Hollow fiber membrane module and method for producing the same, and method for producing ultrapure water using the hollow fiber membrane module

Abstract

To provide a hollow fiber membrane module which achieves both shortening of cleaning time at the start of use and elimination of an impact on the quality of ultrapure water to be produced, a method for producing the same, and a method for producing ultrapure water using the hollow fiber membrane module.SOLUTION: There is provided a hollow fiber membrane module, comprising: a case; and a plurality of hollow fiber membranes accommodated in the case, where both ends of the hollow-fiber membrane and both ends of the case are fixed with a potting material, the hollow fiber membrane module is a both-end opening filtration membrane module that collects a filtered liquid from both ends of the case, and after water to be treated is filtered by the hollow-fiber membrane modules under external pressure at a water temperature of 25°C, and a permeation flux of 5 m / d for 1 hour, the number of fine particles having diameters equal to or larger than 50 nm in the filtered liquid is 1 particle / mL or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hollow fiber membrane module suitable as a final filter for removing fine particles in water to be treated in an ultrapure water production process, a method for manufacturing the same, and a method for producing ultrapure water using the hollow fiber membrane module.

Background Art

[0002] In a line for producing ultrapure water used in the manufacture of electronic and electrical components such as semiconductors and display elements, a filtration membrane module is used as a final filter for removing fine particles from the water to be treated immediately before supplying the water to be treated, which is produced using a microfiltration membrane, an ion exchange resin, or a reverse osmosis filtration membrane, to the use point. As the filtration membrane module for this application, an external pressure filtration type hollow fiber membrane module in which raw water is supplied to the outside of the hollow fiber membrane for filtration is mainly used because of the merit that the filtration flow rate per module can be increased.

[0003] As properties required for the filtration membrane module for this application, it is required that the water quality as ultrapure water, that is, the number of fine particles in the filtered water, the conductivity of the filtered water, and the total organic carbon (TOC) which is the organic matter content in the filtered water, reach the required level in a short time after the start of use. Therefore, generally, in the filtration membrane module for this application, a cleaning process for reducing the generation of fine particles, elution of ion components, and elution of organic substances from the filter is provided at the end of the product manufacturing process, and the product is shipped in a state where it has been cleaned to a clean state.

[0004] In addition, in order for the filtration membrane module to maintain its filtration performance and suppress the growth of microorganisms in the product, it is necessary to use a preservation solution having a bactericidal and antibacterial action after manufacture, or to sterilize after enclosing water and store it in a wet state. For example, Patent Document 1 discloses enclosing water sterilized at a high temperature as a preservation solution. The filtration membrane module described in Patent Document 1 sterilizes the enclosed preservation solution and shortens the cleaning time of the filtration membrane module, thereby efficiently producing ultrapure water.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In an ultrapure water production line, it is required to maintain the hollow fiber membrane module in a state where its cleanliness is enhanced, that is, substances derived from the hollow fiber membrane module (for example, fine particles, microorganisms, etc.) do not affect the quality of the produced ultrapure water. However, for example, Patent Document 1 has considered the sterilization of the preservation solution, but has not considered enhancing the cleanliness of the filter membrane module itself.

[0007] An aspect of the present invention aims to provide a hollow fiber membrane module, a method for manufacturing the same, and a method for producing ultrapure water using the hollow fiber membrane module that achieve both shortening of the cleaning time at the start of use and not affecting the quality of the produced ultrapure water.

Means for Solving the Problems

[0008] That is, the present invention satisfies the following aspects. <Aspect 1> A hollow fiber membrane module, wherein the hollow fiber membrane module has a case and a plurality of hollow fiber membranes housed in the case, both ends of the hollow fiber membranes and both ends of the case are fixed with a potting material, and the hollow fiber membrane module is an open-ended filter membrane module that collects the filtered liquid from both ends of the case. The hollow fiber membrane module, wherein the number of particles with a diameter of 50 nm or more in the filtrate after subjecting the water to be treated to external pressure filtration for 1 hour at a water temperature of 25 °C and a permeation flux of 5 m / d is 1 particle / mL or less. <Mode 2> The hollow fiber membrane module according to Mode 1, wherein the number of particles with a diameter of 20 nm or more in the filtrate after subjecting the water to be treated to external pressure filtration for 1 hour at a water temperature of 25 °C and a permeation flux of 5 m / d is 3 particles / mL or less. <Mode 3> A method for manufacturing the hollow fiber membrane module according to Mode 1 or 2, comprising: a step of fixing both ends of a plurality of hollow fiber membranes and both ends of a case with a potting material; a cutting step of cutting off the excess of the potting material to open the hollow portions at both ends of the hollow fiber membrane; The method for manufacturing a hollow fiber membrane module, wherein the cutting step is a step of cutting using a diamond band saw. <Mode 4> The method for manufacturing a hollow fiber membrane module according to Mode 3, further comprising a step of washing the hollow fiber membrane with pure water at a washing temperature of 50 °C or higher after the cutting step. <Mode 5> A method for manufacturing the hollow fiber membrane module according to Mode 1 or 2, comprising: a step of fixing both ends of a plurality of hollow fiber membranes and both ends of a case with a potting material; a cutting step of cutting off the excess of the potting material to open the hollow portions at both ends of the hollow fiber membrane; a step of washing the hollow fiber membrane with pure water at 50 °C or higher after the cutting step; A method for manufacturing a hollow fiber membrane module, comprising: <Mode 6> The washing is a circulating washing in which the pure water is supplied from the outer surface to the inner surface of the hollow fiber membrane and permeated to recover the filtered water from both ends of the case, and the recovered filtered water is supplied to the outer surface of the hollow fiber membrane again; The method for manufacturing a hollow fiber membrane module according to Mode 4 or 5, wherein the permeation flux of the pure water is 5 m / d or more. <Mode 7> The manufacturing method of the hollow fiber membrane module according to any one of modes 4 to 6, wherein the washing temperature is 95°C or lower. <Mode 8> The manufacturing method of the hollow fiber membrane module according to mode 3 or 4, wherein the peripheral speed of the diamond band saw is 10 to 1000 m / min. <Mode 9> The manufacturing method of the hollow fiber membrane module according to mode 3 or 4, wherein the peripheral speed of the diamond band saw is 300 to 500 m / min. <Mode 10> The manufacturing method of the hollow fiber membrane module according to mode 3 or 4, wherein when using the diamond band saw, water is brought into contact with the cut surface of the hollow fiber membrane in an amount of 0.5 L / min or more to cool the cut surface. <Mode 11> A method for producing ultrapure water, comprising removing fine particles in the water to be treated using the hollow fiber membrane module according to mode 1 or 2.

Advantages of the Invention

[0009] According to one aspect of the present invention, it is possible to provide a hollow fiber membrane module and a method for manufacturing the same, which achieve both shortening of the washing time at the start of use and not affecting the water quality of the produced ultrapure water, and a method for producing ultrapure water using the hollow fiber membrane module.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0011] According to the method for manufacturing the hollow fiber membrane module of the present embodiment, the generation of dust derived from the potting material can be reduced in advance. In addition, according to the method for manufacturing the hollow fiber membrane module of the present embodiment, the rinsing time of the hollow fiber membrane module at the start of use of the hollow fiber membrane module after the hollow fiber membrane module is installed in the ultrapure water production line can be significantly shortened, so that the production of ultrapure water can be achieved promptly.

