WO2016204222A1 - Water-treatment membrane, water-treatment membrane element and method for producing same, and support layer - Google Patents

Abstract

The water-treatment membrane according to the present invention has a support layer and a porous membrane layer, wherein, after 83 L of water per m² of the membrane surface area has been passed through the water-treatment membrane at 20°C and then the water-treatment membrane is immersed in 22 L of water per m² of the membrane surface area at 20°C for 16 h, the amount of all organic carbon that is eluted into the immersion water is 2.0 mg/L or less, or the amount of a non-ionic surfactant that is eluted into the immersion water is 0.5 mg/L or less. The method for producing a water-treatment membrane element according to the present invention has step (a) or (b). Step (a): immersing a water-treatment membrane having a support layer and a porous membrane layer in washing liquid which can dissolve a non-ionic surfactant so that at least the porous membrane layer of the water-treatment membrane is in contact with the washing liquid, and thereafter, causing the washing liquid to permeate from the porous membrane layer into the support layer, and discharging the washing liquid permeating the support layer to the outside of the water-treatment membrane. Step (b): washing the support layer with at least two different solvents, and thereafter, forming the porous membrane layer so that the porous membrane layer is adjacent to the washed support layer.

Description

Water treatment membrane, water treatment membrane element and method for producing the same, and support layer

The present invention relates to a water treatment membrane, a water treatment membrane element, a production method thereof, and a support layer.
This application claims priority based on Japanese Patent Application No. 2015-123747 filed in Japan on June 19, 2015 and Japanese Patent Application No. 2015-204508 filed in Japan on October 16, 2015. And the contents thereof are incorporated herein.

In recent years, due to increasing interest in environmental pollution and stricter regulations, water treatment by a membrane method using a filtration membrane, which is excellent in separation completeness and compactness, has attracted attention.
In particular, filtration techniques using porous membranes such as microfiltration membranes and ultrafiltration membranes are spreading to water treatment fields such as water purification and wastewater treatment.
Examples of the material for the porous membrane include polysulfone, polyacrylonitrile, cellulose acetate, and polyvinylidene fluoride. Examples of the porous membrane include a flat membrane, a hollow fiber membrane, and a tubular membrane.
In particular, the hollow fiber membrane is manufactured by microphase-separating a polymer solution and then coagulating the polymer solution in a non-solvent, and has a high porosity and an asymmetric structure. A volume of water can be filtered.
However, a filtration membrane consisting only of such a polymer phase separation structure tends to have insufficient mechanical strength, and the membrane may be damaged by long-term use.

As a countermeasure against damage, for example, there is a method of forming a porous membrane layer adjacent to a support layer (also referred to as a “support”) formed by processing a multifilament into a hollow string or sheet. (For example, refer to Patent Documents 1 and 2). The water treatment membrane having such a configuration enhances physical strength and greatly reduces the risk of breakage. In particular, a support layer made of a hollow knitted string is low in cost, and is excellent in the peel resistance of a polymer porous body.

A general method for producing a hollow fiber membrane using the above string-like material as a support layer includes the following steps.
(1) Manufacture of a hollow string.
(2) Application of a film-forming stock solution on a hollow string (for example, a knitted string).
(3) Coagulation, washing and drying of the film-forming stock solution.

By the way, in the production of multifilaments used for the production of such a string-like material, in order to prevent yarn breakage and strength reduction during the spinning process and the winding process, and to stabilize the process, spinning, In addition, a spinning oil and after-oil are usually attached before stretching and processing (for example, Patent Documents 3 and 4).
The spinning oil and after oil contain mineral oil and surfactant. As the spinning oil, for example, an aqueous emulsion made with a nonionic surfactant is used. The spinning oil remains after spinning and after the general production of the hollow fiber membrane.

As a method for removing the spinning oil remaining in the fibrous material such as multifilament, for example, as described in Patent Document 5, a treatment tank filled with a cleaning liquid containing a scouring agent containing a surfactant is used. In general, a method of scouring a fibrous material under alkaline conditions is known.

Patent Document 6 discloses a method for reducing the cloudiness of a test liquid containing a surfactant in a subsequent inspection process by defining the amount of after oil attached to a spinning oil in a hollow fiber membrane containing multifilaments. ing.
However, the method described in Patent Document 6 only immerses the hollow fiber membrane in a surfactant and does not sufficiently remove the spinning oil. Further, in order to eliminate the occurrence of fuzz that causes defects in the hollow fiber membrane, for example, it is necessary to add 0.4 or more by weight with respect to the spinning oil agent. Even when no after oil is added, spinning is not necessary. The oil remains.

Since spinning oils, especially nonionic surfactants, can cause foaming, mixing in drinking water is not desirable. In Japan, as a tap water, the “Ministerial Ordinance on Water Quality Standards” is based on the provisions of Article 4 of the Water Supply Law. There are standards such as 0.02 mg / L or less as the water quality to be regulated, and 0.005 mg / L for elution into water in a water advancement test as a water membrane module performance survey of the Association for Promotion of Membrane Separation Technology.

The residual nonionic surfactant in the hollow fiber membrane is eluted in the treated water when filtration is performed using the hollow fiber membrane. Therefore, it is not preferable that the filtration membrane used when producing drinking water by filtration contains a spinning oil agent.
Therefore, when using a hollow fiber membrane or the like having a hollow string-like support layer as a filtration membrane for drinking water, it is generally washed before use of the hollow fiber membrane and membrane module to remove the spinning oil and the like. It is desirable to keep it.

U.S. Pat. No. 5,472,607 International Publication No. 2009/142279 JP 55-90610 A JP-A-10-219524 JP 2013-155470 A JP 2013-198889 A

As described above, in the methods of Patent Documents 1 to 6, the spinning oil tends to remain in the hollow fiber membrane and is not suitable for drinking water filtration.

An object of the present invention is to provide a water treatment membrane, a water treatment membrane element and a support layer from which the spinning oil remaining in the multifilament is sufficiently removed.
Moreover, the objective of this invention is providing the manufacturing method of the water treatment membrane element which removes the spinning oil agent which remain | survives in a multifilament efficiently.

The present invention has the following aspects.
[1] A water treatment membrane having a support layer that is a multifilament workpiece and a porous membrane layer provided adjacent to the support layer, and having 83 L of water per 1 m ² of membrane surface area of the water treatment membrane The amount of elution of total organic carbon in the immersion water after immersion of the water treatment membrane after passing water at 20 ° C. for 16 hours at 20 ° C. in 22 L of water per 1 m ² of membrane surface area of the water treatment membrane was 2.0 mg. Water treatment membrane that is / L or less.
[2] A water treatment membrane having a support layer that is a multifilament workpiece and a porous membrane layer provided adjacent to the support layer, and having 83 L of water per 1 m ² of membrane surface area of the water treatment membrane The elution amount of the nonionic surfactant in the immersion water after dipping the water treatment membrane after passing water at 20 ° C. in 22 L of water per 1 m ² of membrane surface area of the water treatment membrane at 20 ° C. for 16 hours The water treatment film | membrane which is 0.5 mg / L or less.
[3] A water treatment membrane element comprising the water treatment membrane according to [1] or [2].

