WO2021040001A1 - Method for hydrophilizing polyvinylidene fluoride-based porous separation membrane - Google Patents

Method for hydrophilizing polyvinylidene fluoride-based porous separation membrane Download PDF

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WO2021040001A1
WO2021040001A1 PCT/JP2020/032699 JP2020032699W WO2021040001A1 WO 2021040001 A1 WO2021040001 A1 WO 2021040001A1 JP 2020032699 W JP2020032699 W JP 2020032699W WO 2021040001 A1 WO2021040001 A1 WO 2021040001A1
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Prior art keywords
separation membrane
polyvinylidene fluoride
porous separation
based porous
hydrophilizing
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PCT/JP2020/032699
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French (fr)
Japanese (ja)
Inventor
健太 岩井
花川　正行
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東レ株式会社
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Priority to CN202080060862.7A priority Critical patent/CN114269458B/en
Priority to JP2020545606A priority patent/JP7004079B2/en
Publication of WO2021040001A1 publication Critical patent/WO2021040001A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/34—Polyvinylidene fluoride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C08J9/40—Impregnation
    • C08J9/42—Impregnation with macromolecular compounds

Definitions

  • the present invention relates to a method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane.
  • porous separation membranes such as microfiltration membranes and ultrafiltration membranes have been used in various fields such as water treatment fields such as water purification or wastewater treatment, medical fields such as blood purification, food industry fields, and wastewater treatment. ing. Porous separation membranes in such fields are premised on repeated use and are washed or sterilized with various chemicals. Therefore, chemical resistance, stain resistance, weather resistance, oxidation deterioration resistance, etc. are required. There is.
  • Hydrophobic resins are often selected as the membrane material for the porous separation membrane because of the required characteristics, and polyvinylidene fluoride-based resin, which has excellent chemical resistance, is particularly preferably used. Further, in recent years, there has been an increasing demand for higher quality permeate, and there are increasing cases where an ultrafiltration membrane having a small pore diameter and excellent removal performance of fine particles and organic substances is selected.
  • Examples of the method for hydrophilizing the porous separation membrane include a method of immersing the porous separation membrane in ethanol and then replacing it with water (Patent Document 1), and a method of immersing the porous separation membrane in a hydrophilic resin aqueous solution and then using water.
  • Patent Document 2 A method of substituting
  • Patent Document 3 a method of immersing the porous separation membrane in an aqueous solution of a surfactant and then drying it (Patent Document 3) have been proposed.
  • Hydrophilization with a lower alcohol promotes hydrophilicity sufficiently and the water permeability of the porous separation membrane is well restored.
  • a lower alcohol such as ethanol
  • the handling amount is strictly limited, and the amount of modules that can be hydrophilized is limited.
  • hydrophilization with a hydrophilic resin aqueous solution solves the problem of the flash point of the hydrophilic resin aqueous solution, and there is no problem of limiting the handling amount of the hydrophilic agent.
  • hydrophilization with a hydrophilic resin aqueous solution solves the problem of the flash point of the hydrophilic resin aqueous solution, and there is no problem of limiting the handling amount of the hydrophilic agent.
  • the porous separation membrane module is produced, and then the porous separation membrane in the dried module is hydrophilized with an aqueous ethanol solution or the like, and further.
  • a step of immersing, replacing, and drying in an aqueous surfactant solution is required, which causes a problem that the step becomes complicated.
  • An object of the present invention is to provide a method for easily hydrophilizing a polyvinylidene fluoride-based porous separation membrane.
  • a method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane which comprises a step of contacting a polyvinylidene fluoride-based porous separation membrane with a hydrophilic agent and then contacting water.
  • the polyvinylidene fluoride-based porous separation membrane contains a polyvinylidene fluoride-based resin, has an average pore diameter of 1 to 20 nm on the surface, and has a contact angle between the surface and water of 80 to 110 °.
  • the hydrophilic agent is a method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane, which contains a surfactant, has a surface tension of 30 to 45 mN / m, and has a density of 1.000 to 1.010 g / cm 3. ..
  • the hydrophilic agent is an aqueous solution containing 3 to 10% by mass of a nonionic surfactant.
  • Method. [5] The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to [3] or [4], wherein the nonionic surfactant has a flash point of 250 ° C. or higher.
  • a hydrophobic porous separation membrane containing a polyvinylidene fluoride-based resin having fine surface pores is immersed in a predetermined hydrophilic agent. Then, the hydrophilic agent efficiently permeates into the pores of the porous separation membrane, and then the entire porous separation membrane is hydrophilized by replacing the hydrophilic agent with water.
