JP2011201289A - Multilayered sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered sheet with capability of removing an exceedingly low concentration ion, high permeability and a high long life.SOLUTION: An ion exchange filter 1 includes: a water permeable cylinder 2; and a laminated sheet 3 of a flow channel material sheet 4 wound on the periphery of this cylinder 2 and an ion exchange sheet 5. The ion exchange sheet 5 is laminated with an electric field spinning nonwoven fabric of an ion exchange fiber and an ion exchange cast film. A part of fibers of this nonwoven fabric is fused to the ion exchange cast film.

Description

  The present invention relates to a multilayer sheet, and in particular, in the treatment of a liquid such as water, an aqueous solution, and an organic solvent, or in the treatment of a gas-liquid mixture, the fluid to be treated is flowed in the surface direction of the multilayer sheet, thereby The present invention relates to a multilayer sheet suitable for use in an ion exchange filter for adsorption separation and exclusion separation of trace amounts of metals, fine particles and the like.

  The demand for high-purity ultrapure water used in semiconductor manufacturing processes is becoming stricter year by year. According to ITRS 2005, a roadmap for reducing the metal ion concentration in ultrapure water to 0.5 ng / L or less was presented in 2008. However, each semiconductor manufacturer has decided to use ultrapure water with a lower metal concentration. Seeking. Water treatment manufacturers have reduced the metal ion concentration ahead of schedule, and some of the latest ultrapure water production facilities can produce ultrapure water with most metals reduced to 0.5 ng / L or less. .

  As a method of reducing the metal concentration in ultrapure water, there is a method of installing an ion exchange filter immediately before a use point.

  As a conventional ion exchange filter, there is a pleated type flat membrane such as a nonwoven fabric or a porous membrane (for example, FIG. 5 of Patent Document 1).

  An ion exchange filter filled with a resin is also known (for example, FIG. 9 of Patent Document 1). A commercially available resin-filled ion exchange 10-inch size has a permeation flow rate of about 200 L / h when operating pressure is applied to 0.1 MPa.

  As an ion exchange membrane, an ion exchange resin is dissolved or dispersed in a solvent to form a cast stock solution. The cast stock solution is cast on a base film, dried, and then peeled off from the base film. Are known (for example, Patent Documents 2 and 3). Patent Document 3 describes a porous ion exchange membrane manufactured by using a phase separation method.

  An electrospinning method (electrostatic spinning method) is known as a method for producing ultrafine nanofibers having a fiber diameter of nanometer order (Patent Documents 4 and 5 below).

JP2009-50761A JP 2000-327809 JP 2006-193709 A JP2007-92237 JP 2006-144138 A

  In the pleated ion exchange filter, the flow tends to be biased in the folded portion of the pleat, and a sufficient removal rate cannot be obtained in an extremely low concentration region such as the above-described ultrapure water. Further, since the film thickness is thin, breakthrough is quick and the life is short. Further, in order to improve the ion removal rate, if the film thickness is increased or the pores of the film are reduced, the water permeability is sacrificed. For example, when the fiber diameter is small, the filter thickness is large, or the number of windings is large, the pressure loss increases and the filtration rate decreases, making it difficult to achieve the required performance. This tendency is particularly noticeable in filters composed of ultrafine nanofibers.

  An ion exchange filter using nanofibers having ion exchange groups has a high ion exchange rate, but a thin layer has a small ion exchange capacity and a short life. When the filter is thickened or laminated to extend the lifetime, the pressure loss increases.

  An object of the present invention is to provide a multilayer sheet having an ability to remove ultra-low concentration ions, a high water permeability and a long life, satisfying the demand for high purity of ultrapure water in the semiconductor industry and the like. It is.

  The multilayer sheet of claim 1 is formed by laminating a first sheet having an adsorptive functional group and a second sheet made of a nonwoven fabric of fibers having an adsorptive functional group.

  The multilayer sheet of claim 2 is characterized in that, in claim 1, the first sheet is made of an ion exchange resin, and the fibers are ion exchange fibers.

  The multilayer sheet of claim 3 is characterized in that, in claim 2, the first sheet is a cast film of an ion exchange resin.

  The multilayer sheet of claim 4 is characterized in that, in claim 3, an ion exchange fiber nonwoven fabric made of ion exchange fibers having an equivalent diameter of 10 to 1000 nm and an ion exchange cast membrane are laminated. is there.

