopentanetricarboxylic acid trichloride, cyclopentanetetracarboxylic acid tetrachloride, cyclohexanetricarboxylic acid trichloride, and tetrahydrofuran. Examples thereof include tetracarboxylic acid tetrachloride, cyclopentane dicarboxylic acid dichloride, cyclobutane dicarboxylic acid dichloride, cyclohexane dicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride.

  These polyfunctional acid halides may be used alone or in combination of two or more. In order to obtain a skin layer having a high salt inhibition performance, it is preferable to use an aromatic polyfunctional acid halide. Moreover, it is preferable to form a crosslinked structure by using a trifunctional or higher polyfunctional acid halide as at least a part of the polyfunctional acid halide component.

  In order to improve the performance of the skin layer containing a polyamide-based resin, a polymer such as polyvinyl alcohol, polyvinyl pyrrolidone, or polyacrylic acid, or a polyhydric alcohol such as sorbitol or glycerin may be copolymerized.

  The porous support that supports the skin layer is not particularly limited as long as it can support the skin layer, and usually an ultrafiltration membrane having micropores with an average pore diameter of about 10 to 500 mm is preferably used. Examples of the material for forming the porous support include polysulfone, polyarylethersulfone such as polyethersulfone, polyimide, polyvinylidene fluoride, and the like. Polysulfone and polyarylethersulfone are preferably used from the viewpoint of stability. The thickness of such a porous support is usually about 25 to 125 μm, preferably about 40 to 75 μm, but is not necessarily limited thereto. In addition, the porous support may be reinforced with a backing by a woven fabric, a nonwoven fabric or the like.

  Moreover, you may use an epoxy resin porous body as a porous support body. The preservation method of the present invention is particularly effective when the porous support is an epoxy resin porous material. Hereinafter, the manufacturing method of an epoxy resin porous body is demonstrated.

  As a raw material for the epoxy resin porous body, an epoxy resin composition containing an epoxy resin, a curing agent, and a porogen is used.

  Examples of the epoxy resin include bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, stilbene type epoxy resin, biphenyl type epoxy resin, bisphenol A novolak type epoxy resin, Contains cresol novolac type epoxy resin, diaminodiphenylmethane type epoxy resin, polyphenyl base epoxy resin such as tetrakis (hydroxyphenyl) ethane base, fluorene-containing epoxy resin, triglycidyl isocyanurate, heteroaromatic ring (eg triazine ring) Aromatic epoxy resins such as epoxy resins; aliphatic glycidyl ether type epoxy resins, aliphatic glycidyl ester type epoxy resins, alicyclic glycidyl esters Ether type epoxy resin, aromatic epoxy resins such as alicyclic glycidyl ester type epoxy resins. These may be used alone or in combination of two or more.

  Among these, bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F are used to form a uniform three-dimensional network skeleton and uniform pores, and to ensure chemical resistance and film strength. Type epoxy resin, bisphenol AD type epoxy resin, fluorene-containing epoxy resin, and at least one aromatic epoxy resin selected from the group consisting of triglycidyl isocyanurate; alicyclic glycidyl ether type epoxy resin, and alicyclic glycidyl It is preferable to use at least one alicyclic epoxy resin selected from the group consisting of ester-type epoxy resins. In particular, from the group consisting of bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol AD type epoxy resin, fluorene-containing epoxy resin, and triglycidyl isocyanurate having an epoxy equivalent of 6000 or less and a melting point of 170 ° C. At least one aromatic epoxy resin selected; selected from the group consisting of an alicyclic glycidyl ether type epoxy resin having an epoxy equivalent of 6000 or less and a melting point of 170 ° C. or less, and an alicyclic glycidyl ester type epoxy resin It is preferable to use at least one alicyclic epoxy resin.