  • the hydrophilization method of the present invention includes a step of contacting the polyvinylidene fluoride-based porous separation membrane with a hydrophilizing agent and then contacting water (hydrophilization step A).
  • the polyvinylidene fluoride-based porous separation membrane contains a polyvinylidene fluoride-based resin, has an average pore diameter of 1 to 20 nm on the surface, and has a contact angle between the surface and water of 80 to 110 °.
  • the hydrophilizing agent contains a surfactant, has a surface tension of 30 to 45 mN / m, and has a density of 1.000 to 1.010 g / cm 3 .
  • the hydrophilization step A can also be applied to a polyvinylidene fluoride-based porous separation membrane having an average pore diameter of larger than 20 nm and a polyvinylidene fluoride-based porous separation membrane having a contact angle between the surface and water of less than 80 °.
  • a polyvinylidene fluoride-based porous separation membrane having an average pore diameter of 1 to 20 nm on the surface and a contact angle between the surface and water of 80 to 110 ° other hydrophilicization is performed. An effect that cannot be obtained with an agent can be obtained.
  • the polyvinylidene fluoride-based resin means a resin containing at least one of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer.
  • the polyvinylidene fluoride-based resin may contain a plurality of types of vinylidene fluoride copolymers.
  • the vinylidene fluoride copolymer is a polymer having a vinylidene fluoride residue structure, and is typically a copolymer of a vinylidene fluoride monomer and another fluorine-based monomer or the like.
  • Examples of such a copolymer include a copolymer of one or more types of monomers selected from vinyl fluoride, ethylene tetrafluoroethylene, propylene hexafluoride, and ethylene trifluoride, and vinylidene fluoride. Be done.
  • a monomer other than the fluorine-based monomer such as ethylene may be copolymerized to the extent that the effect of the present invention is not impaired.
  • the weight average molecular weight of the polyvinylidene fluoride resin used in the present invention may be appropriately selected depending on the required strength and water permeability of the porous separation membrane, but as the weight average molecular weight increases, the water permeability deteriorates and the weight The smaller the average molecular weight, the lower the strength. Therefore, the weight average molecular weight of the polyvinylidene fluoride-based resin is preferably 50,000 or more and 1 million or less.
  • the weight average molecular weight of the polyvinylidene fluoride-based resin is preferably 100,000 or more and 700,000 or less, and more preferably 150,000 or more and 600,000 or less.
  • the polyvinylidene fluoride-based porous separation membrane preferably contains a polyvinylidene fluoride-based resin as a main component.
  • the proportion of the polyvinylidene fluoride-based resin in the polyvinylidene fluoride-based porous separation membrane is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more.
  • the polyvinylidene fluoride-based porous separation membrane may be composed of only a polyvinylidene fluoride-based resin.
  • the polyvinylidene fluoride-based porous separation membrane further contains a hydrophilic resin to improve pure water permeation performance and stain resistance. Therefore, blending a polyvinylidene fluoride resin and a hydrophilic resin is also preferably performed.
  • the hydrophilic resin is a polymer having a high affinity with water, and refers to a polymer that is soluble in water or has a contact angle with water smaller than that of a polyvinylidene fluoride resin.
  • the hydrophilic resin examples include polyvinylpyrrolidone-based resin, polyethylene glycol, polyvinyl alcohol, acrylic-based resin (polyacrylic acid, polymethylmethacrylate, etc.), cellulose ester-based resin, polyacrylonitrile, polysulfone, and the like.
  • a hydrophilic polyolefin resin obtained by copolymerizing an olefin monomer such as ethylene, propylene or vinylidene fluoride with a hydrophilic group can also be used as the hydrophilic resin.
  • the polyvinylidene fluoride-based porous separation membrane to which the hydrophilization method of the present invention is applied has an average pore diameter of 1 to 20 nm on the surface and a contact angle between the surface and water of 80 to 110 °.
  • the contact angle between the surface of the polyvinylidene fluoride-based porous separation membrane and water is preferably 85 to 105 °, more preferably 88 to 102 °.
  • the average pore size and contact angle with water can be measured by the method described in Examples.
  • the method for producing this polyvinylidene fluoride-based porous separation membrane is not particularly limited, but a heat-induced phase separation method, a non-solvent-induced phase separation method, or a composite process thereof is preferable in order to control the average pore diameter on the membrane surface to be small. .. Among them, the non-solvent-induced phase separation method is particularly preferable because it enables precise pore size control.