[4] A method for producing a water treatment membrane element comprising a water treatment membrane having a support layer that is a multifilament workpiece and a porous membrane layer provided adjacent to the support layer, wherein After immersing the water treatment membrane so that at least the porous membrane layer side of the water treatment membrane is in contact with the water treatment membrane, the cleaning solution is permeated from the porous membrane layer side to the support layer, and the cleaning solution that has permeated the support layer is passed through the water treatment membrane. A method for producing a water treatment membrane element, comprising a step of discharging to the outside.
[5] The method for producing a water treatment membrane element according to [4], wherein the cleaning liquid is a surfactant solution containing a surfactant.
[6] The method for producing a water treatment membrane element according to [5], wherein the surfactant in the surfactant solution is a nonionic surfactant.
[7] The method for producing a water treatment membrane element according to [6], wherein the surfactant in the surfactant solution has an HLB of 1 or more and 7 or less.
[8] The production of the water treatment membrane element according to [6] or [7], wherein the surfactant in the surfactant solution is a polyoxypropylene-polyoxyethylene-polyoxypropylene block copolymer. Method.
[9] The method for producing a water treatment membrane element according to [8], wherein the proportion of polyoxyethylene is 45% by mass or less with respect to the total mass of the block copolymer.
[10] The method according to any one of [5] to [9], further comprising a step of drying the water treatment membrane in a state where the surfactant solution remains in at least the porous membrane layer after the step. Manufacturing method of water treatment membrane element.

[11] A method for producing a water treatment membrane element comprising a water treatment membrane having a support layer, which is a multifilament workpiece, and a porous membrane layer provided adjacent to the support layer. A method for producing a water treatment membrane element, comprising the step of forming a porous membrane layer so as to be adjacent to the washed support layer after washing the support layer with the above different solvents.
[12] The support layer is washed with a low SP value solvent having an SP value of 7.0 or more and 10.0 or less and a high SP value solvent having an SP value of more than 10 or 20.0 or less. [11] The manufacturing method of the water treatment membrane element of description.
[13] The support layer is washed so that the amount of elution of total organic carbon in toluene after being immersed in 200 mL of toluene for 3 hours at 40 ° C. per 20 g of the support layer is 20 mg or less per kg of the support layer. [11] Or the manufacturing method of the water treatment membrane element as described in [12].
[14] The support layer is washed so that the elution amount of the nonionic surfactant in toluene after being immersed in 200 mL of toluene for 3 hours at 20 ° C. per 20 g of the support layer is 0.01 mg / L or less. 11] or the method for producing a water treatment membrane element according to [12].
[15] A support layer for a water treatment membrane, which is a multifilament workpiece,
A support layer in which the elution amount of the nonionic surfactant into toluene after being immersed in 200 mL of toluene at 40 ° C. for 3 hours per 20 g of the support layer is 0.01 mg / L or less.

In the water treatment membrane, the water treatment membrane element and the support layer of the present invention, the spinning oil remaining in the multifilament is sufficiently removed.
Moreover, according to the manufacturing method of the water treatment membrane element of this invention, the spinning oil agent which remain | survives in a multifilament can be removed efficiently.

It is the schematic which shows an example of a water treatment film | membrane. It is the schematic which shows an example of a support layer. It is a schematic block diagram which shows an example of the manufacturing apparatus of a support layer. It is a schematic block diagram which shows the other example of the manufacturing apparatus of a support layer. It is sectional drawing which shows typically an example of the state which the washing | cleaning liquid permeate | transmitted from the porous membrane layer side to the support layer. 2 is a schematic diagram for explaining a cleaning / hydrophilization process in Example 1. FIG.

Hereinafter, examples of embodiments of the present invention will be described in detail, but the present invention is not construed as being limited to these embodiments.

"Water treatment membrane"
FIG. 1 is a schematic view showing an example of a water treatment membrane. The form of the water treatment membrane 1 in this example is a hollow fiber membrane, and has a hollow support layer 10 that is a multifilament processed product, and a porous membrane layer 11 provided adjacent to the support layer 10. .
Examples of the form of the water treatment membrane include a hollow fiber membrane, a flat membrane, and a tubular membrane. Among these, a hollow fiber membrane is preferable because it can filter a large volume of water while saving space.

<Support layer>
The support layer is a workpiece formed by processing a multifilament.
When the water treatment membrane is a hollow fiber membrane, the support layer is hollow. Examples of the hollow support layer include hollow string-like objects such as braids and knitted strings. From the viewpoint of mechanical strength and the like, a knitted string support layer using a knitted string as a support layer is preferable.
FIG. 2 is a schematic view showing an example of a hollow support layer. The support layer 10 in this example is a hollow structure made of a hollow knitted string 12 obtained by circular knitting of yarn.

Examples of the fibers constituting the multifilament include synthetic fibers, semi-synthetic fibers, regenerated fibers, and natural fibers.
Synthetic fibers include polyamide fibers such as nylon 6, nylon 66 and aromatic polyamide; polyester fibers such as polyethylene terephthalate, polybutylene terephthalate, polylactic acid and polyglycolic acid; acrylic fibers such as polyacrylonitrile; polyethylene and polypropylene Polyolefin fiber such as polyvinyl alcohol fiber; polyvinylidene chloride fiber; polyvinyl chloride fiber; polyurethane fiber; phenol resin fiber; fluorine fiber such as polyvinylidene fluoride and polytetrafluoroethylene; polyalkylene paraoxybenzoate System fibers and the like.

Examples of semisynthetic fibers include cellulose derivative fibers made from cellulose diacetate, cellulose triacetate, chitin, chitosan, and the like; protein fibers called promixes, and the like.
Examples of the regenerated fiber include cellulosic regenerated fibers (for example, rayon, cupra, polynosic, etc.) obtained by the viscose method, copper-ammonia method, organic solvent method, and the like.
Examples of natural fibers include flax and jute.

Of these fibers, polyester fiber, acrylic fiber, polyvinyl alcohol fiber, polyamide fiber, polyolefin fiber, and polyvinyl chloride fiber are preferable because of excellent chemical resistance. Polyester fiber and acrylic fiber are preferable. More preferred are fiber fibers and polyvinyl chloride fibers. Among these, polyester fiber is particularly preferable from the viewpoint of excellent workability and strength.

The multifilament may be composed of one type of fiber, or may be a mixture of two or more types of different types of fibers.
Here, “different types” means that at least one of fineness, single fiber diameter, mechanical properties, and materials is different.

The method for forming the support layer by processing the multifilament is not particularly limited, and the support layer is formed by a known method. When forming a hollow support layer, a hollow support layer can be easily manufactured by using, for example, the apparatus shown in FIG.
FIG. 3 is a schematic configuration diagram illustrating an example of an apparatus for manufacturing a braided string support layer for hollow fiber membranes (hereinafter also referred to as “support layer manufacturing apparatus”). The support layer manufacturing apparatus 20 in this example is knitted by a circular knitting machine 24 that circularly knits a plurality of bobbins 22, a yarn 16 pulled out from each bobbin 22, and a circular knitting machine 24. A string supply device 26 for pulling the hollow knitted string 12 with a constant tension, a heating die 28 for heat-treating the hollow knitted string 12, a take-up device 30 for taking up the heat-treated hollow knitted string 12, and a hollow knitted string And a winding device 32 that winds 12 around the bobbin as a support layer 10. Further, as shown in FIG. 4, a constant load (tension) may be applied using a dancer roll 27 instead of a string supply device that pulls the hollow knitted string 12 with a constant tension.

In the support layer manufactured as described above, the spinning oil and after oil are adhered to the multifilament.
The spinning oil agent is an oil agent used in the fiber production process for the purpose of imparting smoothness, antistatic property and the like to the fiber and smoothly performing the spinning, drawing process and post-processing process. The spinning oil is generally a mixture of mineral oil, surfactant and the like. For example, when the multifilament is a polyester yarn, an oil agent in which a polyethylene oxide / polypropylene oxide ester-based lubricant is a main agent and an ionic surfactant or the like is mixed is generally used. In the present invention, multifilaments using any spinning oil generally used can be used.

¡After oil is an oil that is applied to prevent the occurrence of yarn breakage and fluff before winding of drawn / processed yarn. After-oil is generally a mixture of mineral oil and surfactant. For example, when the multifilament is a polyester yarn, a mixture of an ester lubricant, a mineral oil, a nonionic surfactant such as polyoxyethylene alkyl ether, an ionic surfactant, water or the like is used. In the present invention, any stringing agent generally used can be used.