[0012] If ultrapure water is produced using the hollow fiber membrane module of the present embodiment, the yield in semiconductor manufacturing can be increased, and semiconductor products can be efficiently manufactured. Hereinafter, the hollow fiber membrane module of the present embodiment will be described with reference to the drawings.

[0013] <Hollow fiber membrane module> The hollow fiber membrane module of the present embodiment can be used as a filtration device for ultrapure water production. The hollow fiber membrane module of the present embodiment can be used for external pressure filtration performed immediately before supplying water produced using a microfiltration membrane, an ion exchange resin, or a reverse osmosis filtration membrane to the use point, and can function as a final filter to remove fine particles. In addition, according to the hollow fiber membrane module of the present embodiment, since the generation of dust from the hollow fiber membrane module itself is suppressed, the ultrapure water production line can be started when the ultrapure water production line is started or immediately after the filter is replaced, and the production of ultrapure water can be started. Furthermore, since undesired substances such as fine particles are removed from the hollow fiber membrane module, the rinsing operation of the hollow fiber membrane module at the ultrapure water production site can be shortened. According to the present embodiment, the time for washing undesired substances such as organic substances (in one aspect, organic substances derived from the potting material, organic substances derived from the preservation solution, and organic substances derived from the membrane-forming stock solution of the hollow fiber membrane), metal ions, and fine particles attached to the hollow fiber membrane at the start of use of the hollow fiber membrane module can be significantly shortened, and / or the mixing of the undesired substances into the product (i.e., ultrapure water) can be suppressed.

[0014] As shown in Fig. 1, the hollow fiber membrane module 1 of this embodiment includes a hollow fiber membrane bundle 3 in which a plurality of hollow fiber membranes 3a are bundled, and a cylindrical case 5 that houses the hollow fiber membrane bundle 3. In one aspect, the hollow fiber membrane module 1 is housed in a case 5 having nozzles on its side surface. In one aspect, the case 5 has a plurality of hollow fiber membranes inside the case 5. In one aspect, both ends of the hollow fiber membrane 3a and both ends of the case 5 are fixed with a potting material. In one aspect, the hollow fiber membrane module 1 is an end-open filtration membrane module that collects the filtered liquid from both ends of the case 5. In one aspect, the inside of the case 5 is filled with a sterilized liquid as a preservation liquid for maintaining the filtration performance of the hollow fiber membrane 3a.

[0015] At both end openings of the case 5, caps 10 and 11 for pipe connection are provided, in which pipe lines 10a and 11a to which pipes are connected are formed, and the caps 10 and 11 for pipe connection are fixedly attached to the case 5 by nuts 13. The nut 13 is screwed onto male threads formed on the side surfaces at both ends of the case 5, and by tightening the nut 13, the space between both ends of the casing and the caps 10 and 11 is sealed by an O-ring 12 disposed in the grooves of the caps 10 and 11.

[0016] Also, on both end portions of the case 5, an upper nozzle 5a and a lower nozzle 5b through which fluid flows are respectively formed. The upper nozzle 5a and the lower nozzle 5b are provided so as to protrude in a direction orthogonal to the longitudinal direction of the case 5.

[0017] At both end faces of the hollow fiber membrane bundle 3, each hollow fiber membrane 3a is open, and the spaces between the respective hollow fiber membranes 3a are adhered by a potting material to form an adhesive portion 14.

[0018] In external pressure filtration, for example, liquid flows in from the lower nozzle 5b, the liquid soaks into the outer surface of each hollow fiber membrane 3a between the bonding parts 14 at both ends, and the liquid that has passed through the hollow part of each hollow fiber membrane 3a flows out from the pipelines 10a, 11a of the caps 10, 11.

[0019] As the hollow fiber membrane 3a, a microfiltration membrane, an ultrafiltration membrane, etc. can be appropriately used. For example, if the hollow fiber membrane module 1 is used for the purpose of a final filter for ultrapure water, the hollow fiber membrane 3a is preferably an ultrafiltration membrane with a fractional molecular weight of 20,000 or less (more preferably 10,000 or less). The material of the hollow fiber membrane 3a is not particularly limited, and examples include polyethylene, polypropylene, polysulfone, polyethersulfone, polyacrylonitrile, polyimide, polyetherimide, polyamide, polyetherketone, polyetheretherketone, polyethylene, polypropylene, poly(4-methylpentene), ethylene-vinyl alcohol copolymer, cellulose, cellulose acetate, polyvinylidene fluoride, polyvinyl alcohol, cellulose acetate, ethylene-tetrafluoroethylene copolymer, and polytetrafluoroethylene, etc., and composite materials thereof can also be used. As the material of the hollow fiber membrane 3a and the case 5, it is preferably a material with little elution, such as a polysulfone-based material.

[0020] The single fiber water permeability of the hollow fiber membrane 3a in terms of inner area at 25°C is preferably 100 L / m 2 / hr / 0.1 MPa (hereinafter, the unit of single fiber water permeability is denoted as "LMH") or more, and particularly preferably 200 LMH or more. The inner diameter of the hollow fiber membrane 3a is 50 μm to 3000 μm, preferably 200 μm to 2000 μm, more preferably 300 μm to 1000 μm, and particularly preferably 300 μm to 850 μm. When the inner diameter is too small, the pressure loss increases and tends to have an adverse effect on filtration. Therefore, the inner diameter of the hollow fiber membrane 3a is preferably 50 μm or more. Also, when the inner diameter is too large, it tends to be difficult to maintain the shape of the hollow fiber membrane during spinning. Therefore, it is preferably 3000 μm or less. When using a hollow fiber membrane having a single fiber water permeability and an inner diameter within the above-specified range, the influence due to vibration during water flow can be suppressed, so that higher module water permeability performance can be realized. In one aspect, the outer diameter of the hollow fiber membrane 3a is 100 μm to 3000 μm, preferably 500 μm to 2000 μm.

[0021] The storage liquid in the hollow fiber membrane module 1 of the present embodiment is a liquid for maintaining the filtration performance of the hollow fiber membrane 3a, and is a storage part 5c formed between the adhesive parts 14 at both ends in the case 5, the space between the caps 10 and 11 and the adhesive part 14, and further a liquid filled in the hollow part and the porous part of the hollow fiber membrane 3a. As the storage liquid of the hollow fiber membrane module 1 of the present embodiment, a sterilized liquid is preferable. For example, the storage liquid of the present embodiment is ultrapure water (in one aspect, sterilized ultrapure water). It is preferable that the storage liquid substantially contains nothing other than the sterilized liquid. In the production of ultrapure water, since it is required that the hollow fiber membrane module does not affect the water quality of the filtered water, the storage liquid of the hollow fiber membrane module 1 preferably keeps the contents of organic substances, metal ions, chloride ions and the number of fine particles within a predetermined range.

[0022] In the hollow fiber membrane module 1 of the present embodiment, it is preferable that the content of organic substances in the storage liquid is less than 50 ppb as TOC (Total Organic Carbon).