  • a specific method for producing a polyvinylidene fluoride-based porous separation membrane a known method disclosed in Japanese Patent Application Laid-Open No. 2006-263721 or International Publication No. 2010/032808 can be used as it is.
  • the surface roughness of the polyvinylidene fluoride-based porous separation membrane to which the hydrophilization method of the present invention is applied is preferably 30 nm or less. This is because, in general, in a porous separation membrane of a hydrophobic material such as polyvinylidene fluoride, the larger the surface roughness, the larger the contact angle between the membrane surface and water. By setting the surface roughness of the polyvinylidene fluoride-based porous separation membrane to 30 nm or less, the effect of the hydrophilization method of the present invention can be maintained high.
  • the polyvinylidene fluoride-based porous separation membrane can be used in either a hollow fiber membrane or a flat membrane, but the hollow fiber membrane can be efficiently filled in a module and per unit volume. It is preferably used because it can increase the effective film area.
  • the method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane of the present invention includes a step of contacting the polyvinylidene fluoride-based porous separation membrane with a hydrophilizing agent and then contacting it with water (hydrophilization step A).
  • the hydrophilization step A Step 1: The hydrophilic agent comes into contact with the pore surface of the polyvinylidene fluoride-based porous separation membrane. Step 2: The hydrophilic agent penetrates into the pores. Step 3: The hydrophilizing agent filled in the pores attracts and replaces water. It has 3 steps of.
  • the wettability at the interface between the polyvinylidene fluoride-based porous separation membrane surface and the hydrophilic agent Becomes important.
  • the contact angle is a quantification of the wettability, and the contact angle is represented by Young's equation (1).
  • ⁇ S ⁇ L cos ⁇ + ⁇ LS ⁇ ⁇ ⁇ (1)
  • ⁇ Contact angle
  • ⁇ S Surface tension of solid
  • ⁇ L Surface tension of liquid
  • ⁇ LS Interfacial tension between liquid / solid
  • the hydrophilic agent in step 1 preferably has a small surface tension.
  • step 2 in which the hydrophilic agent permeates into the pores in step 2 can be expressed by the following equation (2) of the capillary phenomenon, assuming that the pores of the polyvinylidene fluoride-based porous separation membrane are capillaries. it can.
  • h 2 ⁇ L cos ⁇ / ⁇ gr ... (2) h: Capillary liquid level height, ⁇ L : Liquid surface tension, ⁇ : Contact angle, ⁇ : Liquid density, g: Gravity acceleration, r: Tube radius
  • the liquid level h of the capillary can be regarded as the penetration depth into the pores of the polyvinylidene fluoride-based porous separation membrane. That is, in order to increase the penetration depth of the hydrophilic agent into the pores in step 2, the surface tension of the hydrophilic agent is increased, and the contact angle between the hydrophilic agent and the surface of the polyvinylidene fluoride-based porous separation membrane is adjusted. It is important to make it smaller and reduce the density of the hydrophilic agent.
  • the hydrophilizing agent having a well-balanced surface tension Selection is important.
  • the compatibility between the hydrophilic agent and water is important in order to proceed with the replacement efficiently.
  • an index of compatibility for example, when the hydrophilic agent is an aqueous solution of a hydrophilic resin, the solubility of the hydrophilic resin can be used, and when the hydrophilic agent is an aqueous solution of a surfactant, an HLB value can be used. ..
  • the HLB value is an index showing the balance between hydrophilicity and lipophilicity.
  • Oda described in "Introduction to Surfactants” [published by Sanyo Chemical Industries, Ltd. in 2007, by Takehiko Fujimoto] on page 212. It is a value calculated from the ratio of the organic value and the inorganic value of the organic compound by the method.
  • HLB value 10 x (inorganic value) / (organic value)
  • organic value and the inorganic value for deriving the HLB value can be calculated using the values in the table described on page 213 of the above-mentioned "Introduction to Surfactants".
  • thermosetting resin epoxy that is gradually cured by mixing a main agent and a curing agent. Resin or urethane resin is used.
  • the present inventors have conducted a diligent study in consideration of the hydrophilization step of the polyvinylidene fluoride-based porous separation membrane composed of these steps and the influence on other members in water treatment applications.