<Porous membrane layer>
The porous membrane layer is provided adjacent to the support layer. When the form of the water treatment membrane is a hollow fiber membrane, the porous membrane layer is provided adjacent to the outer peripheral surface of the hollow support layer.
The porous membrane layer may be a single layer or a composite porous membrane layer of two or more layers.

The raw material of the porous membrane layer is not particularly limited as long as it can be molded into the shape of the separation membrane, but a hydrophobic material is preferable from the viewpoint of excellent chemical resistance, weather resistance, and oxidation deterioration resistance. Hereinafter, a porous membrane layer formed from a hydrophobic material is also referred to as a “hydrophobic porous membrane layer”.
Examples of the hydrophobic material include cellulose-based, polyolefin-based, polyvinyl alcohol-based, polysulfone-based, polyacrylonitrile-based, and fluorine-based resins. Specific examples include polyethylene, polypropylene, polyvinylidene fluoride, and polytetrafluoroethylene. Examples thereof include fluorinated ethylene, polysulfone, polyvinyl pyrrolidone, and polyethylene glycol. In particular, from the viewpoint of the surface characteristics of the hydrophobic porous membrane, it is preferable to use a highly hydrophobic resin, and a fluororesin is preferable. Among the fluorine-based resins, vinylidene fluoride resin is preferable from the viewpoint of formability to the film and chemical resistance. Further, in terms of chemical resistance and heat resistance, a combination of polyvinylidene fluoride and polyvinylpyrrolidone is preferable.
Here, examples of the vinylidene fluoride resin include a homopolymer of vinylidene fluoride and a copolymer of vinylidene fluoride and a monomer copolymerizable with vinylidene fluoride. Examples of the monomer copolymerizable with vinylidene fluoride include vinyl fluoride, tetrafluoroethylene, ethylene trifluoride, hexafluoropropylene, and the like.

The porous membrane layer is formed by dissolving the raw material of the porous membrane layer in a solvent to form a film-forming stock solution, applying this to the surface of the support layer, and solidifying the film-forming stock solution applied to the support layer. . When the form of the water treatment membrane is a hollow fiber membrane, the porous membrane layer is formed by applying a membrane-forming stock solution on the outer peripheral surface of the hollow support layer and solidifying the membrane-forming stock solution applied to the support layer. .

<Physical properties>
In a first embodiment of the water treatment membranes of the present invention, after passed through at 20 ° C. The water membrane surface area 1m ² per 83L of water treatment membrane water treatment membranes, water treatment film membrane surface area 1m of 22L per ² The amount of elution of total organic carbon (hereinafter referred to as “TOC”) in the immersion water after being immersed in water at 20 ° C. for 16 hours is 2.0 mg / L or less (that is, 2.0 mg or less per 1 L of immersion water). It is. The smaller the TOC elution amount, the better, preferably 1.5 mg / L or less, more preferably 1.2 mg / L or less, and particularly preferably 0 mg / L.
In a second embodiment of the water treatment membranes of the present invention, after passed through at 20 ° C. The water membrane surface area 1m ² per 83L of water treatment membrane water treatment membranes, water treatment film membrane surface area 1m of 22L per ² The elution amount of the nonionic surfactant in the immersion water after being immersed in water at 20 ° C. for 16 hours is 0.5 mg / L or less (that is, 0.5 mg or less per 1 L of immersion water). The smaller the amount of nonionic surfactant eluted, the better. 0.4 mg / L or less is preferred, 0.3 mg / L or less is more preferred, and 0 mg / L is particularly preferred.
Water treatment membranes with an elution amount of TOC in immersion water of 2.0 mg / L or less, or water treatment membranes with an elution amount of nonionic surfactant in immersion water of 0.5 mg / L or less The spinning oil remaining on the filament is sufficiently removed. Therefore, the water treatment membrane of the present invention is suitable as a filtration membrane for drinking water.

"Water treatment membrane element"
For example, one end or both ends (both ends) of the water treatment membrane are fixed by a housing, and the water treatment membrane is used for water treatment as a water treatment membrane element. That is, since the water treatment membrane element includes the water treatment membrane described above, the water treatment membrane element after passing 83 L of water per 1 m ² membrane surface area of the water treatment membrane at 20 ° C. is used as the membrane surface area of 1 m of the water treatment membrane. ^The amount of TOC eluted in the immersion water after immersion in 22 L of water at 20 ° C. for 16 hours is 2.0 mg / L or less. The smaller the TOC elution amount, the better, preferably 1.5 mg / L or less, more preferably 1.2 mg / L or less, and particularly preferably 0 mg / L.
Moreover, the water treatment membrane element after the water membrane surface area 1 m ² per 83L of water treatment membrane is passed through at 20 ° C., it was immersed for 16 hours at 20 ° C. in membrane surface area 1 m ² per 22L of water in the water treatment membranes The elution amount of the nonionic surfactant in the immersion water is 0.5 mg / L or less. The smaller the amount of nonionic surfactant eluted, the better. 0.4 mg / L or less is preferred, 0.3 mg / L or less is more preferred, and 0 mg / L is particularly preferred.

In order to keep the elution amount of TOC in the immersion water and the elution amount of the nonionic surfactant within the above ranges, the water treatment membrane is treated or a support layer (which is used for the water treatment membrane) before becoming a water treatment membrane. What is necessary is just to process a support layer.
Hereinafter, an example of the manufacturing method of a water treatment membrane element is demonstrated.

"Method for manufacturing water treatment membrane element"
<Third embodiment>
The manufacturing method of the water treatment membrane element of 3rd embodiment of this invention has the washing | cleaning process mentioned later. Moreover, although mentioned later in detail, when using surfactant solution as a washing | cleaning liquid, it is preferable to further have a drying process.
The water treatment film before the cleaning process is also referred to as “water-treated film”.

(Washing process)
In the cleaning process of the present embodiment, after immersing the water treatment film so that at least the porous membrane layer side of the water treatment membrane is in contact with the cleaning liquid, the cleaning liquid is allowed to permeate from the porous membrane layer side to the support layer. This is a step of discharging the cleaning liquid permeated to the outside of the water treatment membrane.

The cleaning liquid is not particularly limited as long as it can dissolve a nonionic surfactant. For example, a surfactant solution containing a surfactant; a hydrocarbon solvent such as n-hexane, n-octane, xylene, toluene; Examples include ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone.

By the way, as described above, it is preferable to use a hydrophobic material for the porous membrane layer from the viewpoint of chemical resistance, weather resistance, and oxidation degradation resistance. The hydrophobic porous membrane layer as it is cannot easily permeate water, or even if it can permeate water, a large pressure is required. Therefore, when using a hydrophobic material for a porous membrane layer, it is preferable to hydrophilize the hydrophobic porous membrane layer. By hydrophilizing the hydrophobic porous membrane layer, water can be sufficiently permeated even with a small pressure.
If a surfactant solution containing a surfactant is used as the cleaning liquid, the hydrophobic porous membrane layer can be hydrophilized while washing the water treatment membrane. Hereinafter, the cleaning process in the case of using a surfactant solution containing a surfactant as the cleaning liquid is also referred to as a “cleaning / hydrophilization process”.

Examples of the surfactant contained in the surfactant solution include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant. A nonionic surfactant is particularly preferable from the viewpoint of less foaming and foaming.
Specific examples of the nonionic surfactant contained in the surfactant solution include polyoxypropylene-polyoxyethylene-polyoxypropylene block copolymers and polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymers. Polymer, acetylene glycol surfactant, acetylene alcohol surfactant, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether , Ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxy Tylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate, dimethylpolysiloxane And the like, and fluorine-containing surfactants such as fluorine alkyl esters and perfluoroalkyl carboxylates.

