JP2014140840A - Separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation membrane element capable of increasing a transmission fluid quantity by reducing flow resistance of a transmission-side channel near a hollow tube.SOLUTION: A separation membrane element includes a hollow tube that has outer and inner peripheral surfaces, and at least one separation membrane leaf that is wound around the hollow tube. Characteristically, the hollow tube has a plurality of communication holes that are connected to the inner peripheral surface from the outer peripheral surface, and a distance between the communication holes adjacent to each other on the outer peripheral surface is in the range of 20-5,000 μm.

Description

  The present invention relates to a separation membrane element used for separating components contained in a fluid such as liquid and gas, and a method for producing the same.

  A hollow tube having a plurality of through holes connected from the outer peripheral surface to the inner peripheral surface can be used, for example, as a hollow tube of a separation membrane element used for purification of waste water or seawater desalination. In this separation membrane element, a reverse osmosis membrane, a precision leakage membrane, and an ultrafiltration membrane are used as a separation membrane, and it is put into practical use for desalination and wastewater treatment of seawater and brine. In recent years, demand for such a separation membrane element has increased, and the required separation performance has been significantly improved. Not only the performance of the separation membrane, but also the separation membrane element as a whole can reduce pressure loss in the element. Improvements in performance are being studied.

  Conventionally, for this hollow tube, the effective perforated area calculated by multiplying the hole diameter of the through hole and the open area ratio of the flow passage material around the hollow tube as shown in Patent Document 1 has been studied. In addition, although pressure loss reduction by providing a non-penetrating recess on the outer peripheral surface of the hollow tube as shown in Patent Document 2 has been studied, further improvement in performance is still required.

JP 2004-305823 A JP 2012-20282 A

  An object of this invention is to provide the separation membrane element which can reduce the resistance concerning the permeation fluid in the permeation | transmission side flow path near a hollow tube, and can improve the amount of permeation fluid.

In order to achieve the object described above, the separation membrane element according to the present invention is characterized by the following (1) to (4).
(1) A separation membrane element comprising a hollow tube having an outer peripheral surface and an inner peripheral surface, and at least one separation membrane leaf wound around the hollow tube,
The hollow tube has a plurality of communication holes connected from an outer peripheral surface to an inner peripheral surface, and a distance between the communication holes adjacent to each other on the outer peripheral surface is 20 μm to 5000 μm.
(2) The separation membrane element according to (1), wherein the number of holes per unit area on the outer peripheral surface of the hollow tube is 1 / cm ^{2 to} 10000 / cm ² .
(3) The separation membrane element according to (1) or (2), wherein the communication hole has an average pore diameter of 50 μm to 2000 μm.
(4) The separation membrane element according to any one of (1) to (3), wherein a porosity with respect to the total volume of the hollow tube is 20% to 60%.

  According to the present invention, it is possible to reduce the resistance applied to the permeating fluid before the fluid that has permeated the separation membrane and collected on the outer peripheral surface of the hollow tube flows into the communication hole. Thereby, the amount of permeated fluid can be increased.

It is a perspective view showing a hollow tube concerning one embodiment of the present invention. It is an enlarged view of the surface of the hollow tube which concerns on one Embodiment of this invention. (A) And (b) is a figure explaining the inflow pattern of the permeated fluid in the communicating hole space | interval of a hollow tube. (A)-(c) is sectional drawing of the circumferential direction of the hollow tube which concerns on different embodiment of this invention. It is a principal part expansion perspective view which shows one form of a separation membrane leaf. It is a top view which shows the separation membrane provided with the permeation | transmission side channel material provided continuously in the winding direction of the separation membrane. It is a top view which shows the separation membrane provided with the permeation | transmission side channel material provided discontinuously in the hollow tube longitudinal direction of the separation membrane. It is sectional drawing which shows a separation membrane provided with a permeation | transmission side channel material. It is a development perspective view showing one form of a separation membrane element. (A)-(e) is a perspective view which shows the hollow tube which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description relates to an example of the present invention, and the present invention is not limited to these.

[1. Hollow tube)
FIG. 1 shows a hollow tube 6 used in a separation membrane element according to an embodiment of the present invention. The hollow tube 6 has a cylindrical shape, and has a plurality of communication holes 61 connected from the outer peripheral surface to the inner peripheral surface. The material of the hollow tube 6 is not particularly limited, but the hollow tube 6 is preferably a rigid body that does not have flexibility.

(1-1) Material As the material of the hollow tube 6, for example, a metal, resin, or ceramic material is preferably used.
As the metal, for example, iron, aluminum, stainless steel, copper, brass (brass), bronze, duralumin or an alloy having two or more metal elements can be used, but when used for water purification, the cost, strength and From the viewpoint of corrosion resistance, it is preferable to use stainless steel.

As the resin, a thermosetting resin or a thermoplastic resin can be used. Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin, urea resin (urea resin), alkyd resin, unsaturated polyester resin, polyurethane, thermosetting polyimide, silicone resin, and diallyl phthalate resin. Among these, it is preferable to use an epoxy resin, a melamine resin, or a silicone resin. Examples of the thermoplastic resin include polyethylene resin, polystyrene resin, polypropylene resin, polycarbonate resin, polyacetal resin, polyamide resin, polysulfone resin, polyester resin (for example, polyethylene terephthalate resin and polybutylene terephthalate resin), and modified polyphenylene oxide resin. (For example, modified polyphenylene ether resin), polyphenylene sulfide resin, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polymethyl methacrylate resin, or a mixture or polymer alloy thereof can be used. .

  In order to increase the strength of the resin, a fiber material such as glass fiber or carbon fiber, or a crystalline material such as whisker or liquid crystal polymer may be added to the resin composition. Examples of the glass fiber include glass wool, chopped glass fiber, and milled glass fiber. Examples of the carbon fiber include milled carbon fiber. Examples of the whisker include aluminum borate whisker, potassium titanate whisker, basic magnesium sulfate whisker, calcium silicate whisker, and calcium sulfate whisker.

  Furthermore, various additives may be added for the purpose of improving the properties of the resin. For example, flame retardants, stabilizers, pigments, dyes, mold release materials, lubricants, weather resistance improvers and the like may be added to the resin composition. These additives may be used alone or as a mixture of two or more.

  As the ceramic, for example, alumina, zirconia, titanium oxide, zircon, silicon carbide, zeolite, ferrite, mullite, cordierite, forsterite, steatite, aluminum nitride, silicon nitride, lead zirconate titanate, etc. are appropriately used. be able to.

(1-2) Porous / Communication Hole The hollow tube 6 is provided with a plurality of communication holes 61 communicating from the outer peripheral surface to the inner peripheral surface. In the present embodiment, the distance between the communication holes adjacent to each other on the outer peripheral surface of the hollow tube 6 is 20 μm to 5000 μm. The distance between the communication holes is preferably 50 μm to 3000 μm, and more preferably 100 μm to 2000 μm.
Here, the distance between the communication holes adjacent to each other is the shortest distance passing through the outer peripheral surface of the hollow tube from the boundary of one hole to the boundary of the other hole in the communication holes 61 adjacent to each other as shown in FIG. Refers to the distance L. Since the distance between the communication holes is in the above range, the distance until the permeated fluid that has reached the periphery of the hollow tube flows into the communication hole is shortened, the inflow efficiency is improved, and the flow resistance can be reduced. The amount of permeated fluid of the membrane element can be improved. The distances between the communication holes are not necessarily the same, and may be different in one hollow tube as long as they are within the above range. For example, the hole interval may be gradually increased or gradually decreased from the upstream side toward the downstream side, and is covered with a central portion and an end portion in the longitudinal direction of the hollow tube 6, more specifically, with a separation membrane leaf. The number of holes per unit area may be different in a portion where the region, the hollow tube 6 and the separation membrane leaf are bonded (hereinafter referred to as a bonded portion).

  Usually, the permeation side flow path 5 formed by the permeation side flow path material 3 described later is formed so as to go straight in the longitudinal direction of the hollow tube as shown in FIG. After reaching the periphery of the tube 6, it moves to the communication hole 61 and flows into the hollow tube. As described above, since the permeation side flow path 5 is formed so as to be orthogonal to the longitudinal direction of the hollow tube, the flow resistance in the longitudinal direction of the hollow tube increases. By making the interval between the communication holes 61 in the longitudinal direction of the hollow tube approximately equal to or smaller than the pitch of the permeate-side flow path 5, the permeated fluid can smoothly flow into the hollow tube 6 as shown in FIG. Can flow in.

The number of holes per unit area on the outer peripheral surface of the hollow tube 6 is not particularly limited, but a porous hollow tube having a number of holes of 1 / cm ^{2 to} 10000 / cm ² is preferably used. be able to. The number of holes is more preferably ² / cm ^{2 to} 5000 / cm ² , and further preferably 10 / cm ^{2 to} 2500 / cm ² . Here, the number of pores per unit area means the number of pores existing in a region separated by 1 cm in the longitudinal direction and 1 cm in the circumferential direction of the hollow tube. It means having. By setting the number of holes per unit area to 1 / cm ² or more, the permeated fluid flows from all directions of the outer peripheral surface of the hollow tube into the inner peripheral portion, so further improvement in inflow efficiency can be expected. By setting it to 10000 pieces / cm ² or less, the strength of the hollow tube can be maintained, and the generation of wrinkles in the step of winding the separation membrane around the hollow tube can be suppressed. The number of holes per unit area does not have to be the same at all locations on the hollow tube 6, and if the number of holes per unit area is within the above range, one hollow tube It may be different, and there may be a part exceeding the above range. For example, the number of holes may gradually increase from the upstream side toward the downstream side, and the hollow tube 6 is covered with a central portion and an end portion in the longitudinal direction, more specifically, with a separation membrane leaf. The number of holes per unit area may be different between the portion and the bonded portion. However, in the portion covered with the separation membrane leaf in the longitudinal direction of the hollow tube 6, if there is an extreme bias in the arrangement of the holes, for example, there is a wide range of regions where no holes exist, smooth introduction into the hollow tube It is preferable that it exists as a whole in order to prevent a smooth flow.

  The shape of the hole of the communication hole 61 is not particularly limited, and includes an ellipse, a circle, an oval, a trapezoid, a triangle, a rectangle, a square, a parallelogram, a rhombus, and an indefinite shape. Further, it may be a through hole that linearly connects the outer peripheral surface and the inner peripheral surface as shown in FIG. 4 (a), or meanders in the hollow tube interior 63 as shown in FIG. 4 (b). Also good. Furthermore, the individual communication holes 61 may be independent, and as shown in FIG. 4C, the plurality of communication holes 61 communicate with each other in the hollow tube interior 63, and the number of holes on the outer peripheral surface and the inner peripheral surface The number of holes above does not have to match.

  The method of providing the plurality of communication holes 61 is not particularly limited, and the holes may be provided at the time of forming the hollow tube, or the holes may be provided by a drill, a laser, or the like after the forming.

  When the hollow tube is molded from a resin, examples of the molding method of the porous resin include a method of sintering and molding resin powder to form pores, a method of directly blowing air or nitrogen gas during molding, and foaming during molding. A method of adding an agent can be used as appropriate. Examples of the foaming agent include a low-boiling solvent that is vaporized by heating or pressure release, such as heptane, hexane, chlorofluorocarbon, and the like that generate gas during thermal decomposition of sodium hydrogen carbonate, sodium carbonate, calcium carbonate, and the like. . Moreover, what forms pores by eluting in a solvent after molding such as salts is also included.