  • a polyvinylidene fluoride-based porous separation membrane having a pore size of 1 to 20 nm and a contact angle between the surface and water of 80 to 110 °, a surfactant is contained, the surface tension is 30 to 45 mN / m, and the density is high. It has been found that the polyvinylidene-based porous separation membrane is satisfactorily hydrophilized by being immersed in a hydrophilic agent of 1,000 to 1.010 g / cm 3 and then contacting with water.
  • the surface tension of the hydrophilic agent is less than 30 mN / m, the surface of the polyvinylidene fluoride-based porous separation membrane has good wettability and begins to become familiar immediately, but the penetration into the inside of the polyvinylidene fluoride-based porous separation membrane is slow. As a result, the hydrophilic effect is reduced.
  • the surface tension of the hydrophilizing agent exceeds 45 mN / m, the wettability with the polyvinylidene fluoride-based porous separation membrane is poor, and the hydrophilicizing effect is reduced.
  • the surface tension of the hydrophilic agent is preferably 33 to 43 mN / m, more preferably 35 to 39 mN / m.
  • Density of hydrophilizing agent is preferably 1.000 ⁇ 1.008g / cm 3, more preferably 1.001 ⁇ 1.005g / cm 3.
  • the surface tension and density can be measured by the method described in the examples.
  • the hydrophilic agent in the present invention is preferably an aqueous solution of a nonionic surfactant having an HLB value of 14 or more and less than 20.
  • the HLB value is a value indicating the degree of affinity between water and oil of a surfactant.
  • HBL 0 for paraffins having no hydrophilic group
  • HLB 20 for polyethylene glycol having only a hydrophilic group
  • 1 to 1 to It is set in the range of 20.
  • the HLB value is less than 14
  • the compatibility between the surfactant and water becomes low, and the hydrophilicity effect becomes particularly low.
  • the HLB value of the nonionic surfactant is more preferably 14 or more and less than 19, and even more preferably 14.5 or more and less than 18.
  • the hydrophilic agent in the present invention is preferably an aqueous solution containing 3 to 10% by mass of the above nonionic surfactant.
  • concentration of the nonionic surfactant is less than 3% by mass, the hydrophilic effect in the present invention is small, and when the concentration of the ionic surfactant exceeds 10% by mass, the density of the hydrophilic agent becomes too high. , It takes time to replace with water in step 3.
  • the flash point of the nonionic surfactant is preferably 250 ° C. or higher, more preferably 260 to 300 ° C., from the viewpoint of safety and handleability.
  • hydrophilic agent in the present invention it is preferable to use a relatively high concentration (for example, 3 to 10% by mass) of a surfactant.
  • a surfactant usually form micelles above a certain concentration in aqueous solution. This concentration is called the critical micelle concentration, and since the surface tension hardly changes even if the concentration is higher than that, a high-concentration aqueous surfactant solution is rarely used.
  • the high-concentration aqueous surfactant solution has a high density, it becomes difficult to permeate in step 2 of the hydrophilic step A, and it becomes difficult to replace it with water in step 3. Therefore, the polyvinylidene fluoride-based porous separation of the present invention is difficult. It was not actively used in the process of hydrophilizing the membrane.
  • the average pore size of the surface is as small as 1 to 20 nm, and the contact angle between the surface and water is 80 to 110 °, which is a highly hydrophobic polyvinylidene fluoride-based porous separation membrane. It was found that a high-concentration surfactant aqueous solution having a high surface tension and a high density has a higher hydrophilic effect than a low-concentration surfactant aqueous solution.
  • the wettability to the surface of the polyvinylidene fluoride-based porous separation membrane does not change, and the hydrophilicity is high with a high-concentration surfactant that makes it difficult for the polyvinylidene fluoride-based porous separation membrane to penetrate into the pores due to high density.
  • the reason for this is unknown, but it is considered that the hydrophilization step A (steps 1 to 3) is well-balanced.
  • a good hydrophilic effect can be obtained by using a 3 to 10% by mass aqueous solution of a nonionic surfactant having an HLB value of 14 or more and less than 20 as a hydrophilic agent.
  • a surfactant containing a polyoxyethylene sorbitan fatty acid ester having an HLB value of 16 or more and less than 20 it is more preferable to use an aqueous solution of a surfactant containing a polyoxyethylene sorbitan fatty acid ester having an HLB value of 16 or more and less than 20 as a main component.
  • the concentration of the polyoxyethylene sorbitan fatty acid ester having an HLB value of 16 or more and less than 20 in the hydrophilizing agent is preferably 3 to 8% by mass, more preferably 3 to 5% by mass.