Among the nonionic surfactants contained in the surfactant solution, among the above-mentioned, the block copolymer weight of polyoxypropylene-polyoxyethylene-polyoxypropylene is particularly excellent in terms of low foaming and emulsifying properties. Coalescence is preferred. In particular, the effect can be further exhibited when the ratio of polyoxyethylene is 45% by mass or less with respect to the total mass of the block copolymer. In addition, a polyoxypropylene-polyoxyethylene-polyoxypropylene block copolymer having a polyoxyethylene ratio of 45% by mass or less is a relatively stable substance, and is dependent on organisms even during long-term film storage. It also has the feature of being less susceptible to corruption. From the viewpoint of the above effects, the nonionic surfactant is a polyoxypropylene-polyoxyethylene-polyoxypropylene block in which the proportion of polyoxyethylene is 45% by mass or less with respect to the total mass of the block copolymer. A copolymer is preferable, 40 mass% or less is more preferable, 30 mass% or less is further more preferable, and 25 mass% or less is especially preferable. The ratio of polyoxyethylene to the total mass of the block copolymer is preferably 10% by mass or more.

The HLB (hydrophilic hydrophobic balance) of the nonionic surfactant contained in the surfactant solution is preferably 1 or more and 7 or less. When the HLB of the nonionic surfactant is within the above range, the affinity for the spinning oil is improved, and the oil remaining on the multifilament is more easily removed. When the HLB of the nonionic surfactant is larger than 7, the foaming property becomes high, and therefore, when used for a water treatment membrane, the filtrated water tends to foam easily at the beginning of filtration. The HLB of the nonionic surfactant is more preferably 3 or more, and further preferably 3.5 or more. Further, the HLB of the nonionic surfactant is more preferably 6 or less, and further preferably 5.5 or less.

Here, the HLB of the nonionic surfactant is calculated by the Griffin method and is represented by the following formula (1).
HLB of nonionic surfactant = (molecular weight of hydrophilic group portion of nonionic surfactant / molecular weight of nonionic surfactant) × 100/5 (1)

As a solvent for the surfactant solution, water, an aqueous solution containing an electrolyte (for example, physiological saline, etc.), a lower alcohol having 1 to 4 carbon atoms, preferably 1 to 2 carbon atoms (for example, ethanol, methanol, etc.) , Pyridine, chloroform, cyclohexane, ethyl acetate, toluene, or a mixed solvent thereof. Among these, it is preferable to use water from the viewpoints of the influence on the porous membrane layer, the post-treatment of the solvent, the handleability, and the cost.
In particular, normal tap water or ion-exchanged water filtered through a filter membrane having a pore diameter of about 0.01 μm or more and 1 μm or less is preferable.

The concentration of the surfactant in the surfactant solution is preferably 0.075% by mass or more and less than 0.3% by mass. When the concentration of the surfactant is 0.075% by mass or more, the hydrophobic porous membrane layer can be sufficiently hydrophilized and the removability of the spinning oil can be improved. On the other hand, if the concentration of the surfactant is less than 0.3% by mass, the amount of the surfactant used can be suppressed, and the cost can be reduced. Moreover, since it can suppress that surfactant remains in a water treatment film | membrane, the usage-amount of the washing | cleaning liquid at the time of wash | cleaning surfactant remaining in a water treatment film | membrane can be reduced.

In the washing step, first, the water treatment film is immersed in a washing solution such as a surfactant solution so that at least the porous membrane layer side of the water treatment membrane (water treatment membrane) is in contact with the solution. Next, for example, as shown in FIG. 5, the cleaning liquid is permeated from the porous membrane layer 11 side of the water treatment film 1 to the support layer 10, and the cleaning liquid that has permeated the support layer 10 is discharged to the outside of the water treatment film 1 (cleaning liquid). Is passed through the water treatment membrane 1). In addition, the code | symbol "F" in FIG. 5 has shown the flow of cleaning liquids, such as surfactant solution.

As a method of allowing the cleaning liquid to permeate from the porous membrane layer to the support layer and discharging the cleaning solution permeated to the support layer to the outside of the water treatment membrane, a method of pressurizing the porous membrane layer side, a method of depressurizing the support layer side, etc. Is mentioned. Examples of the means for pressurizing or depressurizing include a method using a device such as a pump and a method using a water head difference.

The permeation amount of the cleaning liquid is preferably 1 L or more and 4 L or less per 1 m ² of the effective membrane area of the water treatment membrane. If the permeation | transmission amount of a washing | cleaning liquid is 1 L or more, the removability of a spinning oil agent will improve more. On the other hand, if the permeation amount of the cleaning liquid is 4 L or less, it is possible to reduce the trouble of waste liquid treatment and cleaning, and the cost can be reduced. In addition, when a surfactant solution is used as the cleaning liquid, the amount of the surfactant used can be reduced.

The washing fluid permeates from the porous membrane layer to the support layer, and the washing fluid permeated to the support layer is discharged to the outside of the water treatment membrane, whereby the spinning oil remaining in the multifilament can be efficiently removed. In addition, when the porous membrane layer is a hydrophobic porous membrane layer and a surfactant solution is used as the cleaning liquid, the surfactant solution passes through the hydrophobic porous membrane layer, so that the hydrophobic porous membrane layer Is hydrophilized.

The cleaning liquid containing the spinning oil that has permeated from the porous membrane layer to the support layer and removed from the support layer is discharged to the outside of the water treatment membrane. The discharged cleaning liquid is collected and treated as waste liquid or discharged into rivers and sewage. In order to prevent re-contamination of the spinning oil, it is desirable not to contact the water treatment membrane again without treating the recovered cleaning liquid.

(Drying process)
The drying step is a step of drying the water treatment membrane in a state where the surfactant solution remains at least in the hydrophobic porous membrane layer after the washing / hydrophilization step.
By performing the drying step, the pore inner surface of the hydrophobic porous membrane layer is coated with the surfactant, and the hydrophobic porous membrane layer is more effectively hydrophilized. Therefore, by immersing the water treatment membrane in water again after the drying step, the permeability of the hydrophobic porous membrane layer is more easily expressed. Moreover, the effect of weight reduction of a water treatment film | membrane is acquired by performing a drying process, and packing and transportation become easy.

The drying temperature is preferably 20 ° C. or higher, and more preferably 40 ° C. or higher. In particular, if the drying temperature is 40 ° C. or higher, it can be sufficiently dried in a short time. As the drying temperature increases, the drying time can be shortened. However, if the drying temperature is too high, heat shrinkage of the support layer and thermal deformation of the hydrophobic porous membrane layer may occur. Therefore, the drying temperature is preferably 60 ° C. or lower.
The drying time is preferably 5 hours or more. When the drying time is 5 hours or longer, the solvent in the surfactant solution is sufficiently vaporized, and the pore inner surface of the hydrophobic porous membrane layer is sufficiently covered with the surfactant. The longer the drying time, the more the solvent is vaporized and the surface inside the pores is more easily covered with the surfactant, but the effect is low after all the solvent is vaporized. Therefore, the drying time is preferably 15 hours or less.
Examples of the drying method include a method of leaving in the air and a method using a dryer.

In the present embodiment, for example, after the support layer and the porous membrane layer are formed by the above-described method to produce a water-treated membrane, a washing process or the like may be performed, or a commercially available water-treated membrane is coated. You may perform a washing | cleaning process etc. using it as a water treatment film | membrane.
In addition, the water treatment membrane after performing the washing step or the like may be processed into a water treatment membrane element. However, since the washing liquid is passed through the water treatment membrane in the washing step, the water treatment membrane is known in advance. It is preferable to process into a water treatment membrane element by performing the washing step in the state of the water treatment membrane element. It does not restrict | limit especially as a method of processing a to-be-treated membrane into a water treatment membrane element. For example, by bundling a plurality of water treatment membranes, both ends are bonded and fixed by a housing so that the effective length per one becomes a desired value, and one end is opened, so that the water treatment membrane is a water treatment membrane. Can be processed into elements. Alternatively, a plurality of water treatment membranes may be bundled and one end thereof may be bonded and fixed by a housing so that the effective length per one becomes a desired value.

