JP2016203132A - Polymer laminate semipermeable membrane, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semipermeable membrane which exhibits an anti-oxidant property even in the presence of heavy metal while maintaining salt removal performance of the semipermeable membrane, and provide a polymer laminate semipermeable membrane which exhibits pH-resistance, and can be used with various raw water.SOLUTION: A polymer laminate semipermeable membrane includes a semipermeable layer, and a polymer layer formed on the semipermeable layer. The polymer layer contains a compound having a specific structure.SELECTED DRAWING: None

Description

  The present invention relates to a semipermeable membrane useful for selective separation of a liquid mixture, and relates to a polymer laminated semipermeable membrane excellent in oxidation resistance and pH resistance.

  As a water treatment separation membrane that prevents permeation of lysate components, a composite semi-permeable membrane comprising an asymmetric semipermeable membrane made of a polymer such as cellulose acetate, a microporous support membrane, and a separation functional layer provided on the microporous support membrane Permeable membranes are known. In particular, the composite semipermeable membrane in which the separation functional layer is formed of polyamide has an advantage that it can be easily formed by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide, and further has a high pressure resistance, a high desalting rate, It is most widely used because of its high permeation flux (Patent Documents 1 and 2).

  However, the semipermeable membrane as described above has insufficient durability against oxidizing agents, and the desalting performance and selective separation performance of the semipermeable membrane are degraded by chlorine, hydrogen peroxide, etc. used for sterilization of the membrane. To do. Further, for example, Non-Patent Document 1 describes that this oxidation is significantly accelerated by the coexistence of an oxidizing agent and a very small amount of heavy metal. In the use of water treatment membranes, heavy metals are contained in the raw water to be treated in many cases. Therefore, in order to have oxidation resistance in practical use, the deterioration of the membrane is suppressed under the conditions in which an oxidant and heavy metals coexist. It is necessary to

  Examples of techniques that improve the durability of semipermeable membranes to oxidizing agents include membranes in which the nitrogen atoms of polyamide, which is the reaction point between polyamide and oxidizing agent, are substituted with alkyl groups, and the surface of polyamide membrane is polyvinyl acetate, etc. A film obtained by contacting with an emulsion solution of the polymer, followed by heat drying above the glass transition temperature of the polymer, selected from the group consisting of an alkoxysilane structure in the molecule and an amino group and an oxirane ring in the molecule Patent Document 3, Patent Document 4 and Patent Document 5 disclose polyamide films having improved chlorine resistance by interfacial polymerization using an organosilicon compound having at least one functional group.

U.S. Pat. No. 3,133,132 U.S. Pat. No. 4,277,344 JP 2002-336666 A JP 2010-201303 A JP-A-9-99228 Kurihara et al., Polymer Journal, Vol. 23, p513, Society of Polymer Science (1991)

  In the conventional technology, the molecular structure of the semipermeable membrane is changed, so that the original salt removal performance of the semipermeable membrane is impaired, or sufficient oxidation resistance cannot be obtained in the presence of heavy metals. There are practical problems.

  The present invention provides a semipermeable membrane having oxidation resistance while maintaining the salt removal performance of the semipermeable membrane and in the presence of heavy metals. Furthermore, the polymer laminated semipermeable membrane of the present invention has pH resistance and can be used in various raw waters.

  In order to solve the above problems, the present invention comprises any one of the following configurations (1) to (4).

(1) A semipermeable layer and a polymer layer formed on the semipermeable layer,
The polymer laminated semipermeable membrane, wherein the polymer layer contains a compound having a structure of the following formula i.

(However, R1 and R2 are arbitrary hydrocarbon groups, R1 and R2 may be covalently bonded to each other, and n is an integer of 0 or more.)
(2) The thickness of the polymer layer is 50 nm or more and 1000 nm or less,
The polymer laminated semipermeable membrane according to (1) above.

(3) The semipermeable layer is provided with a microporous support membrane, a polyamide separation functional layer provided on the microporous support membrane, and formed by polycondensation of a polyfunctional amine and a polyfunctional acid halide; The polymer laminated semipermeable membrane according to any one of the above (1) or (2).

(4) (A) The surface of a semipermeable layer by contacting the semipermeable layer with a solution or dispersion containing at least one compound having the structure of the following formula ii or a polymer thereof or a condensate thereof: Forming a liquid film on the substrate,
(B) forming a polymer layer on the surface of the semipermeable layer by removing part or all of the solvent of the solution or the dispersion medium of the dispersion from the liquid film;
Including,
The manufacturing method of the polymer lamination semipermeable membrane in any one of said (1)-(3).

(However, X and Y have an arbitrary structure, and Z1 and Z2 are arbitrary hydrolyzable groups.)
(5) X is characterized by having an ethylenically unsaturated group,
The manufacturing method of the polymer lamination semipermeable membrane as described in said (4).

