WO2018003949A1

WO2018003949A1 - Hollow fiber composite membrane module and method for producing same

Info

Publication number: WO2018003949A1
Application number: PCT/JP2017/024041
Authority: WO
Inventors: 敬史大亀
Original assignee: 東洋紡株式会社
Priority date: 2016-07-01
Filing date: 2017-06-29
Publication date: 2018-01-04
Also published as: JP6931490B2; JPWO2018003949A1

Abstract

Provided is a method for producing a hollow fiber composite membrane module having high selective permeability and a high specific surface are ratio, whereby it becomes possible to prevent the deterioration of separation layers caused by friction generated upon the insertion of the module into a housing and also prevent the deterioration in performance resulting from the deterioration of the separation layers. The production method according to the present invention comprises the steps of: (i) producing a hollow fiber membrane having, on the outer surface thereof, a first separation layer made from a polymer having an anionic functional group; (ii) winding up the hollow fiber membrane to produce a fiber bundle; (iii) inserting the fiber bundle of the hollow fiber membrane into a housing; (iv) bonding at least one end of the fiber bundle of the hollow fiber membrane with a resin and performing an opening processing; (v) bringing the outer surface of the hollow fiber membrane into contact with an aqueous solution of a modified polyvinyl alcohol having at least one cationic or anionic functional group to form a second separation layer composed of an absorption layer made from the modified polyvinyl alcohol; and (vi) bringing the second separation layer into contact with an aqueous solution of an aldehyde compound to acetalize some of hydroxyl groups in the modified polyvinyl alcohol.

Description

Hollow fiber composite membrane module and manufacturing method thereof

The present invention relates to a hollow fiber composite membrane module suitable for water treatment by reverse osmosis or nanofiltration and a method for producing the same, and in particular, an external pressure filtration type hollow fiber comprising a yarn bundle of hollow fiber composite membranes provided with a separation layer on the outer surface. The present invention relates to a high-performance external pressure filtration type hollow fiber composite membrane module and an efficient manufacturing method thereof that do not have a problem of performance deterioration caused by friction of a yarn bundle during module manufacture.

Water treatment by membrane separation, especially water treatment using modules composed of reverse osmosis (Reverse Osmosis, RO) membranes or nanofiltration (Nanofiltration, NF) membranes, as well as separation of polymers, colloids and inorganic particles, NF membranes In the module, low molecular weight of 1000-200 molecular weight, and in RO membrane module, low molecular weight of 200 or less, or even 100 or less, can be highly separated, and monovalent ions or multivalent ions can also be separated. It has the feature of being. Moreover, it has the advantage that it is energy saving compared with distillation separation, and does not accompany the deterioration and modification | denaturation of the solute by heat. Therefore, RO and NF membrane modules are used in fruit juice concentration processes, food processes such as beer enzyme separation, drinking water by desalination of seawater and brine, production of ultrapure water, production of sterile water for medical use, and valuable materials from wastewater. Has been established as an indispensable separation process.

In the RO membrane and the NF membrane, in order to achieve both high water permeability and separability, the structure of the composite separation membrane can be suitably used. The composite separation membrane is a membrane structure obtained by forming a thin separation layer having a thickness of several tens of nm to several μm on the surface of a hollow fiber support membrane having excellent mechanical properties and high water permeability. It is possible to obtain higher permselectivity than the asymmetric membrane structure obtained by the phase separation method.

On the other hand, two main types of modules composed of RO membranes and NF membranes are spiral flat membrane modules and hollow fiber membrane modules. Among these, the hollow fiber membrane module can be classified into an internal pressure filtration module and an external pressure filtration module.

The external pressure filtration type hollow fiber membrane module is composed of a yarn bundle formed by bundling hollow fiber membranes having a separation layer on the outer surface, and of these, a relatively thin hollow fiber membrane yarn having an outer diameter of 100 μm or more and 800 μm or less. The module composed of bundles has a feature that the specific surface area (ratio of the surface area based on the outer diameter of the hollow fiber membrane in the volume of the filtration chamber in the module) is larger than that of other module configurations.

Therefore, an external pressure filtration type hollow fiber membrane module having a composite membrane structure having a high permselectivity and comprising a bundle of hollow fiber membranes having a relatively small diameter is different from a separation membrane module of another form. In comparison, it is expected to be excellent in water production efficiency. Further, an advantage of the external pressure filtration type hollow fiber membrane module is that the room for designing the flow path in the module is large because the supply liquid flows outside the hollow fiber membrane. As the physical cleaning method for the fouled membrane surface, various cleaning methods such as aeration, flushing and back pressure cleaning can be combined, which is excellent in terms of stable operation and life of the module.

FIG. 1 shows an outline of a general manufacturing process of an external pressure filtration type hollow fiber composite membrane module. As shown in FIG. 1, as a general production process, (a) a hollow fiber membrane production process, (b) a process of winding up several thousand to several million hollow fiber membranes to produce a yarn bundle, (C) a step of inserting a hollow fiber membrane yarn bundle into a housing such as a cylindrical pressure vessel, (d) a resin bonded end of the hollow fiber membrane yarn bundle, and then cutting the cured resin end face Main steps include opening the end of the yarn membrane, and (e) moistening the yarn bundle of the hollow fiber membrane in the module with a solvent having a low surface tension such as alcohol, if necessary, and then hydrating the entire membrane. Can be cited as a simple process.

However, since the hollow fiber composite membrane has a fiber shape and has a dense and thin separation layer in the outer layer, in the production steps (a) to (e), between the yarn bundles of the hollow fiber membrane and the yarn There is a problem that it is difficult to avoid performance degradation of the separation layer due to friction between the fibers generated in the bundle. Particularly in the step (c), when a high-density hollow fiber membrane yarn bundle is inserted into the housing, the separation layer deteriorates due to not only the friction between fibers but also the friction between the fibers and the housing member, and the separation performance is serious. There is a problem that it is easy to cause a decrease.

Conventionally, as a method for producing such a hollow fiber composite membrane having a separation layer as an outer layer, a method of forming a crosslinked polyamide thin film on the surface of a hollow fiber-like hollow fiber support membrane has been used. For example, Patent Document 1 discloses a method for producing a hollow fiber composite membrane in which a polyamide thin film crosslinked by interfacial polymerization is formed on the surface of a hollow fiber support membrane.

However, the polyamide separation layer is extremely fragile in terms of the abrasion resistance of the fiber surface in the module manufacturing process, although it is a very suitable structure in terms of being able to express high RO and NF membrane performance. And has the problem that it is difficult to avoid performance degradation due to friction in the manufacturing process described above.

Further, in Patent Document 2, as a method for reducing the inter-fiber friction in the yarn bundle of the hollow fiber membrane at the time of assembling the module, the high water absorption member is hollowed when the polyamide hollow fiber composite membrane is inserted into the module. A method of inserting a yarn bundle with a yarn bundle into a housing is disclosed.

However, in this case as well, the friction between fibers in the yarn bundle cannot be avoided, and the dense and thin polyamide separation layer deteriorates due to slight friction and suffers performance degradation. Therefore, a lubricant such as an oil agent is used as a film. Even if it is given, the above problem is not completely solved. In addition, there is a problem that the specific surface area of the module is reduced by the amount of insertion of a member other than the yarn bundle of the hollow fiber membrane that does not contribute to separation.

Japanese Patent No. 3250644 JP-A-8-309155

The present invention has been made in view of the problems of the prior art, and the object thereof is a hollow fiber having a relatively small diameter, in particular, provided on the outer surface with a separation layer having a high barrier property capable of separating RO and NF. High permselectivity and specific surface area ratio in the manufacturing method of external pressure filtration module composed of composite membrane yarn bundles, avoiding degradation of the separation layer due to friction when inserting the yarn bundle into the housing and resulting performance degradation It is an object to provide a method for producing a hollow fiber composite membrane module having high water production efficiency.

As a result of intensive studies to achieve the above object, the present inventor completed an external pressure filtration type hollow fiber membrane module and a manufacturing method thereof based on the following knowledge.

First, a hollow fiber membrane made of a polymer having an anionic functional group and having a flexible and highly friction-resistant first separation layer on the outer surface as a protective layer is manufactured, and the module manufacturing steps (a) to (e) described above are performed. To produce a hollow fiber membrane module having a high filling rate and containing water.

After that, the yarn bundle of the hollow fiber membrane having the first separated layer in the module and contained in the module is in contact with an aqueous solution of polyvinyl alcohol having at least one cationic functional group and polyvinyl alcohol having an anionic functional group. As described above, by passing the aqueous solution through the module at least once in total, a second separation composed of an adsorption thin film of polyvinyl alcohol is formed on the first separation layer by an alternating lamination method (Layer-by-Layer Assembly). A layer is formed. Furthermore, by passing an aqueous solution of aldehydes through the module, the second separation layer is subjected to acetal crosslinking treatment to form a crosslinked thin film having a dense and high permselectivity.

The hollow fiber composite membrane module produced in this way is surprisingly composed of high-density hollow fiber membrane yarn bundles having a large number of contact points and entanglement points. Adsorption through the ionic interaction between the surface of the first separation layer and the cationic polyvinyl alcohol is performed very quickly and uniformly on the entire surface of each of the hollow fiber membranes. It was found that high separation performance applicable to RO and NF is expressed. The reason for this is that the modified polyvinyl alcohol having a certain cation number or a balance between the anion number and the degree of saponification is adsorbed on the surface of the hollow fiber membrane because the molecular dispersibility is very good in an aqueous solution. Later, it is considered that repulsive force is generated between the surfaces of the yarn bundle to prevent the hollow fiber membranes from sticking to each other in the yarn bundle.

The method that can collectively process the process of uniformly forming the separation layer in the module on the outer surface of the fiber bundle of the hollow fiber membrane is novel and has great advantages in the separation membrane industry. In general, for example, when the cross-linked polyamide separation layer is formed by the above-described interfacial polymerization method, when the interfacial polymerization treatment is performed on the bundle of hollow fibers in the module as described above, defects at the contact points and entanglement points of the yarns As a result, it is extremely difficult to obtain a separation membrane that can withstand practical use. In addition, it is difficult to directly apply another conventional method such as a polymer solution coating method and a spray method to a bundle of hollow fiber membranes.