  In addition, when the hollow tube is formed of ceramics, the porous ceramic is formed by a method of firing at a low temperature that is not densified at the time of firing, or by adding a pore-forming agent such as carbon or starch and oxidizing and removing at the time of firing. Examples thereof include a method, a method in which a ceramic slurry is soaked into another pore material such as sponge, and the sponge is oxidized and removed.

  Further, when the hollow tube is formed of a metal, the porous metal is formed by sintering a bundle of metal fibers, dissolving a gas atom in a molten metal and then solidifying it, metal powder and hydrogen. Examples thereof include a method in which foaming agents such as titanium fluoride and sodium hydrogen carbonate are mixed and compressed and solidified, and then heated to generate bubbles.

  Although the average hole diameter of the communication hole 61 is not specifically limited, 50-2000 micrometers is preferable and 100 micrometers-1000 micrometers are more preferable. When the average pore diameter is 50 μm or more, the resistance in the communication hole can be reduced, and when it is 2000 μm or less, the permeation-side channel material or the separation membrane can be suppressed from dropping into the communication hole. Under conditions where the salt concentration of raw fluids such as brine and tap water is low and the operating pressure is low, the effect of the drop is small, but under conditions where the salt concentration of the raw fluid such as seawater is high and the operating pressure is high, the effect of the drop is considered. There is a need to. The hole diameter is not necessarily the same for all holes. For example, as shown in FIGS. 10C to 10E, the configuration in which the hole diameter gradually increases from the upstream side toward the downstream side (FIG. 10C) and the hole diameters are alternately arranged. Configuration (FIG. 10 (d)), a configuration in which the hole diameter is different between the central portion and the end in the longitudinal direction of the hollow tube 6, more specifically, the portion covered with the separation membrane leaf and the bonded portion (FIG. 10 (e)) It may be.

The average pore diameter can be calculated from a pore diameter distribution measured according to a mercury intrusion method (JIS R1655 (2003)). The outline of the method for measuring the average pore diameter is shown below. After weighing the sample to be measured, the sample is filled into a glass or stainless steel sample container. After installing the sample container in the measurement chamber, the sample container is evacuated to a vacuum state (10 Pa or less). Mercury is injected in a vacuum state, the vacuum state is gradually released, and the pressure is increased to the required pressure. The pressure P and mercury intrusion amount at that time are measured. Using the values thus measured, the pore diameter d is calculated by the following Washburn equation, and the pore diameter distribution and the average pore diameter are calculated by measuring the mercury intrusion amount while changing the pressure.
d = −4σ (cos θ) / P
Here, σ represents the surface tension of mercury, and θ represents the contact angle between the sample and mercury. The surface tension σ of mercury is a unique value and is 0.480 N / m at 25 ° C. The contact angle θ can be obtained from the angle between the tangent drawn on the mercury droplet image and the plane of the molded body after dropping a mercury droplet on the surface of the molded body.

Depending on the material used, the hollow tube may be crushed during the measurement by the mercury intrusion method. In this case, it is possible to calculate and substitute by directly measuring the diameter of the communication hole on the outer peripheral surface. A commercially available microscope etc. can be used for the hole diameter measurement on an outer peripheral surface, for example. It is obtained by measuring the diameter of 30 or more randomly extracted holes and calculating the average value. When the hole is not circular, the area is calculated and the representative hole diameter D is calculated by the following formula.
D = 4 × S / l
Here, S represents the area of the hole, and l represents the circumference of the hole. The value obtained as a result of at least 30 measurements obtained in this way should satisfy the above range.

  The porosity of the communication hole 61 is not particularly limited, but is preferably 20% to 60% and more preferably 30% to 50% with respect to the total volume of the hollow tube 6. Here, the porosity means the ratio of the pore portion, that is, the void portion, out of the total volume occupied by the hollow tube (excluding the volume of the central hollow portion). When the porosity is 20% or more, a sufficient flow path can be secured, and when it is 60% or less, the strength of the hollow tube is maintained, and the stress applied in the process of winding the separation membrane around the hollow tube It can withstand the pressure applied during operation of the separation membrane element.

The porosity can be measured according to JIS Z2501 (2000). The outline of the measurement method is shown below. The test piece of the sample is washed by immersing it in a solvent, and the weight (m ₁ ) after drying is measured. Deaerated in a vacuum state immersed in the oil of density [rho _1, to measure the weight after the oil-impregnated (m _2). The test piece after impregnation is immersed in a liquid having a density ρ ₂ and the weight (m ₃ ) is measured. Using the values thus measured, the volume V and the porosity P are calculated by the following formula.
V = (m ₂ −m ₃ ) / ρ ₂
P = 100 × (m ₂ −m ₁ ) / ρ ₁ · V

  In general, when connecting separation membrane elements or connecting to a pressure vessel, there are an inner connector type that connects from the inner peripheral surface side of the hollow tube and an outer connector type that connects from the outer peripheral surface side of the hollow tube. In the latter case, in the longitudinal direction of the hollow tube, the hollow tube is present on the end side of the position covered with the separation membrane leaf, so that if the communication hole 61 exists in the entire hollow tube, the raw fluid, or There is a possibility that the concentrated fluid flows into the permeate fluid and the separation efficiency is deteriorated. The separation membrane in the separation membrane element generally has a structure in which three sides are sealed by folding in two or pasting, but at the end of the hollow tube 6, the vicinity of the sealing portion is bonded to the hollow tube 6. Has been. When the communication hole 61 overlaps with this bonding portion, the adhesive may permeate into the hollow tube 6 through the communication hole 61, thereby blocking the permeate flow path and reducing the amount of permeated water. Therefore, it is preferable that the range in which the communication hole 61 exists does not reach both end portions (bonding portions) of the hollow tube 6 so that the communication hole 61 is provided in the region covered with the separation membrane leaf. When the communication hole 61 extends beyond the portion covered with the separation membrane leaf to the bonding portion, the diameter of the communication hole 61 at the end including the bonding portion is made smaller than that of the region covered with the separation membrane leaf. The blockage of the hollow tube can be suppressed by making it difficult for the adhesive to permeate or by forming the bonded portion as a non-communication hole that does not communicate with the inner peripheral surface of the hollow tube. In this case, in addition to the above-described blockage suppressing effect, it is possible to suppress a decrease in the effective membrane area due to the spread of the adhesive after applying the adhesive around the hollow tube 6, thereby further improving the amount of permeated fluid of the separation membrane element be able to. If the communication hole 61 exists beyond the bonded portion to both ends of the hollow tube 6, the raw fluid and the concentrated fluid may leak to the permeate side, resulting in poor separation efficiency. This can be dealt with by sealing the bonded part and the part not covered with the separation membrane leaf.

(2-1) Overview of Separation Membrane A separation membrane is a membrane that can separate components in the fluid supplied to the surface of the separation membrane and obtain a permeated fluid that has permeated the separation membrane. The separation membrane includes a separation membrane main body and a permeate-side channel material disposed on the separation membrane main body.
Hereinafter, details of each part of the separation membrane will be described with reference to FIGS. In the drawing, x-axis, y-axis, and z-axis direction axes are shown, and the x-axis may be referred to as a hollow tube longitudinal direction and the y-axis may be referred to as a winding direction.

As an example of such a separation membrane, the separation membrane 1 of the present embodiment includes a separation membrane body 2 and a permeate-side flow path member 3 as shown in FIG. The separation membrane main body 2 includes a supply-side surface 21 and a permeation-side surface 22, and the permeation-side flow path material 3 is provided on the permeation-side surface 22 of the separation membrane main body 2 so as to form a flow path. It has been.
In this document, the “supply side surface” of the separation membrane main body 2 means a surface on the side of the separation membrane main body 2 on which the raw fluid is supplied. The “transmission side surface” means the opposite side surface. As will be described later, when the separation membrane body 2 includes a base material and a separation functional layer, generally, the surface on the separation functional layer side is the surface on the supply side, and the surface on the base material side is the surface on the transmission side. . As shown in FIG. 9 and the like, the separation membrane body 2 is rectangular, and the longitudinal direction and the winding direction of the hollow tube are parallel to the outer edge of the separation membrane body 2. The longitudinal direction of the hollow tube may be referred to as the width direction, and the winding direction may be referred to as the length direction.

(2-2) Separation membrane body <Overview>
As the separation membrane body 2, a membrane having separation performance according to the method of use, purpose and the like is used. The separation membrane body 2 may be formed of a single layer or a composite membrane including a separation functional layer and a base material. In the composite membrane, a porous support layer may be formed between the separation functional layer and the substrate.

<Separation function layer>
The thickness of the separation functional layer is not limited to a specific numerical value, but is preferably 5 nm or more and 3000 nm or less in terms of separation performance and transmission performance. In particular, in the case of a reverse osmosis membrane, a forward osmosis membrane, and a nanofiltration membrane, the thickness is preferably 5 nm or more and 300 nm or less.
The thickness of the separation functional layer can be based on the conventional method for measuring the thickness of the separation membrane. For example, the separation membrane is embedded with resin, and an ultrathin section is prepared by cutting the separation membrane, and the obtained section is subjected to processing such as staining. Thereafter, the thickness can be measured by observing with a transmission electron microscope. Further, when the separation functional layer has a pleat structure, measurement can be made at intervals of 50 nm in the cross-sectional length direction of the pleat structure located above the porous support layer, the number of pleats can be measured, and the average can be obtained. it can.

  The separation function layer may be a layer having both a separation function and a support function, or may have only a separation function. The “separation function layer” refers to a layer having at least a separation function.

  When the separation functional layer has both a separation function and a support function, a layer containing cellulose, polyvinylidene fluoride, polyether sulfone, or polysulfone as a main component is preferably applied as the separation functional layer.

  In this document, “X contains Y as a main component” means that the Y content in X is 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably. It means 90% by weight or more, most preferably 95% by weight or more. In addition, when there are a plurality of components corresponding to Y, the total amount of these components only needs to satisfy the above range.

  On the other hand, as the separation functional layer having a porous support layer, a crosslinked polymer is preferably used in terms of easy control of the pore diameter and excellent durability. In particular, a polyamide separation functional layer obtained by polycondensation of a polyfunctional amine and a polyfunctional acid halide, an organic / inorganic hybrid functional layer, and the like are preferably used in that the separation performance of components in the raw fluid is excellent. These separation functional layers can be formed by polycondensation of monomers on the porous support layer.

  For example, the separation functional layer can contain polyamide as a main component. Such a film is formed by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide by a known method. For example, by applying a polyfunctional amine aqueous solution to the porous support layer, removing the excess amine aqueous solution with an air knife or the like, and then applying an organic solvent solution containing a polyfunctional acid halide, the polyamide separation functional layer Is obtained.