  According to the present invention, by forming a polymer layer having oxidation resistance and water permeability on the semipermeable layer and capable of removing heavy metals, the oxidation resistance in the presence of heavy metals in the semipermeable membrane is improved. A membrane can be obtained. By improving the oxidation resistance in the presence of heavy metals, stable operation can be continued while demonstrating high salt removal performance even for raw water in which oxidant remains due to sterilization treatment or the like. Furthermore, since the hydrocarbon group is directly bonded to the silicon atoms constituting the polymer layer, the polymer layer is improved in hydrophobicity and pH resistance, so that it can be used at various pH water quality. .

I. Polymer laminated semipermeable membrane The polymer laminated semipermeable membrane is a membrane having a function of removing ions from an aqueous solution. Specific examples of the polymer laminated semipermeable membrane include an RO (Reverse Osmosis) membrane and an NF (Nanofiltration) membrane.

[1. Semi-permeable layer]
In this document, the semipermeable layer is a layer substantially responsible for the ion removability of the polymer laminated semipermeable membrane. That is, the semipermeable layer alone has a function of removing ions from the aqueous solution, and can function as an RO membrane or an NF membrane. The semipermeable layer is roughly classified into an asymmetrical semipermeable layer (ie, an asymmetrical semipermeable membrane) and a composite semipermeable layer (ie, a composite semipermeable membrane).

(1-1) Asymmetrical semipermeable layer The asymmetrical semipermeable layer is a semipermeable layer having a structure in which the pore diameter increases from the membrane surface toward the inside, and the vicinity of the dense membrane surface exhibits separation performance. In addition, the inside of the large pore diameter plays a role of reducing water permeation resistance and maintaining water permeability and membrane strength.

  Cellulose acetate, cellulose triacetate, polyamide, or the like is used as the material for the asymmetric semipermeable layer.

(1-2) Composite Semipermeable Layer The composite semipermeable layer includes a microporous support membrane and a separation functional layer provided on the microporous support membrane.

(1-2-1) Microporous support membrane The microporous support membrane provides strength to the composite semipermeable layer by supporting the separation functional layer. The separation functional layer is provided on at least one surface of the microporous support membrane.

  The microporous support membrane may be provided on a substrate described later. The pore diameter on the surface of the microporous support membrane is preferably in the range of 1 nm to 100 nm. When 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. Further, the obtained composite semipermeable layer has a high pure water permeation flux, and the structure can be maintained without the separation functional layer falling into the support membrane hole during the pressurizing operation.

  The pore diameter on 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 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 layer tends to decrease. When the thickness is large, it becomes difficult to handle when the microporous support membrane and the composite semipermeable layer obtained therefrom are bent. In order to increase the strength of the composite semipermeable layer, 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 constituting the microporous support membrane is not particularly limited. The microporous support membrane is, for example, a polysulfone, polyethersulfone, polyamide, polyester, cellulosic polymer, vinyl polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, polyphenylene oxide, or other homopolymer or copolymer microporous support membrane. May contain only a single polymer among these polymers, or may contain a plurality of types of polymers.

  Among the above polymers, 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. As the polymer, homopolymers and copolymers such as polysulfone, polyethersulfone, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferable. Further, among these materials, polysulfone and polyethersulfone, which have high chemical stability, mechanical strength, and thermal stability and are easy to mold, are particularly preferable.

  The microporous support membrane preferably contains these polymers as main components. Specifically, the proportion of these polymers in the microporous support membrane is preferably 80% by weight or more, 90% by weight or more, or 95% by weight or more. Further, the microporous support membrane may be composed only of these polymers.

(1-2-2) Separation functional layer The separation functional layer has a function of separating ions from the aqueous solution. The separation functional layer may be a polyamide layer formed by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide on a microporous support membrane, or acetic acid by the non-solvent induced phase separation method. It may be a polymer layer formed of cellulose, cellulose triacetate, polyamide or the like.

  The polyamide layer by interfacial polycondensation will be described.

  The polyfunctional amine is at least one component selected from an aliphatic polyfunctional amine and an aromatic polyfunctional amine.

  An aliphatic polyfunctional amine is an aliphatic amine having two or more amino groups in one molecule. The aliphatic polyfunctional amine is not limited to a specific compound, but is preferably a piperazine-based amine and a derivative thereof. Examples of aliphatic polyfunctional amines include piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5-trimethylpiperazine, 2,5-diethylpiperazine, 2,3, Exemplified is at least one compound selected from the group consisting of 5-triethylpiperazine, 2-n-propylpiperazine, and 2,5-di-n-butylpiperazine. As the amine, piperazine and 2,5-dimethylpiperazine are particularly preferable.

  The aromatic polyfunctional amine is an aromatic amine having two or more amino groups in one molecule. The aromatic polyfunctional amine is not limited to a specific compound, but examples of the aliphatic polyfunctional amine include metaphenylene diamine, paraphenylene diamine, and 1,3,5-triaminobenzene. At least one selected from the group consisting of N, N-dimethylmetaphenylenediamine, N, N-diethylmetaphenylenediamine, N, N-dimethylparaphenylenediamine, and N, N-diethylparaphenylenediamine as the N-alkylated product. Examples of the compound are exemplified, and metaphenylenediamine and 1,3,5-triaminobenzene are particularly preferable as the aliphatic polyfunctional amine in view of the stability of performance expression.