Since the process of forming the second separation layer of the present invention is performed in a state where the hollow fiber membrane bundle is immersed in water in the module thus completed, an operation that may cause friction between the hollow fiber fibers is performed. Nothing at all. Therefore, it is possible to easily obtain an external pressure filtration type hollow fiber membrane module having an advanced separation function without defects. Moreover, since the formation process of a 2nd separated layer is performed only by the simple process of flowing various aqueous solution in a module, it is very economical and efficient.

The present invention has been completed based on the above findings, and has the following configurations (1) to (8).
(1) Method for producing an external pressure filtration type hollow fiber composite membrane module comprising a bundle of hollow fiber membranes having an outer diameter of 100 μm or more and 800 μm or less, and a net hollow fiber membrane filling rate of 20% or more and 60% or less In the manufacturing method comprising the following steps (i) to (vi):
(I) producing a hollow fiber membrane having a first separation layer made of a polymer containing an anionic functional group on the outer surface;
(Ii) a step of winding the hollow fiber membrane to produce a yarn bundle,
(Iii) inserting the yarn bundle of the hollow fiber membrane into a housing;
(Iv) a step of resin-bonding at least one end of the yarn bundle of the hollow fiber membrane and performing an opening treatment;
(V) A modified polyvinyl alcohol aqueous solution having at least one kind of cationic functional group or anionic functional group is brought into contact with the outer surface of the hollow fiber membrane to form a second separation layer comprising an adsorption layer of the modified polyvinyl alcohol. And (vi) a step of bringing the second separation layer into contact with an aqueous solution of aldehydes to acetalize part of the hydroxyl groups of the modified polyvinyl alcohol.
(2) A sulfonated polyarylene ether in which the polymer constituting the first separation layer has a repeating structure of a hydrophobic segment represented by the following formula (IV) and a hydrophilic segment represented by the following formula (V) (1) The method for producing an external pressure filtration type hollow fiber composite membrane module according to (1).

In the above formula,

And

And

And

And
The same Y and W are not selected,
a and b each represent a natural number of 1 or more,
R ¹ and R ² represent —SO ₃ M or —SO ₃ H, M represents a metal element,
Sulfonation rate expressed as a percentage of the number of repetitions of formula (V) to the total number of repetitions of formula (IV) and formula (V) in the sulfonated polyarylene ether copolymer is from 5% Is larger than 80%.
(3) The sulfonated polymer constituting the first separation layer is a sulfonated polymer comprising a repeating structure of a hydrophobic segment represented by the following formula (I) and a hydrophilic segment represented by the following formula (II). The method for producing an external pressure filtration type hollow fiber composite membrane module according to (1) or (2), which is an arylene ether.

In the above formula, m and n each represent a natural number of 1 or more, R ¹ and R ² represent —SO ₃ M or —SO ₃ H, M represents a metal element, and a sulfonated polyarylene ether copolymer The sulfonation rate expressed as a percentage ratio of the number of repetitions of formula (II) to the sum of the number of repetitions of formula (I) and formula (II) is greater than 5% and less than 80% .
(4) A component of the hollow fiber membrane other than the first separation layer and the second separation layer of the hollow fiber membrane is composed of polyphenylene ether, according to any one of (1) to (3) Manufacturing method of hollow fiber composite membrane module of external pressure filtration type.
(5) In an external pressure filtration type hollow fiber membrane module comprising a bundle of hollow fiber membranes having an outer diameter of 100 μm or more and 800 μm or less, and a net hollow fiber membrane filling rate of 20% or more and 60% or less, (I) to (iii) are satisfied, an external pressure filtration type hollow fiber composite membrane module.
(I) a first separation layer and a second separation layer are provided in this order on the outer surface of the hollow fiber membrane;
(Ii) the first separating layer is composed of a polymer containing an anionic functional group, and (iii) the modified polyvinyl having at least one cationic functional group or anionic functional group in the second separating layer. Consists of cross-linked alcohol aldehydes.
(6) A sulfonated polyarylene ether in which the polymer constituting the first separation layer has a repeating structure of a hydrophobic segment represented by the following formula (IV) and a hydrophilic segment represented by the following formula (V) The external pressure filtration type hollow fiber composite membrane module according to (5), wherein

In the above formula,

And

And

And

And
The same Y and W are not selected,
a and b each represent a natural number of 1 or more,
R ¹ and R ² represent —SO ₃ M or —SO ₃ H, M represents a metal element,
Sulfonation rate expressed as a percentage of the number of repetitions of formula (V) to the total number of repetitions of formula (IV) and formula (V) in the sulfonated polyarylene ether copolymer is from 5% Is larger than 80%.
(7) The sulfonated polymer constituting the first separation layer is a sulfonated polymer comprising a repeating structure of a hydrophobic segment represented by the following formula (I) and a hydrophilic segment represented by the following formula (II): The external pressure filtration type hollow fiber composite membrane module according to (5) or (6), which is an arylene ether.

In the formula, m and n represent a natural number of 1 or more, respectively, ^{R 1} and ^{R 2} represents -SO ₃ M or -SO ₃ H, M represents a metal element, sulfonated polyarylene ether copolymers The sulfonation rate expressed as a percentage ratio of the number of repetitions of formula (II) to the sum of the number of repetitions of formula (I) and formula (II) is greater than 5% and less than 80% .
(8) The constituent part of the hollow fiber membrane other than the first separation layer and the second separation layer of the hollow fiber membrane is composed of polyphenylene ether, (5) to (7), The external pressure filtration type hollow fiber composite membrane module.

The external pressure filtration type hollow fiber composite membrane module of the present invention is a hollow fiber membrane in which a first separation layer as a protective layer is provided on the outer surface, and then a yarn bundle wound with the hollow fiber membrane is inserted into a housing. In this state, by passing a specific aqueous solution of polyvinyl alcohol, the second separation layer is formed on the first separation layer by the alternating lamination method, so that the defect of the separation layer on the outer surface due to friction does not occur. High water permeability and separability can be achieved. In addition, the manufacturing method of the external pressure filtration type hollow fiber composite membrane module of the present invention only allows a desired liquid to pass through the module after filling the module with the hollow fiber membrane whose outer surface is protected by the first separation layer. Since the second separation layer can be formed, it is extremely economical and efficient.

FIG. 1 is a flowchart showing the manufacturing process of the hollow fiber membrane module. FIG. 2 is a schematic explanatory view of a cross section of a hollow fiber membrane that can be used in the present invention. FIG. 3 is a schematic explanatory view showing an example of an embodiment of the hollow fiber membrane module of the present invention. FIG. 4 is a schematic explanatory view showing an example of another embodiment of the hollow fiber membrane module of the present invention. FIG. 5 is a schematic explanatory view showing an example of still another embodiment of the hollow fiber membrane module of the present invention. FIG. 6 is a schematic view showing the relationship between the outer diameter of the hollow fiber membrane and the specific surface area.

The method for producing an external pressure filtration type hollow fiber composite membrane module of the present invention includes the following steps (i) to (vi).
(I) producing a hollow fiber membrane having a first separation layer made of a polymer containing an anionic functional group on the outer surface;
(Ii) a step of winding the hollow fiber membrane to produce a yarn bundle,
(Iii) inserting the yarn bundle of the hollow fiber membrane into a housing;
(Iv) a step of resin-bonding at least one end of the yarn bundle of the hollow fiber membrane and performing an opening treatment;
(V) A modified polyvinyl alcohol aqueous solution having at least one kind of cationic functional group or anionic functional group is brought into contact with the outer surface of the hollow fiber membrane to form a second separation layer comprising an adsorption layer of the modified polyvinyl alcohol. And (vi) a step of bringing the second separation layer into contact with an aqueous solution of aldehydes to acetalize part of the hydroxyl groups of the modified polyvinyl alcohol.

First, the manufacturing process of the hollow fiber membrane having the first separation layer will be described.

The first separation layer provided on the outer surface of the hollow fiber membrane is composed of a polymer having an anionic functional group, and is particularly preferably composed of a polymer having a sulfonic acid group, a carboxyl group, or a phosphonic acid group. More preferably, it is preferably composed of a polymer having a sulfonic acid group from the viewpoint of easy production or availability. Specifically, sulfonated polysulfone, sulfonated polyimide, sulfonated polyarylene ether, sulfonated polysulfone, sulfonated polyphenylene ether (sulfonated polyphenylene oxide), sulfonated polyetherimide, sulfonated polyether ether ketone, sulfonated polyphenylene It is preferably composed of sulfide, sulfonated polybenzimidazole or the like. These polymers can have a high sulfonic acid group density while maintaining the mechanical strength of the first separation layer.

The sulfonated polymer is obtained by sulfonating a known polymer such as polyphenylene ether (polyphenylene oxide), polyimide, polysulfone, polyethersulfone, polyetherimide using chlorosulfuric acid or concentrated sulfuric acid. Preferably there is. More preferable examples include a sulfonated polymer obtained by copolymerizing a hydrophilic monomer having a sulfonic acid group and a hydrophobic monomer having no sulfonic acid group. Such a copolymer sulfonated polymer can precisely control the amount of sulfonic acid group introduced with good reproducibility, and by selecting a desired monomer, it has excellent mechanical strength, high sulfonic acid group density and friction resistance. Can be compatible.

As the copolymerized sulfonated polymer, a sulfonated polymer having a polymer composed of a repeating structure of a hydrophobic segment represented by the following formula (IV) and a hydrophilic segment represented by the following formula (V) as a basic skeleton: Arylene ether (SPAE) is preferred. Such a polymer exhibits a rigid molecular skeleton and excellent chemical durability, and has excellent mechanical strength and good friction resistance.

In the above formula,

And

And

And

And
The same Y and W are not selected,
a and b each represent a natural number of 1 or more,
R ¹ and R ² represent —SO ₃ M or —SO ₃ H, M represents a metal element,
Sulfonation rate expressed as a percentage of the number of repetitions of formula (V) to the total number of repetitions of formula (IV) and formula (V) in the sulfonated polyarylene ether copolymer is from 5% Is larger than 80%.

Furthermore, as the copolymer sulfonated polymer having higher mechanical strength and having both high flexibility and friction resistance, a hydrophobic segment represented by the following formula (I) and a hydrophilic segment represented by the following formula (II) A sulfonated polyarylene ether having a repeating structure of

In the above formula, m and n each represent a natural number of 1 or more, R ¹ and R ² represent —SO ₃ M or —SO ₃ H, M represents a metal element, and a sulfonated polyarylene ether copolymer The sulfonation rate expressed as a percentage ratio of the number of repetitions of formula (II) to the sum of the number of repetitions of formula (I) and formula (II) is greater than 5% and less than 80% .