[0023] Also, if the TOC in the storage liquid is less than 50 ppb, the amount of discarded filtered water at the start of use of the hollow fiber membrane module 1 can be reduced, and even when the storage liquid is not completely sterilized (that is, the bacteria are not completely killed), the carbon source can be reduced, so that the growth of bacteria can be suppressed. Furthermore, the time for washing the organic substances attached to the hollow fiber membrane at the start of use of the hollow fiber membrane module 1 can be significantly reduced, and ultrapure water can be supplied promptly. In one aspect, the organic matter content in the preservation solution is less than 50 ppb, or 15 ppb or less, or 10 ppb or less as TOC (Total Organic Carbon).

[0024] In the ultrapure water production process, the mixing of metal ions that have an adverse effect on semiconductor manufacturing should be avoided, and the lower the content of metal ions in the preservation solution, the better. In the hollow fiber membrane module 1 of the present embodiment, it is preferable that the concentration of metal ions contained in the preservation solution is less than 100 ppt. More preferably, when the metal ions contained in the preservation solution are less than 50 ppt, the time for discharging water at the start of use of the hollow fiber membrane module 1 can be significantly reduced. In one aspect, the metal ion concentration contained in the preservation solution is less than 50 ppt, or 40 ppt or less, or 30 ppt or less, or 20 ppt or less, or 10 ppt or less.

[0025] Similarly, in the hollow fiber membrane module 1 of the present embodiment, it is preferable that the concentration of chloride ions contained in the preservation solution is less than 1,000 ppt. Chloride ions also erode circuits in semiconductor manufacturing, so it is required to be controlled at an extremely low concentration in ultrapure water. The TOC, chloride ion and metal ion concentrations in the preservation solution are measured by the method described in the examples.

[0026] The pure water in the present embodiment may be water obtained by treating river water or the like with a microfiltration membrane, a reverse osmosis membrane, an ion exchange resin, UV sterilization, etc. In one aspect, the specific resistance value of the pure water is 1.0 MΩ·cm or more. In one aspect, the number of particles with a diameter of 50 nm or more in the pure water is 25 particles / mL or less, or 20 particles / mL or less, or 10 particles / mL or less, or 5 particles / mL or less, or 3 particles / mL or less. Also, in one aspect, the number of particles with a diameter of 20 nm or more in the pure water is 30 particles / mL or less, or 25 particles / mL or less, 20 particles / mL or less, or 10 particles / mL or less, or 5 particles / mL or less.

[0027] In one aspect, pure water is water filtered by a reverse osmosis membrane, an ultrafiltration membrane, or the like, in which ionic components (e.g., metal ions and chloride ions) are reduced, but it does not meet the criteria for ultrapure water. In one aspect, the electrical conductivity of pure water is 1 μS / cm or more. In one aspect, the organic matter content in pure water is preferably less than 1 ppm as TOC. In one aspect, the concentration of metal ions in pure water is preferably less than 1 ppb. Also, the concentration of chloride ions contained in pure water is preferably less than 1 ppb.

[0028] The pure water in the present embodiment may be used as the cleaning water used in the method for manufacturing the hollow fiber membrane module of the present embodiment, the water to be treated before filtration by the hollow fiber membrane module of the present embodiment, and / or the water in the preservation solution.

[0029] In the present embodiment, ultrapure water may be obtained as the filtrate when the water to be treated, which may be pure water or ultrapure water, is filtered (e.g., external pressure filtration or internal pressure filtration) by the hollow fiber membrane module 1 of the present embodiment. In one aspect, the specific resistance value of ultrapure water is 18.0 MΩ·cm or more. In one aspect, the organic matter content in ultrapure water is 50 ppb or less, or 45 ppb or less, or 40 ppb or less, or 35 ppb or less, or 30 ppb or less as TOC (Total Organic Carbon).

[0030] In one aspect, the metal ion concentration in ultrapure water is 50 ppt or less, or 45 ppt or less, or 40 ppt or less, or 35 ppt or less, or 30 ppt or less, or 25 ppt or less, or 20 ppt or less, or 15 ppt or less, or 10 ppt or less. In one aspect, the chloride ion concentration in ultrapure water is less than 100 ppt, or 50 ppt or less, or 40 ppt or less, or 30 ppt or less.

[0031] In one aspect, the number of particles with a diameter of 50 nm or more in the ultrapure water produced in this embodiment is 1 particle / mL or less, or 0.7 particle / mL or less, or 0.6 particle / mL or less, or 0.5 particle / mL or less, or 0.3 particle / mL or less, or 0.1 particle / mL or less. In one aspect, the number of particles with a diameter of 20 nm or more in the ultrapure water produced in this embodiment is 3 particles / mL or less, or 2 particles / mL or less, or 1 particle / mL or less, or 0.5 particle / mL or less, or 0.3 particle / mL or less, or 0.1 particle / mL or less.

[0032] When the water to be treated is filtered using the hollow fiber membrane module of this embodiment, the number of particles with a diameter of 50 nm or more in the filtered water can be kept within the above-specified range. In a preferred aspect, at least one, or at least two, or at least three, or all four of the number of particles with a diameter of 20 nm or more, TOC, metal ion concentration, and chloride ion concentration in the filtered water can be kept within the above-specified range. According to the hollow fiber membrane module of this embodiment, ultrapure water can be efficiently produced even if the cleaning time at the start of use is short. Note that the TOC, metal ion concentration, chloride ion concentration, and the number of the above-mentioned particles with a diameter of 20 nm or more or 50 nm or more in the filtered water are measured after 1-hour external pressure filtration at a water temperature of 25°C and a permeate flux of 5 m / d. The external pressure filtration is performed by the method described in the examples.

[0033] In one aspect, since particles with a diameter of 20 nm or more are smaller than particles with a diameter of 50 nm or more, it is difficult to prevent their mixing into the ultrapure water. However, according to the hollow fiber membrane module of this embodiment, in addition to the number of particles with a diameter of 50 nm or more in the ultrapure water after external pressure filtration under the above conditions being within the above range, in a preferred aspect, the number of particles with a diameter of 20 nm or more can also be kept within the above range. The hollow fiber membrane module of this embodiment can be a hollow fiber membrane module in which the mixing of substances derived from the hollow fiber membrane module into the filtered water is sufficiently suppressed by short-time cleaning at the start of use, that is, a hollow fiber membrane module that achieves both the shortening of the cleaning time at the start of use and no influence on the quality of the produced ultrapure water.

[0034] <Method for manufacturing hollow fiber membrane module> Next, a method for manufacturing the hollow fiber membrane module 1 of the present embodiment will be described. The method for manufacturing the hollow fiber membrane module of the present embodiment includes a step of fixing both ends of a plurality of hollow fiber membranes and both ends of a case with a potting material. In one aspect, the method for manufacturing the hollow fiber membrane module of the present embodiment includes a cutting step of cutting off the excess of the potting material in order to open the hollow portions at both ends of the hollow fiber membrane. In one aspect, the cutting step is a step of cutting off the excess of the potting material using a diamond band saw. In one aspect, the method for manufacturing the hollow fiber membrane module of the present embodiment includes a step of washing the hollow fiber membrane using washing water (for example, pure water or ultrapure water).