  The multilayer sheet of claim 5 is characterized in that, in any one of claims 1 to 4, the fiber is an electrospun fiber of an ion exchange resin.

  The multilayer sheet of claim 6 is characterized in that, in claim 5, the nonwoven fabric of the fibers is formed on the first sheet.

  A multilayer sheet according to a seventh aspect is characterized in that, in the sixth aspect, a part of the fibers of the nonwoven fabric is fused to the first sheet.

  In the multilayer sheet of the present invention, a first sheet having an adsorptive functional group and a nonwoven fabric of fibers having an adsorptive functional group are laminated. Thus, by laminating the nonwoven fabric of fibers having an adsorptive functional group on the first sheet, the specific surface area of the first sheet is increased, and the water flow at the interface is turbulent. Since the diffusion at the interface is promoted, the adsorption efficiency is improved.

  Since the first sheet also has an adsorptive functional group, the substance adsorbed on the fiber moves to the first sheet and is contained therein, so that the adsorption capacity of the multilayer sheet becomes large.

It is a block diagram which shows the ion exchange filter which concerns on embodiment. It is sectional drawing of the ion exchange filter which concerns on embodiment. It is sectional drawing of the ion exchange filter which concerns on another embodiment. It is sectional drawing of the lamination sheet used for the ion exchange filter which concerns on different embodiment. It is a top view of the lamination sheet used for the ion exchange filter which concerns on different embodiment. It is sectional drawing of a filter cartridge. It is a schematic explanatory drawing of the electrospinning method.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 (a) is a sectional view showing a method for manufacturing an ion exchange filter according to an embodiment, FIG. 1 (b) is a sectional view of a laminated sheet, FIG. 1 (c) is a perspective view of the laminated sheet, and FIG. The figure is a plan view of the laminated sheet. FIG. 2 is a schematic cross-sectional view of the ion exchange filter in the direction perpendicular to the cylinder axis direction.

  The ion exchange filter 1 includes a water permeable cylinder 2 and a laminated sheet 3 wound around the outer periphery of the cylinder 2. The laminated sheet 3 is obtained by laminating a flow path material sheet 4 and an ion exchange sheet 5.

The cylindrical body 2 has a cylindrical shape and is provided with circular small holes 2a having a diameter of about 1 to 10 mm so as to have an opening ratio of 10 to 90%, particularly about 30 to 80%. The cylindrical body 2 may be made of a water-permeable material like a porous metal or ceramic sintered body, and the small holes 2a may be omitted. The inner diameter of the cylindrical body 2 is preferably about 5 to 50 mm, but is not limited thereto. The thickness of the cylindrical body 2 is preferably about 0.5 to 5 mm, but is not limited thereto.
The shape of the small hole 2a is not limited to a circle, and may be an ellipse or a polygon. In this case, the equivalent diameter of the small hole (= area of small hole / perimeter length × 4) is regarded as the diameter.

  The flow path material sheet 4 is preferably a non-woven fabric, woven fabric, grid-like net or the like made of polyolefin (polyethylene, polypropylene), polyester, polysulfone or the like. The thickness of the flow path material sheet is preferably 0.1 mm to 5 mm, particularly about 0.5 to 2 mm, and the pore diameter is preferably about 100 μm or more (opening: 50% to 90%).

  The ion exchange sheet 5 is made of a woven or nonwoven fabric of ion exchange fibers, an ion exchange cast membrane, or the like. A suitable example of the ion exchange sheet 5 will be described in detail later.

  The laminated sheet 3 is a strip having a width a of about 50 to 600 mm, particularly about 100 to 400 mm, and a length sufficient to be wound around the cylindrical body 2 as many times as necessary.

  In the laminated sheet 3, an opening 8 that penetrates the ion exchange sheet 5 is provided. In this embodiment, the openings 8 are arranged along both side edges 3 a and 3 b in the longitudinal direction (winding direction) of the laminated sheet 3.

  In this embodiment, the opening 8 is located on the other side 3b side so as to be symmetrical with the midpoint between the openings 8 and 8 along the one side 3a. The distance b from the opening 8 to the nearest side 3a or 3b is preferably about 5 to 50 mm, particularly about 10 to 30 mm. In FIG. 2, the opening 8 is arranged so that the opening 8 exists in the same phase every time the laminated sheet 3 is wound twice.