(Function and effect)
According to the method for producing a water treatment membrane element of the third embodiment of the present invention, a specific cleaning liquid is passed through the water treatment membrane to treat the water treatment membrane, so that the spinning oil remaining in the multifilament is efficiently removed. Can be removed.
When the porous membrane layer is a hydrophobic porous membrane layer, if a surfactant solution is used as the cleaning liquid, the hydrophobic porous membrane layer can be hydrophilized while removing the spinning oil. In particular, if the drying step is performed after the washing / hydrophilization step, the hydrophobic porous membrane layer can be made more hydrophilic. Moreover, if a surfactant solution is used as the cleaning liquid, the hydrophobic porous membrane layer can be hydrophilized without using glycerin. Thus, after the hydrophobic porous membrane layer is hydrophilized, a large amount of cleaning liquid is not required when cleaning the water treatment membrane, and the amount of cleaning waste liquid can be reduced.

When a surfactant solution is used as the cleaning liquid, the surfactant solution is attached to at least the water treatment membrane of the water treatment membrane element obtained by this embodiment. Therefore, it is preferable to wash the water treatment film with a washing liquid after the washing / hydrophilization step (after the drying step when the drying step is performed).
Examples of the cleaning method include a method of allowing the cleaning liquid to pass through the water treatment membrane, specifically, a method of pressurizing the hydrophobic porous membrane layer side using a pump or the like or utilizing a water head difference, and support. Examples include a method of reducing the pressure on the layer side.
Examples of the cleaning liquid include water and ethanol. Since cleaning in a water treatment facility is also assumed, water is preferable among them in consideration of the necessity of removing the cleaning liquid.

<Fourth embodiment>
The method for manufacturing a water treatment membrane element according to the fourth embodiment of the present invention includes a cleaning step and a film forming step described later.

(Washing process)
The cleaning step of this embodiment is a step of cleaning the support layer with two or more different solvents.
As a support layer, what was formed by the method mentioned above, for example may be used, and a commercial item may be used.

As the method for washing the support layer, any method such as immersion washing with a solvent, immersion washing with a surfactant solution, washing with water, removal by heating, etc. can be used, but immersion washing with a solvent is preferable because of easy washing. . More preferably, it is desirable to perform immersion cleaning with two or more solvents having different polarities.

It is preferable that the temperature during immersion cleaning is not higher than the boiling point of the solvent used. Moreover, it is preferable that it is room temperature or more from the ease of temperature control.

As the solvent used for washing, any solvent that does not dissolve the multifilament can be used. For example, n-hexane (SP value 7.3), toluene (SP value 8.8), ethyl acetate (SP value 9. 0), acetone (SP value 10.0), isopropanol (SP value 11.5), ethanol (SP value 12.7), methanol (SP value 14.5) and the like.
From the viewpoint of detergency (solubility) of the nonionic surfactant, it is preferable to use a solvent having a solubility parameter (hereinafter referred to as SP value) of 7 or more and 20 or less.
Further, from the viewpoint of detergency (solubility) of the nonionic surfactant, it is preferable to wash the support layer with a low SP value solvent (low polarity solvent) and a high SP value solvent (high polarity solvent), respectively. More preferably, the support layer is washed with a low polarity solvent having 7.0 ≦ SP value ≦ 10.0 and a high polarity solvent having 10.0 <SP value ≦ 20.0. Examples of the combination of the low polarity solvent and the high polarity solvent include a combination of n-hexane (SP value 7.3) and ethanol (SP value 12.7), acetone (SP value 9.9) and ethanol (SP value 12). 7) and the like.
The SP value in the present invention is a value described in Polymer Handbook (John Wiley & Sons, Second Edition (1996), IV-347 to 352).

The amount of the solvent used for washing is preferably not less than the amount in which the entire support layer is immersed, and more preferably not less than 10 as the volume ratio to the support layer. From the viewpoint of the solubility of the nonionic surfactant, the washing temperature is preferably 0 ° C. or higher and not higher than the boiling point of each solvent, more preferably 20 ° C. or higher and not higher than the boiling point of each solvent.

In the washing step, the support layer is mixed with two or more different solvents so that the amount of TOC dissolved in toluene after 20 hours of immersion in 200 mL of toluene per 20 g of the support layer is 20 mg or less per kg of the support layer. Is preferably washed. Further, the elution amount of the nonionic surfactant into toluene after being immersed in 200 mL of toluene at 20 ° C. for 3 hours per 20 g of the support layer is 0.01 mg / L or less (that is, 0.01 mg or less per 1 L of toluene). As such, it is preferable to wash the support layer with two or more different solvents.
By washing the support layer with a low polarity solvent and a high polarity solvent, the TOC elution amount and the nonionic surfactant elution amount in toluene are likely to be within the above ranges.

In the support layer washed by the washing step, the elution amount of the nonionic surfactant in toluene after being immersed in 200 mL of toluene per 20 g of the support layer at 40 ° C. for 3 hours tends to be 0.01 mg / L or less. Further, the support layer washed by the washing step tends to have a TOC elution amount of 20 mg or less per 1 kg of the support layer after being immersed in 200 mL of toluene per 20 g of the support layer at 40 ° C. for 3 hours.
The elution amount of TOC and nonionic surfactant in toluene corresponds to the content of TOC and nonionic surfactant contained in the support layer (content in the support layer).

(Film forming process)
The film forming step is a step of forming a porous membrane layer so as to be adjacent to the support layer after washing. By forming the porous membrane layer so as to be adjacent to the support layer, a water treatment membrane can be obtained.
The porous membrane layer is prepared by dissolving the raw material of the porous membrane layer in a solvent to form a film-forming stock solution, applying this to the surface of the support layer after washing, and coagulating the film-forming stock solution applied to the support layer. It is formed. When the form of the water treatment membrane is a hollow fiber membrane, the porous membrane layer is formed by applying a membrane-forming stock solution on the outer peripheral surface of the hollow support layer and solidifying the membrane-forming stock solution applied to the support layer. .

When the porous membrane layer is a composite porous membrane layer having two layers, the water treatment membrane is produced by a production method having the following steps (i) to (vii), for example.
(I) The process of apply | coating a 1st film forming undiluted | stock solution to the outer peripheral surface of a support layer;
(Ii) a step of solidifying the first membrane-forming solution applied to the support layer to form a first porous membrane layer to obtain a hollow fiber membrane precursor;
(Iii) a step of applying a second membrane-forming solution on the outer peripheral surface of the hollow fiber membrane precursor;
(Iv) a step of solidifying the second membrane-forming solution applied to the hollow fiber membrane precursor to form a second porous membrane layer to obtain a hollow fiber membrane;
(V) a step of washing the hollow fiber membrane;
(Vi) drying the hollow fiber membrane;
(Vii) a step of winding the hollow fiber membrane;

The water treatment membrane obtained by the film forming process is processed by a known method to obtain a water treatment membrane element. It does not restrict | limit especially as a method of processing a water treatment membrane into a water treatment membrane element. For example, a plurality of water treatment membranes are bundled together, and both ends are bonded and fixed by a housing so that the effective length per one becomes a desired value, and one end is opened, so that the water treatment membrane is a water treatment membrane element. Can be processed. Alternatively, a plurality of water treatment membranes may be bundled and one end thereof may be bonded and fixed by a housing so that the effective length per one becomes a desired value.

(Function and effect)
According to the method for producing a water treatment membrane element of the fourth embodiment of the present invention, since the support layer is washed in advance using two or more different solvents, the spinning oil remaining in the multifilament is efficiently removed. Can be removed. Therefore, it is possible to easily obtain a water treatment membrane and a water treatment membrane element with extremely low elution of nonionic surfactant and TOC.