[0035] As the case constituting the hollow fiber membrane module 1 of the present embodiment, a polysulfone case similar to the cylindrical case 5 shown in FIG. 1 can be used, but the material is not limited thereto. For example, other materials such as polyethersulfone and polyphenylsulfone can also be used as the material of the case 5. The case diameter is, in one aspect, 50 mm or more and 250 mm or less, preferably 100 mm or more and 200 mm or less, more preferably 120 mm or more and 180 mm or less. If the case diameter is 50 mm or more, the membrane area per hollow fiber membrane module 1 is large and the efficiency is good. Further, if the case diameter exceeds 250 mm, when casting the hollow fiber membrane and the case, an epoxy resin or the like has a large capacity and generates a large amount of heat, and casting tends to be difficult. Inside the cylindrical case, a rectifying cylinder for rectifying the flow of water inside the case may be arranged at the upper and lower ends of the case so that the water flow does not directly hit the hollow fiber membrane bundle.

[0036] As the rectifying cylinder constituting the hollow fiber membrane module 1 of the present embodiment, a cylinder made of polysulfone (in one aspect, made of transparent polysulfone) can be used. As the material of the rectifying cylinder, polypropylene, polyethylene, polyethersulfone, polyphenylsulfone, etc. can be used. The rectifying cylinder only needs to be installed inside the case. As the rectifying cylinder, one with a diameter about 10% smaller than the inner diameter of the case can be appropriately selected. Four protrusions are provided on the side surface of the rectifying cylinder, and by joining these protrusions to the inner surface of the cylindrical case, the rectifying cylinder can be fixed in advance at both ends of the cylindrical case.

[0037] In the manufacturing method of the hollow fiber membrane module 1 of the present embodiment, the hollow fiber membrane bundle 3 is formed by a plurality of hollow fiber membranes 3a. The hollow fiber membrane bundle 3 may be a small bundle formed by wrapping it with a net such as polyethylene in a certain unit of quantity. One to four bundles of the hollow fiber membranes 3a may be grouped together as a small bundle. A plurality of hollow fiber membranes 3a can be grouped together to form the hollow fiber membrane bundle 3, and it is also preferable to group the divided state into a plurality of small bundles into one bundle of the hollow fiber membrane bundle 3. In particular, it is more preferable to form one bundle of the hollow fiber membrane bundle 3 in a state where a small bundle composed of a plurality of hollow fiber membranes 3a is wrapped with a net. By providing a portion in the hollow fiber membrane module 1 where the hollow fiber membrane is not filled (a portion with a low membrane filling density) in this way, the resistance of the water flowing outside the hollow fiber membrane 3a is reduced, and thus a higher module water permeability performance can be realized. Note that as long as it can cover the surface of the small bundle and is made of a material having water permeability, non-woven fabric or the like may be used instead of the net.

[0038] The hollow part is closed at positions about 2 mm from both ends of the hollow fiber membrane 3a. As the means for closing the hollow part, gypsum or the like may be inserted into the hollow part, or the hollow part may be closed with an adhesive such as urethane resin.

[0039] ≪Step of fixing with potting material≫ Insert the hollow fiber membrane bundle 3 into a rectifying cylinder provided in a cylindrical case, and fix it by casting both ends of a plurality of hollow fiber membranes 3a and both ends of the case 5 with an adhesive by means of a centrifugal casting method. The adhesive (in one aspect, a potting material or casting resin) can be appropriately selected. As the adhesive, polymer materials such as epoxy resin, vinyl ester resin, unsaturated polyester resin, olefin-based polymer, urethane resin, silicone resin, acrylic resin, and fluorine-containing resin are preferable, and these polymer materials can be used alone or in combination of a plurality of kinds. In the ultrapure water production process, since the constituent members are required to have heat resistance to hot water and low elution property to filtered water, it is preferable to use an epoxy resin as the potting material. Centrifuge until the fluidity of the adhesive is lost, and cure at a temperature of 50 to 90 °C for 5 to 48 hours in order to completely solidify if necessary.

[0040] The hardness of the cured casting resin is preferably 50 or more on the Shore D scale, more preferably 60 or more, and still more preferably 70 or more. If the hardness of the cured casting resin is 50 or more on the Shore D scale, it can withstand the water pressure during the filtration operation. If the hardness of the cured casting resin is 70 or more on the Shore D scale, it can also withstand the water pressure at high temperatures. On the other hand, if the hardness of the cured casting resin on the Shore D scale is too large, stress is generated at the interface between the hollow fiber membrane 3a and the adhesive due to the vibration during water flow, and this part tends to break easily. From this viewpoint, the upper limit of the hardness on the Shore D scale is preferably 120 or less. After the potting material, the casting resin, is completely cured, cut both ends of the casting portions of the hollow fiber membranes 3a fixed to both ends of the case 5 to open the hollow portions of the hollow fiber membranes 3a to produce the hollow fiber membrane module 1. Enclose water (for example, pure water) in the case 5 of the produced hollow fiber membrane module 1.

[0041] <<Cutting process>> When cutting the excess of the potting material cast with resin using a saw blade such as a saw, there is dust generation of about several millimeters in thickness of the saw blade generated from the cured resin and the hollow fiber membrane 3a, and fine particles of the cured resin, which are cutting powder, may accumulate in the hollow fiber membrane module 1. On the other hand, when cutting the excess of the potting material using a blade with a long blade width such as a guillotine blade, there is no dust generation due to cutting powder in principle. However, when cutting a cured resin with high hardness (in one aspect, a large-sized epoxy resin cured product with a hardness of 60 or more on the Shore D scale), the cured resin may crack, making the cutting very difficult, and fragments of the cured resin and the like may become dust generation sources.

[0042] In one aspect, in the cutting step in the method for manufacturing the hollow fiber membrane module 1 of the present embodiment, in order to open the hollow portion of the hollow fiber membrane 3a, the excess of the potting material is cut with a diamond band saw. By this method, even when the hardness of the cast resin is high, since the thickness of the blade is as thin as 1 mm or less, it is possible to cut efficiently while preventing dust generation, and thus it is possible to produce the hollow fiber membrane module 1 that achieves both workability and low dust generation. Also, in one aspect, in the cutting step in the method for manufacturing the hollow fiber membrane module 1 of the present embodiment, in order to open the hollow portion of the hollow fiber membrane 3a, the excess of the potting material may be cut with a blade other than a diamond band saw (for example, a circular saw). In this case, it is preferable to further perform a cleaning step described later.

[0043] The fine particles in the present embodiment are fine particles with a diameter of 20 nm or more or a diameter of 50 nm or more. In one aspect, the fine particles in the present embodiment are fine particles derived from the potting material generated when manufacturing the hollow fiber membrane module 1 of the present embodiment. The hollow fiber membrane module 1 of the present embodiment produced using a diamond band saw contains few fine particles derived from the potting material. In one aspect, the number of fine particles with a diameter of 20 nm or more and 50 nm or more contained in the filtered water can be 3 particles / mL or less and 1 particle / mL or less, respectively. Therefore, at the start of use, the time required to wash the fine particles eluted from the hollow fiber membrane module 1 can be significantly shortened, and ultrapure water can be produced promptly.

[0044] In one aspect, the number of fine particles with a diameter of 50 nm or more contained in the filtered water is 1 particle / mL or less, or 0.7 particle / mL or less, or 0.6 particle / mL or less, or 0.5 particle / mL or less, or 0.3 particle / mL or less, or 0.1 particle / mL or less. In one aspect, the number of fine particles with a diameter of 20 nm or more contained in the filtered water is 3 particles / mL or less, or 2 particles / mL or less, or 1 particle / mL or less, or 0.7 particle / mL or less, or 0.5 particle / mL or less, or 0.3 particle / mL or less, or 0.1 particle / mL or less. The number of fine particles with a diameter of 20 nm or more and 50 nm or more in the filtered water is measured using Ultra DI 20 and Ultra DI 50 manufactured by Particle Measuring Systems (PMS), respectively.