  The polyfunctional acid halide is an acid halide having two or more carbonyl halide groups in one molecule, and may be any one that generates a polyamide by reaction with the amine. The polyfunctional acid halide is not limited to a specific compound. Examples of the polyfunctional acid halide include oxalic acid, malonic acid, maleic acid, fumaric acid, glutaric acid, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid. 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, and at least one compound selected from the group consisting of 1,4-benzenedicarboxylic acid Acid halides can be used. Among acid halides, acid chlorides are preferred, and are acid halides of 1,3,5-benzenetricarboxylic acid, particularly in terms of economy, availability, ease of handling, and ease of reactivity. Trimesic acid chloride is preferred. Although the said polyfunctional acid halide can also be used independently, you may use it as a mixture.

  Details of the interfacial polymerization will be described later.

(1-2-3) Substrate From the viewpoints of the strength and dimensional stability of the composite semipermeable layer, the composite semipermeable layer may have a substrate. As the base material, a fibrous base material is preferably used in terms of strength, unevenness forming ability and fluid permeability.

  As the substrate, both long fiber nonwoven fabrics and short fiber nonwoven fabrics are preferably used. In particular, since the long fiber nonwoven fabric has excellent film-forming properties, when the polymer polymer solution is cast, the solution penetrates due to excessive penetration, and the microporous support layer peels off from the substrate. In addition, it is possible to suppress the non-uniform thickness of the composite semipermeable layer due to the fluffing of the base material and the like, and the occurrence of defects such as pinholes.

  In addition, since the base material is made of a long-fiber nonwoven fabric composed of thermoplastic continuous filaments, compared to a short-fiber nonwoven fabric, thickness nonuniformity and film defects caused by fiber fluffing during polymer solution casting can be prevented. Can be suppressed. Furthermore, since the composite semipermeable layer 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.

  In the long-fiber nonwoven fabric, in terms of moldability and strength, it is preferable that the fibers in the surface layer on the side opposite to the microporous support membrane have a longitudinal orientation than the fibers in the surface layer on the microporous support membrane side. According to such a structure, the high effect which prevents a film tear etc. is implement | achieved by maintaining intensity | strength. When unevenness is imparted to the composite semipermeable layer by embossing or the like, if the base material is a long-fiber nonwoven fabric, the moldability of the laminate including the microporous support film and the base material is also improved, and the composite semipermeable layer It is preferable because the uneven shape on the surface is stabilized.

[2. Polymer layer]
The polymer laminated semipermeable membrane of the present invention has a polymer layer provided on the semipermeable membrane.

  The polymer layer is characterized by having the structure of the above formula i.

  R1 and R2 are hydrocarbon groups. The structure of the hydrocarbon group is not particularly limited, and examples of the structure include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Furthermore, it may be a hydrocarbon group generally represented by — (CH 2 CH 2) n — (n: an integer of 1 or more), and n may be adjusted as appropriate. R1 and R2 may further have an unsaturated bond in a part of the structure, may have a branched or cyclic structure, or may have a crosslinked structure. Furthermore, R1 and R2 may form a covalent bond with each other. When the hydrocarbon group is directly bonded to the silicon atoms constituting the polymer layer, the hydrophobicity of the polymer layer is improved and the pH resistance of the film is improved. R1 and R2 may be formed by polymerization of an ethylenically unsaturated group described later.

  The polymer layer has Si—O—Si (siloxane bond). The siloxane bond may be a part of a structure repeating unit structure generally represented by (Si-O-Si) n (n: integer). Further, (Si—O—Si) n may be linear, branched, cyclic, crosslinked, or a part thereof. In order for the polymer layer to exhibit the ability to remove heavy metals, a crosslinked structure is particularly preferable.

  Furthermore, in addition to the above, it may further have a structure composed of C—C (carbon-carbon) bonds. The carbon-carbon bond may be a part of a repeating unit structure of (C—C) n (n: an integer of 1 or more). Further, (C—C) n may be linear, branched or cyclic. Furthermore, a crosslinked structure may be used. This structure may be formed by polymerization of an ethylenically unsaturated group described later.

The compound constituting the polymer layer may be, for example, polyalkylsiloxane, polyalkoxide, polysilsesquioxane, polysilazane, polysilane, or a derivative thereof, and is not particularly limited. Furthermore, the crosslinked body of these polymers and a condensate may be sufficient.

  Such a polymer layer has oxidation resistance because the polymer layer itself does not have a reactive site for the oxidant. Furthermore, when the hydrocarbon group is directly bonded to the silicon atoms constituting the polymer layer, the hydrophobicity of the polymer layer is improved and the hydrolysis resistance of the film is improved. Furthermore, it is possible to form a dense structure capable of blocking salts such as heavy metals by the crosslinked structure.