  Examples of the curing agent include aromatic amines (eg, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, benzyldimethylamine, dimethylaminomethylbenzene), aromatic acid anhydrides (eg, phthalic anhydride, trimellitic anhydride). Acid, pyromellitic anhydride, etc.), phenolic resins, phenol novolac resins, heteroaromatic ring-containing amines (eg, triazine ring-containing amines), etc .; aliphatic amines (eg, ethylenediamine, diethylenetriamine, triethylene) Tetramine, tetraethylenepentamine, iminobispropylamine, bis (hexamethylene) triamine, 1,3,6-trisaminomethylhexane, polymethylenediamine, trimethylhexamethylenediamine, polyether Diamine), alicyclic amines (isophoronediamine, menthanediamine, N-aminoethylpiperazine, 3,9-bis (3-aminopropyl) 2,4,8,10-tetraoxaspiro (5,5) undecane) Non-aromatic curing agents such as adducts, bis (4-amino-3-methylcyclohexyl) methane, bis (4-aminocyclohexyl) methane, modified products thereof, and the like, and aliphatic polyamidoamines composed of polyamines and dimer acids. Can be mentioned. These may be used alone or in combination of two or more.

  Among these, in order to form a uniform three-dimensional network skeleton and uniform pores, and to ensure film strength and elastic modulus, metaphenylenediamine having two or more primary amines in the molecule, diaminodiphenylmethane, And at least one aromatic amine curing agent selected from the group consisting of diaminodiphenylsulfone; bis (4-amino-3-methylcyclohexyl) methane having two or more primary amines in the molecule, and bis (4-amino) It is preferred to use at least one alicyclic amine curing agent selected from the group consisting of (cyclohexyl) methane.

  Moreover, as a combination of an epoxy resin and a hardening | curing agent, the combination of an aromatic epoxy resin and an alicyclic amine hardening | curing agent or the combination of an alicyclic epoxy resin and an aromatic amine hardening | curing agent is preferable. These combinations increase the heat resistance of the resulting epoxy resin porous body and are suitably used as a porous support for a composite semipermeable membrane.

  A porogen is a solvent that can dissolve an epoxy resin and a curing agent, and can cause reaction-induced phase separation after the epoxy resin and the curing agent are polymerized, such as methyl cellosolve and ethyl cellosolve. Examples include cellosolves, esters such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and glycols such as polyethylene glycol and polypropylene glycol. These may be used alone or in combination of two or more.

  Among these, in order to form a uniform three-dimensional network skeleton and uniform pores, methyl cellosolve, ethyl cellosolve, polyethylene glycol having a molecular weight of 600 or less, ethylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate should be used. In particular, polyethylene glycol having a molecular weight of 200 or less and propylene glycol monomethyl ether acetate are preferably used.

  Moreover, even if it is insoluble or hardly soluble at room temperature with each epoxy resin or curing agent, a solvent in which a reaction product of the epoxy resin and the curing agent is soluble can be used as a porogen. Examples of such porogen include brominated bisphenol A type epoxy resin (“Epicoat 5058” manufactured by Japan Epoxy Resin Co., Ltd.).

  The porosity, average pore size, pore size distribution, etc. of the epoxy resin porous material are the types of raw materials such as epoxy resin, curing agent, porogen, etc. and the mixing ratio, and the reaction such as the heating temperature and heating time during reaction-induced phase separation. Since it varies depending on the conditions, it is preferable to create a phase diagram of the system and select the optimum conditions in order to obtain the desired porosity, average pore diameter, and pore diameter distribution. In addition, by controlling the molecular weight, molecular weight distribution, system viscosity, crosslinking reaction rate, etc. of the crosslinked epoxy resin during phase separation, the co-continuous structure of the crosslinked epoxy resin and porogen is fixed in a specific state and stable. A porous structure can be obtained.

  Moreover, the kind and compounding ratio of an epoxy resin and a hardening | curing agent may be determined so that the carbon atom ratio derived from the aromatic ring with respect to all the carbon atoms which comprise an epoxy resin porous body may become the range of 0.1-0.65. preferable. When the above value is less than 0.1, the recognizability of the planar structure of the separation medium, which is a characteristic of the epoxy resin porous body, tends to decrease. On the other hand, when it exceeds 0.65, it becomes difficult to form a uniform three-dimensional network skeleton.

  Moreover, as for the mixture ratio of the hardening | curing agent with respect to an epoxy resin, it is preferable that hardening | curing agent equivalent is 0.6-1.5 with respect to 1 equivalent of epoxy groups. When the curing agent equivalent is less than 0.6, the crosslinking density of the cured product is lowered, and the heat resistance, solvent resistance and the like tend to be lowered. On the other hand, if it exceeds 1.5, unreacted curing agent remains or tends to hinder the improvement of the crosslinking density. In addition to the above-described curing agent, a curing accelerator may be added to the solution in order to obtain a target porous structure. Known curing accelerators can be used, for example, tertiary amines such as triethylamine and tributylamine, 2-phenol-4-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenol- Examples thereof include imidazoles such as 4,5-dihydroxyimidazole.