  This laminated sheet 3 is wound around the outer periphery of the cylindrical body 2 in a spiral shape (spiral shape) to form an ion exchange filter 1 (FIG. 2). The number of layers by this winding (when the cylinder 2 is rotated, the total number of rotations) is preferably about 5 to 50, particularly about 10 to 30. When the laminated sheet 3 is wound, a roll-shaped wound body is formed. The end surface of the roll-shaped wound body is sealed with a sealing material such as a plate or an adhesive so that the liquid to be treated does not flow from the end surface. To.

  FIG. 6 is a sectional view showing an example of a filter cartridge in which the ion exchange filter 1 of FIGS. 1 and 2 is incorporated.

  In this filter cartridge 10, an ion exchange filter 1 is disposed in a casing 13 having an inlet 11 for water to be treated and an outlet 12 for filtered water so that the cylinder axis direction is the vertical direction. .

  A flange 24 that also serves as an end plate that closes one end of the cylinder 2 is provided on the lower surface of the ion exchange filter 1. A flange 25 is provided on the upper end surface of the ion exchange filter 1. The upper end of the cylindrical body 2 extends upward, and a connecting flange 2b is provided at the tip.

  A filtered water outlet pipe 14 is connected to the outlet 12. A flange 14 a is provided at the lower end of the take-out pipe 14 and is connected to the flange 2 b of the cylindrical body 2. In addition, you may make it fit the upper end of the cylinder 2 and the lower ends of the extraction pipe | tube 14 via an O-ring instead of the connection by such flanges 2b and 14a.

  The water to be treated is introduced into the casing 13 from the inlet 11, passes through the ion exchange filter 1 in the centripetal direction, flows into the cylindrical body 2 through the small hole 2 a, and is taken out through the extraction pipe 14 and the outlet 12. It is.

  The liquid to be treated flows spirally from the outer peripheral surface of the ion exchange filter 1 through the channel material sheet 4 as indicated by arrow A in FIG. 2, and during this time both sides on the outer peripheral side and inner peripheral side of the channel material sheet 4 Is contacted with the ion exchange sheet 5 present in the substrate and deionized. Since the liquid to be processed flows in a spiral shape in this way, the contact time between the liquid to be processed and the ion exchange sheet 5 is long, and the deionization process is sufficiently performed.

  In this embodiment, the ion exchange sheet 5 is provided with the openings 8 at a predetermined interval so that the openings 8 are present once in two rounds of the overlapping sheet in the same cross section. When the liquid flowing in the flow path material sheet 4 encounters the opening 8, a part of the liquid passes through the opening 8 as shown by an arrow B in FIG. Shortcut to flow in a short circuit. For this reason, water passage pressure loss is also reduced. The liquid that has flowed to the innermost periphery of the flow path material sheet 4 flows into the cylindrical body 2 through the small holes 2a and is taken out as a processing liquid.

  In this embodiment, the liquid that has passed through the opening 8 reaches the next opening 8 after making a round of the ion exchange filter 1. Therefore, it is possible to prevent a situation in which the liquid that has been short-cut to the next layer through one opening 8 immediately short-circuits to the next layer through the next opening, and the liquid to be processed is sufficiently deionized to form the cylinder 2. To reach.

  In this description, the liquid to be treated is supplied from the outer peripheral side, and the processing liquid is taken out from the cylindrical body 2. Conversely, the liquid to be processed is supplied into the cylindrical body 2 and the processing liquid is taken out from the outer peripheral side. The liquid may be passed as shown in FIG.

[Another embodiment]
In the ion exchange filter 1 shown in FIGS. 1 and 2, openings 8 are provided in the overlap sheet once every two rounds, and the liquid passing through one opening 8 makes one round in the flow path sheet 4. In the ion exchange filter 1A shown in FIG. 3, the opening 8 is provided at a frequency of once every 1.5 rounds in the overlap sheet. In this case, the liquid that has passed through one opening 8 reaches the next opening 8 after at least a half turn in the flow path material sheet 4. Therefore, also in this case, the liquid flowing in the flow path material sheet 4 does not pass through the opening 8 one after another and reaches the innermost circumference, and the deionization process is sufficiently performed. The other structure of FIG. 3 is the same as that of FIG. 2, and the same code | symbol has shown the identical part.