  That is, in the polymer laminated semipermeable membrane of the present invention, since the molecular structure of the semipermeable layer is the same as before the polymer layer is laminated, the polymer laminated semipermeable membrane has at least the same separation performance as the semipermeable layer. Has separation performance. Furthermore, when the polymer layer itself removes heavy metal, the semipermeable layer located in the lower layer becomes difficult to contact simultaneously with the heavy metal and the oxidizing agent. Therefore, the deterioration of the semipermeable layer due to the oxidizing agent is suppressed. As a result, it is possible to provide a semipermeable membrane having oxidation resistance even in the presence of heavy metal, and the carbon atom is formed on the silicon atoms constituting the polymer layer. When the hydrogen groups are directly bonded, the hydrophobicity of the polymer layer is improved and the pH resistance of the membrane is improved. As a result, it can be used with raw water having various pHs.

  The thickness of the polymer layer formed on the semipermeable layer can be confirmed from a cross-sectional photograph taken with a scanning electron microscope. The thickness of the polymer layer is preferably 50 nm or more, and more preferably 100 nm. As the thickness of the polymer layer increases, the effect of chlorine resistance increases. Therefore, the upper limit is not particularly important as long as the water permeability of the polymer laminated semipermeable membrane is ensured, but it is usually preferably 1000 nm or less, more preferably 500 nm or less. It is. When the polymer layer is made thin in this range, the separation performance can be exhibited without greatly impairing the water permeability of the semipermeable layer, and the surface of the semipermeable layer can be coated without any defects to impart oxidation resistance.

II. Production method of polymer laminated semipermeable membrane The above-mentioned polymer laminated semipermeable membrane can be produced by a production method comprising a step of forming a polymer layer on the semipermeable layer.

[1. Formation of polymer layer)
The step of forming the polymer layer on the semipermeable layer is as follows:
(A) A liquid film is formed on the surface of the semipermeable layer by bringing the semipermeable layer into contact with a solution or dispersion containing at least one compound having the structure of formula ii or a polymer thereof or a condensate thereof. Forming, and
(B) forming a polymer layer on the surface of the semipermeable layer by removing part or all of the solvent or dispersion medium from the liquid film;
including.
(However, X and Y have an arbitrary structure, and Z1 and Z2 are arbitrary hydrolyzable groups.)
The compound of formula ii will be described.

    X has an arbitrary structure and is not particularly limited, and may have the same structure as Y or Z1, Z2. Furthermore, X may have an ethylenically unsaturated group. Examples of the structure having an ethylenically unsaturated group include a vinyl group, an allyl group, a methacryloxyethyl group, a methacryloxypropyl group, an acryloxyethyl group, an acryloxypropyl group, and a styryl group. From the viewpoint of polymerizability, a methacryloxypropyl group, an acryloxypropyl group, and a styryl group are preferable. X may have at least one such reactive group.

  Y has an arbitrary structure and is not particularly limited, and may have the same structure as X or Z1, Z2.

  Z1 and Z2 are hydrolyzable groups. 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. Among these, as an alkoxy group, a C1-C10 alkoxy group 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. As the hydrolyzable group, an alkoxy group is particularly preferable. This is because a reaction liquid having a viscosity and pot life suitable for film formation can be realized by using an alkoxy group in forming the separation functional layer.

Compounds having the structure of formula ii include vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, styryltrimethoxysilane, styryltriethoxysilane, styrylethyltrimethoxysilane, styrylethyltriethoxy. Silane, methacryloxypropylmethyldimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropyltriethoxysilane, acryloxymethyltrimethoxysilane, acryloxypropyltrimethoxysilane, (acryloxymethyl) Phenethyltrimethoxysilane, bis (triethoxysilyl) ethane, bis (triethoxysilyl) butane, bis (triethoxysilyl) Sun, bis (triethoxysilyl) octane, bis (triethoxysilyl) nonane, bis (triethoxysilyl) decane, bis (triethoxysilyl) dodecane, bis (trimethoxysilyl) tetradodecane, bis (trimethoxysilyl) ethane Bis (trimethoxysilyl) butane, bis (trimethoxysilyl) hexane, bis (trimethoxysilyl) octane, bis (trimethoxysilyl) nonane, bis (trimethoxysilyl) decane, bis (trimethoxysilyl) dodecane, bis (Trimethoxysilyl) tetradodecane, bis (methyldiethoxysilyl) ethane, bis (methyldiethoxysilyl) butane, bis (methyldiethoxysilyl) hexane, bis (methyldiethoxysilyl) octane, bis (methyldiethoxysilyl) Nona Bis (methyldiethoxysilyl) decane, bis (methyldiethoxysilyl) dodecane, bis (methyldiethoxysilyl) tetradodecane, bis (methyldimethoxysilyl) ethane, bis (methyldimethoxysilyl) butane, bis (methyldimethoxysilyl) ) Hexane, bis (methyldimethoxysilyl) octane, bis (methyldimethoxysilyl) nonane, bis (methyldimethoxysilyl) decane, bis (methyldimethoxysilyl) dodecane, bis (methyldimethoxysilyl) tetradodecane, bis (dimethylethoxysilyl) Ethane, bis (dimethylethoxysilyl) butane, bis (dimethylethoxysilyl) hexane, bis (dimethylethoxysilyl) octane, bis (dimethylethoxysilyl) nonane, bis (dimethylethoxysilyl) ) Decane, bis (dimethylethoxysilyl) dodecane, bis (dimethylethoxysilyl) tetradodecane, bis (dimethylmethoxysilyl) ethane, bis (dimethylmethoxysilyl) butane, bis (dimethylmethoxysilyl) hexane, bis (dimethylmethoxysilyl) Octane, bis (dimethylmethoxysilyl) nonane, bis (dimethylmethoxysilyl) decane, bis (dimethylmethoxysilyl) dodecane, bis (dimethylmethoxysilyl) tetradodecane, bis (methyldimethoxysilyl) benzene, bis (methyldiethoxysilyl) Benzene, bis (ethyldimethoxysilylethyl) benzene, bis (ethyldiethoxysilyl) benzene, bis (dimethylmethoxysilyl) benzene, bis (dimethylethoxysilyl) benzene, bis ( Ethyl trimethoxysilyl) benzene, bis (diethyl triethoxysilyl) benzene, bis (trimethoxysilyl) benzene, bis (triethoxysilyl) benzene, and derivatives are exemplified.
Hereinafter, the steps (A) and (B) for forming the polymer layer will be described more specifically.