Further, the separation functional layer may have an organic-inorganic hybrid structure containing Si element or the like. Examples of the separation functional layer having an organic-inorganic hybrid structure include the following compounds (A) and (B):
(A) a silicon compound in which a reactive group and a hydrolyzable group having an ethylenically unsaturated group are directly bonded to a silicon atom, and (B) a compound other than the compound (A) and having an ethylenically unsaturated group Compounds can be included. Specifically, the separation functional layer contains a hydrolyzable group condensate of compound (A) and a polymer of at least one ethylenically unsaturated group of compound (A) and compound (B). Also good. That is, the separation functional layer is
A polymer formed by condensation or polymerization of only the compound (A),
-The polymer formed by superposing | polymerizing only a compound (B), and-At least 1 sort (s) of polymer of the copolymer of a compound (A) and a compound (B) can be contained. The polymer includes a condensate. In the copolymer of the compound (A) and the compound (B), the compound (A) may be condensed through a hydrolyzable group.

  The hybrid structure can be formed by a known method. An example of a method for forming a hybrid structure is as follows. A reaction solution containing the compound (A) and the compound (B) is applied to the porous support layer. In order to condense the hydrolyzable group after removing the excess reaction solution, heat treatment may be performed. As a polymerization method of the ethylenically unsaturated groups of the compound (A) and the compound (B), heat treatment, electromagnetic wave irradiation, electron beam irradiation, and plasma irradiation may be performed. For the purpose of increasing the polymerization rate, a polymerization initiator, a polymerization accelerator and the like can be added during the formation of the separation functional layer.

  For any separation functional layer, the surface of the membrane may be hydrophilized with an alcohol-containing aqueous solution or an alkaline aqueous solution, for example, before use.

<Porous support layer>
The porous support layer is a layer that supports the separation functional layer, and is also referred to as a porous resin layer.
Although the material used for a porous support layer and its shape are not specifically limited, For example, you may form on a board | substrate with porous resin. As the porous support layer, polysulfone, cellulose acetate, polyvinyl chloride, epoxy resin or a mixture and laminate of them is used, and polysulfone with high chemical, mechanical and thermal stability and easy to control pore size. Is preferably used.

  The porous support layer gives mechanical strength to the separation membrane, and does not have separation performance like a separation membrane for components having a small molecular size such as ions. The pore size and pore distribution of the porous support layer are not particularly limited. For example, the porous support layer may have uniform and fine pores, or the side on which the separation functional layer is formed. It may have a pore size distribution such that the diameter gradually increases from the surface to the other surface. In any case, the projected area equivalent circle diameter of the pores measured using an atomic force microscope or an electron microscope on the surface on the side where the separation functional layer is formed is 1 nm or more and 100 nm or less. preferable. Particularly in terms of interfacial polymerization reactivity and retention of the separation functional layer, the pores on the surface on the side where the separation functional layer is formed in the porous support layer preferably have a projected area equivalent circle diameter of 3 nm to 50 nm. .

  The thickness of the porous support layer is not particularly limited, but is preferably in the range of 20 μm to 500 μm, more preferably 30 μm to 300 μm, for reasons such as giving strength to the separation membrane.

  The form of the porous support layer can be observed with a scanning electron microscope, a transmission electron microscope, or an atomic microscope. For example, when observing with a scanning electron microscope, after peeling off the porous support layer from the substrate, it is cut by the freeze cleaving method to obtain a sample for cross-sectional observation. The sample is thinly coated with platinum, platinum-palladium, or ruthenium tetrachloride, preferably ruthenium tetrachloride, and observed with a high-resolution field emission scanning electron microscope (UHR-FE-SEM) at an acceleration voltage of 3 kV to 6 kV. A Hitachi S-900 electron microscope or the like can be used as the high-resolution field emission scanning electron microscope. Based on the obtained electron micrograph, the film thickness of the porous support layer and the projected area equivalent circle diameter of the surface can be measured.

  The thickness and pore diameter of the porous support layer are average values, and the thickness of the porous support layer is measured at intervals of 20 μm in a direction perpendicular to the thickness direction by cross-sectional observation, and is an average value of 20 points. Moreover, a hole diameter is an average value of each projected area circle equivalent diameter measured about 200 holes.

  Next, a method for forming the porous support layer will be described. For example, the porous support layer is prepared by pouring an N, N-dimethylformamide (hereinafter referred to as DMF) solution of the above polysulfone into a constant thickness on a substrate to be described later, for example, a densely woven polyester cloth or non-woven cloth. It can be produced by molding and wet coagulating it in water.

The porous support layer is “Office of Saleen Water Research and Development Progress Report” no. 359 (1968). In addition, in order to obtain a desired form, the polymer concentration, the temperature of the solvent, and the poor solvent can be adjusted.
For example, a predetermined amount of polysulfone is dissolved in DMF to prepare a polysulfone resin solution having a predetermined concentration. Next, this polysulfone resin solution is applied to a substrate made of polyester cloth or nonwoven fabric to a substantially constant thickness, and after removing the surface solvent in the air for a certain period of time, the polysulfone is coagulated in the coagulation liquid. Can be obtained.

<Base material>
From the viewpoint of the strength and dimensional stability of the separation membrane body, the separation membrane body may have a substrate. As the base material, it is preferable to use a fibrous base material in terms of strength, unevenness forming ability and fluid permeability.

  As a base material, both a long fiber nonwoven fabric and a short fiber nonwoven fabric can be used preferably. In particular, since the long fiber nonwoven fabric has excellent film-forming properties, when the polymer solution is cast, the solution penetrates through the permeation, the porous support layer peels off, and Can suppress the film from becoming non-uniform due to fluffing of the substrate and the like, and the occurrence of defects such as pinholes. In addition, since the base material is made of a long-fiber non-woven fabric composed of thermoplastic continuous filaments, compared to short-fiber non-woven fabrics, it suppresses the occurrence of non-uniformity and film defects caused by fiber fluffing during casting of a polymer solution. be able to. Furthermore, since the separation membrane is tensioned in the film-forming direction when continuously formed, it is preferable to use a long-fiber nonwoven fabric excellent in 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 porous support layer have a longitudinal orientation than the fibers in the surface layer on the porous support layer side. According to such a structure, not only a high effect of preventing membrane breakage by maintaining strength is realized, but also a laminate comprising a porous support layer and a substrate when imparting irregularities to the separation membrane The moldability is improved, and the uneven shape on the surface of the separation membrane is stabilized, which is preferable.

More specifically, the fiber orientation degree in the surface layer on the side opposite to the porous support layer of the long-fiber nonwoven fabric is preferably 0 ° or more and 25 ° or less, and the fiber orientation in the surface layer on the porous support layer side. The degree of orientation difference with respect to the degree is preferably 10 ° or more and 90 ° or less.
The separation membrane manufacturing process and the element manufacturing process include a heating process, but a phenomenon occurs in which the porous support layer or the separation functional layer contracts due to the heating. In particular, the shrinkage is remarkable in the width direction where no tension is applied in continuous film formation. Since shrinkage causes problems in dimensional stability and the like, a substrate having a small rate of thermal dimensional change is desired. In the nonwoven fabric, when the difference between the fiber orientation degree on the surface layer opposite to the porous support layer and the fiber orientation degree on the porous support layer side surface layer is 10 ° or more and 90 ° or less, the change in the width direction due to heat is suppressed. Can also be preferred.

  Here, the fiber orientation degree is an index indicating the direction of the fibers of the nonwoven fabric substrate constituting the porous support layer. Specifically, the fiber orientation degree is an average value of angles between the film forming direction when continuous film formation is performed, that is, the longitudinal direction of the nonwoven fabric base material, and the fibers constituting the nonwoven fabric base material. That is, if the longitudinal direction of the fiber is parallel to the film forming direction, the fiber orientation degree is 0 °. If the longitudinal direction of the fiber is perpendicular to the film forming direction, that is, if it is parallel to the width direction of the nonwoven fabric substrate, the degree of orientation of the fiber is 90 °. Accordingly, the closer to 0 ° the fiber orientation, the longer the orientation, and the closer to 90 °, the lateral orientation.

  The degree of fiber orientation is measured as follows. First, 10 small piece samples are randomly collected from the nonwoven fabric. Next, the surface of the sample is photographed at 100 to 1000 times with a scanning electron microscope. In the photographed image, 10 samples are selected for each sample, and the angle when the longitudinal direction (longitudinal direction, film forming direction) of the nonwoven fabric is 0 ° is measured. That is, the angle is measured for a total of 100 fibers per nonwoven fabric. An average value is calculated from the angles of 100 fibers thus measured. The value obtained by rounding off the first decimal place of the obtained average value is the fiber orientation degree.

  The thickness of the base material is preferably set so that the total thickness of the base material and the porous support layer is in the range of 30 μm to 300 μm, preferably in the range of 50 μm to 250 μm.

(2-3) Permeation side channel material <Overview>
As shown in FIG. 5, the permeation-side flow path material 3 is provided on the permeation-side surface of the separation membrane body 2 so as to form a permeation-side flow path. “Provided so as to form a permeate-side flow path” means that when the separation membrane 1 is incorporated in a separation membrane element described later, the permeated fluid that has permeated the separation membrane body 2 can reach the hollow tube. In addition, it means that a channel material is formed. Details of the configuration of the permeate-side channel material 3 are as follows.

<Constituent component of permeate side channel material>
The permeate side channel material 3 is preferably formed of a material different from that of the separation membrane body 2. The different material means a material having a composition different from that of the material used in the separation membrane body 2. In particular, the composition of the permeate-side channel material 3 is preferably different from the composition of the surface of the separation membrane body 2 on which the permeate-side channel material 3 is formed, and any layer that forms the separation membrane body 2 It is preferable that the composition is different.

  Although it does not specifically limit as a component which comprises the permeation | transmission side flow path material 3, Resin is used preferably. Specifically, from the viewpoint of chemical resistance, polyolefins such as ethylene vinyl acetate copolymer resin, polyethylene, and polypropylene, and copolymerized polyolefins are preferable, and polymers such as urethane resins and epoxy resins can be selected. It can be used as a mixture comprising two or more types. In particular, since a thermoplastic resin is easy to mold, a channel material having a uniform shape can be formed.

<Shape and arrangement of permeate side channel material>
<< Overview >>
It is preferable that the permeate side channel material 3 is not connected to the groove in order to reduce the flow resistance. Although a sheet-like material or a material fixed to the permeation side of the separation membrane can be used, the flow resistance can be remarkably reduced by fixing it to the permeation side of the separation membrane for the reason described later.
Conventionally, a tricot widely used as a permeate-side channel material is a knitted fabric, and is composed of three-dimensionally intersecting yarns. That is, the tricot has a two-dimensionally continuous structure. When such a tricot is applied as a channel material, the height of the channel is smaller than the thickness of the tricot. That is, the entire thickness of the tricot cannot be used as the height of the flow path.

  On the other hand, in this invention, as shown in FIG. 8 etc., the permeation | transmission side flow path material 3 is arrange | positioned so that it may not mutually overlap. Therefore, all the heights (that is, the thicknesses) of the permeation-side flow path members 3 of the present embodiment are utilized as the heights of the flow path grooves. Therefore, when the permeation side flow path member 3 of the present embodiment is applied, the flow path becomes higher than when a tricot having the same thickness as the permeation side flow path member 3 is applied. That is, since the cross-sectional area of the flow path becomes larger, the flow resistance becomes smaller.

  In the present invention, a plurality of discontinuous permeation-side flow path members 3 are fixed on one separation membrane body 2. “Discontinuous” is a state in which a plurality of permeation-side flow path members are provided at intervals. That is, when the permeation side channel material 3 in one separation membrane is peeled from the separation membrane main body 2, a plurality of permeation side channel materials 3 separated from each other are obtained. On the other hand, members such as nets, tricots, and films exhibit a continuous and integral shape even when separated from the separation membrane body 2.