The SPAEs represented by the above formulas (I), (II), (IV), and (V) have high mechanical strength due to high molecular structure, so that even if the sulfonic acid group density is increased, the SPAE swells. Capable of forming a flexible and strong film that is difficult to resist and excellent in friction resistance. Excellent characteristics as a first separation layer that forms the outer surface of a hollow fiber membrane bundle and inserts it into the housing. Have Furthermore, in the SPAEs represented by the formulas (I) and (II), the hydrophobic segment of the formula (I) contains a benzonitrile structure, so that it has excellent chemical durability and has a hydrophobic portion. Since the cohesive force becomes strong, a film structure in which hydrophilic domains are supported on a strong hydrophobic matrix is formed. As a result, it has a feature that both high sulfonic acid group density and friction resistance can be achieved.

The preferred ion exchange capacity IEC for the degree of sulfonation of the polymer (that is, milliequivalents of sulfonic acid groups per gram of sulfonated polymer) is 0.5 to 3.0 meq. / G, and the preferred range of sulfonation rate DS is greater than 5% and less than 80%. When IEC and DS are lower than the above ranges, the anionic charge density on the surface of the first separation layer becomes small because there are too few sulfonic acid groups. Therefore, there is a tendency that the formation process of the second separation layer by the alternate lamination method described later does not proceed uniformly, which is not preferable. Moreover, when IEC and DS are higher than the said range, since the hydrophilic property of a polymer becomes large too much and a 1st separated layer will swell excessively, it is unpreferable. A more preferable IEC range is 0.7 to 2.9 meq. Further, the range of the sulfonation rate DS is more preferably 10% to 70%.

The hollow fiber membrane serving as the base material of the first separation layer can be an asymmetric membrane composed of the same polymer as the first separation layer (see (a1) in FIG. 2). For example, the above-mentioned sulfonated polymer is molded by a known phase separation method, for example, a wet phase separation method or a dry / wet phase separation method, so that a layer (skin layer) having a high polymer density can be easily separated on the hollow fiber outer layer side. Can be obtained as a layer.

Moreover, the hollow fiber membrane used as the base material of the first separation layer is an asymmetric membrane made of a material different from that of the first separation layer, and a composite membrane in which the first separation layer is provided on the outer surface of the asymmetric membrane. It can also be a structure (see (b1) in FIG. 2). In the present invention, the structure of (b1) in FIG. 2 is preferable as the hollow fiber membrane provided with the first separation layer. In this case, the constituent parts of the hollow fiber membrane excluding the first separation layer on the outer surface are polyphenylene ether (polyphenylene oxide), polysulfone, polyethersulfone, polyetherimide, polyketone, polyimide, polyacrylonitrile, polystyrene, polyvinylidene fluoride, etc. Preferred are asymmetric membranes of polymers selected from known solution-castable polymers. In particular, the constituent part of the hollow fiber membrane is preferably an asymmetric membrane of polyphenylene ether.

As a method for compounding the first separation layer of a different material to the hollow fiber membrane, a known method can be used. Specifically, a coating method such as a dip coating method or a spray method, or a co-extrusion method. (That is, using a triple cylindrical tube nozzle having a core liquid tube at the center and a double annular slit around it, the solution of the sulfonated polymer of the first separation layer is removed from the outer annular slit to the inner annular shape. A polymer solution constituting the hollow fiber membrane part is extruded from the slit, and a fluid such as water, a solvent, or a gas is simultaneously extruded from the core liquid tube at the center part, and then combined by a known wet or dry wet phase separation. A method for obtaining a film structure) can be used. Among these, the dip coating method is preferable from the viewpoint of obtaining a high-quality separation layer stably and simply.

The hollow fiber membrane having the first separation layer composed of the sulfonated polymer has a NaCl rejection of 60% or less for the purpose of being flexible and excellent in wear resistance and increasing water permeability. preferable. Depending on the manufacturing conditions, it is possible to impart sufficient separability, but the water permeability is significantly impaired, and as a result of the dense separation layer, defects on the membrane surface due to friction tend to occur. It is not preferable. More preferably, the NaCl rejection is 30% or less. More preferably, the NaCl rejection is 20% or less. However, the measurement conditions for the NaCl rejection are 0.5 MPa (5 bar), a NaCl concentration of 1500 ppm, and a recovery rate of about 5%.

The thickness of the first separation layer is preferably 50 nm or more and 10 μm or less. When the thickness is too small, the wear resistance is not sufficient, which is not preferable. When the thickness is too large, the permeation resistance becomes too large and sufficient water permeability cannot be obtained. More preferably, it is 100 nm or more and 1 μm or less.

The hollow fiber membrane having the above first separation layer is formed by a membrane formation step (FIG. 1 (a)) by a wet phase separation method or a dry / wet phase separation method, followed by a water washing step, a drying step, dip coating. Etc. can be obtained by a desired combination of known techniques such as a compounding step, a winding step, an unwinding step and the like.

A large number of hollow fiber membranes thus obtained are wound up into thousands to millions of yarn bundles by a yarn bundle forming step ((b) in FIG. 1). Subsequently, after the step of inserting this yarn bundle into the housing (pressure container or cartridge frame (FIG. 1 (c)), resin bonding / end opening processing (FIG. 1 (d)) is performed, and if necessary Then, after the membrane is completely wetted with a solvent having a low surface tension such as alcohol, a module can be obtained by performing a hydrophilization / water-containing step ((e) in FIG. 1) in which the membrane is gradually replaced with water. . However, from the viewpoint of making the manufacturing efficiency and the module structure suitable, the steps (b) to (e) in FIG. 1 may be performed simultaneously or the order may be changed.

Next, the configuration of the hollow fiber composite membrane module will be described. The arrangement of the yarn bundles of the hollow fiber membranes in the module may be either a parallel arrangement or a cross arrangement, but it is preferable that the hollow fibers are slightly shaken or vibrated during physical washing such as back pressure washing or flushing. Further, from the viewpoint of uniformly forming the second separation layer, which will be described later, it is preferable that there is a margin in which a slight gap is generated in the yarn bundle of the water-containing hollow fiber membrane. Therefore, the filling rate of the net hollow fiber membrane is preferably 20% or more and 60% or less. When the filling rate is lower than this range, the specific surface area as the final module product becomes small, and the water production efficiency is lowered. When the filling rate is higher than this range, it becomes difficult to substantially fill the housing due to the bulkiness of the yarn bundle, and a resin impregnation defect tends to occur in the resin bonding step of the module end face. More preferably, it is 30% or more and 50% or less.

Here, the net filling factor of the module is a ratio of the volume based on the outer diameter of the hollow fiber membrane to the volume of the filtration chamber in the module, and is expressed by the following formula.
(Filling _{_{rate) = 100 × NL H πR H}} 2 / (L M S M) (vol%)
N: number of hollow fibers, L _H : average effective length of hollow fiber membrane, R _H : outer radius of hollow fiber membrane, L _M : length of filtration chamber, S _M : average cross-sectional area of filtration chamber where L _H is an average value of the length of the effective portion of the hollow fiber membrane that comes into contact with the supply liquid in the filtration chamber, and excludes the resin adhesion portion. L _M except the resin bonding portion, the hollow fiber membrane is the length of the filtration chamber of the net has been filled (for example a L _M in FIGS. 3-5). _SM represents the cross-sectional area of the filtration chamber including the hollow fiber membrane part after removing all cross-sectional areas of members other than the hollow fiber membrane such as the container wall, the core tube part, the partition plate, and the liquid introduction pipe part. is the average value in the range of L _M.

The outer diameter of the hollow fiber membrane filled in the module is preferably 100 μm or more and 800 μm or less. More preferably, it is 200 μm or more and 600 μm or less. The smaller the outer diameter of the hollow fiber membrane, the larger the specific surface area of the module. Here, the specific surface area is expressed as a ratio (m ² / m ³ ) of the hollow fiber membrane outer diameter standard surface area to the net filtration chamber volume (L _M S _M ). As a reference, FIG. 6 shows a graph in which the specific surface area when the filtration chamber is a simple cylinder and the hollow fiber membrane is arranged completely in parallel to this is calculated for various filling ratios and hollow fiber membrane outer diameters. As the external pressure filtration type hollow fiber membrane module, the specific surface area is preferably 3000 m ² / m ³ or more so that the specific surface area is superior to other-type modules such as a spiral flat membrane. And more preferably 4000 m ² / ^{m 3} or more. The filling ratio and outer diameter of the preferred hollow fiber membrane described above correspond to the preferred range of this specific surface area. On the other hand, if the outer diameter of the hollow fiber membrane is smaller than this range, the productivity is deteriorated, the breaking strength per single yarn is reduced, and troubles such as yarn breakage are liable to occur in the module manufacturing process.

From the viewpoint of designing the channel in the module where membrane surface fouling is less likely to occur due to contaminants, a partition plate that divides the bundle of multiple hollow fiber membranes in parallel to the longitudinal direction of the yarn is provided, or the center of the module A structure may be provided in which a core pipe is provided, and supply water is introduced from the core pipe.

The member configuration / arrangement method of the external pressure filtration module is not particularly limited, and a known method can be adopted. An integral module in which the resin bonded portion of the yarn bundle end of the hollow fiber membrane and the pressure vessel are fixed, or the yarn bundle of the hollow fiber membrane and the resin bonded end are fixed with a member such as a cap or a core tube for protection. A detachable cartridge type module in which a wrapped cartridge (or element) is configured, inserted into a pressure resistant container, and sealed with an O-ring or the like can be preferably employed. Specifically, the module structure shown in FIGS. 3 to 5 can be cited as a preferred example of the present invention.

FIG. 3 shows an example of an external pressure filtration type hollow fiber membrane module having a hollow fiber opening end (A1) only at one end and capable of collecting water from the permeate outlet (A7). The hollow fiber membrane thread bundle (A3) and The bonding portion 1 (A2) is an integrated module fixed to the pressure vessel (A8). The other end (A11) of the yarn bundle (A3) of the hollow fiber membrane is preferably looped or resin-bonded in a cut state. This end (A11) is preferably suspended or fixed to the pressure resistant vessel (A8) at a position where the hollow fiber membrane is bent sufficiently. Other inlets (A4, A5, A12) provided in the module can be used as inlets / outlets of supply water or as inlets / outlets of membrane cleaning air bubbles, chemicals, and the like. Further, the permeate outlet (A7) can be used as an inlet for the cleaning liquid during back pressure cleaning. There is no problem even if an inlet for back pressure cleaning is added to the cap (A9).