  The average pore diameter of the epoxy resin porous body is preferably 0.01 to 0.4 μm. In order to adjust to the average pore diameter, the porogen is 40 to 80 with respect to the total weight of the epoxy resin, the curing agent, and the porogen. It is preferable to use by weight. When the amount of the porogen is less than 40% by weight, the average pore diameter tends to be too small or no pores are formed. On the other hand, when the amount of the porogen exceeds 80% by weight, the average pore diameter becomes too large to form a uniform skin layer on the porous body, or the salt rejection tends to be remarkably reduced. The average pore diameter of the epoxy resin porous body is preferably 0.05 to 0.2 μm. For that purpose, it is more preferable to use 60 to 70% by weight of porogen, and particularly preferably 60 to 65% by weight.

  Moreover, as a method for adjusting the average pore diameter of the epoxy resin porous body to 0.01 to 0.4 μm, a method in which two or more epoxy resins having different epoxy equivalents are mixed and used is also suitable. At that time, the difference in epoxy equivalent is preferably 100 or more.

  Moreover, the average pore diameter of the epoxy resin porous body can be adjusted to the target range by appropriately setting various conditions such as the total epoxy equivalent and the porogen ratio and the curing temperature.

  The said epoxy resin porous body can be produced with the following method, for example.

  1) An epoxy resin composition containing an epoxy resin, a curing agent, and a porogen is applied onto a substrate, and then the applied epoxy resin composition is heated to three-dimensionally crosslink the epoxy resin. At that time, a co-continuous structure is formed by phase separation of the crosslinked epoxy resin and the porogen. Thereafter, the porogen is washed and removed from the obtained epoxy resin sheet and dried to produce an epoxy resin porous body having pores communicating with the three-dimensional network skeleton. The substrate to be used is not particularly limited, and examples thereof include a plastic substrate, a glass substrate, and a metal plate.

  2) An epoxy resin composition containing an epoxy resin, a curing agent, and a porogen is applied onto a substrate, and then another substrate is placed on the applied epoxy resin composition to produce a sandwich structure. In order to provide a certain thickness between the substrates, it is preferable to provide spacers (for example, double-sided tape) at the four corners of the substrates. Then, the sandwich structure is heated to cross-link the epoxy resin three-dimensionally. At that time, a co-continuous structure is formed by phase separation of the crosslinked epoxy resin and the porogen. Thereafter, the obtained epoxy resin sheet is taken out, and the porogen is washed and removed, followed by drying to produce an epoxy resin porous body having pores communicating with the three-dimensional network skeleton. The substrate to be used is not particularly limited, and examples thereof include a plastic substrate, a glass substrate, and a metal plate, and it is particularly preferable to use a glass substrate.

  3) An epoxy resin composition containing an epoxy resin, a curing agent, and a porogen is filled in a mold having a predetermined shape, and then heated to three-dimensionally crosslink the epoxy resin to produce a cylindrical or columnar resin block. . At that time, a co-continuous structure is formed by phase separation of the crosslinked epoxy resin and the porogen. Thereafter, the surface of the block is cut with a predetermined thickness while rotating the block about the cylindrical axis or the columnar axis to produce a long epoxy resin sheet. Then, the porogen in the epoxy resin sheet is washed and removed, and dried to produce an epoxy resin porous body having pores communicating with the three-dimensional network skeleton.

  The conditions for heating the epoxy resin composition are not particularly limited, but the temperature is about 100 to 150 ° C., and the heating time is about 10 minutes to 5 hours. Post-curing may be performed after the heat treatment in order to increase the degree of crosslinking of the crosslinked epoxy resin.

  Examples of the solvent used for removing the porogen from the obtained epoxy resin sheet include water, DMF, DMSO, THF, and mixed solvents thereof, and are appropriately selected according to the type of porogen.

  Although the drying conditions of the epoxy resin porous body from which the porogen has been removed are not particularly limited, the temperature is about 40 to 120 ° C., and the drying time is about 0.2 to 3 hours.