  By providing a plurality of discontinuous permeation-side flow path members 3, the separation membrane 1 can keep pressure loss low when incorporated into the separation membrane element 100 described later. As an example of such a configuration, in FIG. 6, the permeate-side flow path material 3 is formed discontinuously only in the longitudinal direction of the hollow tube, and in FIG. It is formed continuously.

  The separation membrane is preferably arranged in the separation membrane element so that its winding direction coincides with the winding direction of the separation membrane element. That is, in the separation membrane element, the separation membrane may be arranged so that the longitudinal direction of the hollow tube is parallel to the longitudinal direction of the hollow tube 6 and the winding direction is orthogonal to the longitudinal direction of the hollow tube 6. preferable.

  The permeate-side channel material 3 is provided discontinuously in the longitudinal direction of the hollow tube, and is provided so as to continue from one end to the other end of the separation membrane body 2 in the winding direction. That is, as shown in FIG. 9, when the separation membrane 1 is incorporated in the separation membrane element 100, the permeation side flow path material 3 is continuous from the inner end to the outer end of the separation membrane 1 in the winding direction. To be arranged. The inner side in the winding direction is the side close to the hollow tube in the separation membrane, and the outer side in the winding direction is the side far from the hollow tube in the separation membrane.

The passage material is “continuous in the winding direction” means that the permeate-side flow passage material 3 is provided without interruption in the winding direction of the separation membrane body 2 as shown in FIG. In addition, although there are places where the permeation-side channel material 3 is interrupted, both cases where the permeation-side channel material 3 is substantially continuous in the winding direction of the separation membrane body 2 are included. In the “substantially continuous” form, preferably, the interval e between the permeate-side flow path members 3 in the winding direction (that is, the length of the portion where the permeate-side flow path material is interrupted) is 5 mm or less. In particular, the interval e is more preferably 1 mm or less, and further preferably 0.5 mm or less. Further, the total value of the intervals e included from the beginning to the end of the row of permeate-side flow path materials 3 arranged in the winding direction is preferably 100 mm or less, more preferably 30 mm or less, and 3 mm or less. More preferably. In the form shown in FIG. 6, the interval e is 0 (zero).
When the permeate-side flow path material 3 is provided without interruption as shown in FIG. 6, membrane drop is suppressed during pressure filtration. Membrane sagging is that the membrane falls into the channel and narrows the channel.

  In FIG. 7, the permeation side flow path member 3 is discontinuously provided not only in the longitudinal direction of the hollow tube but also in the winding direction. That is, the permeation-side channel material 3 is provided at intervals in the length direction. However, as described above, the permeation-side channel material 3 is substantially continuous in the winding direction, so that the film sagging is suppressed. Further, by providing the discontinuous permeation-side flow path material 3 in the two directions as described above, the contact area between the flow path material and the fluid is reduced, so that the pressure loss is reduced. In other words, this form is a configuration in which the flow path 5 includes a branch point. In other words, in the configuration of FIG. 7, the permeating fluid is divided by the permeation-side flow path member 3 while flowing through the flow path 5, and can further merge downstream.

  As described above, in FIG. 6, the permeate-side channel material 3 is provided so as to continue from one end to the other end of the separation membrane body 2 in the longitudinal direction (winding direction) of the hollow tube. In FIG. 7, the permeate-side flow path material 3 is divided into a plurality of portions in the longitudinal direction (winding direction) of the hollow tube. It is provided to line up.

  The passage material is “provided from one end to the other end of the separation membrane body” means that the permeation side passage material 3 is provided up to the edge of the separation membrane body 2 and the permeation side passage in the vicinity of the edge. It includes both a form in which there is a region where the material 3 is not provided. That is, the flow path material only needs to be distributed in the winding direction to such an extent that a flow path on the permeation side can be formed, and there is a portion in the separation membrane body 2 where the permeation side flow path material 3 is not provided. May be. For example, it is not necessary to provide the permeation-side flow path material 3 at a portion where the permeation side surface is bonded to another separation membrane. Moreover, the area | region where the permeation | transmission side flow-path material 3 is not arrange | positioned may be provided in some places, such as the edge part of a separation membrane, for the reason on other specifications or manufacture.

  Also in the longitudinal direction of the hollow tube, the permeation side flow path material 3 can be distributed substantially evenly over the entire separation membrane body. However, similarly to the distribution in the winding direction, it is not necessary to provide the permeation-side flow path material 3 at the adhesion portion with the other separation membrane on the permeation-side surface. Moreover, the area | region where the permeation | transmission side flow-path material 3 is not arrange | positioned may be provided in some places, such as the edge part of a separation membrane, for the reason on other specifications or manufacture.

<< Dimensions of separation membrane body and permeate side channel material >>
Here, the dimension of the permeation side flow path member 3 with respect to the dimension of the separation membrane main body 2 will be described. 6 to 8, a to f indicate the following values.
a: Length of the separation membrane main body 2 b: Distance between the permeation side flow path material 3 in the width direction of the separation membrane main body 2 c: Height of the permeation side flow path material (the permeation side flow path material 3 and the separation membrane main body 2 Difference in height from the transmission side surface 22)
d: Width of the permeate side channel material 3 e: Interval of the permeate side channel material 3 in the length direction of the separation membrane body 2 f: Length of the permeate side channel material 3 For measuring the values a to f, for example, A commercially available shape measuring system or a microscope can be used. Each value is obtained by performing measurement at 30 or more locations on one separation membrane, and calculating an average value by dividing the sum of these values by the number of measurement total locations. Thus, each value obtained as a result of the measurement at at least 30 locations only needs to satisfy the above range.

(Length of separation membrane body a)
The length a is a distance from one end of the separation membrane body 2 to the other end in the winding direction. When this distance is not constant, the length a can be obtained by measuring this distance at 30 or more positions in one separation membrane body 2 and obtaining an average value.

(Interval b of transmission-side flow path material in the longitudinal direction of the hollow tube)
The interval between the permeate-side channel members 3 in the longitudinal direction of the hollow tube, that is, the interval b between the permeate-side channel members 3 in the width direction of the separation membrane body 2 corresponds to the width of the channel 5. When the width of one flow path 5 is not constant in one cross section, that is, when the side surfaces of two adjacent transmission side flow path materials 3 are not parallel, the maximum width of one flow path 5 within one cross section The average value of the value and the minimum value is measured, and the average value is calculated. As shown in FIG. 8, in the cross section perpendicular to the winding direction, when the permeate-side channel material 3 has a trapezoidal shape with a narrow top and a thick bottom, first, between the upper portions of two adjacent permeate-side channel materials 3 The distance between and the distance between the lower parts is measured, and the average value is calculated. In any cross section of 30 or more locations, the interval between the permeation side flow path materials 3 is measured, and an average value is calculated in each cross section. And the space | interval b is calculated by calculating further the arithmetic mean value of the average value obtained in this way.

As the distance b increases, membrane drop tends to occur during pressure filtration, and it becomes difficult to secure a flow path around the hollow tube 6. Conversely, the smaller the distance b, the less likely the film will drop, but the flow resistance becomes larger because the flow path becomes smaller. Considering the flow resistance, the interval b is preferably 0.05 mm or more, more preferably 0.2 mm or more, and further preferably 0.3 mm or more. In terms of suppression of film sagging, the interval b is preferably 5 mm or less, more preferably 3 mm or less, still more preferably 2 mm or less, and most preferably 0.8 mm or less.
These upper and lower limits can be combined arbitrarily. For example, the interval b is preferably 0.2 mm or more and 5 mm or less, and if it is within this range, the flow resistance can be reduced while suppressing the film drop. The distance b is more preferably 0.05 mm or more and 3 mm or less, 0.2 mm or more and 2 mm or less, and further preferably 0.3 mm or more and 0.8 mm or less.

(Height c of permeate side channel material)
The height c is a difference in height between the permeate-side channel material 3 and the surface of the separation membrane body 2. As shown in FIG. 8, the height c is a difference in height between the highest portion of the permeate-side flow path member 3 and the permeate side surface of the separation membrane body 2 in a cross section perpendicular to the winding direction. That is, in the height c, the thickness of the portion impregnated in the base material is not considered. The height c is a value obtained by measuring and averaging the heights of 30 or more permeation side flow path materials 3. The height c of the permeate-side channel material 3 may be obtained by observing the cross section of the channel material in the same plane, or may be obtained by observing the cross section of the channel material in a plurality of planes.

The height c can be appropriately selected according to the use condition and purpose of the element, but may be set as follows, for example.
The larger the height c, the smaller the flow resistance. Therefore, the height c is preferably 0.03 mm or more, more preferably 0.05 mm or more, and further preferably 0.1 mm or more. On the other hand, the smaller the height c, the larger the number of films filled per element. Therefore, the height c is preferably 0.8 mm or less, more preferably 0.4 mm or less, and even more preferably 0.32 mm or less. These upper limits and lower limits can be combined. For example, the height c is preferably 0.03 mm or more and 0.8 mm or less, preferably 0.05 mm or more and 0.4 mm or less, and 0.1 mm or more. More preferably, it is 0.32 mm or less.

Moreover, it is preferable that the difference of the height of two adjacent permeation | transmission side channel materials is small. If the difference in height is large, the separation membrane is distorted during pressure filtration, so that defects may occur in the separation membrane. The difference in height between two adjacent permeation-side flow path members is preferably 0.1 mm or less, more preferably 0.06 mm or less, and even more preferably 0.04 mm or less.
For the same reason, the maximum height difference of all the permeation side flow path materials provided in the separation membrane is preferably 0.25 mm or less, particularly preferably 0.1 mm or less, more preferably 0.03 mm or less. It is.

(Width d of permeate side channel material)
The width d of the permeation side channel material 3 is measured as follows. First, in one cross section perpendicular to the longitudinal direction of the hollow tube 6, the average value of the maximum width and the minimum width of one permeation side flow path member 3 is calculated. That is, in the permeation side channel material 3 as shown in FIG. 8 where the upper part is thin and the lower part is thick, the width of the lower part and the upper part of the channel material are measured and the average value is calculated. By calculating such an average value in at least 30 cross-sections and calculating the arithmetic average thereof, the width d per film can be calculated.

  The width d of the permeate-side channel material 3 is preferably 0.2 mm or more, and more preferably 0.3 mm or more. When the width d is 0.2 mm or more, the shape of the flow path material can be maintained even when pressure is applied to the permeation side flow path material 3 during operation of the separation membrane element, and the permeation side flow path can be stably provided. It is formed. The width d is preferably 2 mm or less, and more preferably 1.5 mm or less. When the width d is 2 mm or less, a sufficient flow path on the permeate side can be secured.

  The permeate side channel material 3 is formed such that its length is greater than its width. Such a long permeate-side channel material 3 is also referred to as a “wall-like object”.

(Interval e of permeate-side channel material in the winding direction)
The interval between the permeate-side channel members 3 in the winding direction, that is, the interval e between the permeate-side channel members 3 in the length direction of the separation membrane body 2 is the shortest distance between the adjacent permeate-side channel members 3 in the winding direction. It is. As shown in FIG. 6, the permeate-side flow path material 3 is continuous from one end to the other end of the separation membrane body 2 in the winding direction (in the separation membrane element, from the inner end to the outer end in the winding direction). The distance e is 0 mm. As shown in FIG. 7, when the permeate-side channel material 3 is interrupted in the winding direction, the interval e is preferably 5 mm or less, more preferably 1 mm or less, and still more preferably 0. 5 mm or less. When the distance e is within the above range, the mechanical load on the film is small even when the film is dropped, and the pressure loss due to the blockage of the flow path can be relatively small. In addition, the minimum of the space | interval e is 0 mm.