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

"Measuring method"
<Measurement 1: Measurement of TOC elution amount>
Using a combustion-type total organic carbon analyzer (“TOC-300V” manufactured by Mitsubishi Chemical Analytech Co., Ltd.), the amount of TOC eluted in the immersion water was measured.

<Measurement 2: Measurement of TOC elution amount>
The toluene phase after immersing the support layer or the hollow fiber membrane was dried at 115 ° C. to remove toluene. After the residue was redissolved in ultrapure water, the amount of TOC was measured using a combustion-type total organic carbon analyzer (“TOC-300V” manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

<Measurement 3: Measurement of elution amount of nonionic surfactant>
The elution amount of the nonionic surfactant in the immersion water was measured by the solid phase extraction-HPLC method as follows.
That is, the nonionic surfactant eluted in the immersion water is extracted with a solid phase column and then eluted with toluene. Further, an aqueous solution of ammonium thiocyanocobalt (II) is added to form a complex with cobalt, which is taken into the toluene phase. The cobalt was reacted with PAR (4- (2-pyridylazo) -resorcinol), and Co-PAR in the aqueous phase was quantified by HPLC method to elute from the hollow fiber membrane or the water treatment membrane element into the immersion water. Nonionic surfactant was quantified using heptaoxyethylene dodecyl ether as a standard.

<Measurement 4: Measurement of elution amount of nonionic surfactant>
The elution amount of the nonionic surfactant in toluene was measured by the absorbance method as follows.
That is, after concentrating the toluene phase after immersing the support layer or the hollow fiber membrane, an aqueous solution of ammonium thiocyanocobalt (II) is added to the nonionic surfactant eluted in toluene, and complexed with cobalt to form toluene. Cobalt incorporated into the phase is reacted with PAR (4- (2-pyridylazo) -resorcinol), and Co-PAR in the aqueous phase is quantified spectrophotometrically to convert the support layer or hollow fiber membrane into toluene. The eluted nonionic surfactant was quantified. The quantified value is regarded as the content of the nonionic surfactant in the support layer or the hollow fiber membrane. In addition, it quantified using heptaoxyethylene dodecyl ether as a standard reagent.

"Example 1"
As a nonionic surfactant, a polyoxypropylene-polyoxyethylene-polyoxypropylene block copolymer (Pluronic RPE2520 (manufactured by BASF), HLB: 4, polyoxyethylene based on the total mass of the block copolymer) The ratio (20% by mass) was diluted with pure water so that the concentration became 0.1% by mass to prepare a surfactant solution (cleaning solution).

As shown in FIG. 6, an outer diameter of a water treatment membrane 1 in which a hydrophobic porous membrane layer made of polyvinylidene fluoride is formed on the outer peripheral surface of a support layer obtained by processing multifilaments made of polyester fibers into a hollow shape. Using an 8 mm hollow fiber membrane (manufactured by Mitsubishi Rayon Co., Ltd.), 15 bundles of these hollow fiber membranes are bonded and fixed to each other by a housing 41 so that the effective length per one is 350 mm. A treated membrane element 40 was produced.
The hollow fiber membrane was immersed in pure water of 22 L per 1 m ² of membrane surface area at 20 ° C., and the TOC eluted in pure water (immersion water) after standing for 16 hours was measured by the method of Measurement 1. However, it was 4.8 mg / L. Similarly, when the nonionic surfactant eluted in the immersion water was measured by the method of Measurement 3, it was 0.95 mg / L.

As shown in FIG. 6, the water treatment membrane element 40 was placed in the water tank 50 filled with the surfactant solution 51 and immersed in the surfactant solution 51 for 30 minutes. Thereafter, the pump 52 is connected to one housing 41 of the water treatment membrane element 40, the surfactant solution 51 permeates from the hydrophobic porous membrane layer to the support layer, and the surfactant solution 51 permeated to the support layer becomes water. Suction filtration was performed for 4 minutes at a flux of 3 m / day so as to be discharged to the outside of the treatment membrane 1, and the surfactant solution 51 was passed through the water treatment membrane 1 (cleaning / hydrophilization step). At this time, the filtrate (surfactant solution discharged to the outside of the water treatment membrane 1) is placed in a container (not shown) separate from the water tank 50 so as not to mix with the surfactant solution 51 in the water tank 50. The filtrate was drained. Further, filtration was performed in a sufficient amount of the surfactant solution 51 so that the water treatment membrane 1 was not exposed to the atmosphere during filtration.
After filtration, the water treatment membrane element 40 was taken out from the water tank 50 and left to stand in the atmosphere for 16 hours or more to dry (drying process).

After drying, the water treatment membrane element was installed in a water tank filled with pure water maintained at 20 ° C., and a pump was connected to one housing of the water treatment membrane element. The surfactant in the water treatment membrane element was sufficiently removed by immediately suction filtration at a flux of 1 m / day for 2 hours so that 83 L of pure water per 1 m ² of membrane surface area of the water treatment membrane could flow. At this time, the filtrate of the container separate from the water tank was drained so that the filtrate (pure water discharged to the outside of the water treatment membrane) was not mixed with the pure water in the water tank. In addition, new pure water was sequentially supplied to the water tank so that the water treatment film was not exposed to the atmosphere.
After removing the surfactant, the water treatment membrane element was immersed at 20 ° C. in 22 L of pure water per 1 m ² of membrane surface area of the hollow fiber membrane (water treatment membrane) and allowed to stand for 16 hours. Thereafter, the water treatment membrane element was taken out from the pure water, and the TOC and nonionic surfactant eluted in the pure water (immersion water) were measured by the method of Measurement 1 or Measurement 3. The results are shown in Table 1.

"Example 2"
As a surfactant, a polyoxypropylene-polyoxyethylene-polyoxypropylene block copolymer (Pluronic RPE1740 (manufactured by BASF), HLB: 8, ratio of polyoxyethylene to the total mass of the block copolymer: 40 The water treatment membrane was treated in the same manner as in Example 1 except that a surfactant solution (cleaning solution) prepared by diluting with pure water so that the concentration was 0.1% by mass was used. The TOC and nonionic surfactant eluted in the immersion water were measured by the method of Measurement 1 or Measurement 3. The results are shown in Table 1.

"Example 3"
As a surfactant, a polyoxypropylene-polyoxyethylene-polyoxypropylene block copolymer (Pluronic RPE3110 (manufactured by BASF), HLB: 2, ratio of polyoxyethylene to the total mass of the block copolymer: 10 The water treatment membrane was treated in the same manner as in Example 1 except that a surfactant solution (cleaning solution) prepared by diluting with pure water so that the concentration was 0.1% by mass was used. The TOC and nonionic surfactant eluted in the immersion water were measured by the method of Measurement 1 or Measurement 3. The results are shown in Table 1.

Example 4
The support layer 10 made of the hollow knitted string 12 was manufactured using the support layer manufacturing apparatus 20 shown in FIG. As a fiber constituting the support layer, a polyester fiber (fineness: 84 dtex, number of filaments: 36) having an oil content of 0.4% by mass was used. As the bobbin 22, five pieces of the polyester fiber wound with 5kg were prepared. As the circular knitting machine 24, a table-type string knitting machine (manufactured by Sakurai Textile Machinery Co., Ltd., number of knitting needles: 12, needle size: 16 gauge, spindle circumferential diameter: 8 mm) was used. As the string supply device 26 and the take-up device 30, a Nelson roll was used. As the heating die 28, a stainless steel die having a heating means (inner diameter D: 5 mm, inner diameter d: 2.2 mm, length: 300 mm) was used.