FIG. 4 shows an example of an external pressure filtration type hollow fiber membrane module in which the hollow fiber opening end (B1) is at both ends and water can be collected from two permeate outlets (B7). The thread bundle (B3) and the adhesive part 1 (B2) are an integrated module fixed to the pressure vessel (B8). Since both ends of the yarn bundle (B3) of the hollow fiber membrane are fixed, it is preferable to adjust the hollow fiber membrane so that the yarn does not stretch by giving a slight deflection in the longitudinal direction. Other inlets (B4, B5) provided in the module can be used as inlets / outlets of supply water, or as inlets / outlets of membrane cleaning air bubbles, chemicals, and the like. Further, the permeate outlet (B7) can be used as an inlet for the cleaning liquid during back pressure cleaning. There is no problem even if an inlet for back pressure cleaning is added to the cap (B9).

FIG. 5 is an example of an external pressure filtration type hollow fiber membrane module in which the hollow fiber opening end (C1) has only one end and can collect water from the permeate outlet (C10), and the hollow fiber membrane thread bundle (C4) and The adhering portion (C2) is a cartridge (or element) type module attached by a removable water stop mechanism (C3) such as packing. The other end (C5) of the yarn bundle (C4) of the hollow fiber membrane is preferably resin-bonded in a loop or cut state. The end (C5) may be in a suspended state, or may be fixed to the core tube (C7) or the pressure vessel (C11) at a position where the hollow fiber membrane is adequately bent. The core tube (C7) and other inlets (C8) having a plurality of apertures (C14) in the module should be used as inlets / outlets for supply water, or as membrane inlet / outlet for membrane cleaning. Can do. From the viewpoint of channel design, it is also preferable to provide a partition plate (C13).

In the present invention, a module having a pattern in which the module configurations shown in FIGS. 3 to 5 are combined may be employed as desired.

The hollow fiber membrane yarn bundle having the first separation layer is inserted into the module container, and at least one end of the hollow fiber membrane yarn bundle is resin-bonded to perform an opening process ((d in FIG. 1). ))I do. As the resin, for example, an epoxy resin, a urethane resin, or the like is preferably selected, and any of known static potting or centrifugal potting can be used. The opening treatment of the hollow fiber membrane at the bonded end for collecting the filtrate can be performed by a cutting device such as a guillotine or a grinder.

The hollow fiber membrane module thus obtained is preferably filled with alcohol such as methanol, ethanol, isopropyl alcohol, etc., and subjected to a hydrophilization treatment to wet the hollow fiber membrane. It is preferable to perform a hydrophilization / water-containing step ((e) of FIG. 1) in which the inside and outside of the substrate are completely replaced with water. The water to be introduced is preferably filtered in advance so that dust and microorganisms do not adhere to the membrane. In order to completely remove the remaining alcohol components in the membrane, it is also preferable to perform a water permeation treatment while applying external pressure. Furthermore, it is also preferable to perform this step while cleaning the membrane surface by increasing the linear velocity of the membrane surface by cross-flow filtration.

In this hydrophilization / water-containing step ((e) of FIG. 1), in order to efficiently promote the adsorption of the modified polyvinyl alcohol having a cationic group or an anionic group, which will be described later, to the first separation layer, the water charged in the module The electrical conductivity is preferably 100 μS / cm or less. More preferably, it is 10 μS / cm or less. If the conductivity is high beyond this range and the ion concentration in the solution is high, the modified polyvinyl alcohol has a coulomb shielding effect in the solution, depending on the amount of ionic functional groups introduced into the modified polyvinyl alcohol. Is not preferable because adsorption to the first separation layer is hindered.

Next, a method for forming the second separation layer will be described. The second separation layer can be formed by a method (Layer-by-Layer method) in which a cationic polymer and an anionic polymer are alternately laminated starting from the first separation layer having an anionic surface.

First, an aqueous solution of a modified polyvinyl alcohol having a cationic functional group is filled into the module containing water. The solution is preferably filled from the bottom of the module so that air bubbles do not enter the module. A CPVA adsorption treatment is performed by bringing a cationic polyvinyl alcohol (hereinafter, CPVA) solution into contact with the anionic surface of the first separation layer of the hollow fiber membrane for a certain time. From the viewpoint of forming a thin separation layer without defects, the solution is preferably kept in contact for a period of 10 seconds to 10 hours. More preferably, it is 1 minute or more and 3 hours or less. Thereafter, the CPVA aqueous solution is extracted and rinsed with pure water. Preferably, rinsing is performed for 10 seconds or more to remove excess polymer other than CPVA adsorbed on the hollow fiber membrane from the module. These solution switching steps are preferably performed continuously in order to keep the gap in the yarn bundle of the hollow fiber membrane filled with the solution or water.

Thereafter, an aqueous solution of an anionic polyvinyl alcohol (hereinafter referred to as APVA) having an anionic functional group is preferably filled, and an APVA layer adsorption layer is further formed on the surface of the CPVA adsorption layer. The adsorption time and pure water rinse treatment may be performed by the same method as described above.

The above-described adsorption treatment of CPVA and APVA can be alternately repeated starting from the anionic first separation layer. It is preferable to perform at least one CPVA adsorption. More preferably, APVA adsorption is added to CPVA adsorption because an effect of improving separation performance is observed. It is also preferable to perform each treatment twice or more. However, even if it is performed three times or more, the performance change is not so much seen.

The concentrations of the CPVA and APVA aqueous solutions are each preferably 0.01% to 1% by weight. When the concentration is smaller than this range, the adsorption is not sufficiently performed and the film performance is deteriorated. If the concentration is too high, the adsorption layer tends to be too thick, and the viscosity of the aqueous solution becomes high.

The solvent of the CPVA and APVA aqueous solutions is preferably pure water, and it is preferable to use pure water having a conductivity of preferably 10 μS / cm or less, more preferably 1 μS / cm or less. If the conductivity of water as a solvent is too high, the adsorption of the modified PVA to the first separation layer via electrostatic interaction tends to be hindered due to the influence of Coulomb shielding as described above.

After the adsorption treatment of CPVA and APVA, it is preferable to acetal crosslink the hydroxyl groups of CPVA and APVA by filling the module with an aqueous solution of aldehydes. The modified PVA adsorbing layer not subjected to cross-linking has almost no separability. Only after the crosslinking treatment can the separation performance of RO and NF membranes with a molecular weight cut off of 100-1000 be achieved. Surprisingly, such a cross-linked adsorption layer is formed to be extremely uniform and thin compared to a PVA separation layer formed by a conventional coating method or the like. it can.

As the aldehyde as the crosslinking agent, for example, formaldehyde, glutaraldehyde, glyoxal, benzaldehyde, orthophthalaldehyde, isophthalaldehyde, terephthalaldehyde and the like can be preferably used. More preferably, glutaraldehyde or orthophthalaldehyde can be used in terms of high water solubility, relatively low toxicity, and good separation membrane performance after the crosslinking treatment.

In the above crosslinking treatment, the crosslinking time is preferably 10 minutes or more and 40 hours or less. When the crosslinking time is too short, the blocking performance of the second separation layer is small. In addition, if the crosslinking time is too long, there is not much effect. From the viewpoint of promoting the crosslinking reaction, it is also preferable to maintain the temperature of the aldehyde aqueous solution at 20 ° C. or more and 60 ° C. or less.

After the crosslinking treatment, the module and the hollow fiber membrane are sufficiently washed with pure water. From the viewpoint of completely removing aldehydes in the membrane, it is preferable to enhance the cleaning effect by performing a cross flow operation using pure water under a pressure of about 1 to 10 atm. Furthermore, when a cross-linking agent with a slightly low water solubility and strong hydrophobicity, such as orthophthalaldehyde, is used, the cross-linking agent tends to remain in the membrane. For example, a sodium hydrogen sulfite aqueous solution is filled in the module. In addition, an aldehyde and an adduct can be formed to enhance the cleaning effect. Or, for example, under alkaline conditions of pH 9 or higher, an aqueous solution of reducing sugar (glucose, fructose, glucosamine, etc.) having reducibility is filled in the module, and unreacted aldehyde groups and reducing sugars outside and inside the membrane are removed. A process of reacting and detoxifying can also be suitably used.

Thus, it is preferable that the module which has been subjected to the crosslinking treatment with aldehydes and sufficiently washed with water is again subjected to the adsorption treatment of CPVA and APVA and the aldehyde crosslinking in exactly the same manner. By repeating this adsorption / crosslinking treatment cycle, a high separation performance (for example, a magnesium sulfate rejection of 98% or more and a fractional molecular weight of 100 to 300) can be obtained. Preferably, the adsorption / crosslinking treatment cycle is repeated twice or more.

The thickness of the second separation layer is preferably 1 nm or more and 200 nm or less. When the thickness is too thin, the adsorption of the modified PVA is insufficient and the separability is not sufficiently developed. On the other hand, if it is too thick, the permeation resistance becomes too large and sufficient water permeability cannot be obtained. More preferably, it is 5 nm or more and 100 nm or less.

The structure of the modified PVA constituting the second separation layer will be described below.

The type of the cationic functional group contained in CPVA is not particularly limited, but preferably has a primary to quaternary ammonium group, and a quaternary ammonium group is particularly preferable from the viewpoint of chemical durability and antibacterial properties. Specifically, CPVA is saponified by copolymerizing a quaternary ammonium salt such as diallyldimethylammonium chloride and 3-methacrylamideamidopropyltrimethylammonium chloride with vinyl acetate as an unsaturated monomer having a cationic group. It is preferable that it is a polymer obtained by processing.

As another method for obtaining CPVA, a method in which a quaternary ammonium salt having a glycidyl group is added to a hydroxyl group of ordinary unmodified polyvinyl alcohol under an alkaline condition is also preferable. As the monomer having a glycidyl group, for example, glycidyltrimethylammonium chloride can be preferably used. Both the modification of polyvinyl alcohol by such an addition reaction and the modification by the above copolymerization can be preferably used. Moreover, both methods may be implemented to introduce two or more types of cationic groups into the polymer.

On the other hand, for APVA, the type of anionic functional group is not particularly limited, and PVA having a sulfonic acid group, a phosphonic acid group, a carboxyl group, or the like can be used. From the viewpoint of easy production and availability, PVA having a sulfonic acid group is preferably used. For example, sulfonated PVA obtained by copolymerizing 2-acrylamido-2-methylpropanesulfonate and vinyl acetate and saponifying can be used. Similar to CPVA, two or more types of anionic groups may be introduced into the polymer.