  In step (A), a compound having the structure of formula ii, a polymer thereof or a condensate thereof is prepared in advance.

  Next, preparation of the polymer will be described. At least one compound having the structure of formula ii is dissolved in a solvent or dispersion medium. In this step, the solvent is not particularly limited as long as it dissolves the compound and a polymerization initiator added as necessary. Such a solvent or dispersion medium is preferably water, an alcohol-based organic solvent, an ether-based organic solvent, a ketone-based organic solvent, or a mixture thereof. If necessary, acid or alkali may be added to promote dissolution.

  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 diethyl ether, dipropyl ether, dibutyl ether, diamyl ether, diethyl acetal, dihexyl ether, dimethoxymethane, dimethoxyethane, trioxane, dioxane and the like. In addition, 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, di Acetone alcohol etc. are mentioned.

  Next, the compound is polymerized in a solvent via an ethylenically unsaturated group. This step can be performed by heat treatment, electromagnetic wave irradiation, electron beam irradiation, or plasma irradiation. Here, electromagnetic waves include ultraviolet rays, X-rays, γ-rays and the like. The polymerization method may be appropriately selected according to reactivity, running cost, productivity, and the like. Among electromagnetic waves, ultraviolet irradiation is preferable from the viewpoint of simplicity. When the polymerization is actually performed using ultraviolet rays, these light sources need not selectively generate only light in the ultraviolet wavelength region, but may be any material that contains electromagnetic waves in the ultraviolet wavelength region. However, from the viewpoint of shortening the polymerization time and ease of controlling the polymerization conditions, it is preferable that the intensity of these ultraviolet rays 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. Such ultraviolet rays can be generated by a low-pressure mercury lamp or an excimer laser lamp.

  You may add a polymerization accelerator etc. to the reaction liquid used for superposition | polymerization. Thereby, the polymerization rate can be increased. Here, the polymerization accelerator is not particularly limited, and is appropriately selected according to the structure of the compound 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 the initiation of polymerization. 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 preferable in order to accelerate the initiation of polymerization. In this way, a solution or dispersion containing a polymer of the compound having the structure of formula ii is obtained.

  Next, preparation of the condensate will be described. First, a compound having the structure of formula ii is added to a solvent or dispersion medium. Furthermore, an acid or base catalyst may be added as appropriate to promote hydrolysis of the compound having the structure of formula ii and adjust the solubility. Subsequently, the solution or dispersion liquid containing the condensate of the compound having the structure of formula ii is obtained by standing or stirring as necessary to promote condensation of the hydrolyzable group.

  Examples of the solvent or dispersion medium include alcohol-based organic solvents such as methanol, ethoxymethanol, ethanol, propanol, butanol, amyl alcohol, cyclohexanol, methylcyclohexanol, ethylene glycol monomethyl ether (2-methoxyethanol), ethylene glycol mono Examples include acetoester, diethylene glycol monomethyl ether, diethylene glycol monoacetate, propylene glycol monoethyl ether, propylene glycol monoacetate, dipropylene glycol monoethyl ether, methoxybutanol and the like. Examples of ether organic solvents include diethyl ether, dipropyl ether, dibutyl ether, diamyl ether, diethyl acetal, dihexyl ether, dimethoxymethane, dimethoxyethane, trioxane, dioxane and the like. In addition, 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, di Acetone alcohol etc. are mentioned.

  The solution or dispersion prepared in the step (A) may include at least one compound having the structure of the above formula ii, a polymer thereof or a condensate thereof, and may be a mixture thereof, These materials may be further mixed.