As the string oil agent, an oil agent composed of mineral oil, sorbitan monooleate, sodium phosphate ester, polyoxyethylene alkyl ether is used, and the oil agent is adhered to the bobbin so that the content is 1.0% by mass with respect to the yarn. The polyester fibers drawn out from 22 are combined into one yarn 16 (total fineness is 420 dtex), and then circular knitted by a circular knitting machine 24 to form a hollow knitted string 12. It passed through the heating die 28 at 195 ° C., and the heat-treated hollow knitted string 12 was wound around the winding device 32 as a support layer 10 at a winding speed of 100 m / hr. The support layer 10 was manufactured until the polyester fiber of the bobbin 22 was exhausted.

The obtained support layer was immersed and washed with ethanol (SP value 12.7) so that the mass ratio with respect to the solvent (solvent / support layer) was 20, followed by n-hexane (SP value 7.3). ), And then dried by heating at 80 ° C. for 3 hours.
When the nonionic surfactant eluted in 200 mL of toluene per 20 g of dried support layer at 40 ° C. and allowed to stand for 3 hours and then eluted in toluene was measured by the method of Measurement 4, it was 0.008 mg / L. That is, the content of the nonionic surfactant in the support layer was 0.08 mg per 1 kg of the support layer. Similarly, when the TOC eluted in toluene was measured by the method of Measurement 2, it was 10 mg per kg of the support layer. This is defined as the TOC content in the support layer.
Moreover, it immersed at 20 degreeC in ultrapure water so that mass ratio (water / support layer) of a support layer and water might be set to 50 degreeC, and left still for 8 hours. Thereafter, the support layer was taken out from the ultrapure water, and the elution amount of the nonionic surfactant eluted in the ultrapure water (immersion water) was measured by the method of measurement 3. As a result, it was 0.002 mg / L.

Next, a hydrophobic porous membrane layer made of polyvinylidene fluoride and polyvinylpyrrolidone was formed on the outer peripheral surface of the dried support layer as follows to obtain a hollow fiber membrane.
First, polyvinylidene fluoride (manufactured by Arkema Japan: “Kyner 761A”) and polyvinylpyrrolidone (“K80-M” manufactured by Nippon Shokubai Co., Ltd.) are mixed with N, N′-dimethylacetamide in a mass ratio (polyvinylidene fluoride / polyvinylpyrrolidone / N, N′-dimethylacetamide) was dissolved to be 18/10/72 to prepare a film forming stock solution.
The support layer is immersed in the obtained film-forming stock solution at 40 ° C. for 30 minutes, passed through a nozzle made of a silicone sheet having a pore size of 3.0 mm, and then a coagulation liquid (mass ratio) made of water and N, N′-dimethylacetamide. (Water / N, N′-dimethylacetamide) = 60/40) at 25 ° C. for 10 minutes.
Next, the support layer after being immersed in the membrane forming stock solution and the coagulating solution is immersed in 10000 mg / L sodium hypochlorite at 60 ° C. for 5 hours, and further immersed in pure water at 60 ° C. for 6 hours. After the replacement, it was immersed in water at 60 ° C. for 6 hours, washed again, heated at 80 ° C. for 3 hours, and then dried at 22 ° C. for 8 hours to obtain a hollow fiber membrane.
When the nonionic surfactant eluted in 200 mL of toluene per 20 g of the obtained hollow fiber membrane at 40 ° C. and allowed to stand for 3 hours and then eluted in toluene was measured by the method of Measurement 4, 0.005 mg / L. That is, the content of the nonionic surfactant in the hollow fiber membrane was less than 0.05 mg per 1 kg of the support layer. Similarly, when the TOC eluted in toluene was measured by the method of Measurement 2, it was 10 mg per 1 kg of the hollow fiber membrane. This is the TOC content in the hollow fiber membrane.

Separately, ethanol was diluted to 50% by mass with pure water to prepare a hydrophilized solution.
The hollow fiber membrane obtained previously was immersed in a hydrophilized solution of 22 L per 1 m ² of membrane surface area of the hollow fiber membrane at 20 ° C. and allowed to stand for 30 minutes. Thereafter, the hollow fiber membrane was rinsed in pure water for 8 hours and dried at 105 ° C. for 3 hours to hydrophilize the hollow fiber membrane.
The hollow fiber membrane after the hydrophilization treatment was immersed in pure water of 22 L per 1 m ² of membrane surface area of the hollow fiber membrane at 20 ° C. and allowed to stand for 16 hours. Thereafter, the hollow fiber membrane was taken out from the pure water, and the TOC and nonionic surfactant eluted in the pure water (immersion water) were measured by the method of Measurement 1 or Measurement 3. The results are shown in Table 1.

"Comparative Example 1"
In the washing / hydrophilization step, the water treatment membrane was treated and eluted in the immersion water in the same manner as in Example 1 except that the suction filtration was not performed (the surfactant solution was not passed through the water treatment membrane). TOC and nonionic surfactant were measured by the method of Measurement 1 or Measurement 3. The results are shown in Table 1.

"Comparative Example 2"
Ethanol was diluted to 50% by mass with pure water to prepare a hydrophilic solution.
In the washing / hydrophilization process, water was used in the same manner as in Example 1 except that the hydrophilic solution obtained was used instead of the surfactant solution, the immersion time was changed to 10 minutes, and the drying process was not performed. The treated membrane was treated, and the TOC and nonionic surfactant eluted in the immersion water were measured by the method of Measurement 1 or Measurement 3. The results are shown in Table 1.

　　　　　　　　　　　　　　　　　 

In Examples 1 to 4, the amount of TOC and nonionic surfactant eluted in the immersion water was low, and the spinning oil remaining in the multifilament could be efficiently removed. Further, the hydrophobic porous membrane layer could be hydrophilized. In particular, Example 1 using a nonionic surfactant having an HLB of 4 and Example 4 in which the support layer was previously washed with two types of solvents were used for the TOC and the nonionic surfactant in immersion water. The amount of elution was lower and it was more effective by removing the spinning oil.
On the other hand, Comparative Example 1 in which only the water treatment membrane element was immersed in the surfactant solution and the surfactant solution was not passed through the water treatment membrane was the elution of TOC and nonionic surfactant in the immersion water. The amount of spinning oil remaining in the multifilament was not sufficiently removed.
In Comparative Example 2 using an ethanol aqueous solution instead of the surfactant solution, the hydrophobic porous membrane layer could be hydrophilized, but the amount of TOC and nonionic surfactant eluted into the immersion water was high. The spinning oil remaining on the surface could not be removed sufficiently.

“Comparative Example 3”
Support was performed in the same manner as in Example 4 except that water (SP value 23.4) was used instead of ethanol (SP value 12.7) and n-hexane (SP value 7.3) in the cleaning of the support layer. Layers were produced and washed and dried.
When the nonionic surfactant eluted in 200 mL of toluene per 20 g of dried support layer at 40 ° C. and allowed to stand for 3 hours and then eluted in toluene was measured by the method of Measurement 4, it was 0.02 g / L. That is, the content of the nonionic surfactant in the support layer was 0.2 g per 1 kg of the support layer. Similarly, when the TOC eluted in toluene was measured by the method of Measurement 2, it was 12 g per kg of the support layer. This is the TOC content in the hollow fiber membrane.
Moreover, it immersed at 20 degreeC in ultrapure water so that mass ratio (water / support layer) of a support layer and water might be set to 50 degreeC, and left still for 8 hours. Thereafter, the support layer was taken out from the ultrapure water, and the elution amount of the nonionic surfactant eluted in the ultrapure water (immersion water) was measured by the method of measurement 3. As a result, it was 0.1 mg / L.