[0045] In the cutting step in the method for manufacturing the hollow fiber membrane module 1 of the present embodiment, the peripheral speed of the diamond band saw is preferably 10 to 1000 m / min, more preferably 200 to 800 m / min, and particularly preferably 300 to 500 m / min. In order to open the hollow portion of the hollow fiber membrane 3a, when cutting the excess potting material with a diamond band saw, by setting the peripheral speed of the diamond band saw within the predetermined range of the present application, the number of fine particles with a diameter of 20 nm or more and 50 nm or more contained in the filtered water can be 1.5 particles / mL or less and 0.5 particles / mL or less, respectively. Therefore, at the start of using the hollow fiber membrane module, the time required to wash the fine particles eluted from the hollow fiber membrane module 1 can be significantly shortened, and ultrapure water can be produced promptly, so the productivity is excellent. When the peripheral speed of the diamond band saw increases, the object can be cut more quickly. However, due to the increase in frictional heat generated between the diamond band saw and the object and the increase in the number of contacts with the object per unit time, burning, roughness, and chipping occur on the cut surface of the hollow fiber membrane. On the other hand, if the peripheral speed of the diamond band saw is too slow, productivity decreases. By controlling the peripheral speed of the diamond band saw within a predetermined range, the effects of the present embodiment can be obtained.

[0046] From the viewpoint of reducing the heat generated when cutting the hollow fiber membrane with a diamond band saw and suppressing burning of the cut surface due to high heat, water may be supplied during the cutting process. In addition, in the application of ultra-pure water production, the cut surface of the hollow fiber membrane (the hollow parts at both ends of the hollow fiber membrane), which is the outlet on the filtration side, requires cleanliness. Therefore, it is also preferable to supply water for the purpose of removing cutting chips and the like from the cut surface. In the cutting process in the method for manufacturing the hollow fiber membrane module 1 of the present embodiment, it is preferable to cool the cut surface by bringing water into contact with the cut surface of the hollow fiber membrane. Considering the cleanability of the hollow fiber membrane module, the amount of water brought into contact with the cut surface of the hollow fiber membrane is preferably 0.5 L / min or more. However, if the amount of water increases too much, the amount of water during cutting will become a disadvantage and lead to hindering the cutting by the diamond band saw. Therefore, the amount of water brought into contact with the cut surface of the hollow fiber membrane is preferably 5 L / min or less. By controlling the amount of water used during the cutting process within a predetermined range, the effects of the present embodiment can be obtained. The water brought into contact with the cut surface of the hollow fiber membrane may be pure water or ultra-pure water in one aspect, but is not particularly limited as long as the purpose of cooling can be achieved. The temperature of the cooling water is preferably 0°C to 50°C. Further, it is preferable to continuously bring the cooling water into contact with the cut surface of the hollow fiber membrane. In one aspect, the cutting process of the present embodiment includes a process of cooling the cut surface by bringing water into contact with the cut surface of the hollow fiber membrane in an amount of 0.5 L / min or more when using a diamond band saw.

[0047] In order to open the hollow part of the hollow fiber membrane 3a, by setting the amount of water during cutting the excess of the potting material with a diamond band saw within the predetermined range of the present application, the number of fine particles with a diameter of 20 nm or more and 50 nm or more contained in the filtered water can be made 1.5 particles / mL or less and 0.5 particles / mL or less, respectively. Therefore, at the start of using the hollow fiber membrane module, the time for washing the fine particles eluted from the hollow fiber membrane module 1 can be significantly shortened, and ultrapure water can be produced promptly, so it is excellent in productivity.

[0048] ≪Washing step≫ In one aspect, the method for manufacturing the hollow fiber membrane module 1 of the present embodiment includes a washing step. This step may be a step of washing the hollow fiber membrane by circulating and filtering the hollow fiber membrane module 1 with washing water. The washing water may be pure water or ultrapure water in one aspect, but is not limited thereto as long as the purpose of washing can be achieved. Hereinafter, the case of using pure water will be described as an example. In one aspect, after the cutting step, by washing the hollow fiber membrane module 1 with pure water, undesired substances such as TOC, metal ions, and fine particles remaining in the hollow fiber membrane module 1 can be discharged more efficiently. In one aspect, as the temperature of the pure water for washing the hollow fiber membrane module 1 (washing temperature in one aspect), 50°C or higher is preferable, more preferably 60°C or higher, and still more preferably 80°C or higher. If the temperature of the pure water is set to 50°C or higher, undesired substances can be discharged efficiently. If the temperature of the pure water is 80°C or higher, discharge of undesired substances and sterilization can be performed simultaneously. As the upper limit of the temperature of the pure water, 100°C or lower at which water does not boil is preferable, 95°C or lower is more preferable, less than 95°C is even more preferable, and considering the controllability in actual use (preventing sudden boiling), 90°C or lower is particularly preferable.

[0049] By setting the temperature of the pure water for cleaning the hollow fiber membrane module 1 within the predetermined range of the present application, the number of particles with a diameter of 20 nm or more and 50 nm or more contained in the filtered water can be made 1.0 particle / mL or less and 0.5 particle / mL or less, respectively. Therefore, at the start of using the hollow fiber membrane module, the time for cleaning the particles eluted from the hollow fiber membrane module 1 can be significantly shortened, and ultrapure water can be produced promptly, resulting in excellent productivity. When the cleaning temperature with pure water is high, the viscosity of the water decreases, making it easier for the pure water to enter the gap between the adhering particles and the member. Also, with the increase in Brownian motion, the vibration of the particles becomes more intense, making it easier for the particles to peel off. Therefore, the higher the cleaning temperature, the higher the cleaning effect. On the other hand, if the cleaning temperature is too high, the membrane will loosen due to the expansion of the pore diameter of the hollow fiber membrane, and the material properties of the membrane will deteriorate. By setting the cleaning temperature within the predetermined range, the effects of the present embodiment can be obtained.

[0050] In one aspect, the cleaning with pure water is a circulating cleaning by circulating filtration in which pure water is supplied from the outer surface to the inner surface of the hollow fiber membrane 3a and permeated, the filtered water is recovered from both ends of the case 5, and the recovered filtered water is supplied again to the outer surface of the hollow fiber membrane 3a. The flow rate of the pure water (preferably the pure water to be circulated and filtered) depends on the membrane area, but the permeate flux is preferably 3 m / d or more, more preferably 5 m / d or more, still more preferably 6 m / d or more, and preferably 7 m / d or less. The higher the permeate flux, the more efficient it is. If it is 3 m / d or more, a good cleaning effect can be obtained. However, if it is 7 m / d or less, excessive oscillation of the membrane due to the water flow can be prevented, which is advantageous in terms of preventing breakage of the hollow fiber membrane.