  The thickness of the epoxy resin porous body is not particularly limited, but is about 50 to 250 μm from the viewpoints of strength, practical water permeability and salt blocking property. Moreover, the back surface of the epoxy resin porous body may be reinforced with a woven fabric, a nonwoven fabric or the like.

  The method for forming the skin layer containing the polyamide resin on the surface of the porous support is not particularly limited, and any known technique can be used. For example, an interfacial condensation method, a phase separation method, a thin film coating method and the like can be mentioned. Specifically, the interfacial condensation method is a method in which a skin layer is formed by bringing an aqueous amine solution containing a polyfunctional amine component into contact with an organic solution containing a polyfunctional acid halide component to cause interfacial polymerization. Or a method of directly forming the skin layer on the porous support by interfacial polymerization by bringing the two kinds of solutions into contact with each other on the porous support. Details of the conditions of the interfacial condensation method are described in JP-A-58-24303, JP-A-1-180208 and the like, and those known techniques can be appropriately employed.

  In the present invention, an aqueous solution coating layer comprising an aqueous amine solution containing a polyfunctional amine component is formed on a porous support, and then an organic solution containing the polyfunctional acid halide component is contacted with the aqueous solution coating layer to perform interfacial polymerization. The method of forming a skin layer by making it preferable is preferable.

  In the interfacial polymerization method, the concentration of the polyfunctional amine component in the aqueous amine solution is not particularly limited, but is preferably 0.1 to 5% by weight, more preferably 0.5 to 2% by weight. When the concentration of the polyfunctional amine component is less than 0.1% by weight, defects such as pinholes are likely to occur in the skin layer, and the salt blocking performance tends to decrease. On the other hand, when the concentration of the polyfunctional amine component exceeds 5% by weight, the polyfunctional amine component is likely to penetrate into the porous support, or the film thickness becomes too thick to increase the permeation resistance. The bundle tends to decrease.

  The concentration of the polyfunctional acid halide component in the organic solution is not particularly limited, but is preferably 0.01 to 5% by weight, more preferably 0.05 to 3% by weight. If the concentration of the polyfunctional acid halide component is less than 0.01% by weight, the unreacted polyfunctional amine component tends to remain, or defects such as pinholes are likely to occur in the skin layer, resulting in a decrease in salt blocking performance. Tend to. On the other hand, when the concentration of the polyfunctional acid halide component exceeds 5% by weight, the unreacted polyfunctional acid halide component tends to remain, or the film thickness becomes too thick and the permeation resistance increases, so that the permeation flux is increased. It tends to decrease.

  The organic solvent used in the organic solution is not particularly limited as long as it has low solubility in water, does not deteriorate the porous support, and dissolves the polyfunctional acid halide component. For example, cyclohexane, heptane, octane And saturated hydrocarbons such as nonane, and halogen-substituted hydrocarbons such as 1,1,2-trichlorotrifluoroethane. Preferred is a saturated hydrocarbon having a boiling point of 300 ° C. or lower, more preferably a boiling point of 200 ° C. or lower.

Various additives can be added to the aqueous amine solution and the organic solution for the purpose of facilitating film formation and improving the performance of the resulting composite semipermeable membrane. Examples of the additive include surfactants such as sodium dodecylbenzenesulfonate, sodium dodecylsulfate, and sodium laurylsulfate, sodium hydroxide that removes hydrogen halide generated by polymerization, trisodium phosphate, and triethylamine. And basic compounds, acylation catalysts, compounds having a solubility parameter of 8 to 14 (cal / cm ³ ) ^1/2 described in JP-A-8-224452, and the like.

  After contact with the organic solution, the excess organic solution on the porous support is removed, and the formed film on the porous support is dried by heating at 20 to 150 ° C., preferably 70 to 130 ° C. Form. By heat-treating the formed film, the mechanical strength and heat resistance of the skin layer can be increased. The heating time is preferably about 1 to 10 minutes, more preferably about 2 to 8 minutes.

  The thickness of the skin layer formed on the porous support is not particularly limited, but is usually about 0.05 to 2 μm, preferably 0.1 to 1 μm.

  In order to further improve the salt-blocking property, water permeability, oxidation resistance, and the like of the composite semipermeable membrane, various conventionally known treatments may be performed.