“Comparative Example 4”
A support layer was produced in the same manner as in Example 4 except that the support layer was washed only with ethanol (SP value 12.7), and washed and dried.
When the nonionic surfactant eluted in 200 mL of toluene per 20 g of dried support layer at 40 ° C. and allowed to stand for 3 hours and then eluted in toluene was measured by the method of measurement 4, it was 0.16 mg / L. That is, the content of the nonionic surfactant in the support layer was 1.6 mg per 1 kg of the support layer. Similarly, when the TOC eluted in toluene was measured by the method of Measurement 2, it was 130 mg per kg of the support layer. This is the TOC content in the hollow fiber membrane.
Moreover, it immersed at 20 degreeC in ultrapure water so that mass ratio (water / support layer) of a support layer and water might be set to 50 degreeC, and left still for 8 hours. Thereafter, the support layer was taken out from the ultrapure water, and the elution amount of the nonionic surfactant eluted in the ultrapure water (immersion water) was measured by the method of measurement 3. As a result, it was 0.03 mg / L.

"Comparative Example 5"
A support layer was produced in the same manner as in Example 4 except that the support layer was washed only with hexane (SP value 7.3), and washed and dried.
When the nonionic surfactant eluted in 200 mL of toluene per 20 g of dried support layer at 40 ° C. and allowed to stand for 3 hours was measured by the method of measurement 4, it was 0.3 mg / L. That is, the content of the nonionic surfactant in the support layer was 3.0 mg per 1 kg of the support layer. Similarly, when the TOC eluted in toluene was measured by the method of Measurement 2, it was 80 mg per kg of the support layer. This is the TOC content in the hollow fiber membrane.
Moreover, it immersed at 20 degreeC in ultrapure water so that mass ratio (water / support layer) of a support layer and water might be set to 50 degreeC, and left still for 8 hours. Thereafter, the support layer was taken out from the ultrapure water, and the elution amount of the nonionic surfactant eluted in the ultrapure water (immersion water) was measured by the method of measurement 3. As a result, it was 0.056 mg / L.

"Example 5"
A polyester fiber (fineness: 111 dtex, number of filaments: 48) having an oil content of 1.2% by mass is used as a fiber constituting the support layer, and a stainless steel die having a heating means (inner diameter D) is used as the heating die 28. : 5 mm, inner diameter d: 1.5 mm, length: 300 mm), a support layer was produced in the same manner as in Example 4 and washed and dried.
When the nonionic surfactant eluted in 200 mL of toluene per 20 g of dried support layer at 40 ° C. and allowed to stand for 3 hours and then eluted in toluene was measured by the method of Measurement 4, it was 0.005 mg / It was less than L. That is, the content of the nonionic surfactant in the support layer was less than 0.05 mg per 1 kg of the support layer. Similarly, when the TOC eluted in toluene was measured by the method of Measurement 2, it was less than 10 mg per kg of the support layer. This is the TOC content in the hollow fiber membrane.
Moreover, it immersed at 20 degreeC in ultrapure water so that mass ratio (water / support layer) of a support layer and water might be set to 50 degreeC, and left still for 8 hours. Thereafter, the support layer was taken out from the ultrapure water, and the elution amount of the nonionic surfactant eluted in the ultrapure water (immersion water) was measured by the method of measurement 3, and was less than 0.002 mg / L. .

As is apparent from the results of Example 5 and Comparative Examples 3 to 5, the elution amount of the nonionic surfactant into toluene was 0.01 mg / L or less (that is, the nonionic surfactant in the support layer). The amount of nonionic surfactant eluted into the water of the support layer is 0.005 mg / L or less, and water treatment membranes, particularly water treatment used for drinking water applications It is suitable as a support layer for a membrane. In addition, cleaning with two or more different solvents is effective as a method for producing the support layer.

The water treatment membrane of the present invention is suitable as a filtration membrane used for water treatment by microfiltration, ultrafiltration or the like.
According to the method for producing a water treatment membrane element of the present invention, the spinning oil remaining in the multifilament can be efficiently removed.

DESCRIPTION OF SYMBOLS 1 Water treatment membrane 10 Support layer 11 Porous membrane layer 12 Hollow knitted string 16 Yarn 20 Support layer manufacturing apparatus 22 Bobbin 24 Circular knitting machine 26 String supply apparatus 27 Dancer roll 28 Heating die 30 Take-up apparatus 32 Winding apparatus 40 Water Treatment membrane element 41 Housing 50 Water tank 51 Surfactant solution 52 Pump

Claims (15)

1. A water treatment membrane having a support layer that is a multifilament workpiece and a porous membrane layer provided adjacent to the support layer,
   The water treatment film after water flow at 20 ° C. The water membrane surface area 1 m ² per 83L of water treatment membranes, immersion water after immersion for 16 hours at 20 ° C. in membrane surface area 1 m ² per 22L of water in the water treatment membranes The water treatment film | membrane whose elution amount of the total organic carbon to 2.0 mg / L or less.
2. A water treatment membrane having a support layer that is a multifilament workpiece and a porous membrane layer provided adjacent to the support layer,
   The water treatment film after water flow at 20 ° C. The water membrane surface area 1 m ² per 83L of water treatment membranes, immersion water after immersion for 16 hours at 20 ° C. in membrane surface area 1 m ² per 22L of water in the water treatment membranes The water treatment film | membrane whose elution amount of the nonionic surfactant to 0.5 mg / L or less.
3. A water treatment membrane element comprising the water treatment membrane according to claim 1 or 2.
4. A method for producing a water treatment membrane element comprising a water treatment membrane having a support layer that is a multifilament workpiece and a porous membrane layer provided adjacent to the support layer,
   After immersing the water treatment membrane so that at least the porous membrane layer side of the water treatment membrane is in contact with the cleaning solution, the cleaning solution is permeated from the porous membrane layer side to the support layer, and the cleaning solution permeated to the support layer is washed with water. A method for producing a water treatment membrane element, comprising a step of discharging the treatment membrane to the outside.
5. The method for producing a water treatment membrane element according to claim 4, wherein the cleaning liquid is a surfactant solution containing a surfactant.
6. The method for producing a water treatment membrane element according to claim 5, wherein the surfactant in the surfactant solution is a nonionic surfactant.
7. The method for producing a water treatment membrane element according to claim 6, wherein the HLB of the surfactant in the surfactant solution is 1 or more and 7 or less.
8. The method for producing a water treatment membrane element according to claim 6 or 7, wherein the surfactant in the surfactant solution is a polyoxypropylene-polyoxyethylene-polyoxypropylene block copolymer.
9. The method for producing a water treatment membrane element according to claim 8, wherein the proportion of polyoxyethylene is 45% by mass or less based on the total mass of the block copolymer.
10. The water treatment membrane element according to any one of claims 5 to 9, further comprising a step of drying the water treatment membrane after the step while at least the surfactant solution remains in the porous membrane layer. Manufacturing method.
11. A method for producing a water treatment membrane element comprising a water treatment membrane having a support layer that is a multifilament workpiece and a porous membrane layer provided adjacent to the support layer,
    A method for producing a water treatment membrane element, comprising a step of forming a porous membrane layer adjacent to a washed support layer after washing the support layer with two or more different solvents.
12. The support layer is washed with a low SP value solvent having an SP value of 7.0 or more and 10.0 or less and a high SP value solvent having an SP value of more than 10 or 20.0 or less. A method for producing a water treatment membrane element.
13. The support layer is washed according to claim 11 or 12, wherein the amount of elution of total organic carbon in toluene after being immersed in 200 mL of toluene per 20 g of support layer at 40 ° C for 3 hours is 20 mg or less per kg of support layer. The manufacturing method of the water treatment membrane element of description.
14. The support layer is washed so that the elution amount of the nonionic surfactant into toluene after being immersed in 200 mL of toluene per 20 g of the support layer at 40 ° C for 3 hours is 0.01 mg / L or less. 12. A method for producing a water treatment membrane element according to item 12.
15. A support layer for a water treatment membrane, which is a multifilament workpiece,
    A support layer in which the elution amount of the nonionic surfactant into toluene after being immersed in 200 mL of toluene at 40 ° C. for 3 hours per 20 g of the support layer is 0.01 mg / L or less.

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