  In the embodiment shown in FIGS. 1 and 2, the laminated sheet 3 includes one flow path material sheet 4 and one ion exchange sheet 5. A sheet of ion exchange sheets may be superposed. FIG. 4 shows a laminated sheet 3 in which two ion exchange sheets 6 and 7 are superimposed on one flow path material sheet 4. The ion exchange sheets 6 and 7 are any one of a woven fabric of ion exchange fibers, a nonwoven fabric of ion exchange fibers, and an ion exchange cast membrane. The ion exchange sheets 6 and 7 may be the same type or different types. In the latter case, for example, an ion exchange sheet 6 made of a non-woven fabric of ion exchange fibers and an ion exchange sheet 7 made of an ion exchange cast membrane are exemplified, but the combination is not limited to this.

  In the above embodiment, the opening 8 is circular, but may be oval or polygonal. The opening may be a “−” shaped slit. FIG. 5 is a plan view of an ion exchange sheet 5A provided with slit-like openings 9 (9a, 9b). It is preferable that the slit extends in the short width direction of the ion exchange sheet 5A. The length e of the slit is preferably about 1 to 30%, particularly about 5 to 15% of the width a of the ion exchange sheet 5A.

  In FIG. 5, the slit-shaped opening 9 includes an opening 9a disposed on both side portions and an opening 9b disposed in the center in the width direction. The openings 9a, 9a on both sides are arranged on the same straight line, but are not limited to this. The distance f between the opening 9a and the nearest side of the ion exchange sheet is preferably about 5 to 50 mm, particularly about 10 to 30 mm.

[Detailed explanation of ion exchange sheet]
As described above, a cast membrane, a woven fabric or a non-woven fabric of ion exchange fibers, or the like is used for the ion exchange sheet. These will be described in detail below. It is also possible to use a multilayer ion exchange sheet in which two or more layers of cast membranes or ion exchange fiber woven fabrics or nonwoven fabrics are stacked.

[1] Kind of ion exchange sheet (1) Ion exchange fiber sheet As the ion exchange fiber, a material obtained by spinning the following materials (a) to (d) by an electrospinning method or a melt spinning method is preferable. The ion exchange fiber sheet is a nonwoven fabric or a woven fabric using these alone or in combination.

(A) Perfluorocarbon sulfonic acid polymer (Nafion (manufactured by DuPont), Fumion (perfluorosulfonic acid ionomer, FuMA-Tech Gmbh)) as a charged polymer fiber
(B) An ion exchange group chemically attached to a base material made of uncharged polymer fiber (c) Perfluorocarbon sulfonic acid polymer (Nafion, Fumion) supported on a skeleton material as charged polymer fiber (D) A material in which an ion-exchange group is chemically added to a base material made of an uncharged polymer fiber is integrated with a skeleton material. To obtain high mechanical strength The above (c) or (d) is preferred.

The thickness of the non-woven fabric or woven fabric is preferably about 0.01 to 0.5 mm (10 to 500 μm), and the pore diameter is preferably about 0.1 to 10 μm (measured by the air flow method, the same applies hereinafter), The ion exchange capacity is preferably about 0.05 to 2 meq / g, about 0.03 to 1.5 meq / cm ³ .

  When at least a part of the ion exchange sheet is composed of a nonwoven fabric of ion exchange fibers, the pore diameter of the flow path material sheet 4 is preferably larger than the pore diameter of the nonwoven fabric, specifically about 100 to 10,000 times. It is desirable that

[Electrospinning method]
Hereinafter, a method for producing fibers by electrospinning will be described with reference to FIG.

  A voltage is applied between the discharge port (syringe) 31 and the target (opposing surface portion) 33 so that the discharge port 31 side is positive and the target 33 side is negative, and a polymer solution is supplied from the discharge port 31 to the target 33. Then, the fibers 32 are accumulated (deposited) on the target 33.

  The distance between the discharge port 31 and the target 33 is preferably about 50 to 500 mm, particularly about 70 to 300 mm. It is preferable that the applied voltage between the two has a potential gradient of about 1 to 20 kV / cm.

  As shown in FIG. 7, when a fiber is manufactured, the fiber discharged from the discharge port 31 and flying toward the target 33 may be heated to promote the evaporation of the solvent in the fiber. In order to perform this heating, the atmosphere of the fiber flying zone may be heated, and infrared rays may be irradiated toward the flying zone. Further, the evaporation of the solvent may be promoted by heating the fibers deposited on the target 33 or the fibers taken out from the target 33. Thus, by promoting the evaporation of the solvent, a polymer fiber having a high bulk density can be obtained.