(Permeation side channel material length f)
The length f of the permeate-side channel material 3 is the length of the permeate-side channel material 3 in the length direction (that is, the winding direction) of the separation membrane main body 2. The length f is obtained by measuring the lengths of 30 or more permeation side flow path materials 3 in one separation membrane 1 and calculating the average value thereof. The length f of the permeate side channel material 3 may be equal to or less than the length a of the separation membrane body 2. When the length f of the flow path material is equal to the length a of the separation membrane body, the permeate side flow path material 3 is continuously provided from the inner end to the outer end in the winding direction of the separation membrane 1. Refers to that. The length f is preferably 10 mm or more, more preferably 20 mm or more. Since the length f is 10 mm or more, the flow path is secured even under pressure.

(Relationship between dimensions af)
As described above, the permeation-side channel material of the present embodiment can reduce pressure loss as compared with a channel material having a continuous shape like a conventional tricot. In other words, according to the technique of the present embodiment, the leaf length can be made larger than that of the conventional technique even if the pressure loss is equal. If the leaf length can be increased, the number of leaves can be reduced.

The number of leaves can be particularly reduced by setting the dimensions af to satisfy all of the following mathematical expressions i) to v).
i) a ² f ² (b + c) ² (b + d) × 10 ⁻⁶ / b ³ c ³ (e + f) ² ≦ 1400
ii) 850 ≦ a ≦ 7000
iii) b ≦ 2
iv) c ≦ 0.5
v) 0.15 ≦ df / (b + d) (e + f) ≦ 0.85

Thus, by providing the flow path material 3 in a predetermined form on the permeate side of the separation membrane body 2, pressure loss is reduced as compared with a flow path material having a continuous shape like a conventional tricot. Can be lengthened. Therefore, even if the number of leaves per separation membrane element is reduced, a separation membrane element having excellent separation performance can be provided.
In the above formula, mm can be adopted as the unit of length.

(shape)
The shape of the permeate-side channel material is not particularly limited, but a shape that reduces the flow resistance of the channel and stabilizes the channel when permeated can be selected. In these respects, in any cross section perpendicular to the surface direction of the separation membrane, the shape of the flow path material may be a straight column shape, a trapezoidal shape, a curved column shape, or a combination thereof.

  When the cross-sectional shape of the permeate-side channel material is trapezoidal, if the difference between the length of the upper base and the length of the lower base is too large, membrane drop during pressure filtration is likely to occur at the membrane contacting the smaller side. For example, when the upper base of the permeate-side channel material is shorter than the lower base, the upper width of the channel between them is wider than the lower width. Therefore, the upper film tends to drop downward. Therefore, in order to suppress such a drop, the ratio of the length of the upper base to the length of the lower base of the permeate-side channel material is preferably 0.6 or more and 1.4 or less, and 0.8 or more and 1.2 or less. The following is more preferable.

  If the permeate-side channel material is a thermoplastic resin, changing the processing temperature and the type of thermoplastic resin to be selected allows the flow channel material to be freely adjusted so that the required separation characteristics and permeation performance conditions can be satisfied. The shape can be adjusted.

  In addition, the shape of the permeation-side channel material in the planar direction of the separation membrane may be linear as a whole as shown in FIG. 6, and other shapes are, for example, curved, sawtooth, and wavy. May be. In these shapes, the channel material may be a broken line.

  Further, when the shape of the permeation-side channel material in the planar direction of the separation membrane is a straight line, adjacent channel materials may be arranged substantially parallel to each other. “Arranged substantially in parallel” means, for example, that the channel material does not intersect on the separation membrane, and preferably the angle formed by the longitudinal direction of two adjacent channel materials is 0 ° or more and 30 ° or less. More preferably, the angle is 0 ° to 15 ° and the angle is 0 ° to 5 °.

  Further, the angle formed by the longitudinal direction of the permeate-side channel material and the longitudinal direction of the hollow tube is preferably 60 ° or more and 120 ° or less, more preferably 75 ° or more and 105 ° or less, and 85 °. More preferably, it is 95 ° or less. When the angle formed by the longitudinal direction of the flow path material and the longitudinal direction of the hollow tube is within the above range, the permeated water is efficiently collected in the hollow tube.

  In order to stably form the flow path, it is preferable that the separation membrane body can be prevented from dropping when the separation membrane body is pressurized in the separation membrane element. For this purpose, it is preferable that the contact area between the separation membrane main body and the flow path material is large, that is, the area of the flow path material relative to the area of the separation membrane main body (projected area on the membrane surface of the separation membrane main body) is large. On the other hand, in order to reduce pressure loss, it is preferable that the cross-sectional area of a flow path is wide. The cross section of the flow path is defined as a flow path in order to ensure a large contact area between the separation membrane body perpendicular to the longitudinal direction of the flow path and the permeate-side flow path material and a wide cross-sectional area of the flow path. The cross-sectional shape of the road is preferably a concave lens. Further, the permeate-side channel material 3 may have a straight column shape having no change in width in the cross-sectional shape in the direction perpendicular to the winding direction. Moreover, as long as the separation membrane performance is not affected, the cross-sectional shape in the direction perpendicular to the winding direction has a trapezoidal wall-like object having a change in width, an elliptic cylinder, an elliptic cone, four A shape like a pyramid or a hemisphere may be sufficient.

  The shape of the permeate-side channel material is not limited to the shape shown in FIGS. Change the processing temperature and the type of hot-melt resin to be selected when the permeate-side channel material is placed on the permeate-side surface of the separation membrane body by, for example, a hot melt method by fixing the melted material. By doing so, the shape of the permeation-side flow path material can be freely adjusted so that the required separation characteristics and permeation performance conditions can be satisfied.

  In FIG. 5 to FIG. 9, the planar shape of the permeation side flow path member 3 is linear in the length direction. However, the permeation side flow path material 3 can be changed to other shapes as long as it is convex with respect to the surface of the separation membrane body 2 and does not impair the desired effect as the separation membrane element. That is, the shape of the flow path material in the plane direction may be a curved line, a wavy line, or the like. A plurality of flow path materials included in one separation membrane may be formed so that at least one of width and length is different from each other.

(Projected area ratio)
The projected area ratio of the permeate-side channel material to the permeate-side surface of the separation membrane is 0.03 or more and 0.85 or less, particularly in terms of reducing the flow resistance of the permeate-side channel and forming the channel stably. Preferably, it is 0.15 or more and 0.85 or less, more preferably 0.2 or more and 0.75 or less, and further preferably 0.3 or more and 0.6 or less. The projected area ratio is a value obtained by dividing the projected area of the flow path material obtained when the separation membrane is cut out at 5 cm × 5 cm and projected onto a plane parallel to the surface direction of the separation membrane by the cut-out area (25 cm ² ). It is. This value can also be expressed by the above-described equation df / (b + d) (e + f).

[2. Separation membrane element)
(2-1) Overview The separation membrane element 100 includes the hollow tube 6 and any of the above-described configurations, and includes the separation membrane 1 wound around the hollow tube 6. The separation membrane element 100 further includes a member such as an end plate (not shown).

(2-2) Separation membrane <Overview>
The separation membrane 1 is wound around the hollow tube 6 and arranged so that the width direction is along the longitudinal direction of the hollow tube 6. As a result, the separation membrane 1 is disposed such that the length direction is along the winding direction.
Therefore, the permeation-side flow path member 3 that is a wall-like material is discontinuously arranged at least in the longitudinal direction of the hollow tube 6 on the permeation-side surface 22 of the separation membrane 1. That is, the flow path 5 is formed to be continuous from the outer end to the inner end of the separation membrane in the winding direction. As a result, the permeated water easily reaches the hollow tube, that is, the flow resistance is reduced, so that a large amount of permeated fluid is obtained.
The “inner side in the winding direction” and “outer side in the winding direction” are as shown in FIG. That is, the “inner end in the winding direction” and the “outer end in the winding direction” correspond to the end closer to the hollow tube 6 and the far end in the separation membrane 1, respectively.

  As described above, since the permeation side flow path material 3 does not have to reach the edge of the separation membrane 1, for example, the outer end portion of the envelope-like membrane in the winding direction and the envelope in the longitudinal direction of the hollow tube 6. The permeation-side flow path material 3 may not be provided at the end of the film-like film.

<Membrane leaf and envelope membrane>
As shown in FIG. 5, the separation membrane 1 forms a separation membrane leaf 4 (sometimes simply referred to as “leaf” in this document). In the leaf 4, the separation membrane 1 is arranged so that the supply-side surface 21 faces the supply-side surface 71 of another separation membrane 7 with a supply-side flow path material (not shown) interposed therebetween. In the separation membrane leaf 4, a supply-side flow path (not shown) is formed between the supply-side surfaces of the separation membranes facing each other.

Furthermore, the separation membrane 1 and the permeation side surface 72 of the separation membrane 7 of the other membrane leaf facing the permeation side surface 22 of the separation membrane 1 are overlapped by the two separation membrane leaves 4 being overlapped. A film is formed. In the envelope-like membrane, between the opposite permeation side surfaces, the permeated water flows into the hollow tube 6 so that the rectangular shape of the separation membrane is opened only on one side inside the winding direction, and on the other three sides Sealed. The permeate is isolated from the supply water by this envelope membrane.
The form of sealing includes a form bonded by an adhesive or hot melt, a form fused by heating or laser, and a form in which a rubber sheet is sandwiched. Sealing by adhesion is particularly preferable because it is the simplest and most effective.

  Further, on the supply-side surface 21 of the separation membrane 1, the inner end in the winding direction is closed by folding or sealing. Since the supply-side surface 21 of the separation membrane 1 is sealed rather than being folded, bending at the end of the separation membrane is unlikely to occur. By suppressing the occurrence of bending in the vicinity of the crease, the generation of voids between the separation membranes and the occurrence of leaks due to the voids are suppressed when wound.

  By suppressing the occurrence of leak in this way, the recovery rate of the envelope film is improved. The recovery rate of the envelope-like film is obtained as follows. That is, an air leak test (air leak test) of the separation membrane element is performed in water, and the number of envelope-shaped membranes in which the leak has occurred is counted. Based on the count result, the ratio of (number of envelope films in which air leak has occurred / number of envelope films used for evaluation) is calculated as the recovery rate of the envelope film.

  A specific air leak test method is as follows. The end of the hollow tube of the separation membrane element is sealed, and air is injected from the other end. The injected air passes through the hole of the hollow tube and reaches the permeation side of the separation membrane.However, if the separation membrane is not sufficiently folded as described above and the air is bent near the fold, Air moves through the gap. As a result, the air moves to the supply side of the separation membrane, and the air reaches the water from the end (supply side) of the separation membrane element. Thus, air leak can be confirmed as the generation of bubbles.

  When the separation membrane leaf is formed by folding, the longer the leaf (that is, the longer the original separation membrane), the longer the time required for folding the separation membrane. However, by sealing the supply side surface of the separation membrane instead of folding, an increase in manufacturing time can be suppressed even if the leaf is long.