  Next, the solution or dispersion is contacted onto the semipermeable layer. In this step, the polymerized solution or dispersion may be applied as it is, or may be used by diluting or concentrating as appropriate, or adding a stabilizer such as a dissolution aid.

  The application is preferably carried out by a method of uniformly and thinly applying on the semipermeable layer. Specifically, for example, there is a method in which the reaction liquid is coated on the semipermeable layer using a coating apparatus such as a spin coater, a wire bar, a flow coater, a die coater, a roll coater, or a spray.

  At this time, the thickness of the polymer layer to be formed later can be adjusted according to the thickness of the contacted solution layer, the contact time between the semipermeable layer and the solution, the weight percentage of the solid content in the solution, and the like.

  Next, the step (B) will be described. In this step, part or all of the solvent or dispersion medium is removed, and a polymer layer is formed on the surface of the semipermeable layer. This step may also serve as a step of condensing the hydrolyzable group. In the case where the removal of the solvent or the dispersion medium and the condensation are performed simultaneously, the step (B) is preferably a heat treatment.

  The step of condensing the hydrolyzable group is performed by heat treatment. The heating temperature at this time is preferably preferably 20 ° C. or higher, more preferably 40 ° C. or higher, so that the condensation reaction proceeds rapidly. The condensation reaction temperature needs to be lower than the temperature at which the microporous support membrane portion of the semipermeable layer melts, and is preferably 150 ° C. or lower, more preferably 120 ° C. or lower, but is not particularly limited. For example, if the microporous support membrane portion does not melt, it may be heated and fired at a high temperature of 200 ° C. or higher, whereby a part of the hydrocarbon groups contained in the polymer layer may be lost. . If the reaction temperature is 20 ° 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, it is preferable to control the condensation reaction by selecting heating conditions and humidity conditions so that the polymer layer has pores.

  The polymer laminated 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.

[2. Formation of semipermeable layer
The method for producing a polymer laminated semipermeable membrane may include a step of forming a semipermeable layer.

(1) Asymmetrical semipermeable layer An asymmetrical semipermeable layer is prepared by, for example, dissolving a polymer as a membrane material in a solvent, casting the obtained polymer solution onto a glass plate, etc. Such a membrane production method is generally called non-solvent-induced phase separation method (detailed in Japanese Membrane Society, Membrane Experiment Series Artificial Membrane, Kyoritsu Shuppan (1993)). Is listed).

  In the asymmetric type semipermeable layer by the non-solvent induced phase separation method, cellulose acetate, cellulose triacetate, polyamide, etc. are used as membrane materials, and acetone, dimethylformamide, dioxane, N-methyl-2-pyrrolidone, etc. are used as solvents. It is done.

(2) Composite Semipermeable Layer For the reasons of supporting the membrane, preventing clogging, and ensuring water permeability, it is preferable to sequentially layer a fine-grained layer on a coarse-grained layer. Therefore, the composite semipermeable layer is preferably formed in the order of providing a microporous support membrane on the substrate and further providing a separation functional layer on the microporous support membrane.

  The base material is as described above.

  The microporous support membrane is obtained by combining the above-mentioned materials with “Office of Saleen Water Research and Development Progress Report” No. 359 (1968) and can be produced by molding on the above-mentioned substrate.

  For example, a microporous support membrane is prepared by casting an N, N-dimethylformamide solution of polysulfone on a densely woven polyester fabric or nonwoven fabric to a certain thickness, and adding it to sodium dodecyl sulfate 0.5 It is formed by wet coagulation in an aqueous solution containing 2% by weight and 2% by weight of DMF.

  As described above, the step of forming the separation functional layer may include forming a polyamide by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide on a microporous support membrane, It may include forming by a non-solvent induced phase separation method.

  In particular, a method for interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide will be described. Interfacial polycondensation uses, for example, an aqueous solution containing the aforementioned polyfunctional amine and an organic solvent solution that contains the aforementioned polyfunctional acid halide and is immiscible with water, and the aqueous solution and the organic solvent solution are microporous. It is performed by contacting on the support membrane.

  The kind of polyfunctional amine is as already explained.

  The concentration of the polyfunctional amine in the aqueous solution containing the polyfunctional amine is preferably 0.1 to 20% by weight, and more preferably 0.5 to 15% by weight.

  The kind of polyfunctional acid halide is as already described.

  The organic solvent that dissolves the polyfunctional acid halide is preferably immiscible with water and does not destroy the microporous support membrane, as long as it does not inhibit the formation reaction of the crosslinked polyamide. Also good. Typical examples include halogenated hydrocarbons such as liquid hydrocarbons and trichlorotrifluoroethane, but they are substances that do not destroy the ozone layer, are easily available, are easy to handle, and are safe for handling. In consideration of the properties, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, heptadecane, hexadecane, etc., and simple substances such as cyclooctane, ethylcyclohexane, 1-octene, 1-decene or mixtures thereof are preferably used.