  The method for preserving a composite semipermeable membrane according to the present invention is characterized in that at least the skin layer of the composite semipermeable membrane is preserved in contact with an alicyclic diamine-containing aqueous solution. In addition, a composite semipermeable membrane processed into a spiral shape or the like is housed in an element container to produce a membrane element, and at least the skin layer in the membrane element is stored in contact with an alicyclic diamine-containing aqueous solution. The effect is obtained.

  The alicyclic diamine is not particularly limited as long as it is water-soluble, but is preferably a bis type. For example, bis (4-aminocyclohexyl) methane, bis (3-aminocyclohexyl) methane, and bis (2- Aminocyclohexyl) methane and the like. These may be used alone or in combination of two or more.

  The concentration of the alicyclic diamine in the aqueous solution needs to be adjusted as appropriate depending on the material for forming the skin layer and the porous support, but if it is usually 10 ppm to 1500 ppm, a decrease in membrane performance can be suppressed for a long period of time, A more preferred concentration is 50 ppm to 1000 ppm.

  Examples of the method of bringing the skin layer into contact with the alicyclic diamine-containing aqueous solution include all methods such as dipping, spraying, coating, showering, etc., but it is most preferable to immerse in order to preserve the contact state sufficiently. . In addition, at least the skin layer can be brought into contact with the alicyclic diamine-containing aqueous solution to suppress a decrease in membrane performance during storage, but in order to further suppress the decrease in membrane performance, the entire composite semipermeable membrane is alicyclic. It is preferable to contact the diamine-containing aqueous solution.

  The temperature at which the composite semipermeable membrane or membrane element is stored is not particularly limited, but is preferably a low temperature. Specifically, it is about 0-60 degreeC, Preferably it is 15-50 degreeC.

  According to the storage method of the present invention, even when the composite semipermeable membrane or membrane element is stored for about 2 months, the flux ratio (permeation flux after storage / initial permeation flux) is maintained at 0.8 or more. Can do.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(Preparation of porous support)
Production Example 1
A film-forming dope in which 18% by weight of polysulfone (manufactured by Solvay, P-3500) was dissolved in N, N-dimethylformamide (DMF) was uniformly applied to a nonwoven fabric substrate with a wet thickness of 200 μm. Thereafter, the polysulfone-based porous support having a polysulfone microporous layer on the nonwoven fabric substrate is immediately solidified by being immersed in water at 40 to 50 ° C., and DMF which is a solvent is completely extracted and washed. Produced.

Production Example 2
Add 53 g of polyethylene glycol 200 (Tokyo Kasei Co., Ltd.) to 23.3 g of bisphenol A type epoxy resin (Toto Kasei Co., Ltd., trade name “YD-128”, epoxy equivalent: 184-194 (g / eq)), Using an autorotation / revolution mixer (trade name “Awatori Netaro” ARE-250), the mixture was stirred at 2000 rpm for 5 minutes and dissolved to obtain an epoxy resin / polyethylene glycol solution. Next, 5.2 g of bis (4-aminocyclohexyl) methane (Tokyo Kasei Co., Ltd.) is added to the epoxy resin / polyethylene glycol solution, stirred at 2000 rpm for 10 minutes using an autorotation / revolution mixer, dissolved and dissolved in an epoxy resin. A polyethylene glycol / curing agent solution was obtained.
The epoxy resin / polyethylene glycol / curing agent solution was applied on a soda glass plate provided with double-sided tape at the four corners, and another soda glass plate was laminated thereon to obtain a sandwich structure. Thereafter, the sandwich structure was placed in a dryer and reaction-cured at 120 ° C. for 3 hours. After cooling, the epoxy resin sheet was taken out and immersed in water for 12 hours to remove polyethylene glycol. Thereafter, it was dried in a dryer at 50 ° C. for about 4 hours to obtain an epoxy resin porous support. When the average pore diameter of the porous epoxy resin support was measured by an auto pore 9520 apparatus manufactured by Shimadzu Corporation by mercury porosimetry, it was 0.078 μm. As the average pore diameter, a median diameter under the condition of an initial pressure of 7 kPa was adopted.