  When spinning, a polymer fiber body can be obtained by setting a thin film on a target, spinning, and peeling the thin film after spinning. As the material for the thin film, polyolefin such as polyethylene, polyester, polysulfone, aluminum foil and the like can be used.

  On the other hand, when spinning a fiber, a base material integrated fiber can be obtained by placing a porous body on a target and spinning it to integrate the porous material as a base material. As the porous body, a nonwoven fabric, a sintered body, a separation membrane, or the like can be selected. As the raw material of the nonwoven fabric, polyolefin such as polyethylene and polypropylene, polyester, polysulfone, cellulose derivative and the like can be used. As a material of the sintered body, a polymer such as polyolefin, a metal such as stainless steel, glass, or the like can be used. As a material for the separation membrane, polyolefin, polyester, polysulfone, cellulose derivative, polyamide, or the like can be used.

(2) Ion Exchange Cast Membrane A known ion exchange cast membrane can be used as the ion exchange cast membrane. For example, the ion exchange cast membrane is manufactured by a phase separation method using one or more of the following (e) to (h). Nonporous membranes and porous membranes are preferred.

(E) A film-like product obtained by coating a perfluorocarbon sulfonic acid polymer (Nafion, Fumion) on a substrate such as glass and then removing the substrate. (G) A perfluorocarbon sulfonic acid polymer (Nafion, Fumion) is applied to the skeletal material and integrated with the skeletal material. (H) A base material made of an uncharged polymer and having an ion exchange group chemically applied to the base material and integrated with the base material. To obtain high mechanical strength, the above ( The method g) or (h) is preferred.

The thickness of the cast membrane is preferably about 0.01 to 0.5 mm (10 to 500 μm), the pore diameter is preferably 1 μm or less, and the ion exchange capacity is 0.2 to 2 meq / g, 0.1 About ~ 1.8 meq / cm ³ is preferable.

  Examples of the uncharged polymer include polyolefin, polystyrene, polysulfone, polyester, and polyvinylidene fluoride.

  As the ion exchange group, various cation exchange groups or anion exchange groups can be used. For example, as the cation exchange group, a strong acid cation exchange group such as a sulfone group, a neutral acid cation exchange group such as a phosphate group, a weak acid cation exchange group such as a carboxyl group, and an anion exchange group include primary to first-order cation exchange groups. A weakly basic anion exchange group such as a tertiary amino group and a strongly basic anion exchange group such as a quaternary ammonium group can be used, or an ion exchanger having both the cation exchange group and the anion exchange group Can also be used.

  Examples of the skeletal material include nonwoven fabrics and woven fabrics made of polyolefin, polystyrene, polysulfone, polyester, polyvinylidene fluoride, and the like.

(3) Multi-layer ion exchange sheet By using the fiber surface of the ion exchange fiber sheet as a field for ion exchange, the contact efficiency of the fluid around the fiber is improved, so that the ion adsorption rate is increased. However, only the ion exchange fiber sheet has a limit in the retention capacity of the adsorbed ions. On the other hand, in the case of an ion exchange cast membrane, functional groups for removing ions can be held at a high density, and an ion removal capacity can be ensured. Therefore, by bringing the ion-exchange fiber sheet into contact with the ion-exchange fiber sheet, the ions adsorbed on the ion-exchange fiber can be moved to the ion-exchange cast film and held at a high density. Therefore, in the present invention, the above-mentioned ion exchange cast membrane is used as the first sheet, the above-described ion exchange fiber sheet is used as the second sheet, and the first sheet and the second sheet are laminated to form a multilayer. It is preferable to use an ion exchange sheet.

  As a method of laminating the ion exchange fiber sheet and the ion exchange cast membrane, the ion exchange fiber sheet and the ion exchange cast membrane can be prepared separately and then bonded to each other. A multilayer ion exchange sheet can also be produced by directly spinning ion exchange fibers on the surface of the ion exchange membrane by an electrospinning method using an ion exchange cast membrane as the target 33. When electrospun fibers are formed on a sheet made of an ion exchange membrane such as an ion exchange cast membrane, the fibers in contact with the sheet are fused and integrated with the sheet, so the ions collected by the fibers move to the first sheet. It becomes easy to do.