In the separation membrane leaf and the envelope membrane, the separation membranes facing each other (separation membranes 1 and 7 in FIG. 5) may have the same configuration or different configurations. That is, in the separation membrane element, at least one of the two permeate-side surfaces facing each other only needs to be provided with the above-described permeation-side flow path material, and therefore the separation membrane element does not include the permeation-side flow path material. Separation membranes may be alternately stacked. However, for convenience of explanation, in the separation membrane element and the explanation related thereto, the “separation membrane” includes a separation membrane that does not include the permeate-side flow path material (for example, a membrane that has the same configuration as the separation membrane main body).
The separation membranes facing each other on the permeate side surface or the supply side surface may be two different separation membranes, or one membrane folded.

(2-3) Permeation side flow path As described above, the separation membrane 1 includes the permeation side flow path material 3. By the permeation side flow path member 3, a permeation side flow path is formed inside the envelope-shaped membrane, that is, between the permeation side surfaces 22 of the separation membrane 1 facing each other.

(2-4) Supply side channel (channel material)
The separation membrane element 100 includes a channel material (not shown) having a projected area ratio with respect to the separation membrane 1 exceeding 0 and less than 1 between the surfaces on the supply side of the overlapping separation membranes. The projected area ratio of the supply-side channel material is preferably 0.03 or more and 0.50 or less, more preferably 0.10 or more and 0.40 or less, and particularly preferably 0.15 or more and 0.35 or less. It is. When the projected area ratio is 0.03 or more and 0.50 or less, the flow resistance can be suppressed to be relatively small. The projected area ratio refers to the projected area obtained when the separation membrane and the supply-side channel material are cut out at 5 cm × 5 cm, and the supply-side channel material is projected onto a plane parallel to the surface direction of the separation membrane. Divided value.
As will be described later, the height of the supply-side channel material is preferably more than 0.5 mm and not more than 2.0 mm, more preferably not less than 0.6 mm and not more than 1.0 mm, in consideration of the balance of each performance and the operation cost.

  The shape of the supply-side channel material is not particularly limited, and may have a continuous shape or a discontinuous shape. Examples of the channel material having a continuous shape include members such as a film and a net. Here, the continuous shape means that it is continuous over the entire range of the flow path material. The continuous shape may include a portion where a part of the flow path material is discontinuous to the extent that a problem such as a decrease in the amount of permeated fluid does not occur. The definition of “discontinuity” is as described for the passage-side channel material. The material of the supply side channel material is not particularly limited, and may be the same material as the separation membrane or a different material.

(Unevenness processing)
Also, instead of disposing the supply-side flow path material on the separation membrane supply side, a difference in height can be imparted to the separation membrane supply side by a method such as embossing, hydraulic forming, or calendering.
Examples of the embossing method include roll embossing, and the pressure and processing temperature for carrying out this can be appropriately determined according to the melting point of the separation membrane. For example, when the separation membrane has a porous support layer containing an epoxy resin, the linear pressure is preferably 10 kg / cm or more and 60 kg / cm or less, and the heating temperature is preferably 40 ° C. or more and 150 ° C. or less. Moreover, when it has a porous support layer containing heat resistant resins, such as polysulfone, it is preferable that it is 10 to 70 kg / cm of linear pressure, and roll heating temperature 70 to 160 degreeC is preferable. In any case of roll embossing, a winding speed of 1 m / min to 20 m / min is preferable.

  When embossing is performed, the shape of the roll handle is not particularly limited, but it is important to reduce the flow resistance of the flow path and stabilize the flow path when supplying and permeating fluid to the separation membrane element. is there. In these respects, there are ellipses, circles, ellipses, trapezoids, triangles, rectangles, squares, parallelograms, rhombuses, and irregular shapes in the shape observed from the upper surface. Those formed in the surface direction, those formed in a widened form, and those formed in a narrowed form are used.

  The difference in height on the supply-side surface of the separation membrane that can be imparted by embossing can be freely adjusted by changing the pressure heat treatment conditions so as to satisfy the conditions that require separation characteristics and water permeation performance. However, if the difference in height on the supply side surface of the separation membrane is too deep, the flow resistance is reduced, but the number of membrane leaves that can be filled in the vessel when the element is formed is reduced. If the height difference is small, the flow resistance of the flow path increases, and the separation characteristics and water permeation performance deteriorate. Therefore, the fresh water generation capacity of the element is lowered, and the operation cost for increasing the amount of permeated fluid is increased.

Therefore, in consideration of the balance of each performance and the operating cost described above, in the separation membrane, the difference in height on the supply side surface of the separation membrane is preferably more than 0.5 mm and preferably 2.0 mm or less, and 0.6 mm or more. 1.0 mm or less is more preferable.
The difference in height on the supply side surface of the separation membrane can be obtained by the same method as in the case of the above-described difference in height on the permeation side of the separation membrane.
The groove width is preferably 0.2 mm or more and 10 mm or less, more preferably 0.5 mm or more and 3 mm or less.

  The pitch may be appropriately designed between 1/10 and 50 times the groove width. The groove width is the part that sinks on the surface where the height difference exists, and the pitch is the horizontal from the highest point of the high part to the highest part of the adjacent high part on the surface where the height difference exists. It is distance.

  The projected area ratio of the portion that becomes convex by embossing is preferably 0.03 or more and 0.5 or less, more preferably 0.10 or more and 0.40, for the same reason as in the case of the supply-side channel material. Or less, and particularly preferably 0.15 or more and 0.35 or less.

  In the surface of the separation membrane, the “height difference” is the difference in height between the surface of the separation membrane body and the top of the flow channel material (that is, the flow channel material). In the case where the separation membrane main body is processed to be uneven, it is the height difference between the concave portion and the convex portion.

[3. Method for manufacturing separation membrane element]
(3-1) Manufacture of separation membrane body The manufacturing method of the separation membrane body has been described above, but it is summarized as follows.
The resin is dissolved in a good solvent, and the resulting resin solution is cast on a substrate and immersed in pure water to combine the porous support layer and the substrate. Thereafter, as described above, a separation functional layer is formed on the porous support layer. Furthermore, chemical treatment such as chlorine, acid, alkali, nitrous acid, etc. is performed to enhance separation performance and permeation performance as necessary, and the monomer is washed to produce a continuous sheet of the separation membrane body.
In addition, before or after the chemical treatment, unevenness may be formed on the separation membrane main body by embossing or the like.

(3-2) Arrangement of flow path material on the permeation side of the separation membrane main body When the permeation side flow path material is fixed to the separation membrane, the manufacturing method of the separation membrane is discontinuous on the permeation side surface of the separation membrane main body. A step of providing a simple channel material. This step may be performed at any time during the manufacture of the separation membrane. For example, the flow path material may be provided before the porous support layer is formed on the base material, or after the porous support layer is provided and before the separation functional layer is formed. It may be performed after the separation functional layer is formed and before or after the above-described chemical treatment is performed.

  The method for disposing the permeate-side channel material includes, for example, a step of disposing a soft material on the separation membrane and a step of curing it. Specifically, ultraviolet curable resin, chemical polymerization, hot melt, drying, or the like is used for the arrangement of the transmission side channel material. In particular, hot melt is preferably used. Specifically, a step of softening a material such as resin by heat (that is, heat melting), a step of placing the softened material on the separation membrane, and curing the material by cooling. A step of fixing on the separation membrane.

  Examples of the method for arranging the permeation side channel material include coating, printing, spraying, and the like. Examples of the equipment used include a nozzle type hot melt applicator, a spray type hot melt applicator, a flat nozzle type hot melt applicator, a roll type coater, an extrusion type coater, a printing machine, and a sprayer.

(3-3) Formation of the supply-side flow path of the separation membrane body When the supply-side flow path material of the separation membrane body is a discontinuous member formed of a material different from that of the separation membrane body, For the formation, the same method and timing as the formation of the permeation-side channel material can be applied.
Further, instead of forming the supply-side channel material with a different material from the separation membrane main body, a difference in height can be given to the supply side of the separation membrane by a method such as embossing, hydraulic forming, and calendering.

  Examples of the embossing method include roll embossing, and the pressure and processing temperature for carrying out this can be appropriately determined according to the melting point of the separation membrane. For example, when the separation membrane has a porous support layer containing an epoxy resin, the linear pressure is preferably 10 kg / cm or more and 60 kg / cm or less, and the heating temperature is preferably 40 ° C. or more and 150 ° C. or less. Moreover, when it has a porous support layer containing heat resistant resins, such as polysulfone, it is preferable that it is 10 to 70 kg / cm of linear pressure, and roll heating temperature 70 to 160 degreeC is preferable. In any case of roll embossing, a winding speed of 1 m / min to 20 m / min is preferable.

When embossing is performed, the shape of the roll handle is not particularly limited, but it is important to reduce the pressure loss of the flow path and stabilize the flow path when supplying and permeating fluid to the separation membrane element. is there. In these respects, an ellipse, a circle, an ellipse, a trapezoid, a triangle, a rectangle, a square, a parallelogram, a rhombus, an indefinite shape, and the like are adopted as the shape observed from the upper surface. In addition, three-dimensionally, it may be formed so that the width becomes smaller as the height is higher, or conversely, it may be formed so that the width becomes wider as the height is higher, regardless of the height. They may be formed with the same width.
The difference in height on the supply-side surface of the separation membrane that can be imparted by embossing can be freely adjusted by changing the pressure heat treatment conditions so as to satisfy the conditions that require separation characteristics and water permeation performance.

As described above, when the supply-side flow path is formed by fixing the supply-side flow path material to the separation membrane main body, or when the supply-side flow path material is formed by roughening the membrane, these supplies are supplied. The step of forming the side channel may be regarded as one step in the separation membrane manufacturing method.
When the supply-side flow path is a continuously formed member such as a net, after the separation membrane is manufactured by arranging the permeation-side flow path material in the separation membrane body, the separation membrane and the supply-side flow are What is necessary is just to overlap with a road material.

(3-4) Formation of separation membrane leaf As described above, the separation membrane leaf may be formed by folding the separation membrane so that the surface on the supply side faces inward, or two separate sheets It may be formed by attaching a separation membrane.
The manufacturing method of the separation membrane element preferably includes a step of sealing the inner end portion in the winding direction of the separation membrane on the surface on the supply side. In the sealing step, the two separation membranes are overlapped so that the surfaces on the supply side face each other. Further, the inner end in the winding direction of the separated separation membranes, that is, the left end in FIG. 9 is sealed.

  Examples of the method of “sealing” include adhesion by an adhesive or hot melt, fusion by heating or laser, and a method of sandwiching a rubber sheet. Sealing by adhesion is particularly preferable because it is the simplest and most effective.

At this time, a supply-side channel material formed separately from the separation membrane may be disposed inside the overlapped separation membrane. As described above, the arrangement of the supply-side flow path material can be omitted by providing a height difference in advance on the supply-side surface of the separation membrane by embossing or resin coating.
Either the supply-side sealing or the permeation-side sealing (envelope-like membrane formation) may be performed first, or the supply-side sealing is performed while stacking separation membranes. And the sealing of the surface on the transmission side may be performed in parallel. However, in order to suppress the generation of wrinkles in the separation membrane during winding, the adhesive or hot melt at the end in the width direction is allowed to allow the adjacent separation membranes to shift in the length direction due to winding. It is preferable to complete the solidification or the like, that is, the solidification for forming an envelope-like film, after the winding is completed.