(Production of composite semipermeable membrane)
Production Example 3
An amine aqueous solution containing 1% by weight of m-phenylenediamine, 3% by weight of triethylamine, and 6% by weight of camphorsulfonic acid was applied on the polysulfone porous support prepared in Production Example 1, and then an excess aqueous amine solution was used. The aqueous solution coating layer was formed by removing. Next, an isooctane solution containing 0.2% by weight of trimesic acid chloride was applied to the surface of the aqueous solution coating layer. Thereafter, the excess solution is removed, and further maintained in a hot air dryer at 120 ° C. for 3 minutes to form a skin layer containing a polyamide resin on the polysulfone porous support to produce a composite semipermeable membrane A. did.

Production Example 4
An amine aqueous solution containing 1% by weight of m-phenylenediamine, 3% by weight of triethylamine, and 6% by weight of camphorsulfonic acid was applied onto the epoxy resin porous support prepared in Production Example 2, and then an excess aqueous amine solution was applied. The aqueous solution coating layer was formed by removing. Next, an isooctane solution containing 0.2% by weight of trimesic acid chloride was applied to the surface of the aqueous solution coating layer. Thereafter, the excess solution is removed, and further kept in a 120 ° C. hot air dryer for 3 minutes to form a skin layer containing a polyamide-based resin on the porous epoxy resin support to produce a composite semipermeable membrane B did.

(Measurement of initial permeation flux)
The produced composite semipermeable membranes A and B were cut into predetermined shapes and sizes, and set in cells for flat membrane evaluation. An aqueous solution (at 25 ° C.) containing 1500 ppm NaCl and adjusted to pH 6.5 using NaOH is applied to the supply side and permeation side of the membrane, and in the case of the composite semipermeable membrane A, a differential pressure of 1.5 MPa is applied. In the case of the membrane B, a differential pressure of 3.0 MPa was applied and brought into contact with the membrane. The permeation rate of the permeated water obtained by this operation was measured, and the permeation flux (m ³ / m ² · d) was calculated. The results are shown in Table 1.

Example 1
Bis (4-aminocyclohexyl) methane (hereinafter abbreviated as BACM) was added to purified water to prepare a BACM aqueous solution having a concentration of 100 ppm. The composite semipermeable membrane A was completely immersed in the BACM aqueous solution adjusted to 35 ° C., and stored for 11 days, 20 days, and 42 days. In general, it is preferable to store the composite semipermeable membrane at a low temperature, but an accelerated test was performed using a 35 ° C. BACM aqueous solution in order to express the difference in effect in a short period of time. After storage for each period, the composite semipermeable membrane A was taken out from the BACM aqueous solution, and the permeation flux was measured by the same method as described above to determine the flux ratio (permeation flux after storage / initial permeation flux). The results are shown in Table 1.

Examples 2 to 4, Comparative Examples 1 and 2
The composite semipermeable membrane A was stored in the same manner as in Example 1 except that the storage conditions described in Table 1 were employed, and the permeation flux was measured after storage for each period to determine the flux ratio. The results are shown in Table 1.

Example 5, Comparative Examples 3, 4
The composite semipermeable membrane B was used in place of the composite semipermeable membrane A, and the composite semipermeable membrane B was stored in the same manner as in Example 1 except that the storage conditions described in Table 1 were adopted. The flux was measured and the flux ratio was determined. The results are shown in Table 1.

Claims (7)

In a method for preserving a composite semipermeable membrane having a skin layer containing a polyamide-based resin on a porous support, the composite semipermeable membrane is characterized by storing at least the skin layer in contact with an alicyclic diamine-containing aqueous solution. How to preserve the membrane. In a method for storing a membrane element in which a composite semipermeable membrane having a skin layer containing a polyamide-based resin on a porous support is housed in an element container, at least the skin layer is stored in contact with an aqueous solution containing an alicyclic diamine. A method for preserving a membrane element. The preservation method according to claim 1 or 2, wherein the alicyclic diamine is a bis-type alicyclic diamine. The storage method according to claim 3, wherein the bis-type alicyclic diamine is bis (4-aminocyclohexyl) methane. The preservation | save method in any one of Claims 1-4 whose density | concentration of alicyclic diamine in alicyclic diamine containing aqueous solution is 10 ppm-1500 ppm. The preservation method according to any one of claims 1 to 5, wherein the porous support is an epoxy resin porous material. The preservation method according to any one of claims 1 to 6, wherein the polyfunctional amine component which is a raw material component of the polyamide-based resin is an aromatic polyfunctional amine.