It is preferable that the amount of the cationic group or anionic group of CPVA and APVA is at least 0.01 mol% to 30 mol%. More preferably, they are 0.1 mol% or more and 20 mol% or less. When the ionic functional group is smaller than this range, the adsorption to the hollow fiber membrane surface does not proceed sufficiently and the membrane performance is lowered, which is not preferable. On the other hand, if it is larger than this range, the second separation layer swells too much and the separation performance is lowered, which is not preferable.

The degree of saponification of CPVA and APVA is preferably 60 to 99 mol%, more preferably 70 to 95 mol%, still more preferably 75 to 90 mol%. If the degree of saponification is larger than this range, the dispersibility of the modified PVA molecules in an aqueous solution tends to deteriorate. That is, it is easy to form a state in which PVA molecules are associated in a solution. As a result, a phenomenon occurs in which the modified PVA layers adsorbed on the surface of the hollow fiber membrane are bonded to each other, and as a result, a sticking portion tends to be generated in the yarn bundle of the hollow fiber. In this case, the film performance is not sufficiently exhibited, which is not preferable. When the degree of saponification is lower than this range, the stability of the aqueous solution is similarly deteriorated, which is not preferable.

As described above, the external pressure filtration type hollow fiber membrane module of the present invention has a hollow fiber membrane having an anionic first separation layer on the outer surface that is flexible and excellent in friction resistance. Performance degradation due to friction between hollow fibers can be avoided. Furthermore, in the present invention, a thin second separation layer having no defects can be uniformly formed only by a simple process of alternately filling a modified PVA and an aqueous solution of an aldehyde in a state of a hollow fiber membrane module having a high filling rate containing water. It is possible to industrially manufacture a practical and high-performance hollow fiber composite membrane module.

Hereinafter, the effects of the present invention will be specifically described by way of examples, but the present invention is not limited to these.

Example 1
(Preparation of hollow fiber support membrane)
As a polymer for the hollow fiber support membrane, polyphenylene ether PX100L (hereinafter abbreviated as PPE) manufactured by Mitsubishi Engineering Plastics Co., Ltd. was prepared. N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) was added and dissolved at 130 ° C. while kneading so that the PPE would be 20% by mass to obtain a uniform film forming stock solution.

Subsequently, while extruding the film-forming stock solution into a hollow shape from a double cylindrical tube nozzle, a 35% by mass NMP aqueous solution was simultaneously extruded as an internal solution to be molded, and was allowed to dry in the air at room temperature. Further, it was immersed in a 30% by mass NMP coagulation bath at 30 ° C. to prepare a PPE hollow fiber support membrane, and then washed with water.

The obtained PPE hollow fiber support membrane had an outer diameter of 250 μm and a film thickness of 50 μm. When the pure water permeation test was conducted, the pure water flux was 43 L / (m ² · h · bar).

(Formation of the first separation layer)
An SPAE having a repeating structure of the hydrophobic segment represented by the above formula (I) and the hydrophilic segment represented by the above formula (II) was prepared as follows.

Weigh out 3.0000 kg of 3,3'-disulfo-4,4'-dichlorodiphenylsulfone disodium salt (hereinafter abbreviated as S-DCDPS) and 1.7036 kg of 2,6-dichlorobenzonitrile (hereinafter abbreviated as DCBN). The charge molar ratio of S-DCDPS and DCBN was 38:62. Further, 2.9679 kg of 4,4′-biphenol and 2.4213 kg of potassium carbonate were weighed and put into a polymerization tank to flow nitrogen. After adding 25.9 kg of NMP and stirring at 150 ° C. for 50 minutes, the reaction temperature was raised to 195 ° C. to 200 ° C. and the reaction was continued. Thereafter, the mixture was allowed to cool, and after cooling, the polymerization solution was precipitated into a water bath. The obtained polymer was washed in boiling water for 1 hour and then carefully washed with pure water to completely remove residual potassium carbonate. Thereafter, the polymer after removing potassium carbonate was dried to obtain a copolymerized SPAE having a sulfonation degree DS = 38%, which was the target product.

DMSO solvent was added to the obtained SPAE and dissolved while stirring at room temperature to obtain a 1.0 mass% SPAE coating solution.

The PPE hollow fiber support membrane was dip coated in a SPAE coating solution and dried at 120 ° C. in a vertical drying oven. Thereafter, a plurality of composite separation membranes having a first separation layer made of SPAE were wound around a winder. As a result of observation by SEM, the thickness of the first separation layer was 300 nm. At this time, the pure water flux was 30 L / (m ² · h · bar), and the NaCl rejection was 11%.

(Manufacture of modules)
A module of the type shown in FIG. 3 was produced as follows. One yarn bundle in which 70,000 hollow fiber membranes were bundled in parallel was prepared, one end of the yarn bundle was cut, and the opening surface was clogged with a hot melt of polyolefin. This end was placed in a polytetrafluoroethylene (PTFE) container having an inner diameter of 80 mm, filled with an epoxy resin and hardened, and then released to obtain an adhesive end (A11).
Further, the periphery of the above-described yarn bundle was wound with a PTFE film having a thickness of 50 μm to protect the outer surface, and an inner diameter of 100 mm and a length of 1,000 mm provided with two supply liquid inlets / outlets (A4, A5). A cylindrical container made of polyvinyl chloride was filled. Thereafter, the PTFE film was pulled out. Subsequently, with the cylindrical container fixed in an upright state, with the adhesive end (A11) on the upper side and the other end on the lower side, an epoxy resin is poured from the lower part of the cylindrical container, and end bonding is performed. An adhesive end (A2) was obtained. The opening end (A1) was cut so that the hollow fiber membrane was opened after the resin was cured. The obtained module had a hollow fiber membrane effective length L _H and a filtration chamber length L _M of 900 mm, a hollow fiber filling rate of 44 vol%, and a specific surface area of 7,000 m ² / m ³ . A cap (A9) was vertically attached to this module to produce a hollow fiber membrane module having a first separation layer.

(Hydrophilization / moisture treatment)
The module thus produced was filled with ethanol from the lower inlet (A12) and subjected to a hydrophilic treatment for 2 hours. Thereafter, pure water was introduced while the ethanol was expelled from the upper outlet (A5), and a substitution treatment was performed. Thereafter, a cross flow operation was performed with pure water at a pressure of 2 bar to completely remove ethanol in the membrane.

(Formation of second separation layer)
With respect to this water-containing module, a 0.1 wt% aqueous solution in which CPVA (Kuraray CM318) was dissolved in pure water was filled into the module while purifying pure water from the upper outlet (A5). After performing the adsorption treatment by allowing to stand for 30 minutes, rinsing was performed for 5 minutes while substituting with pure water. Thereafter, a 0.1 wt% aqueous solution in which APVA (manufactured by Nippon Synthetic Chemical Co., Ltd. CKS50) was dissolved in pure water was filled in the module. The adsorption treatment was carried out by leaving for 30 minutes. After rinsing for 5 minutes while substituting with pure water, 1 wt% glutaraldehyde (GA) aqueous solution (added with sulfuric acid as an acid catalyst and adjusted to pH = 1) was charged and subjected to crosslinking treatment for 20 hours. . After thoroughly washing the inside of the module with pure water, another CPVA and APVA adsorption treatment and glutaraldehyde crosslinking treatment cycle were carried out based on exactly the same method. Finally, it was sufficiently washed with pure water to complete a hollow fiber membrane module having a second separation layer.

As for the final module performance, at a pressure of 5 bar, the pure water permeation amount of the module was 865 L / h, and the pure water flux per pressure was 3.5 L / (m ² · h · bar). The MgSO ₄ blocking rate was 99.2%, the NaCl blocking rate was 65.0%, the sucrose blocking rate was 99.0%, and the glucose blocking rate was 90.3%.

(Example 2)
(Preparation of hollow fiber support membrane)
A PPE hollow fiber support membrane was obtained in the same manner as in Example 1 except that the shape of the hollow fiber was changed. The outer diameter of the PPE hollow fiber support membrane was 520 μm, and the film thickness was 310 μm. When the pure water permeation test was conducted, the pure water flux was 40 L / (m ² · h · bar).

(Formation of the first separation layer)
In the same manner as in Example 1, the dip coating speed and the drying temperature were finely adjusted to obtain a plurality of composite separation membranes having a first separation layer made of SPAE. As a result of observation by SEM, the thickness of the first separation layer was 180 nm. At this point, the pure water flux ^{28L / (m 2 · h ·} bar), NaCl rejection was 10%.

(Manufacture of modules)
In the same manner as in Example 1, a module of FIG. 3 type was manufactured using a polyvinyl chloride cylindrical container having an inner diameter of 100 mm and a length of 1,000 mm and a yarn bundle of 19,200 hollow fiber membranes. The obtained module had an effective hollow fiber membrane length L _H and a filtration chamber length L _M of 900 mm, a hollow fiber filling rate of 52 vol%, and a specific surface area of 4,000 m ² / m ³ .

(Hydrophilization / moisture treatment)
In the same manner as in Example 1, the membrane was hydrophilized and replaced with pure water.

(Formation of second separation layer)
In the same manner as in Example 1, adsorption treatment of CPVA and APVA and crosslinking treatment with glutaraldehyde were performed.

The final module performance was a module pure water permeation of 508 L / h and a pure water flux per pressure of 3.6 L / (m ² · h · bar) at a pressure of 5 bar. The MgSO ₄ blocking rate was 97.6%, the NaCl blocking rate was 62.0%, the sucrose blocking rate was 98.5%, and the glucose blocking rate was 87.0%.

(Example 3)
(Preparation of hollow fiber support membrane)
A PPE hollow fiber support membrane was obtained in the same manner as in Example 1 except that the shape of the hollow fiber was changed. The outer diameter of the PPE hollow fiber support membrane was 260 μm, and the film thickness was 170 μm. Was subjected to a pure water permeation test, pure water flux was ^{83L / (m 2 · h ·} bar).

(Formation of the first separation layer)
In the same manner as in Example 1, the dip coating speed and the drying temperature were finely adjusted to obtain a plurality of composite separation membranes having a first separation layer made of SPAE. As a result of observation by SEM, the thickness of the first separation layer was 150 nm. At this time, the pure water flux was 42 L / (m ² · h · bar), and the NaCl rejection was 11%.