  • the HLB value of the polyoxyethylene sorbitan fatty acid ester is preferably 16.3 or more and less than 18, and more preferably 16.5 or more and less than 17.
  • Polyoxyethylene sorbitan fatty acid ester has an HLB value of 16 or more and has a high affinity with water, so that the aqueous solution does not suspend even at a high concentration and becomes a homogeneous state, and the effect as a hydrophilic agent becomes higher. Further, the polyoxyethylene sorbitan fatty acid ester is considered to have a good substitution efficiency even in the water substitution step of the above step 3 because of its high affinity with water.
  • the water permeability performance expression rate of the hydrophilic agent calculated in the examples is preferably 90% or more, assuming actual use.
  • Scan mode ScanAsyst Probe: Silicon cantilever (manufactured by Bruker AXS; ScanAsyst-Air) Scanning range: 2.5 ⁇ m x 2.5 ⁇ m Scanning speed: 0.5Hz Number of pixels: 256 x 256 Measurement temperature: 25 ° C
  • the pure water permeability of the hydrophilized porous separation membrane was measured by the following method, and the pure water permeability A was calculated.
  • Distilled water was supplied to the porous separation membrane at a temperature of 25 ° C. and a filtration differential pressure of 10 kPa for 1 hour to filter the entire amount, and the obtained permeated water amount (m 3 ) was measured for a unit time (h) and. It was calculated by converting it into a numerical value per unit film area (m 2 ) and further converting it into a pressure (50 kPa).
  • the composite membrane having a support in addition to the porous separation membrane the entire composite membrane including the support was evaluated.
  • Water permeability performance expression rate of the hydrophilic agent (pure water permeability A / pure water permeability B) x 100
  • Example 1 A vinylidene fluoride homopolymer having a weight average molecular weight of 417,000 and ⁇ -butyrolactone were dissolved at a temperature of 170 ° C. at a ratio of 38% by mass and 62% by mass, respectively, to obtain a polymer solution.
  • This polymer solution is discharged from the mouthpiece with ⁇ -butyrolactone as a hollow part-forming liquid, and solidified in a cooling bath consisting of an 80% by mass aqueous solution of ⁇ -butyrolactone at a temperature of 20 ° C. to form a hollow fiber membrane M10 having a spherical structure.
  • a cooling bath consisting of an 80% by mass aqueous solution of ⁇ -butyrolactone at a temperature of 20 ° C.
  • a polymer solution was prepared by mixing and dissolving at a temperature of 95 ° C. at a ratio of mass%. This polymer solution was uniformly applied to the surface of the hollow fiber membrane M10, and immediately coagulated in a coagulation bath of 100% water at 25 ° C. to form a three-dimensional network structure layer on the spherical structure layer. A hollow fiber membrane M11 was produced.
  • the obtained hollow fiber membrane M11 was dried in a vacuum dryer at 25 ° C. for 24 hours to obtain a porous separation membrane applied to the present invention.
  • the surfactant Ionet T-20C polyoxyethylene sorbitan fatty acid ester-based nonionic surfactant, main component: polyoxyethylene (20) sorbitan monolaurate, HLB value 16.7, ignition point 297 ° C.
  • a hydrophilizing agent consisting of a 5% by mass aqueous solution of the above was prepared. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
  • Example 2 Surfactant Leodor TW-L120 (polyoxyethylene sorbitan fatty acid ester-based nonionic surfactant, main component: polyoxyethylene (20) sorbitan monolaurate, HLB value 16.7, ignition point 297 ° C) 3
  • a hydrophilic agent composed of a mass% aqueous solution was used. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
  • Example 3 From a 5% by mass aqueous solution of the surfactant Ionet T-60V (polyoxyethylene sorbitan fatty acid ester-based nonionic surfactant, main component: polyoxyethylene sorbitan stearate, HLB value 14.9, ignition point 277 ° C) The same operation as in Example 1 was carried out except that the hydrophilic agent was used. This hydrophilizing agent contained an insoluble component in a cloudy suspension solution.
  • the surfactant Ionet T-60V polyoxyethylene sorbitan fatty acid ester-based nonionic surfactant, main component: polyoxyethylene sorbitan stearate, HLB value 14.9, ignition point 277 ° C
  • Example 4 Uses a hydrophilic agent consisting of a 10% by mass aqueous solution of the surfactant Naroacty CL400 (synthetic alcohol-based nonionic surfactant, main component: polyoxyethylene alkyl ether, HLB value 17.8, flash point 262 ° C). The same operation as in Example 1 was performed except that there was a problem. This hydrophilic agent was a colorless transparent solution with no insoluble components.