The thickness of the multilayer sheet of the ion exchange fiber sheet and the ion exchange cast membrane is preferably about 0.03 to 3 mm, and the ion exchange capacity is 0.2 to ³ meq / g, 0.1 to 2 meq / cm ^3. The degree is preferred. The thickness of the ion exchange fiber sheet used for the multilayer sheet is preferably about 0.005 to 0.1 mm (5 to 100 μm), and the pore diameter is preferably about 0.05 to 100 μm, and the ion exchange capacity. Is preferably about 0.2 to 2 meq / g, about 0.1 to 1 meq / cm ³ . The thickness of the ion exchange cast membrane is preferably about 0.01 to 3 mm (10 to 3000 μm), and the ion exchange capacity is preferably about 0.2 to ³ meq / g and about 0.1 to 2 meq / cm ^3. is there.

[2] Fiber Diameter and Length of Ion Exchange Fiber As the ion exchange fiber, an extremely thin fiber having an equivalent diameter of 1 to 1000 nm, particularly about 10 to 700 nm is preferable. Here, “equivalent diameter” is calculated by (equivalent diameter) = 4 × (cross-sectional area) / (peripheral length of cross-section) from the cross-sectional area of one fiber (fiber) and the outer peripheral length of the cross-sectional area. Value.

  The length of the ion exchange fiber is preferably 1 μm or more. In addition, when produced by electrospinning, the length can be several tens of centimeters, and since continuous spinning is possible, the length can be increased without an upper limit.

[3] Ion removal performance (1) In the case of an ion exchange fiber sheet By using the fiber surface as an ion exchange field, the contact efficiency of the fluid around the fiber is improved, so that the ion adsorption rate is increased.

(2) In the case of an ion exchange cast membrane The functional groups for removing ions can be held at a high density, and the ion removal capacity can be secured.

[4] Suppression of pressure loss In the case of an ion exchange fiber sheet, the ion exchange capacity can be increased by thinning the ion exchange fiber to increase the specific surface area. However, if the fiber layer is thick, the permeation resistance is reduced. The problem arises that it increases and lacks practicality. This is particularly noticeable when the ion exchange fiber is composed of ultrafine fibers such as nanofibers.

  On the other hand, the ion exchange cast membrane is denser than the ion exchange fiber sheet, and the permeation resistance is further increased.

  Therefore, an opening is provided in the ion exchange sheet made of the ion exchange fiber sheet or the ion exchange cast membrane, and the fluid is partially short-circuited. Thereby, pressure loss can be suppressed.

[5] Detailed Description of Arrangement of Openings In the present invention, it is preferable that the liquid that has passed through one opening flows more than half a circumference in the circumferential direction before reaching the next opening. It is preferable to be provided at a rate of once per 1.5 or more times of the laminated sheet 3 to be wound, and for example, it is preferably provided at a rate of 1 per 1.5 to 3 times. When the interval between the openings is set to be constant, the water passing through one opening has an average circumference length, that is, [{(perimeter length of the cylinder 2) + (perimeter length of the outer periphery of the ion exchange filter 1)]. } / 2], it is preferable to arrange each opening so as to reach the next opening after flowing about 0.5 times or more.

  Further, in order to effectively utilize the film surface, it is preferable that a predetermined amount or more of the liquid to be treated does not pass through the opening 8 (shortcut) but flows one or more times along the spiral flow path. Therefore, the size of the opening is preferably set so that the shortcut flow rate ratio is within a predetermined range in consideration of the thickness of the flow path material sheet and the openings.

  Further, from the viewpoint of effectively utilizing the film surface, the next opening is alternately arranged on both sides such as one side and the other side in the length direction of the filter as shown in FIG. 1 (d). It is preferable. As a result, it is possible to lengthen the flow path for removing ions from the water to be treated which has a shortcut to the opening by the width of the flow path material sheet.