(Manufacture of modules)
In the same manner as in Example 1, a module of FIG. 3 type was prepared using a cylindrical container made of polyvinyl chloride having an inner diameter of 100 mm and a length of 1,000 mm, and a bundle of 36,000 hollow fiber membranes. The hollow fiber membrane obtained modules effective length _{L H} and filtration chamber length _{L M} are both 900 mm, the hollow fiber packing ratio 24vol%, a specific surface area of 3,700m ² / ^{m 3.}

The final module performance was a pure water permeation amount of 595 L / h and a pure water flux of 4.5 L / (m ² · h · bar) at a pressure of 5 bar. The MgSO ₄ blocking rate was 98.5%, the NaCl blocking rate was 65.0%, the sucrose blocking rate was 99.0%, and the glucose blocking rate was 91.0%.

(Example 4)
(Preparation of hollow fiber support membrane)
A PPE hollow fiber support membrane was obtained in the same manner as in Example 1 except that the shape of the hollow fiber was changed. The outer diameter of the PPE hollow fiber support membrane was 670 μm, and the film thickness was 420 μm. When the pure water permeation test was conducted, the pure water flux was 117 L / (m ² · h · bar).

(Formation of the first separation layer)
In the same manner as in Example 1, the dip coating speed and the drying temperature were finely adjusted to obtain a plurality of composite separation membranes having a first separation layer made of SPAE. As a result of observation by SEM, the thickness of the first separation layer was 200 nm. At this time, the pure water flux was 62 L / (m ² · h · bar), and the NaCl rejection was 9%.

(Manufacture of modules)
In the same manner as in Example 1, a module of FIG. 3 type was prepared using a cylindrical container made of polyvinyl chloride having an inner diameter of 100 mm and a length of 1,000 mm and a bundle of 12,400 hollow fiber membranes. The obtained module had an effective hollow fiber membrane length L _H and a filtration chamber length L _M of 900 mm, a hollow fiber filling rate of 56 vol%, and a specific surface area of 3,300 m ² / m ³ .

The final module performance was a pure water permeation amount of 564 L / h and a pure water flux per pressure of 4.8 L / (m ² · h · bar) at a pressure of 5 bar. The MgSO ₄ rejection 97.5% NaCl rejection 63.0%, sucrose rejection 98.4%, 88.0% glucose rejection.

(Example 5)
(Preparation of hollow fiber support membrane)
A PPE hollow fiber support membrane was obtained in the same manner as in Example 1 except that the shape of the hollow fiber was changed. The outer diameter of the PPE hollow fiber support membrane was 260 μm, and the film thickness was 170 μm. When the pure water permeation test was conducted, the pure water flux was 83 L / (m ² · h · bar).

(Formation of the first separation layer)
A SPAE having a repeating structure of a hydrophobic segment represented by the following formula (VI) and a hydrophilic segment represented by the following formula (VII) was prepared as follows. First, weigh 30.000 g of 3,3'-disulfo-4,4'-dichlorodiphenylsulfone disodium salt (hereinafter abbreviated as S-DCDPS) and 70.936 g of 4,4'-dichlorodiphenylsulfone (hereinafter abbreviated as DCDPS). The charge molar ratio of S-DCDPS and DCDPS was 20:80. Further, 56.386 g of 4,4′-biphenol, 46.004 g of potassium carbonate, and molecular sieve were weighed into a four-necked flask and flushed with nitrogen. After adding 534 g of NMP and stirring at 150 ° C. for 50 minutes, the reaction temperature was increased to 195 ° C. to 200 ° C., and the reaction was continued with the aim of sufficiently increasing the viscosity of the system. Thereafter, the mixture was allowed to cool and then allowed to cool, and the precipitated molecular sieve was removed and the mixture was precipitated in water. The obtained polymer was washed in boiling water for 1 hour and then carefully washed with pure water to completely remove residual potassium carbonate. Thereafter, the polymer after removing the potassium carbonate was dried to obtain a copolymerized SPAE having a sulfonation degree DS of 20%, which was the target product.

In the above formula, a and b, R ¹ and R ² have the same meaning as defined in the above formulas (IV) and (V).

DMSO solvent was added to the obtained SPAE and dissolved while stirring at room temperature to obtain a coating solution having a concentration of 1.0% by mass.

The PPE hollow fiber support membrane was dip coated in a SPAE coating solution and dried at 140 ° C. in a vertical drying oven. Thereafter, a plurality of composite separation membranes having a first separation layer made of SPAE were wound around a winder. As a result of observation by SEM, the thickness of the first separation layer was 140 nm. At this time, the pure water flux was 26 L / (m ² · h · bar), and the NaCl rejection was 15%.

(Manufacture of modules)
The module of FIG. 3 type was produced as follows. Prepare one yarn bundle of 1,100 hollow fiber membranes bundled in parallel, tie one loop end of the yarn bundle with a string, and place this end in a PTFE cylinder container with an inner diameter of 10 mm. This was filled with an epoxy resin and hardened, and then released to obtain an adhesive end (A11). Next, the circumference of the yarn bundle is wound with a PTFE film having a thickness of 50 μm to protect the outer surface, and polyvinyl chloride having an inner diameter of 13 mm and a length of 300 mm having two supply liquid inlets / outlets (A4, A5) is provided. Filled into a cylindrical container. Thereafter, the PTFE film was pulled out. Subsequently, with the cylindrical container fixed in an upright state, with the adhesive end (A11) on the upper side and the other end on the lower side, an epoxy resin is poured from the lower part of the cylindrical container, and end bonding is performed. An adhesive end (A2) was obtained. The opening end (A1) was cut so that the hollow fiber membrane was opened after the resin was cured. The obtained module had an effective hollow fiber membrane length L _H and a filtration chamber length L _M of 240 mm, a hollow fiber filling rate of 44 vol%, and a specific surface area of 6,800 m ² / m ³ . A cap (A9) was vertically attached to this module to produce a hollow fiber membrane module having a first separation layer.

The final module performance was a module pure water permeation of 3.0 L / h and a pure water flux per pressure of 2.8 L / (m ² · h · bar) at a pressure of 5 bar. The MgSO ₄ blocking rate was 98.0%, the NaCl blocking rate was 63.0%, the sucrose blocking rate was 99.0%, and the glucose blocking rate was 89.0%.

(Example 6)
(Preparation of hollow fiber support membrane)
A PPE hollow fiber support membrane was obtained in the same manner as in Example 1 except that the shape of the hollow fiber was changed. The outer diameter of the PPE hollow fiber support membrane was 260 μm, and the film thickness was 170 μm. When the pure water permeation test was conducted, the pure water flux was 83 L / (m ² · h · bar).

(Formation of the first separation layer)
In the same manner as in Example 1, the dip coating speed and the drying temperature were finely adjusted to obtain a plurality of composite separation membranes having a first separation layer made of SPAE. As a result of observation by SEM, the thickness of the first separation layer was 180 nm. At this point, the pure water flux ^{42L / (m 2 · h ·} bar), NaCl rejection was 11%.

(Manufacture of modules)
In the same manner as in Example 5, a module of FIG. 3 type was manufactured using a cylindrical container made of polyvinyl chloride having an inner diameter of 13 mm and a length of 300 mm and a bundle of 1,100 hollow fiber membranes. The obtained module had an effective hollow fiber membrane length L _H and a filtration chamber length L _M of 240 mm, a hollow fiber filling rate of 44 vol%, and a specific surface area of 6,800 m ² / m ³ .

(Formation of second separation layer)
Except for using aldehyde cross-linking agent as a 1 wt% orthophthalaldehyde (OPA) aqueous solution (adding sulfuric acid as an acid catalyst and adjusting to pH = 1) for a cross-linking time of 10 hours and a cross-linking liquid temperature of 40 ° C. In the same manner as in Example 1, CPVA and APVA adsorption treatment and cross-linking treatment with orthophthalaldehyde were performed. However, after the second OPA cross-linking treatment, the inside of the module was washed with pure water, and then 2% fructose aqueous solution (prepared to sodium hydroxide pH = 11) was filled into the module and left for 24 hours to form a membrane Unreacted aldehyde groups of the inner and outer OPA were reacted with fructose, which is a reducing sugar, to detoxify until the aldehyde odor disappeared completely. Finally, the module was completed by thoroughly washing with pure water.

The final module performance, at a pressure 5 bar, pure water permeation rate 1.1 L / h of the module was deionized water flux 1.0 L ^/ per pressure (m 2 · h · bar) . The MgSO ₄ blocking rate was 99.4%, the NaCl blocking rate was 96.0%, the sucrose blocking rate was 99.2%, and the glucose blocking rate was 98.7%.

(Example 7)
(Preparation of SPAE hollow fiber membrane)
An asymmetric membrane in which the hollow fiber support membrane and the first separation layer were composed of the same SPAE was produced as follows. First, SPAE having a repeating structure of the hydrophobic segment represented by the above formula (I) and the hydrophilic segment represented by the above formula (II) was prepared as follows.

Weigh out 30.0000 g of 3,3'-disulfo-4,4'-dichlorodiphenylsulfone disodium salt (hereinafter abbreviated as S-DCDPS) and 93.9709 g of 2,6-dichlorobenzonitrile (hereinafter abbreviated as DCBN). The charge molar ratio of S-DCDPS and DCBN was 10:90. Further, 112.7715 g of 4,4′-biphenol, 92.0078 g of potassium carbonate, and molecular sieve were weighed into a four-necked flask and flushed with nitrogen. After adding 767.9 g of NMP and stirring at 150 ° C. for 50 minutes, the reaction temperature was increased to 195 ° C. to 200 ° C., and the reaction was continued with the aim of sufficiently increasing the viscosity of the system. Thereafter, the mixture was allowed to cool and then allowed to cool, and the precipitated molecular sieve was removed and the mixture was precipitated in water. The obtained polymer was washed in boiling water for 1 hour and then carefully washed with pure water to completely remove residual potassium carbonate. Thereafter, the polymer after removing potassium carbonate was dried to obtain a copolymerized SPAE of the formula (I) and the formula (II) having a sulfonation degree DS = 10% as a target product.

The SPAE was dissolved at 180 ° C. while adding and kneading NMP so as to be 35% by mass to obtain a uniform film forming stock solution.