  • Naroacty CL400 synthetic alcohol-based nonionic surfactant, main component: polyoxyethylene alkyl ether, HLB value 17.8, flash point 262 ° C
  • Example 5 Hydrophile consisting of 10% by mass aqueous solution of surfactant New Pole PE-68 (pluronic nonionic surfactant, main component: polyoxyethylene polyoxypropylene block polymer, HLB value 15.6, ignition point 279 ° C) The same operation as in Example 1 was carried out except that the agent was used. This hydrophilic agent was a colorless transparent solution with no insoluble components.
  • surfactant New Pole PE-68 plural nonionic surfactant, main component: polyoxyethylene polyoxypropylene block polymer, HLB value 15.6, ignition point 279 ° C
  • Example 6 A hollow fiber membrane M10 was produced in the same manner as in Example 1.
  • the obtained hollow fiber membrane M61 was washed with water to remove the surfactant and N-methyl-2-pyrrolidone, and then dried in a vacuum dryer at 25 ° C. for 24 hours to obtain a porous separation membrane applied to the present invention. It was.
  • hydrophilic agent composed of a 10% by mass aqueous solution of the surfactant Ionet T-20C was prepared.
  • This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
  • Example 7 A hollow fiber membrane M10 was produced in the same manner as in Example 1.
  • the obtained hollow fiber membrane M71 was washed with water to remove the surfactant and N-methyl-2-pyrrolidone, and then dried in a vacuum dryer at 25 ° C. for 24 hours to obtain a porous separation membrane applied to the present invention. It was.
  • hydrophilic agent composed of a 10% by mass aqueous solution of the surfactant Ionet T-20C was prepared.
  • This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
  • Example 1 The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 1% by mass aqueous solution of the surfactant Ionet T-20C was used. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
  • Example 2 The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 5% by mass aqueous solution of the surfactant Orphine EXP4036 (HLB value 13.0, no flash point) was used. This hydrophilizing agent contained an insoluble component in a cloudy suspension solution.
  • a hydrophilic agent composed of a 5% by mass aqueous solution of the surfactant Orphine EXP4036 (HLB value 13.0, no flash point) was used.
  • This hydrophilizing agent contained an insoluble component in a cloudy suspension solution.
  • Example 3 The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 10% by mass aqueous solution of the surfactant Orphine EXP4036 (HLB value 13.0, no flash point) was used. This hydrophilizing agent contained an insoluble component in a cloudy suspension solution.
  • Example 4 The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 3% by mass aqueous solution of polyvinylpyrrolidone k-30 was used. This hydrophilic agent was a colorless transparent solution with no insoluble components.
  • the method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane of the present invention can be used in water treatment fields such as drinking water production, water purification treatment, and wastewater treatment, pharmaceutical manufacturing fields, food industry fields, and blood purification membrane fields. it can.

Abstract

The present invention pertains to a method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane, the method comprising a step for bringing a polyvinylidene fluoride-based porous separation membrane into contact with a hydrophilizing agent and then with water, wherein: the separation membrane contains a polyvinylidene fluoride-based resin, and has an average pore diameter of 1-20 nm on the surface thereof and a contact angle between the surface and water of 80-110°; and the hydrophilizing agent contains a surfactant, and has a surface tension of 30-45 mN/m and a density of 1.000-1.010 g/cm3.

Description

ポリフッ化ビニリデン系多孔質分離膜の親水化方法Method for making polyvinylidene fluoride-based porous separation membrane hydrophilic
　本発明は、ポリフッ化ビニリデン系多孔質分離膜の親水化方法に関する。 The present invention relates to a method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane.
　近年、精密ろ過膜や限外ろ過膜等の多孔質分離膜は、浄水又は排水処理等の水処理分野、血液浄化等の医療分野、食品工業分野、下廃水処理等、様々な分野で利用されている。このような分野における多孔質分離膜は、繰り返し使用を前提としており、多様な薬品で洗浄又は殺菌されることから、耐薬品性、耐汚染性、耐候性及び耐酸化劣化性等が求められている。 In recent years, porous separation membranes such as microfiltration membranes and ultrafiltration membranes have been used in various fields such as water treatment fields such as water purification or wastewater treatment, medical fields such as blood purification, food industry fields, and wastewater treatment. ing. Porous separation membranes in such fields are premised on repeated use and are washed or sterilized with various chemicals. Therefore, chemical resistance, stain resistance, weather resistance, oxidation deterioration resistance, etc. are required. There is.