(3-5) Formation of Envelope-shaped Membrane One separation membrane is folded and bonded so that the transmission side faces inward, or two separation membranes are stacked and bonded so that the transmission side faces inward. Thus, an envelope-like film can be formed. In the rectangular envelope film, the other three sides are sealed so that only one end in the length direction is opened. Sealing can be performed by bonding with an adhesive or hot melt, or by fusion with heat or laser.

  The adhesive used for forming the envelope film preferably has a viscosity in the range of 40 P (Poise) to 150 P, more preferably 50 P to 120 P. If the adhesive viscosity is too high, wrinkles are likely to occur when the laminated leaves are wrapped around the hollow tube. Wrinkles may impair the performance of the separation membrane element. Conversely, if the adhesive viscosity is too low, the adhesive may flow out of the end of the leaf and soil the device. Moreover, when an adhesive adheres to a portion other than the portion to be bonded, the performance of the separation membrane element is impaired, and the work efficiency is significantly reduced due to the processing operation of the adhesive that has flowed out.

  The amount of the adhesive applied is preferably such that the width of the portion to which the adhesive is applied after the leaf is wrapped around the hollow tube is 10 mm or more and 100 mm or less. As a result, the separation membrane is securely bonded, and the inflow of the raw fluid to the permeate side is suppressed. Also, a relatively large effective membrane area can be secured.

  As the adhesive, a urethane-based adhesive is preferable, and in order to set the viscosity in the range of 40 P (Poise) or more and 150 P or less, the main component isocyanate and the curing agent polyol are used as isocyanate: polyol = 1: 1 to 1: 5. What mixed in the ratio is preferable. The viscosity of the adhesive is obtained by measuring the viscosity of a mixture in which the main agent, the curing agent alone, and the blending ratio are defined in advance with a B-type viscometer (JIS K 6833-1 (2008)).

(3-6) Winding of separation membrane A conventional element manufacturing apparatus can be used for manufacturing a separation membrane element. In addition, as an element manufacturing method, methods described in reference documents (Japanese Patent Publication No. 44-14216, Japanese Patent Publication No. 4-11928, Japanese Patent Application Laid-Open No. 11-226366) can be used. Details are as follows.

When the separation membrane is wound around the hollow tube, the separation membrane is disposed so that the closed end of the leaf, that is, the closed portion of the envelope-shaped membrane faces the hollow tube. By winding the separation membrane around the hollow tube in such an arrangement, the separation membrane is wound in a spiral shape.
Usually, when the separation membrane is wound around the hollow tube, a spacer such as a tricot or a substrate is wound to secure a flow path around the hollow tube. When using a sheet-like material such as tricot as the permeate side channel material, it can be dealt with by adjusting the length wound around the hollow tube, but in the configuration where the channel material is fixed to the permeate side of the separation membrane It is necessary to provide a separate spacer. However, in this embodiment, the permeated fluid that has reached the hollow tube can reach the communication hole without moving in the longitudinal direction of the hollow tube, and is smoothly guided to the inner peripheral portion of the hollow tube. Spacers can be omitted.

(3-7) Other steps The method for producing a separation membrane element may include further winding a film, a filament, and the like around the outer periphery of the wound membrane of the separation membrane formed as described above. Further steps such as edge cutting for aligning the end of the separation membrane in the longitudinal direction of the hollow tube, attachment of an end plate, and the like may be included.

[4. (Use of separation membrane element)
The separation membrane element may be further used as a separation membrane module by being connected in series or in parallel and housed in a pressure vessel.
In addition, the separation membrane element and module described above can be combined with a pump that supplies fluid to them, a device that pretreats the fluid, and the like to form a fluid separation device. By using this separation device, for example, the supplied water can be separated into permeated water such as drinking water and concentrated water that has not permeated through the membrane, and water suitable for the purpose can be obtained.

  The higher the operating pressure of the fluid separator, the higher the removal rate, but the energy required for operation also increases, and considering the retention of the separation membrane element supply channel and permeation channel, the membrane module The operating pressure when passing through the water to be treated is preferably 0.2 MPa or more and 5 MPa or less. As the feed water temperature increases, the salt removal rate decreases, but as the supply water temperature decreases, the membrane permeation flux also decreases. In addition, when the pH of the feed water is in a neutral region, even if the feed water is a high salt concentration liquid such as seawater, the generation of scales such as magnesium is suppressed, and the deterioration of the membrane is also suppressed.

  The fluid to be treated by the separation membrane element is not particularly limited, but when used for water treatment, the feed water is TDS (Total Dissolved Solids: total dissolved solids) of 500 mg / L or more and 100 g / L or less, such as seawater, brine, and wastewater A liquid mixture containing a solid content). Generally, TDS refers to the total amount of dissolved solids and is expressed by “weight ÷ volume”, but 1 L may be regarded as 1 kg and may be expressed by “weight ratio”. According to the definition, the solution filtered through a 0.45 μm filter can be calculated from the weight of the residue by evaporating at a temperature of 39.5 to 40.5 ° C., but more simply converted from the practical salt content (S). .

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

(Number of holes per unit area of hollow tube)
Using the KEYENCE digital microscope VHX-1000, the number of holes in the hollow tube longitudinal direction 1 cm x circumferential direction 1 cm is measured, and the average value of 10 randomly extracted points is the number of holes per unit area. It was. When the number exceeds 100, the number of holes in the hollow tube longitudinal direction 1 mm × circumferential direction 1 mm was measured, and the average value of 10 randomly extracted points was converted into the number per square centimeter. .

(Difference in the separation membrane permeation side)
Using a high-precision shape measurement system KS-1100 manufactured by Keyence, the average height difference was analyzed from the measurement result on the transmission side of 5 cm × 5 cm. Thirty points with a height difference of 10 μm or more were measured, and the total value of each height value was divided by the number of total measurement points.

(Pitch and spacing of permeate channel material)
A scanning electron microscope (S-800) (manufactured by Hitachi, Ltd.) was used to photograph a cross section of 30 arbitrary channel materials at 500 times, and from the apex of the channel material on the permeation side of the separation membrane, The horizontal distance to the top of the road material was measured at 200 locations, and the average value was calculated as the pitch.
Further, the interval b was measured by the method described above in the photograph in which the pitch was measured.

(Projection area ratio of permeate side channel material)
The separation membrane was cut out at 5 cm × 5 cm together with the permeation-side channel material, and the stage was moved using a laser microscope (selected from 10 to 500 times magnification) to measure the total projected area of the channel material. The projected area ratio obtained by dividing the projected area obtained when the channel material was projected from the separation membrane permeation side or the supply side was taken as the projected area ratio.

(Average water production of 8-inch size separation membrane element)
Using a saline solution having a concentration of 500 mg / L and pH 6.5 as supply water, a preliminary operation was performed for 3 hours under conditions of an operation pressure of 0.7 MPa, an operation temperature of 25 ° C., and a recovery rate of 15%, and then permeate for 10 minutes. Were collected. From the volume of the obtained permeated water, the permeation amount per cubic membrane element per day (cubic meter) was calculated as the amount of water produced (m ³ / day). This evaluation was performed on 30 separation membrane elements, and the average value of the water production amount of each separation membrane element was defined as the average water production amount of the separation membrane element of 8 inch size.

(Average water production of 2-inch separation membrane element)
Using a saline solution having a concentration of 500 mg / L and pH 6.5 as supply water, a preliminary operation was performed for 3 hours under conditions of an operation pressure of 0.4 MPa, an operation temperature of 25 ° C., and a recovery rate of 15%, and then permeate for 10 minutes. Were collected. From the volume of the obtained permeated water, the permeation amount per cubic membrane element per day (cubic meter) was calculated as the amount of water produced (m ³ / day). This evaluation was performed on 30 separation membrane elements, and the average value of the water production amount of each separation membrane element was defined as the average water production amount of the separation membrane element of 2 inch size.

(Average desalination rate (TDS removal rate))
For the feed water and the sampled permeate used in the 10-minute operation in measuring the average water production, the TDS concentration was determined by conductivity measurement, and the TDS removal rate was calculated from the following formula.
TDS removal rate (%) = 100 × {1− (TDS concentration in permeated water / TDS concentration in feed water)}
This evaluation was carried out for 30 separation membrane elements, and the average value of the desalting rate of each separation membrane element was defined as the average desalting rate.

Example 1
A 15.0 wt% DMF solution of polysulfone on a non-woven fabric (thread diameter: 1 dtex, thickness: 90 μm, air permeability: 0.9 cc / cm ² / sec) obtained by a papermaking method comprising polyethylene terephthalate fibers is 180 μm. A porous support layer (thickness) comprising a fiber-reinforced polysulfone support membrane, cast at a room temperature (25 ° C.), immediately immersed in pure water, left for 5 minutes and immersed in warm water at 80 ° C. for 1 minute. 130 μm) roll was produced.
Thereafter, the porous support layer roll is unwound, and the polysulfone surface is coated with 2.1% by weight of m-PDA and 4.5% by weight of ε-caprolactam in an aqueous solution. After removing the aqueous solution, an n-decane solution at 25 ° C. containing 0.07% by weight of trimesic acid chloride was applied so that the surface was completely wetted. Thereafter, excess solution was removed from the membrane by air blowing, washed with hot water at 80 ° C., and drained by air blowing to obtain a separation membrane roll.

  Then, using an applicator loaded with a comb-shaped shim having a slit width of 0.8 mm and a pitch of 1.5 mm, the temperature of the backup roll is adjusted to 20 ° C., and when the separation membrane element is used, the longitudinal direction of the hollow tube In the case of a vertical and envelope-like membrane, ethylene vinyl acetate hot melt 8220M (manufactured by Sekisui Fuller Co., Ltd.) is linearly formed so as to be perpendicular to the longitudinal direction of the hollow tube from the inner end to the outer end in the winding direction. ) With a resin temperature of 170 ° C. and a traveling speed of 3.0 m / min. A permeate-side flow path material having a flow path material interval of 0.7 mm, a pitch of 1.5 mm, and a projected area ratio of 0.53 in the longitudinal direction was fixed to the entire separation membrane.

The obtained separation membrane roll was folded and cut so that the effective area of the separation membrane element was 37 m ^2, and the net (thickness: 0.8 mm, pitch: 5 mm × 5 mm, fiber diameter: 350 μm, projected area ratio: 0.13) was used as the supply side channel material, and 26 leaves were produced with a width of 900 mm and a leaf length of 800 mm.

A hollow tube made of ABS (width: 1,020 mm, outer diameter: 40 mm, inner diameter: 30 mm, thickness: 5 mm) on the opposite side from the outer peripheral surface of the hollow tube at intervals of 200 μm so as to be linear in the longitudinal direction of the hollow tube A hole having a hole diameter of 300 μm was arranged using a commercially available punching machine so as to penetrate to the outer peripheral surface (number of holes per unit area: 3.2 holes / cm ² , porosity: 0.3%). A urethane-based adhesive was applied to the prepared leaf, wound around the hollow tube in a spiral shape, and a film was further wound around the outer periphery. After fixing with tape, edge cutting, end plate mounting, and filament winding were performed to produce a separation membrane element having a diameter of 8 inches. The same operation was repeated to produce a total of 30 separation membrane elements.
When this element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water, the average water production and the average desalting rate were 31.5 m ³ / day and 98.4%, respectively.