Subsequently, while extruding the membrane-forming solution from a double cylindrical tube nozzle into a hollow shape, a solution in which ethylene glycol and NMP are mixed at a weight ratio of 70:30 is extruded as an inner solution and simultaneously molded to form air at room temperature. After running and drying, it was immersed in a pure water coagulation bath at 25 ° C. to produce a SPAE hollow fiber membrane, and then washed with water. The obtained SPAE hollow fiber membrane had an outer diameter of 180 μm and a film thickness of 110 μm. At this time, the pure water flux was 2.3 L / (m ² · h · bar), and the NaCl rejection was 62%.

(Manufacture of modules)
Since the membrane performance of the SPAE hollow fiber membrane was remarkably lowered when it was dried, a module of FIG. 3 type was produced as described below in the state of the wet membrane washed with water after film formation. One yarn bundle in which 2,200 water-containing SPAE hollow fiber membranes were bundled in parallel was prepared, and the yarn bundle was covered with a wet cloth so as not to be dried. One end of the loop of the yarn bundle is dried with a dryer and tied with a string. The end is placed in a Teflon (registered trademark) tube container having an inner diameter of 10 mm, and filled with an epoxy resin and hardened. The adhesive end (A11) was obtained by molding. Next, the periphery of the yarn bundle is wound with a Teflon (registered trademark) film having a thickness of 50 μm to protect the outer surface, and the inner diameter is 13 mm and the length is 300 mm provided with two supply liquid inlets / outlets (A4, A5). A cylindrical container made of polyvinyl chloride was filled. Thereafter, the Teflon (registered trademark) film was pulled out. Subsequently, the cylindrical container is fixed in an upright state, and the epoxy resin is poured from the lower part of the cylindrical container into the end dried with a dryer, with the adhesive end (A11) on the upper side and the other end on the lower side. Then, end bonding was performed to obtain a bonded end (A2). The opening end (A1) was cut so that the hollow fiber membrane was opened after the resin was cured. The obtained module had an effective length of the hollow fiber membrane and a filtration chamber length L _M of 240 mm, a hollow fiber filling rate of 42 vol%, and a specific surface area of 9,400 m ² / m ³ . After the cap (A9) was vertically attached to this module, pure water was filled into the module to obtain a SPAE hollow fiber membrane module having a first separation layer (skin layer).

The final module performance was a module pure water permeation of 0.6 L / h and a pure water flux per pressure of 0.4 L / (m ² · h · bar) at a pressure of 5 bar. The MgSO ₄ blocking rate was 98.6%, the NaCl blocking rate was 92.0%, the sucrose blocking rate was 99.1%, and the glucose blocking rate was 96.0%.

(Example 8)
(Preparation of hollow fiber support membrane)
A PPE hollow fiber support membrane was obtained in the same manner as in Example 1 except that the shape of the hollow fiber was changed. The outer diameter of the PPE hollow fiber support membrane was 260 μm, and the film thickness was 170 μm. When the pure water permeation test was conducted, the pure water flux was 83 L / (m ² · h · bar).

(Formation of the first separation layer)
In the same manner as in Example 1, the dip coating speed and the drying temperature were finely adjusted to obtain a plurality of composite separation membranes having a first separation layer made of SPAE. As a result of observation by SEM, the thickness of the first separation layer was 160 nm. At this time, the pure water flux was 42 L / (m ² · h · bar), and the NaCl rejection was 10%.

(Formation of second separation layer)
CPVA and APVA adsorption treatment and glutaraldehyde crosslinking treatment were performed in the same manner as in Example 1 except that the type of CPVA was changed and K434 (Nippon GOHSEI cation-modified polyvinyl alcohol) was used.

The final module performance was a pure water permeation amount of 4.7 L / h and a pure water flux per pressure of 4.4 L / (m ² · h · bar) at a pressure of 5 bar. The MgSO ₄ blocking rate was 98.2%, the NaCl blocking rate was 61.0%, the sucrose blocking rate was 99.0%, and the glucose blocking rate was 89.4%.

(Comparative Example 1)
As described below, after performing the process of sequentially forming the first separation layer and the second separation layer on the hollow fiber membrane, a method for constructing the module was examined.

(Preparation of hollow fiber support membrane)
In the same manner as in Example 1, a PPE hollow fiber support membrane was obtained. The outer diameter of the PPE hollow fiber support membrane was 250 μm, and the film thickness was 150 μm. When the pure water permeation test was conducted, the pure water flux was 43 L / (m ² · h · bar).

(Formation of the first separation layer)
In the same manner as in Example 1, a plurality of composite separation membranes having a first separation layer made of SPAE were obtained. As a result of observation by SEM, the thickness of the first separation layer was 160 nm. At this time, the pure water flux was 30 L / (m ² · h · bar), and the NaCl rejection was 11%.

(Formation of second separation layer)
Using this hollow fiber membrane, 1,200 loop yarn bundles having a length of 500 mm were produced. The loop yarn bundle was dipped in a vat filled with ethanol for 2 hours, and was gradually replaced with pure water to perform hydrophilization / moisture treatment. Subsequently, the yarn bundle was dipped in a plastic tank filled with a 0.1 wt% aqueous solution of CPVA (Kuraray CM318), left to stand for 30 minutes for adsorption treatment, and then placed in a tank filled with pure water. Rinsing was performed by dipping for a minute. Thereafter, the yarn bundle was immersed in a tank filled with a 0.1 wt% aqueous solution in which APVA (manufactured by Nippon Synthetic Chemical Co., Ltd.) was dissolved in pure water, left to stand for 30 minutes, and subjected to an adsorption treatment. A rinsing treatment was performed for 5 minutes in the tank. Next, the yarn bundle was immersed in a tank filled with a 1 wt% aqueous solution of glutaraldehyde (GA) (added sulfuric acid as an acid catalyst and adjusted to pH = 1) and subjected to a crosslinking treatment for 20 hours. After sufficiently washing the yarn bundle of the hollow fiber membrane with water, another treatment cycle of CPVA and APVA adsorption treatment and glutaraldehyde crosslinking was performed. Finally, it was sufficiently washed with pure water to obtain a hollow fiber membrane yarn bundle having a second separation layer.

(Manufacture of modules)
A yarn bundle was prepared by air-drying the above-mentioned hollow fiber membrane bundle overnight. In the same procedure as in Example 5, a module of the type shown in FIG. 3 was produced using a cylindrical container made of polyvinyl chloride having an inner diameter of 13 mm and a length of 300 mm. The hollow fiber membrane obtained modules effective length _{L H} and filtration chamber length _{L M} are both 240 mm, the hollow fiber packing ratio is 44 vol%, a specific surface area of 7,100m ² / ^{m 3.}

(Hydrophilization / moisture treatment)
In order to rehydrate the dried module, hydrophilization treatment and water treatment were performed in the same manner as in Example 1.

The final module performance was a module pure water permeation of 6.1 L / h and a pure water flux of 5.4 L / (m ² · h · bar) at a pressure of 5 bar. Further, the MgSO ₄ blocking rate is 54%, the NaCl blocking rate is 30%, the sucrose blocking rate is 62%, and the glucose blocking rate is 31%. Compared with the method of Example 1, the second separation layer is formed and then modularization is performed. When it performed, the process became complicated and the performance of the membrane was lowered in the modularization process, and the performance expression was insufficient.

(Comparative Example 2)
As described below, a method for forming a module by forming a second separation layer composed of unmodified polyvinyl alcohol by a conventional solution coating method was studied.

(Formation of the first separation layer)
In the same manner as in Example 1, a plurality of composite separation membranes having a first separation layer made of SPAE were obtained. As a result of observation by SEM, the thickness of the first separation layer was 160 nm. At this point, the pure water flux ^{30L / (m 2 · h ·} bar), NaCl rejection was 11%.

(Formation of second separation layer)
As the polymer of the second separation layer, ordinary unmodified polyvinyl alcohol (Sigma-Aldrich, product number: 363073, average molecular weight of 31,000 to 50,000, saponification degree of 87 to 89%) was prepared. Polyvinyl alcohol (PVA) was dissolved in pure water to prepare a 1.0% by weight aqueous solution, which was filled in the bathtub. The hollow fiber membrane wound up by the winder was wound, the dip coating process was performed to this bathtub, and it dried at 80 degreeC. Subsequently, the hollow fiber membrane was introduced into a 1% glutaraldehyde aqueous solution (sulfuric acid was added as an acid catalyst and adjusted to pH = 2), impregnated, and then dried at 120 ° C. in a vertical drying furnace. And finally, it wound up by the winder and obtained the hollow fiber membrane which has the 2nd separated layer of PVA.

(Manufacture of modules)
A thread bundle of 1200 hollow fiber membranes was prepared, and a module of FIG. 3 type was produced using a polyvinyl chloride cylindrical container having an inner diameter of 13 mm and a length of 300 mm in the same procedure as in Example 5. The hollow fiber membrane obtained modules effective length _{L H} and filtration chamber length _{L M} are both 240 mm, the hollow fiber packing ratio is 44 vol%, specific surface area of 7,100m ² / ^{m 3.} When observed by SEM, the thickness of the PVA separation layer was 180 nm.

(Hydrophilization / moisture treatment)
Hydrophilic treatment / moisture treatment was performed in the same manner as in Example 1.

The final module performance was a module pure water permeation of 0.3 L / h and a pure water flux of 0.3 L / (m ² · h · bar) at a pressure of 5 bar. Further, the MgSO ₄ blocking rate is 89%, the NaCl blocking rate is 88%, the sucrose blocking rate is 87.2%, and the glucose blocking rate is 46%. Compared with the method of Example 1, the cross-linked PVA is thicker by the conventional coating method. When the modularization was performed after forming the second separation layer by the above, the process became complicated, the water permeability was low, and the expression of the separation performance was insufficient.

(Comparative Example 3)
As described below, a hollow fiber membrane having only a first separation layer imparted with relatively high separation performance was prepared, and production of a module was examined.

(Preparation of hollow fiber support membrane)
A PPE hollow fiber support membrane was obtained in the same manner as in Example 1 except that the shape of the hollow fiber was changed. The outer diameter of the PPE hollow fiber support membrane was 260 μm, and the film thickness was 170 μm. When the pure water permeation test was conducted, the pure water flux was 83 L / (m ² · h · bar).

(Formation of the first separation layer)
In the same manner as in Example 1, the drying temperature was set to 180 ° C., and a plurality of composite separation membranes having a first separation layer made of SPAE were obtained. As a result of observation by SEM, the thickness of the first separation layer was 160 nm. At this time, the pure water flux was 1.5 L / (m ² · h · bar), and the NaCl rejection was 72%.