[0051] In one aspect, the cleaning time of the hollow fiber membrane module 1 is preferably 1 hour or more, more preferably 3 hours or more, and still more preferably 5 hours or more. Also, in one aspect, the cleaning time of the hollow fiber membrane module 1 is preferably 300 hours or less, more preferably 200 hours or less, and still more preferably 100 hours or less. After the cleaning process, the case may be sealed with a sealing member in a state where the preservation liquid is enclosed, and optionally, post-treatment such as sterilization may be performed to obtain the target hollow fiber membrane module 1. The preservation liquid may be the cleaning water or may be water different from the cleaning water. In one aspect, the preservation liquid can be ultrapure water.

[0052] ≪Method for Producing Ultrapure Water≫ This embodiment also provides a method for producing ultrapure water using a hollow fiber membrane module. By removing fine particles in the water to be treated using the hollow fiber membrane module of this embodiment, it becomes possible to easily produce ultrapure water that satisfies the water quality requirements when used in semiconductor manufacturing and the like.

[0053] FIG. 3 is a diagram showing a detailed configuration of each part of the water treatment apparatus 100 using the hollow fiber membrane module 1 shown in FIG. 1. In one aspect, the method for producing ultrapure water can be implemented using a water treatment apparatus as shown in FIG. 3. Note that in the water treatment apparatus 100 for producing ultrapure water, an example of an external pressure filtration method is assumed.

[0054] As shown in FIG. 3, the water treatment apparatus 100 is, for example, for the final filter of ultrapure water. The water to be treated is supplied from the lower nozzle 5b to the storage part 5c outside the hollow fiber membrane 3a, filtered to the inside (hollow part) side of the hollow fiber membrane 3a, and the filtered water is discharged from the pipelines 10a and 11a at both ends of the hollow fiber bundle 3. Also, the circulating water is discharged through the upper nozzle 5a.

[0055] The water treatment device 100 includes a supply pipe 101 connected to the lower nozzle 5b of the hollow fiber membrane module 1 to supply the water to be treated, and a circulation pipe 102 connected to the upper nozzle 5a to send out the circulating water. Further, in the middle of the supply pipe 101 and the circulation pipe 102, a pressure gauge, various valves 101a, 102a, etc. are arranged. Also, the water treatment device 100 includes a first filtered water collecting pipe 103 and a second filtered water collecting pipe 104 that serve as flow paths for the filtered water. The first filtered water collecting pipe 103 and the second filtered water collecting pipe 104 are connected to a confluence pipe 105 for the filtered water, and the confluence pipe 105 communicates with an external pipe (not shown). Note that a pressure gauge, various valves 105a, etc. are arranged in the confluence pipe 105.

[0056] When installing the hollow fiber membrane module 1 in the above-described water treatment device 100, first, the sealing member 10b that seals the hollow fiber membrane module 1 is removed, and the preservation liquid enclosed in the hollow fiber membrane module 1 is discarded outside the pipes of the water treatment device 100. Then, thereafter, the hollow fiber membrane module 1 is attached to the pipes of the water treatment device 100.

[0057] Normally, when installing a sterilized hollow fiber membrane module in a water treatment device, in order to prevent contamination by fungi, etc., it is attached to the pipe in a closed form, or it is attached without discarding the preservation liquid in the hollow fiber membrane module, and the preservation liquid in the hollow fiber membrane module is discarded while replacing it with the supply water. However, in the case of a water treatment device for ultrapure water used in a semiconductor device, etc., if the preservation liquid in the hollow fiber membrane module flows into the system, the cleanliness of the ultrapure water decreases, and it takes time to make the system clean. Therefore, in the present embodiment, after actively discarding the preservation liquid in the hollow fiber membrane module 1 outside the system, it is attached to the water treatment device 100.

[0058] The hollow fiber membrane module 1 is vertically arranged with the upper nozzle 5a side facing upward. The upper nozzle 5a is connected to the circulation pipe 102, and the pipe 10a of the cap 10 is connected to the first filtered water collecting pipe 103. Also, the lower nozzle 5b is connected to the supply pipe 101, and the pipe 11a of the cap 11 is connected to the second filtered water collecting pipe 104.

[0059] The water to be treated is introduced from the supply pipe 101 into the storage part 5c of the hollow fiber membrane module 1 at a predetermined pressure through the lower nozzle 5b. In the case 5, most of the introduced water to be treated is filtered by the hollow fiber membrane 3a and reaches the hollow part, and then moves upward or downward as the filtered water. The filtered water that has moved upward or downward passes through the openings at the ends of the hollow fiber membrane 3a and exits into the cap 10 or the cap 11, and is discharged into the confluence pipe 105 through the respective pipelines 10a, 11a, the first filtered water collecting pipe 103 or the second filtered water collecting pipe 104, and is collected through the external pipe. On the other hand, the water to be treated that has risen in the storage part 5c in the case 5 without passing through the hollow fiber membrane 3a is discharged from the upper nozzle 5a as circulating water and sent to the circulation pipe 102. The above-collected filtered water can be recovered as the ultrapure water of this embodiment.

[0060] Inside both ends (in one aspect, the upper end and the lower end) of the hollow fiber membrane bundle 3 housed in the case 5, bias regulating members 25A and 26A are arranged in order to reduce the bias in the density distribution of the plurality of hollow fiber membranes 3a. As the bias regulating members 25A and 26A, for example, those having a plate shape or a rod shape (column shape) can be appropriately selected. In this embodiment, the bias regulating member 25A has a flat plate shape, and the bias regulating member 26A has a rod shape. In this embodiment, the bias regulating members 25A and 26A are inserted into both ends of the hollow fiber membrane bundle 3, and the bias in the density distribution of the hollow fiber membrane 3a is reduced at both ends of the hollow fiber membrane bundle 3. Note that the bias regulating members 25A and 26A can also be inserted only into one end of the hollow fiber membrane bundle 3. Even in this aspect, the bias in the density distribution of the hollow fiber membrane 3a is reduced at one end of the hollow fiber membrane bundle 3 by the bias regulating members 25A and 26A inserted into either one.

[0061] In this embodiment, as an example of the bias regulating member, a cross plate 25A having a cross-sectional X shape formed by two rectangular flat plates intersecting orthogonally and an insertion rod 26A composed of a plurality of rod-shaped members will be described as an example.

[0062] The cross plate 25A is arranged such that the intersection portion 25b of the two rectangular flat plates is along the longitudinal direction of the hollow fiber membrane bundle 3. The cross plate 25A includes four plate pieces 25a (see FIGS. 4 and 5) protruding radially from the intersection portion 25b. The upper end portion or the lower end portion of the hollow fiber membrane bundle 3 is substantially evenly divided into four by the four plate pieces 25a, and the bias in the distribution of the hollow fibers 3a is corrected.

[0063] Also, the insertion rod 26A is arranged such that its extending direction is along the longitudinal direction of the hollow fiber membrane bundle 3. The number of insertion rods 26A necessary to correct the bias in the density distribution of the hollow fibers 3a is inserted into each section that is substantially evenly divided by the cross plate 25A. The insertion rods 26A are, for example, arranged substantially evenly on the circumference of a concentric circle with the intersection portion 25b as the axis in each section (see FIGS. 4 and 5). The bias in the density distribution of the hollow fibers 3a is corrected by the cross plate 25A and the insertion rod 26A. Note that the cross plate 25A is arranged in the adhesive fixing layer while avoiding the facing side with the upper nozzle 5a or the lower nozzle 5b.