　多孔質分離膜の膜素材としては、要求特性から疎水性樹脂が多く選定されており、とりわけ耐薬品性に優れるポリフッ化ビニリデン系樹脂が好適に用いられている。また、近年では透過液の高品質化の要求が高まっており、細孔径が小さく、微粒子や有機物等の除去性能に優れる限外ろ過膜が選定されるケースが増えている。 Hydrophobic resins are often selected as the membrane material for the porous separation membrane because of the required characteristics, and polyvinylidene fluoride-based resin, which has excellent chemical resistance, is particularly preferably used. Further, in recent years, there has been an increasing demand for higher quality permeate, and there are increasing cases where an ultrafiltration membrane having a small pore diameter and excellent removal performance of fine particles and organic substances is selected.
　一方で、特に下廃水処理等の水処理用途においてはコストに対する要求も厳しく、その要求は多孔質分離膜やモジュールの価格に加え、輸送時における重量削減にも及んでいる。重量削減のためにはモジュール内に液体を封入しないこと、すなわち輸送先での親水化処理（透水性回復）が必要とされている。 On the other hand, especially in water treatment applications such as wastewater treatment, cost requirements are strict, and the requirements extend to weight reduction during transportation in addition to the price of porous separation membranes and modules. In order to reduce the weight, it is necessary not to enclose the liquid in the module, that is, the hydrophilization treatment (recovery of water permeability) at the transportation destination.
　多孔質分離膜の親水化方法としては、例えば多孔質分離膜をエタノールに浸漬した後、水で置換する方法（特許文献１）、多孔質分離膜を親水性樹脂水溶液に浸漬した後、水で置換する方法（特許文献２）、予め多孔質分離膜を界面活性剤水溶液に浸漬させた後に乾燥させておく方法（特許文献３）などが提案されている。 Examples of the method for hydrophilizing the porous separation membrane include a method of immersing the porous separation membrane in ethanol and then replacing it with water (Patent Document 1), and a method of immersing the porous separation membrane in a hydrophilic resin aqueous solution and then using water. A method of substituting (Patent Document 2), a method of immersing the porous separation membrane in an aqueous solution of a surfactant and then drying it (Patent Document 3) have been proposed.
　エタノールのような低級アルコールによる親水化では、十分に親水化が進み多孔質分離膜の透水性が良好に回復する。しかしながら、低級アルコールが低引火点を有するため取扱量の制限が厳しく、親水化処理可能なモジュール量には限界があった。 Hydrophilization with a lower alcohol such as ethanol promotes hydrophilicity sufficiently and the water permeability of the porous separation membrane is well restored. However, since the lower alcohol has a low flash point, the handling amount is strictly limited, and the amount of modules that can be hydrophilized is limited.
　一方、親水性樹脂水溶液による親水化では、親水性樹脂水溶液の引火点の問題が解決され、親水化剤の取扱量制限の問題がない。しかしながら、特に細孔の小さい限外ろ過膜においては溶液の膜細孔内への浸透が進みにくく、多孔質分離膜の透水性の回復性が低い問題がある。 On the other hand, hydrophilization with a hydrophilic resin aqueous solution solves the problem of the flash point of the hydrophilic resin aqueous solution, and there is no problem of limiting the handling amount of the hydrophilic agent. However, especially in the ultrafiltration membrane having small pores, it is difficult for the solution to penetrate into the membrane pores, and there is a problem that the water permeability of the porous separation membrane is not recoverable.
　多孔質分離膜に界面活性剤を保持させた後、乾燥させる親水化方法では、多孔質分離膜モジュールを製造した後に、乾燥したモジュール内の多孔質分離膜をエタノール水溶液などにより親水化させ、さらに界面活性剤水溶液に浸漬、置換、乾燥する工程が必要であり、工程が煩雑になる問題がある。 In the hydrophilization method in which the surfactant is retained in the porous separation membrane and then dried, the porous separation membrane module is produced, and then the porous separation membrane in the dried module is hydrophilized with an aqueous ethanol solution or the like, and further. A step of immersing, replacing, and drying in an aqueous surfactant solution is required, which causes a problem that the step becomes complicated.