The difference in the length of the adsorption band between the conventional filter and the filter of the present invention will be described as follows with reference to FIG. 1 and specific numerical examples.
When water to be treated is passed in the centripetal direction (opposite to the radial direction) with respect to an ion exchange filter according to a conventional example in which an ion exchange sheet is wound to a thickness of 20 mm around the outer periphery of a water permeable cylinder having a radius of 20 mm, The thickness becomes the length of the adsorption band, which is about 20 mm.
On the other hand, an ion exchange with an outer circle radius R = 40 mm in which a laminated sheet 3 of 1.5 mm is wound around the outer periphery of a water-permeable cylinder having a radius of r = 20 mm and the laminated thickness is 20 mm as shown in FIG. In the filter, the sheet width (filter length) a is 10 inches (254 mm), and a plurality of openings 8 are provided on both sides at a position where the length b is 27 mm from the side of the sheet. distance c of the opening 8 adjacent sides side is 740mm, when the winding start side of the ion exchange filter of the present invention the distance L ₁ was 250mm up to the first opening 8, the total length of the adsorption band of the filter Is obtained as follows.
When the product of the average perimeter of the stack and the number of stacks is regarded as the total sheet length L, L = {2π (r + R) / 2} × 13 layers≈2450 mm. Here, since L / c × 2 = 6.6..., The number of openings 8 is six. On the other hand, the distance between the opposing openings 8 on both sides (the length of the adsorption band until the fluid changes direction) is {square root} {(c / 2) ² + (a−2b) ² } ≈420 mm. Therefore, the total length of the adsorption band of the filter of the present invention is about 420 mm × 6 pieces≈2,500 mm.
Thus, the length of the adsorption band when the fluid is simply permeated through the conventional filter is about 20 mm, whereas the total length of the adsorption band is about 2500 mm in the filter of the present invention. An adsorption band length as much as 125 times can be obtained.

When the ion exchange filter 1 is manufactured by winding the laminated sheet 3 around the outer periphery of the water permeable cylindrical body 2 having the radius r of the outer peripheral surface, as shown in FIG. The distance L _n (L ₁ , L ₂ , L ₃ , L ₄ , L ₅ ...) From the short side) to the nth opening 8 is preferably determined according to the following equation.
Ln = (πR _n ² −πr ² ) / (T + t)
R _n : Distance in the radial direction between the n-th opening 8 and the axis of the cylinder 3 (mm)
r: radius of the outer peripheral surface of the cylinder 3 (distance in the radial direction between the outer peripheral surface of the cylinder 3 and the axis (mm)
T: thickness of the flow path material sheet 4 (mm)
t: Thickness of ion exchange sheet (mm)

  In the above embodiment, the ion exchange cast membrane and the ion exchange fiber sheet were used as the first sheet having the adsorptive functional group and the second sheet made of the nonwoven fabric of the fiber having the adsorptive functional group, respectively. A material having an adsorptive functional group other than the exchange group may be used. Examples of such materials include solid electrolytes such as acrylate polymers, polyphosphazene polymers, polysiloxane polymers, carbon, mesoporous silica, chelate resins, calix arenes, molecular template resins, and the like. Can do. Moreover, as a 1st sheet | seat, the film-form thing which does not use fiber bodies, such as a cast film | membrane, can be used.

  The ion exchange sheets used in the following examples and comparative examples are the ion exchange fiber sheets F1 and F2 shown in Table 1 or the ion exchange cast membrane M1 or M2. The used flow path material sheet is the polypropylene grid net S1, S2 or S3 shown in Table 2. The used cylindrical body 2 is made of a polypropylene pipe having an outer diameter of 10 mm and an inner diameter of 6 mm, and a plurality of small holes having a diameter of 2 mm are perforated at a hole interval of 2 mm on the peripheral surface.

[Experiment 1]
As shown in Experiment 1 in Table 3, the ion exchange fiber sheet and the flow path material sheet were overlapped on a cylindrical body having a diameter of 10 mm, wound in a roll shape so as to have an outer diameter of 80 mm, and cut to a length of 225 mm. The cut ends were sealed with an adhesive so that water did not escape.

[Experiments 2-8]
Along each side of the ion exchange sheet having a width a = 225 mm, circular holes having a diameter of 2 mm or slits having a length of 20 mm were provided as openings at 800 mm pitch. That is, c in FIG. 1 (d) was set to 800 mm. L was 400mm only _one. The distance from the side of the ion exchange sheet to the opening is 15 mm. This was superposed on the flow path material sheet, wound around the outer periphery of the cylinder so as to have an outer diameter of 80 mm, and cut to a length of 225 mm. The both sides of the cut surface were bonded so that water did not escape. The circular hole was provided as shown in FIG. 1 (d), and the slit was provided as the slit 9a in FIG.

3) Water flow test conditions The filter was set in the filter cartridge of FIG. 6, and pure water containing 1 ng / L of Na ions was passed at 20 L / min. The results are shown in Table 3.

4) Results and Discussion As shown in Table 3, Experiments 5 to 8 (Examples) have a high ion removal rate over a long period of time with the pressure loss kept low.