  The concentration of the polyfunctional acid halide in the organic solvent solution is preferably in the range of 0.01 to 10% by weight, and more preferably in the range of 0.02 to 2.0% by weight. Within this range, a sufficient reaction rate can be obtained, and the occurrence of side reactions can be suppressed. Further, it is more preferable that an acylation catalyst such as N, N-dimethylformamide is contained in the organic solvent solution because interfacial polycondensation is promoted.

  In the case of an aqueous solution containing a polyfunctional amine or an organic solvent solution containing a polyfunctional acid halide, an acylation catalyst, a polar solvent, an acid scavenger may be used as long as it does not interfere with the reaction between the two components. In addition, compounds such as surfactants and antioxidants may be contained.

  After the polyfunctional amine aqueous solution is contained in the microporous support membrane by dipping or coating, the excess aqueous solution is sufficiently drained 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. As a method for draining liquid, for example, there is a method in which the film surface is allowed to flow naturally while being held in a vertical direction. As a method for draining, for example, as described in JP-A-2-78428, the microporous support membrane after contacting with the polyfunctional amine aqueous solution is vertically gripped to allow the excess aqueous solution to flow down naturally. A method or a method of forcibly draining an air stream such as nitrogen from an air nozzle can be used. In addition, after draining, the membrane surface can be dried to partially remove water from the aqueous solution.

  Then, the organic solvent solution containing the polyfunctional acid halide described above is applied to the microporous support membrane containing polyfunctional amine, and a separation functional layer of crosslinked polyamide is formed by interfacial polycondensation.

  After interfacial polycondensation is performed by contacting an organic solvent solution of a polyfunctional acid halide to form a separation functional layer containing a crosslinked polyamide on the microporous support membrane, excess solvent may be drained. As a method for draining, for example, a method in which a film is held in a vertical direction and excess organic solvent is allowed to flow down and removed can be used. In this case, the gripping time in the vertical direction is preferably between 10 seconds and 5 minutes, and more preferably between 30 seconds and 3 minutes. If it is too short, the separation functional layer will not be completely formed, and if it is too long, the organic solvent will be overdried and defects will easily occur and performance will be deteriorated.

  The composite semipermeable membrane obtained by the above-described method includes a step of hydrothermal treatment in the range of 40 to 150 ° C, preferably in the range of 40 to 130 ° C for 1 to 10 minutes, more preferably 2 to 8 minutes. By adding, the solute blocking performance and water permeability of the composite semipermeable membrane can be further improved.

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

(1) Desalination rate and permeation flux Membrane filtration treatment is performed by supplying a salt solution with a salt concentration of 500 mg / L adjusted to a temperature of 25 ° C. and pH 6.5 to a semipermeable membrane described later at an operating pressure of 0.75 MPa. Was done.

  By measuring the quality of the permeated water obtained, the desalting rate was determined from the following equation.

Desalination rate (%) = 100 × {1- (Salt concentration in permeated water / Salt concentration in feed water)}
Moreover, the membrane permeation flux (m ³ / m ² / day) was determined from the amount of water per day (cubic meter) per square meter of membrane obtained under the above conditions.

(2) Chlorine resistance test Further, as a chlorine resistance test, a sodium hypochlorite prepared by adjusting a semipermeable membrane or a polymer laminated semipermeable membrane to 1 mg / L of copper (II) chloride and adjusting the chlorine concentration to 500 mg / L. It was immersed in an aqueous solution for 15 hours, and the desalting rate and membrane permeation flux were measured. As an index of chlorine resistance, the change ratio of the salt permeability was obtained from the following formula.

Salt permeability change ratio = salt permeability after chlorine resistance test / salt permeability of initial performance (3) Production and test of semipermeable membrane of comparative example (3-1) Comparative example 1: polyamide semipermeable membrane polyethylene terephthalate A 16% by weight dimethylformamide solution of polysulfone was cast on a nonwoven fabric in a thickness of 200 μm at room temperature (25 ° C.). After casting, the substrate was immediately immersed in pure water and allowed to stand for 5 minutes to prepare a microporous support membrane.

  The microporous support membrane thus obtained was immersed in a 2.5% by weight aqueous solution of metaphenylenediamine for 1 minute, the support membrane was slowly pulled up in the vertical direction, and nitrogen was blown from an air nozzle to support the surface of the support membrane After removing the excess aqueous solution, 0.08 wt% n-decane solution of trimesic acid chloride was applied so that the surface was completely wetted and allowed to stand for 30 seconds. Next, in order to remove excess solution from the film, the film was vertically held for 1 minute to drain the liquid, and n-decane on the film surface was removed with a blower at room temperature. Thereafter, it was washed with hot water at 90 ° C. for 2 minutes to obtain a semipermeable membrane.

  Table 1 shows the initial performance of the semipermeable membrane and the performance after the chlorine resistance test.

Comparative Example 2 Cellulose Acetate Semipermeable Membrane Table 1 shows the initial performance of the Toray SC-3000 membrane, which is an asymmetric semipermeable membrane made of cellulose acetate, and the performance after a chlorine resistance test.