(Example 2)
A separation membrane element was produced in the same manner as in Example 1 except that a hollow tube having a communication hole 61 arranged in a spiral shape as shown in FIG. 10A was used (hole interval: 200 μm, hole diameter). : 300 μm, number of pores per unit area: 2.3 / cm ² , porosity: 0.2%).
The element was placed in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average water production and the average desalting rate were 33.6 m ³ / day and 98.5%, respectively.

(Example 3)
As a hollow tube, as shown in FIG. 10 (b), a separation membrane element was produced in the same manner as in Example 1 except that the communication holes 61 having a pore diameter of 2000 μm were arranged in a lattice pattern having a spacing of 5000 μm (hole spacing: 5000 μm). Pore diameter: 2000 μm, number of holes per unit area: 2.0 / cm ² , porosity: 7.3%).
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeate, the average water production and average desalination rate were 34.5 m ³ / day and 98.6%, respectively.

(Example 4)
A separation membrane element was prepared in the same manner as in Example 1 except that the sintered porous material made of PP was used as the material of the hollow tube (pore spacing: 20 to 50 μm, hole diameter: 50 μm, number of holes per unit area) : 10000 / cm ² , porosity: 30%). The sintered porous body made of PP was prepared by filling PP powder into a mold, firing at a temperature of 80 ° C., and cooling and solidifying.
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water, the average water production and the average desalination rate were 31.2 m ³ / day and 98.4%, respectively.

(Example 5)
A separation membrane element was prepared in the same manner as in Example 4 except that a PP sintered porous body having a different hole interval, hole diameter, and number of holes per unit area was used as the material of the hollow tube (hole interval: 50). ˜100 μm, pore diameter: 100 μm, number of holes per unit area: 2000 / cm ² , porosity: 30%).
The element was placed in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average water production and the average desalting rate were 33.6 m ³ / day and 98.5%, respectively.

(Example 6)
A separation membrane element was prepared in the same manner as in Example 4 except that a PP sintered porous body having a different hole interval, hole diameter, and number of holes per unit area was used as the material of the hollow tube (hole interval: 200). ˜500 μm, pore diameter: 200 μm, number of pores per unit area: 200 / cm ² , porosity: 30%).
The element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average water production and the average desalting rate were 35.4 m ³ / day and 98.7%, respectively.

(Example 7)
A separation membrane element was prepared in the same manner as in Example 4 except that a PP sintered porous body having different hole spacing, hole diameter, and number of holes per unit area was used as the material of the hollow tube (hole spacing: 3000). ˜5000 μm, pore diameter: 1500 μm, number of pores per unit area: 1.2 / cm ² , porosity: 30%).
The element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average water production and the average desalting rate were 30.5 m ³ / day and 98.3%, respectively.

(Example 8)
A separation membrane element was prepared in the same manner as in Example 6 except that tricot (thickness: 280 μm, groove width: 400 μm, ridge width: 300 μm, groove height: 105 μm, made of polyethylene terephthalate) was used as the permeate-side channel material. (Hole interval: 200 to 500 μm, hole diameter: 200 μm, number of holes per unit area: 200 / cm ² , porosity: 30%).
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeate, the average water production and the average desalting rate were 33.4 m ³ / day and 98.5%, respectively.

Example 9
The separation membrane roll to which the wall-like material obtained in Example 1 was fixed was folded and cut so that the effective area at the separation membrane element was 0.5 m ^2, and a net (thickness: 510 μm, pitch: 2 mm × 2 mm, Two leaves with a width of 250 mm were prepared using a fiber diameter: 255 μm, a projected area ratio: 0.21) as a supply-side channel material.
Thereafter, the two leaves were wound while being wrapped around a hollow tube (width: 300 mm, outer diameter: 17 mm, inner diameter: 10 mm, thickness 3.5 mm) made of a plastic sintered porous body (Fuji Chemical Co., Ltd., made of polypropylene). A separation membrane element wound in a spiral shape was prepared, a film was wound around the outer periphery and fixed with a tape, and then edge cutting and end plate attachment were performed to produce a separation membrane element having a diameter of 2 inches (hole interval: 200 to 200). 500 μm, pore diameter: 200 μm, number of pores per unit area: 200 / cm ² , porosity: 30%).
The element was placed in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average water production and the average desalting rate were 0.46 m ³ / day and 98.7%, respectively.

(Example 10)
A separation membrane element was produced in the same manner as in Example 1 except that ceramic sintered porous body FA060 (Fuji Chemical Co., Ltd., made of alumina) was used as the material of the hollow tube (pore spacing: 100 to 500 μm, pore diameter) : 200 μm, number of holes per unit area: 200 / cm ² , porosity: 50%).
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeate, the average water production and the average desalination rate were 34.5 m ³ / day and 98.5%, respectively.

(Example 11)
A separation membrane element was prepared in the same manner as in Example 1 except that a porous metal (made of SUS) was used as the material of the hollow tube (pore spacing: 200 to 500 μm, hole diameter: 400 μm, number of holes per unit area) : 100 / cm ² , porosity: 60%).
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeate, the average water production and the average desalination rate were 34.6 m ³ / day and 98.6%, respectively.

(Example 12)
Separation membrane elements were prepared in the same manner as in Example 1 except that the diameter of the communication hole of the hollow tube was 3000 μm and the interval was 5000 μm (number of holes per unit area: 0.2 / cm ² , pores Rate: 1.6%).
The element was placed in a pressure vessel and operated under the above conditions to obtain permeated water. The average water production and the average desalination rate were 30.3 m ³ / day and 98.6%, respectively.

(Example 13)
As a hollow tube, as shown in FIG. 10 (b), a separation membrane element was prepared in the same manner as in Example 1 except that the communication holes 61 with a pore diameter of 3000 μm were arranged in a lattice pattern with a spacing of 3000 μm (hole spacing: 5000 μm). Pore diameter: 2000 μm, number of holes per unit area: 2.7 / cm ² , porosity: 21%).
The element was placed in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average amount of water produced and the average desalting rate were 33.5 m ³ / day and 98.4%, respectively.

(Example 14)
As a hollow tube, as shown in FIG. 10 (e), the separation membrane element was the same as in Example 1 except that the communication holes 61 were arranged in a lattice shape with different hole diameters and intervals between the center and both ends. (Center part width: 820 mm, both end part width: 100 mm, hole interval: center part 2000 μm, end part 100 μm, hole diameter: center part 2000 μm, end part 50 μm, number of holes per unit area: 120 / cm ² , Porosity: 20%).
The element was placed in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average water production and the average desalting rate were 35.9 m ³ / day and 98.9%, respectively.

(Comparative Example 1)
Separation membrane elements were prepared in the same manner as in Example 1 except that the diameter of the communication hole of the hollow tube was 3000 μm and the interval was 7000 μm (number of holes per unit area: 0.2 / cm ² , pores Rate: 1.2%).
The element was placed in a pressure vessel and operated under the above conditions to obtain permeated water. The average water production and the average desalting rate were 15.7 m ³ / day and 98.0%, respectively.

(Comparative Example 2)
Separation membrane elements were prepared in the same manner as in Example 1 except that holes having a pore diameter of 3000 μm were arranged in a lattice pattern with a spacing of 7000 μm as shown in FIG. Number of holes per unit area: 0.5 / cm ² , porosity: 3.1%).
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeate, the average water production and the average desalination rate were 20.1 m ³ / day and 98.0%, respectively.

(Comparative Example 3)
An attempt was made to produce a separation membrane element in the same manner as in Example 4 except that a sintered porous body made of PP having a different hole interval, hole diameter, number of holes per unit area and porosity was used as the material of the hollow tube. As a result, the hollow tube was damaged in the process of surrounding the separation membrane element, and was not evaluated (hole interval: 5 to 15 μm, hole diameter: 40 μm, number of holes per unit area: 20000 / cm ² , porosity: 65%).

(Comparative Example 4)
An ABS hollow tube (width: 300 mm, with a hole diameter of 3000 μm arranged so as to penetrate from the outer peripheral surface of the hollow tube to the opposite outer peripheral surface at intervals of 7000 μm so as to be linear in the longitudinal direction of the hollow tube A separation membrane element was produced in the same manner as in Example 9 except that the outer diameter was 17 mm (number of holes per unit area: 0.1 / cm ² , porosity: 1.2%).
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water, the average water production and the average desalting rate were 0.21 m ³ / day and 98.1%, respectively.

(Comparative Example 5)
A separation membrane element was prepared in the same manner as in Comparative Example 1 except that tricot (thickness: 280 μm, groove width: 400 μm, ridge width: 300 μm, groove height: 105 μm, made of polyethylene terephthalate) was used as the permeate side channel material. (Number of holes per unit area: 0.2 / cm ² , porosity: 1.2%).
The element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water. The average water production and the average desalting rate were 28.5 m ³ / day and 98.1%, respectively.

(Comparative Example 6)
Separation membrane elements were prepared in the same manner as in Example 3 except that the diameter of the communication hole of the hollow tube was 1000 μm and the interval was 6000 μm (number of holes per unit area: 1.4 / cm ² , pores Rate: 1.2%).
When the element was put in a pressure vessel and operated under the above-mentioned conditions to obtain permeated water, the average water production and the average desalting rate were 24.1 m ³ / day and 98.0%, respectively.

From the results of Tables 1 to 4, the 8-inch sized separation membrane elements of Examples 1 to 8 and 10 to 14 have an average water production (m ³ / day) of 30.0 m ³ / day or more. It has a higher average water production amount than the membrane element. Similarly, the 2-inch size separation membrane element of Example 9 also has an average water production amount superior to that of the separation membrane element of Comparative Example 4. all right.

  The membrane element of the present invention can be suitably used particularly for brine or seawater desalination.

DESCRIPTION OF SYMBOLS 1 Separation membrane 2 Separation membrane main body 3 Permeation side channel material 4 Separation membrane leaf 5 Permeation side channel 6 Hollow tube 61 Communication hole 62 Distance between holes 63 Hollow tube inside 7 Separation membrane 21 Supply side surface 22 Permeation side surface Surface 71 Supply side surface 72 Permeation side surface 100 Separation membrane element a Length of separation membrane main body (leaf) b Separation of permeation side flow channel material in width direction of separation membrane main body c Height of permeation side flow channel material d Width of permeate side channel material e Interval of permeate side channel material in length direction of separation membrane body f Length of permeate side channel material

Claims (4)

A separation membrane element comprising a hollow tube having an outer peripheral surface and an inner peripheral surface, and at least one separation membrane leaf wound around the hollow tube,
The hollow tube has a plurality of communication holes connected from an outer peripheral surface to an inner peripheral surface, and a distance between the communication holes adjacent to each other on the outer peripheral surface is 20 μm to 5000 μm. The separation membrane element according to claim 1, wherein the number of holes per unit area on the outer peripheral surface of the hollow tube is 1 / cm ^{2 to} 10,000 / cm ² .   The separation membrane element according to claim 1 or 2, wherein an average pore diameter of the communication holes is 50 µm to 2000 µm.   The separation membrane element according to any one of claims 1 to 3, wherein a porosity with respect to a total volume of the hollow tube is 20% to 60%.

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