[Experiments 9-12]
Also in the following experiments 9 to 12, an ion exchange filter in which an ion exchange sheet and a flow path material sheet were spirally wound as shown in FIGS. 1 (a) and 1 (b) was manufactured. However, in these experiments 9 to 12, the hole 8 and the slit 9 were not provided. Water was passed through the ion exchange filter in a direction parallel to the core material.

  The ion exchange sheet used for the ion exchange filter is an ion exchange cast membrane M3, an ion exchange fiber sheet F3, a laminate sheet of both, and a multilayer sheet obtained by electrospinning an ion exchange fiber sheet directly on M3. This is an ion exchange sheet C. In addition, when the nonwoven fabric was partially peeled off from this ion exchange sheet C and the interface was observed with SEM, it was confirmed that the fibers were fused to the cast film M3.

  The used flow path material sheet is a polyester lattice net S4 having a thickness of 0.63 μm, an opening of ≧ 2.5 mm, and a width of 192 mm. The core material is a polypropylene mandrel having a diameter of 5 mm.

  In both experiments 9 to 12, the ion exchange fiber sheet F3, the ion exchange cast membrane M3, the multilayer sheet C, and the flow path material sheet S4 shown in Table 4 are stacked as specified in Table 5 so that the outer diameter becomes 80 mm. The material was wound into a roll.

3) Water flow test conditions The filter was set in a filter cartridge, and pure water containing 1 ng / L of Na ions was passed through the core material in the direction parallel to the core material from one end surface to the other end surface at 20 L / min. The results are shown in Table 5. Note that the pressure loss was 50 kPa or less.

4) Results and Discussion In Experiment 10, an ion removal rate as high as 98% was initially obtained, but the ion removal rate gradually decreased.
Since the ion exchange fiber has a high adsorption rate, a high ion removal rate was obtained in the initial stage. However, the ion exchange capacity of the ion exchange fiber is small, and thus the ion removal rate seems to have decreased over time.
In Experiment 9 using only the ion exchange cast membrane, an ion removal rate of 91% could be obtained continuously, but the ion removal rate was lower than in Experiments 11 and 12.
Since the ion exchange cast membrane has a low adsorption rate, a high ion removal rate cannot be obtained. However, since the ion exchange cast membrane has a large ion exchange capacity, it seems that the performance can be maintained for a long time.
Experiments 11 and 12 in which ion exchange fibers and ion exchange cast membranes are stacked are used over a long period of time, compared to Experiment 10 using only ion exchange fibers and Experiment 9 using only ion exchange cast membranes. A high ion removal rate could be obtained.
It seems to be a synergistic effect of the high adsorption rate of the ion exchange fiber and the large ion exchange capacity of the ion exchange cast membrane.
In addition, in Experiment 12, a higher ion removal rate was obtained over a longer period than in Experiment 11. This is because the movement rate of Na ions is higher in the experiment 12 in which the ion exchange fibers are fused on both sides of the ion exchange cast membrane than in the experiment 11 in which the ion exchange cast membrane and the ion exchange fiber are simply overlapped. I think that the.

DESCRIPTION OF SYMBOLS 1,1A Ion exchange filter 2 Cylindrical body 3 Laminated sheet 4 Channel material sheet 5, 6, 7 Ion exchange sheet 8 Opening 9 Slit-like opening 10 Filter cartridge 11 Inlet 12 Outlet 13 Casing 31 Outlet (syringe)
32 fibers 33 targets

Claims (7)

  A multilayer sheet obtained by laminating a first sheet having an adsorptive functional group and a second sheet made of a nonwoven fabric of fibers having an adsorptive functional group.   2. The multilayer sheet according to claim 1, wherein the first sheet is made of an ion exchange resin, and the fibers are ion exchange fibers.   3. The multilayer sheet according to claim 2, wherein the first sheet is a cast film of an ion exchange resin.   The multilayer sheet according to claim 3, wherein the ion exchange fiber nonwoven fabric made of ion exchange fibers having an equivalent diameter of 10 to 1000 nm and an ion exchange cast membrane are laminated.   The multilayer sheet according to any one of claims 1 to 4, wherein the fiber is an electrospun fiber of an ion exchange resin.   6. The multilayer sheet according to claim 5, wherein the nonwoven fabric of the fibers is formed on the first sheet.   The multilayer sheet according to claim 6, wherein some of the fibers of the nonwoven fabric are fused to the first sheet.

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