(4) Production and test of semipermeable membrane of Examples and Comparative Examples (Examples 1 to 3)
Using a UV irradiation apparatus capable of dissolving compound P having the structure of formula ii in water at a concentration of 150 mM, photopolymerization initiator 2,2-dimethoxy-2-phenylacetophenone at a concentration of 8.5 mM, and subsequently irradiating with 365 nm ultraviolet rays Then, the polymer layer solution was prepared by irradiating with ultraviolet rays while setting the irradiation intensity to 40 mW / cm ² when using the ultraviolet light quantity meter.

  After this polymer layer solution was brought into contact with the polyamide semipermeable membrane (semipermeable layer) of Comparative Example 1 for 30 seconds, the excess solution was removed using a spin coater, and the polymer layer was placed on the polyamide semipermeable membrane. A layer of solution was formed. At this time, films having different polymer layer thicknesses were formed by adjusting the rotation speed of the spin coater.

  Next, the semipermeable membrane on which the layer of the polymer layer solution is formed is held in a hot air dryer at 100 ° C. for 5 minutes to condense the silicon compound in which the hydrolyzable group is directly bonded to the silicon atom, A polymer laminated semipermeable membrane having a structure was obtained. The thickness of the polymer layer of the polymer laminated semipermeable membrane was calculated by observing a cross section of a sample obtained by vacuum drying the membrane piece with a scanning electron microscope and averaging the thicknesses of 10 representative portions.

Table 1 shows the thickness of the polymer layer of the polymer laminated semipermeable membrane thus obtained, the initial performance immediately after the production, and the performance after the chlorine resistance test.
(Examples 4 to 6)
Compound P having the structure of formula ii was dissolved in water at a concentration of 200 mM to prepare a solution of compound P having the structure of formula ii.

  This solution was brought into contact with the polyamide semipermeable membrane (semipermeable layer) of Comparative Example 1 for 30 seconds, and then the excess solution was removed using a spin coater, and the solution layer was formed on the polyamide semipermeable membrane. Formed. At this time, films having different thicknesses were formed by adjusting the rotation speed of the spin coater.

  Next, the semipermeable membrane on which the liquid layer is formed is held in a hot air dryer at 100 ° C. for 5 minutes to condense a silicon compound in which a hydrolyzable group is directly bonded to a silicon atom, thereby having a structure of formula i A polymer laminated semipermeable membrane was obtained. The thickness of the polymer layer of the polymer laminated semipermeable membrane was calculated by observing a cross section of a sample obtained by vacuum drying the membrane piece with a scanning electron microscope and averaging the thicknesses of 10 representative portions.

  Table 1 shows the thickness of the polymer layer of the polymer laminated semipermeable membrane thus obtained, the initial performance immediately after the production, and the performance after the chlorine resistance test.

(Examples 7 to 8)
The test was conducted in the same manner as in Examples 1 and 4 except that SC-3000 manufactured by Toray Industries, Ltd., which is a reverse osmosis membrane made of cellulose acetate, was used as the semipermeable membrane. The results are shown in Table 1.

  In Table 1, the polymer laminated semipermeable membranes shown in the examples have a desalination rate equal to or higher than that of the semipermeable membranes of Comparative Examples 1 and 2 and have a small salt permeability change ratio. It can be seen that it has oxidation resistance even in the presence of heavy metals while maintaining its salt removal performance.

P-1: acryloxymethyltrimethoxysilane, P-2: vinyltrimethoxysilane, P-3: styrylethyltrimethoxysilane, P-4: bis (triethoxysilyl) ethane, P-5: bis ( Triethoxysilyl) butane, P-6: methacryloxypropylmethyldiethoxysilane

  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 (5)

A semipermeable layer, and a polymer layer formed on the semipermeable layer,
The polymer laminated semipermeable membrane, wherein the polymer layer contains a compound having a structure of the following formula i.

(However, R1 and R2 are arbitrary hydrocarbon groups, R1 and R2 may be covalently bonded to each other, and n is an integer of 0 or more.) The polymer layer has a thickness of 50 nm or more and 1000 nm or less,
The polymer laminated semipermeable membrane according to claim 1. The semipermeable layer includes a microporous support membrane, and a polyamide separation functional layer provided on the microporous support membrane and formed by polycondensation of a polyfunctional amine and a polyfunctional acid halide. Item 3. The polymer laminated semipermeable membrane according to any one of Items 1 and 2. (A) A liquid film is formed on the surface of the semipermeable layer by bringing the semipermeable layer into contact with a solution or dispersion containing at least one compound having the structure of the following formula ii or a polymer thereof or a condensate thereof. Forming a step;
(B) forming a polymer layer on the surface of the semipermeable layer by removing part or all of the solvent of the solution or the dispersion medium of the dispersion from the liquid film;
Including,
The manufacturing method of the polymer laminated semipermeable membrane in any one of Claims 1-3.

(However, X and Y have an arbitrary structure, and Z1 and Z2 are arbitrary hydrolyzable groups.) X is characterized by having an ethylenically unsaturated group,
The manufacturing method of the polymer lamination semipermeable membrane of Claim 4.