(Manufacture of modules)
In the same manner as in Example 5, a module of the type shown in FIG. 3 was produced using a cylindrical container made of polyvinyl chloride having an inner diameter of 13 mm and a length of 300 mm and a bundle of 1,100 hollow fiber membranes. The obtained module had an effective hollow fiber membrane length L _H and a filtration chamber length L _M of 240 mm, a hollow fiber filling rate of 44 vol%, and a specific surface area of 6,800 m ² / m ³ .

The final module performance was 1.7 L / h of pure water permeation of the module at a pressure of 5 bar and 1.5 L / (m ² · h · bar) of pure water per pressure. The MgSO ₄ rejection 73% NaCl rejection 65.0%, sucrose rejection of 74%, a glucose rejection of 38%, was insufficient in permeability and separability both.

Hereinafter, the measurement and evaluation methods in the present invention will be described.

(Measurement of sulfonation degree DS of SPAE polymer)
The degree of sulfonation DS of the SPAE polymer was evaluated as follows. 20 mg of the polymer dried overnight at 100 ° C. in a vacuum dryer was dissolved in 1 mL of deuterated DMSO (DMSO-d6) manufactured by Nacalai Tesque, and this was dissolved in BRUKER AVANCE500 (frequency 500.13 MHz, temperature 30 ° C., FT integration) 32 times) proton NMR measurement. In the obtained spectrum chart, the relationship between each proton contained in the hydrophobic segment and the hydrophilic segment and the peak position is identified, and the independent peak among the protons in the hydrophobic segment and the independent peak among the protons in the hydrophilic segment Was obtained from the ratio of the integrated intensity per proton.

(Shape of hollow fiber membrane)
An appropriate amount of a hollow fiber membrane is filled in a 3 mm-thick SUS plate hole with a 3 mm diameter or 6 mm diameter hole, cut with a razor blade to expose the cross section, and then a Nikon microscope (ECLIPSE LV100) and Nikon The cross-sectional shape was photographed using an image processing device (DIGITAL SIGN DS-U2) and a CCD camera (DS-Ri1), and the outside of the cross section of the hollow fiber membrane was imaged using image analysis software (NIS Element D3.00 SP6). The outer diameter, inner diameter and thickness of the hollow fiber membrane were calculated by measuring the diameter and inner diameter using the measurement function of the analysis software.

(Thickness of the first separation layer)
The hollow fiber membrane in a water-containing state is frozen with liquid nitrogen, cleaved, air-dried, and Pt is sputtered onto the fractured surface. Using a scanning electron microscope S-4800 manufactured by Hitachi, Ltd., the acceleration voltage Observed at 5 kV.

(Filtration evaluation of hollow fiber membrane module)
The modules produced in the examples and comparative examples are connected to a module testing device consisting of a feed water tank and a pressure pump (for a small module with an inner diameter of 13 mm, a small testing device having almost the same configuration) and subjected to a filtration test by crossflow Carried out. The evaluation pressure was unified at 5 bar (0.5 MPa), and the supply liquid temperature was unified at 25 ° C. The feed liquid flow rate was adjusted so that the recovery rate was about 5%. Sodium chloride (NaCl), magnesium sulfate (MgSO ₄ ), sucrose (molecular weight 342), and glucose (molecular weight 180) were used as solutes for the separation test. All solute concentrations were adjusted to 1500 mg / L. After performing the filtration operation for about 1 hour, the amount of permeated water from the membrane was measured with the flow meter of the test apparatus, the permeate was sampled, and the solute concentration was measured.
The amount of water per pressure was calculated from the following formula.
FR [L / (m ² · h · bar)] = permeated water amount [L] / membrane area [m ² ] / collection time [min] / operating pressure [bar]

When the supply solution is NaCl or MgSO ₄ , the conductivity of the membrane permeated water collected in the filtration test and the supply aqueous solution is measured using an electric conductivity meter (CM-25R, Toa DKK Corporation), and the ion blocking rate is measured. Was calculated from the following formula.
Blocking rate [%] = (1−conductivity of filtrate [μS / cm] / conductivity of feed aqueous solution [μS / cm]) × 100

When the feed solution was sucrose or glucose, the membrane permeated water collected by the water permeation measurement and the sugar concentration of the feed aqueous solution were evaluated by the phenol-sulfuric acid method. Specifically, 1.0 mL of the above-mentioned supply liquid or permeate diluted 10-fold with pure water is placed in a test tube, and 1.0 mL of a 5% phenol aqueous solution is added and stirred. On top of that, 5.0 mL of concentrated sulfuric acid (96% concentration) is quickly added and stirred. The colored solution is subjected to absorbance measurement at 490 nm, the concentration is calculated from a calibration curve prepared in advance, and the value obtained by multiplying by 10 is used as the actual concentration value. In the phenol-sulfuric acid method, the range in which the linearity between each sugar concentration and absorbance is good is from 0 to 200 mg / L. Therefore, the above-mentioned 1500 mg / L supply solution or filtrate is diluted 10 times and measured. I do. The solute rejection was calculated from the following equation.
Blocking rate [%] = (1−sugar concentration of the filtrate [mg / L] / sugar concentration of the feed aqueous solution [mg / L]) × 100

Table 1 shows details and evaluation results of Examples 1 to 8 and Comparative Examples 1 to 3.

According to the present invention, in an external pressure filtration type hollow fiber composite membrane module in which a bundle of hollow fiber composite membranes having relatively small diameters is inserted into a housing, the separation layer is deteriorated due to friction when the housing is inserted, and the performance is thereby reduced. It can avoid and can provide what achieved high selective permeability and specific surface area ratio.

Claims

In the manufacturing method of a hollow fiber composite membrane module of an external pressure filtration type, which is composed of a bundle of hollow fiber membranes having an outer diameter of 100 μm or more and 800 μm or less and whose net hollow fiber membrane filling rate is 20% or more and 60% or less, A production method comprising the steps of (i) to (vi):
(I) producing a hollow fiber membrane having a first separation layer made of a polymer containing an anionic functional group on the outer surface;
(Ii) a step of winding the hollow fiber membrane to produce a yarn bundle,
(Iii) inserting the yarn bundle of the hollow fiber membrane into a housing;
(Iv) a step of resin-bonding at least one end of the yarn bundle of the hollow fiber membrane and performing an opening treatment;
(V) A modified polyvinyl alcohol aqueous solution having at least one kind of cationic functional group or anionic functional group is brought into contact with the outer surface of the hollow fiber membrane to form a second separation layer comprising an adsorption layer of the modified polyvinyl alcohol. And (vi) a step of bringing the second separation layer into contact with an aqueous solution of aldehydes to acetalize part of the hydroxyl groups of the modified polyvinyl alcohol.
The polymer constituting the first separation layer is a sulfonated polyarylene ether having a repeating structure of a hydrophobic segment represented by the following formula (IV) and a hydrophilic segment represented by the following formula (V). The method for producing an external pressure filtration type hollow fiber composite membrane module according to claim 1.

In the above formula,

And

And

And

And
The same Y and W are not selected,
a and b each represent a natural number of 1 or more,
R 1 and R 2 represent —SO 3 M or —SO 3 H, M represents a metal element,
Sulfonation rate expressed as a percentage of the number of repetitions of formula (V) to the total number of repetitions of formula (IV) and formula (V) in the sulfonated polyarylene ether copolymer is from 5% Is larger than 80%.
The sulfonated polymer constituting the first separation layer is a sulfonated polyarylene ether comprising a repeating structure of a hydrophobic segment represented by the following formula (I) and a hydrophilic segment represented by the following formula (II). The method for producing an external pressure filtration type hollow fiber composite membrane module according to claim 1 or 2, wherein:

In the above formula, m and n each represent a natural number of 1 or more, R 1 and R 2 represent —SO 3 M or —SO 3 H, M represents a metal element, and a sulfonated polyarylene ether copolymer The sulfonation rate expressed as a percentage ratio of the number of repetitions of formula (II) to the sum of the number of repetitions of formula (I) and formula (II) is greater than 5% and less than 80% .
The external pressure filtration type according to any one of claims 1 to 3, wherein the constituent parts of the hollow fiber membrane other than the first separation layer and the second separation layer of the hollow fiber membrane are composed of polyphenylene ether. Manufacturing method of hollow fiber composite membrane module.
In the external pressure filtration type hollow fiber membrane module, which is composed of a bundle of hollow fiber membranes having an outer diameter of 100 μm or more and 800 μm or less, and whose net hollow fiber membrane filling rate is 20% or more and 60% or less, the following (i ) To (iii) are satisfied, an external pressure filtration type hollow fiber composite membrane module.
(I) a first separation layer and a second separation layer are provided in this order on the outer surface of the hollow fiber membrane;
(Ii) the first separating layer is composed of a polymer containing an anionic functional group, and (iii) the modified polyvinyl having at least one cationic functional group or anionic functional group in the second separating layer. Consists of cross-linked alcohol aldehydes.
The polymer constituting the first separation layer is a sulfonated polyarylene ether having a repeating structure of a hydrophobic segment represented by the following formula (IV) and a hydrophilic segment represented by the following formula (V). An external pressure filtration type hollow fiber composite membrane module according to claim 5.

In the above formula,

And

And

And

And
The same Y and W are not selected,
a and b each represent a natural number of 1 or more,
R 1 and R 2 represent —SO 3 M or —SO 3 H, M represents a metal element,
Sulfonation rate expressed as a percentage of the number of repetitions of formula (V) to the total number of repetitions of formula (IV) and formula (V) in the sulfonated polyarylene ether copolymer is from 5% Is larger than 80%.
The sulfonated polymer constituting the first separation layer is a sulfonated polyarylene ether comprising a repeating structure of a hydrophobic segment represented by the following formula (I) and a hydrophilic segment represented by the following formula (II). The external pressure filtration type hollow fiber composite membrane module according to claim 5 or 6, wherein the external pressure filtration type hollow fiber composite membrane module is provided.

In the above formula, m and n each represent a natural number of 1 or more, R 1 and R 2 represent —SO 3 M or —SO 3 H, M represents a metal element, and a sulfonated polyarylene ether copolymer The sulfonation rate expressed as a percentage ratio of the number of repetitions of formula (II) to the sum of the number of repetitions of formula (I) and formula (II) is greater than 5% and less than 80% .
A component of the hollow fiber membrane other than the first separation layer and the second separation layer of the hollow fiber membrane is composed of polyphenylene ether. Hollow fiber composite membrane module.