[0064] (Bias regulating member) In this embodiment, a bias regulating member composed of the cross plate 25A and the insertion rod 26A is exemplified. However, originally, the shape of the bias regulating member is not particularly limited, for example, it can be circular, elliptical, polygonal such as quadrilateral or hexagonal, or star-shaped, plate-shaped, rod-shaped, etc. Also, these members can be used in combination. By combining and using the flat cross plate 25A and the rod-shaped insertion rod 26A as in this embodiment, it is possible to easily and preferably achieve the uniformization of the density distribution of the hollow fibers on the inner end surface of the adhesive fixing layer.

[0065] In addition, the thickness of the bias regulating member is preferably 3 times or more and 20 times or less the outer diameter of the hollow fiber membrane, because it is easy to control the distribution of the hollow fiber membrane. In particular, by setting it to 3 times or more, the distance between the hollow fiber membranes formed by the arrangement of the bias regulating member can be surely made 3 times or more the outer diameter of the hollow fiber membrane on the outer end surface of the adhesive fixing layer. Here, the "thickness" means the equivalent diameter of a circle of the portion having the largest cross-sectional area in the length direction of the bias regulating member. Further, since the outer diameter of the hollow fiber membrane is generally 0.6 mm to 2.5 mm, specifically, a range of 1.8 mm to 50 mm is particularly preferably used. In addition, it is preferable that the tip portion of the bias regulating member is formed into a tapered shape so as to be easily inserted into the hollow fiber membrane bundle 3.

[0066] As the material of the bias regulating member, polymer materials, inorganic materials, etc. can be widely used and are not particularly limited. However, those having good compatibility with the adhesive constituting the adhesive fixing layer and capable of expecting a sufficient adhesive effect, and having a tensile elastic modulus equal to or higher than that of the adhesive are used. In particular, when the hollow fiber membrane module is used for ultrapure water applications, it is preferable to use an organic polymer material with less elution of ionic components.

[0067] In the production of ultrapure water, in addition to high-pressure conditions (where the transfer destination of the water to be treated is at a high place) and high-temperature conditions associated with sterilization, etc., high water quality is required. Since the breakage of the membrane and the damage of the potting material significantly affect the deterioration of water quality, reinforcement of the potting material constituting the hollow fiber membrane module and an orderly arrangement of the hollow fiber membrane bundle, etc. are required. The bias regulating member of the present embodiment contributes to reducing the bias of the water flow in the hollow fiber membrane module and suppressing the breakage of the hollow fiber membrane by reinforcing the potting material and arranging the hollow fiber membrane bundle in an orderly manner.

Examples

[0068] Hereinafter, the present embodiment will be described more specifically with reference to examples and comparative examples, but the present embodiment is not limited only to these examples.

[0069] In the following examples and comparative examples, the preparation and property evaluation of the hollow fiber membrane module were carried out as follows.

[0070] <Evaluation method> [Water quality analysis] The analysis of various components in the washing water, the water to be treated, and the filtered water was carried out using the following equipment. Number of particles with a diameter of 20 nm or more: UltraDI-20 manufactured by Particle Measuring Systems (PMS) Number of particles with a diameter of 50 nm or more: UltraDI-50 manufactured by Particle Measuring Systems (PMS) TOC: TOC5000A manufactured by Shimadzu Corporation Metal ion concentration: ICP-MS 7500cs manufactured by Agilent Technologies Chloride ion concentration: 930 Compact IC manufactured by Metrohm

[0071] [Properties of the hollow fiber membrane] A hollow fiber membrane was prepared by the method described in Example 1 of JP-A-2-164428. Material: Polysulfone Molecular weight cut-off: 6,000 Da (ultrafiltration membrane) Inner diameter / outer diameter: 0.6 mm / 1.0 mm Water permeability: 0.7 m 3 / hr·m 2 ·atm

[0072] <Preparation of the hollow fiber membrane module> [Case used for the preparation of the hollow fiber membrane module] Material: Polysulfone Shape: Cylindrical Size: Inner diameter / outer diameter of the cylindrical part in the filtration area: 154 mm / 170 mm Inner diameter / outer diameter of the cylindrical part in the nozzle part: 162 mm / 183 mm Inner diameter of the nozzle: 58 mm Length of the cylindrical case / Center distance between nozzles: 1050 mm / 872 mm

[0073] Two cylinders made of transparent polysulfone for use as a rectifying cylinder (dimensions are as follows) were prepared. Inner diameter / outer diameter of the base end: 142 mm / 147 mm, Inner diameter / outer diameter of the tip end: 142 mm / 146 mm, Length: 135 mm, Four protrusions were provided on the side surface of the rectifying cylinder, and by joining these protrusions to the inner surface of the cylindrical case, the rectifying cylinder was preliminarily fixed to both ends of the cylindrical case.

[0074] [Procedure for manufacturing the hollow fiber membrane module] One hollow fiber membrane bundle formed by wrapping 11,600 of the above-mentioned hollow fibers with a polyethylene net was prepared. From both ends of the hollow fibers of the shaped membrane bundle to a position about 2 mm, the hollow part was impregnated with a urethane resin (manufactured by Sanyurec Co., Ltd., SA-8100) and closed. At the end of the hollow fiber membrane bundle, as a bias regulating member, the same epoxy resin as the epoxy resin for forming the adhesive fixing layer was used, a cross-shaped cross plate with a height of 70 mm, a width of 138 mm, and a thickness of 5 mm, and a cylindrical insertion rod with a height of 75 mm and a diameter of 10 mm were inserted. Further, the cross plate was arranged in the adhesive fixing layer while avoiding the facing side with the lower nozzle or the upper nozzle. The separation distance between the cross plate and the rectifying cylinder was 22 mm, the height of the cross plate in the adhesive fixing layer was 23 mm, and the distance from the inner end surface of the adhesive fixing layer to the cross plate was 28 mm. Thereafter, the hollow fiber membrane bundle was inserted into the rectifying cylinder provided in the cylindrical case, and a thermosetting epoxy resin (main agent: DEN431 100 parts by weight manufactured by Dow Chemical Company, curing agent: Sunmide 328 45 parts by weight manufactured by Evonik Industries AG) was injected from both ends by the centrifugal casting method, and a centrifugal force of 50 G was applied by the centrifugal casting method until the fluidity disappeared. After centrifugation was completed, it was heated in an oven at 50 °C for 24 hours and then at 90 °C for 24 hours for curing to completely solidify the epoxy resin. At this time, the hardness of the epoxy resin measured by JIS Z2246 was Shore D 82. Next, the excess of the potting material of the hollow fiber membrane cast with this epoxy resin was cut. For cutting, a diamond band saw (manufactured by Maiwa Forcys Co., Ltd., diamond band saw BS-312) or a circular saw (manufactured by Sugiyama Co., Ltd., G2 chip saw, outer diameter: 560 mm, number of blades: 130, and blade thickness: 6.0 mm) was used to obtain a hollow fiber membrane module before washing. The cutting conditions are shown below. The peripheral speed of the diamond band saw was set within the range shown in Table 1, and the excess of the potting material of the hollow fiber membrane was cut. When cutting the excess of the potting material of the hollow fiber membrane using a diamond band saw, cooling water (pure water at 25°C) was brought into contact with the cutting surface of the hollow fiber membrane in an amount within the range shown in Table 1.

[0075] Next, the hollow fiber membrane module before washing prepared above was attached to a predetermined pipe of the water treatment apparatus having the configuration shown in FIG. 3, and the hollow fiber membrane module was rinsed by circulating washing using washing water. The washing water was produced by subjecting river water to treatment with a microfiltration membrane, a reverse osmosis membrane, and an ion exchange resin, as well as UV sterilization treatment. In the washing water, the specific resistance value was 18.1 MΩ·cm, the TOC was 30 ppb, the metal ion concentration was 10 ppt, and the number of fine particles having a diameter of 20 nm or more and 50 nm or more in the washing water was 25 particles / mL and 20 particles / mL, respectively.

[0076] At this time, the supply flow rate of the washing water to the hollow fiber membrane module was adjusted by adjusting the opening degree of the pump outlet valve so that the permeate flux became a predetermined flux, and the amount of water flowing to the filtration side was 98% and the amount of water flowing to the concentration side was 2%. Other washing conditions such as the washing temperature were set as shown in Table 1. Through the above procedure, a hollow fiber membrane module was obtained.

[0077] <Initial Filtration Test: Water Quality at the Start of Use of the Hollow Fiber Membrane Module> The hollow fiber membrane modules according to the examples and comparative examples were subjected to the following water quality tests. With each hollow fiber membrane module, the water to be treated was filtered under external pressure at a temperature of 25°C and a permeate flux of 5 m / d for 1 hour. The water quality analysis results are shown in Table 1.

[0078] The water to be treated was produced by subjecting river water to treatment with a microfiltration membrane, a reverse osmosis membrane, an ion exchange resin, and UV sterilization treatment. The quality of the water to be treated was such that the specific resistance value was 18.1 MΩ·cm, the TOC was 30 ppb, the chloride ion concentration was 30 ppt, the metal ion concentration was 10 ppt, and the number of particles with a diameter of 20 nm or more and 50 nm or more was 25 particles / mL and 20 particles / mL, respectively. At this time, the supply flow rate of the water to be treated to the hollow fiber membrane module was adjusted by the opening degree of the pump outlet valve so that the permeation flow rate became 7.1 m 3 / h, and the valve on the concentrate side was closed so that the entire amount of the water to be treated flowed to the filtration side. The filtration conditions of the hollow fiber membrane modules according to the examples and comparative examples were set as shown in Table 1.

[0079] The measurement of the quality of the filtered water was carried out at a water temperature of 25°C after the passage of the filtration time through the hollow fiber membrane module. Table 1 shows the measurement results of the quality of the filtered water. The concentration of chloride ions in the filtered water filtered by the hollow fiber membrane modules according to Examples 1 to 9 was all 30 to 40 ppt.

[0080] The hollow fiber membrane modules according to Comparative Examples 1 and 2 could not suppress the mixing of particles with a diameter of 20 nm or more and 50 nm or more in the filtered water when performing external pressure filtration for a predetermined time. Therefore, it can be seen that the hollow fiber membrane modules according to Comparative Examples 1 and 2 cannot rapidly produce ultrapure water at the start of use and affect the quality of the produced ultrapure water. On the other hand, the hollow fiber membrane modules according to Examples 1 to 9 could suppress the mixing of particles with a diameter of 20 nm or more and 50 nm or more in the filtered water when performing external pressure filtration for a predetermined time. Therefore, the hollow fiber membrane modules according to Examples 1 to 9 can rapidly produce ultrapure water at the start of use and do not affect the quality of the produced ultrapure water, so they can be used for semiconductor manufacturing without delay.

[0081]

Table 1

Explanation of Symbols

[0082] 1 Hollow fiber membrane module 3 Hollow fiber membrane bundle 3a Hollow fiber membrane 5 Case 5a Upper nozzle 5b Lower nozzle 5c Storage part 10, 11 Cap 10a, 11a Pipeline 10b Sealing member 12 O-ring 13 Nut 14 Adhesive part 25A Deviation regulating member (cross plate) 26A Deviation regulating member (insertion rod) 100 Water treatment device 101 Supply pipe 101a, 102a, 105a Various valves 102 Circulation pipe 103 First filtered water collecting pipe 104 Second filtered water collecting pipe 105 Confluence pipe

Industrial Applicability

[0083] According to the hollow fiber membrane module and its manufacturing method according to the present invention, highly pure water can be efficiently produced.

Claims

1. A hollow fiber membrane module, comprising: The hollow fiber membrane module has a case and a plurality of hollow fiber membranes housed in the case, Both ends of the hollow fiber membrane and both ends of the case are fixed with a potting material, The hollow fiber membrane module is a double-open filtration membrane module that collects filtered liquid from both ends of the case, The hollow fiber membrane module, wherein the filtrate after external pressure filtration of the water to be treated with the hollow fiber membrane module at a water temperature of 25°C and a permeation flux of 5 m / d for 1 hour has 1 particle / mL or less of fine particles having a diameter of 50 nm or more in the filtrate.

2. 2. The hollow fiber membrane module according to claim 1, wherein the number of fine particles having a diameter of 20 nm or more in the filtrate after external pressure filtration of the water to be treated in the hollow fiber membrane module at a water temperature of 25° C. and a permeation flux of 5 m / d for 1 hour is 3 particles / mL or less.

3. A method for producing the hollow fiber membrane module according to claim 1 or 2, comprising the steps of: a step of fixing both ends of the plurality of hollow fiber membranes and both ends of the case with a potting material; a cutting step of cutting off an excess of the potting material in order to open hollow portions at both ends of the hollow fiber membrane, The method for producing a hollow fiber membrane module, wherein the cutting step is a step of cutting using a diamond band saw.

4. The method for producing a hollow fiber membrane module according to claim 3, further comprising the step of washing the hollow fiber membranes with pure water having a washing temperature of 50°C or higher after the cutting step.

5. A method for producing the hollow fiber membrane module according to claim 1 or 2, comprising the steps of: a step of fixing both ends of the plurality of hollow fiber membranes and both ends of the case with a potting material; a cutting step of cutting off an excess of the potting material in order to open hollow portions at both ends of the hollow fiber membrane; After the cutting step, a step of washing the hollow fiber membrane with pure water at 50° C. or higher; A method for producing a hollow fiber membrane module, comprising:

6. The cleaning is a circulation cleaning in which the pure water is supplied from the outer surface to the inner surface of the hollow fiber membrane, the pure water is allowed to permeate through the hollow fiber membrane, the filtrate is collected from both ends of the case, and the collected filtrate is again supplied to the outer surface of the hollow fiber membrane. The method for producing a hollow fiber membrane module according to claim 4, wherein the pure water permeation flux is 5 m / d or more.

7. The method for producing a hollow fiber membrane module according to claim 4, wherein the washing temperature is 95°C or lower.

8. The method for producing a hollow fiber membrane module according to claim 3, wherein the peripheral speed of the diamond band saw is 10 to 1000 m / min.

9. The method for producing a hollow fiber membrane module according to claim 3, wherein the peripheral speed of the diamond band saw is 300 to 500 m / min.

10. 4. The method for producing a hollow fiber membrane module according to claim 3, wherein when using the diamond band saw, the cut surfaces of the hollow fiber membranes are cooled by contacting the cut surfaces with water at a rate of 0.5 L / min or more.

11. 3. A method for producing ultrapure water, comprising removing fine particles from water to be treated by using the hollow fiber membrane module according to claim 1 or 2.

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