日本国特開２００６－６３０９５号公報Japanese Patent Application Laid-Open No. 2006-63095 日本国特開平８－１３１７９３号公報Japanese Patent Application Laid-Open No. 8-131793 日本国特開昭６３－２７７２５１号公報Japanese Patent Application Laid-Open No. 63-277251
　本発明の目的は、ポリフッ化ビニリデン系多孔質分離膜を簡便に親水化する方法を提供することである。 An object of the present invention is to provide a method for easily hydrophilizing a polyvinylidene fluoride-based porous separation membrane.
　本発明者らは、前記課題を解決すべく鋭意研究し実験を重ねた結果、ポリフッ化ビニリデン系多孔質分離膜に対し、特定の親水化剤を用いることにより上記課題を解決できることを見出し、本発明を完成するに至ったものである。 As a result of diligent research and experiments to solve the above problems, the present inventors have found that the above problems can be solved by using a specific hydrophilicizing agent for a polyvinylidene fluoride-based porous separation membrane. This is what led to the completion of the invention.
　すなわち本発明は以下のとおりのものである。
［１］ポリフッ化ビニリデン系多孔質分離膜に対し、親水化剤を接触させた後、水を接触させる工程を有する、ポリフッ化ビニリデン系多孔質分離膜の親水化方法であって、
　前記ポリフッ化ビニリデン系多孔質分離膜は、ポリフッ化ビニリデン系樹脂を含み、表面の平均孔径が１～２０ｎｍであり、表面と水との接触角が８０～１１０°であり、
　前記親水化剤は、界面活性剤を含み、表面張力が３０～４５ｍＮ／ｍであり、密度が１．０００～１．０１０ｇ／ｃｍ3である、ポリフッ化ビニリデン系多孔質分離膜の親水化方法。
［２］前記ポリフッ化ビニリデン系多孔質分離膜の表面の平均孔径が５～２０ｎｍである、［１］に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。
［３］前記親水化剤は、非イオン性界面活性剤を３～１０質量％含む水溶液であり、
　前記非イオン性界面活性剤のＨＬＢ値が１４以上２０未満である、［１］又は［２］に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。
［４］前記非イオン性界面活性剤は、ポリオキシエチレンソルビタン脂肪酸エステルを主成分とし、ＨＬＢ値が１６以上２０未満である、［３］に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。
［５］前記非イオン性界面活性剤の引火点が２５０℃以上である、［３］又は［４］に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。 That is, the present invention is as follows.
[1] A method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane, which comprises a step of contacting a polyvinylidene fluoride-based porous separation membrane with a hydrophilic agent and then contacting water.
The polyvinylidene fluoride-based porous separation membrane contains a polyvinylidene fluoride-based resin, has an average pore diameter of 1 to 20 nm on the surface, and has a contact angle between the surface and water of 80 to 110 °.
The hydrophilic agent is a method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane, which contains a surfactant, has a surface tension of 30 to 45 mN / m, and has a density of 1.000 to 1.010 g / cm 3. ..
[2] The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to [1], wherein the average pore size on the surface of the polyvinylidene fluoride-based porous separation membrane is 5 to 20 nm.
[3] The hydrophilic agent is an aqueous solution containing 3 to 10% by mass of a nonionic surfactant.
The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to [1] or [2], wherein the HLB value of the nonionic surfactant is 14 or more and less than 20.
[4] The polyvinylidene fluoride-based porous separation membrane according to [3], wherein the nonionic surfactant contains a polyoxyethylene sorbitan fatty acid ester as a main component and has an HLB value of 16 or more and less than 20. Method.
[5] The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to [3] or [4], wherein the nonionic surfactant has a flash point of 250 ° C. or higher.
　本発明にかかるポリフッ化ビニリデン系多孔質分離膜の親水化方法によれば、表面細孔が微細なポリフッ化ビニリデン系樹脂を含む疎水性多孔質分離膜を、所定の親水化剤に浸漬することで、多孔質分離膜の細孔内に親水化剤が効率的に浸透し、その後、親水化剤を水に置換することで多孔質分離膜全体が親水化される。 According to the method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to the present invention, a hydrophobic porous separation membrane containing a polyvinylidene fluoride-based resin having fine surface pores is immersed in a predetermined hydrophilic agent. Then, the hydrophilic agent efficiently permeates into the pores of the porous separation membrane, and then the entire porous separation membrane is hydrophilized by replacing the hydrophilic agent with water.
　従って、低引火点を有する低級アルコールを大量に使用するといった安全面の問題も無く、乾燥した膜を用いて作製したモジュールに親水化剤を付与、乾燥させるといった工程煩雑化の問題もないため、親水化工程が簡素化されるといった効果を奏する。 Therefore, there is no safety problem such as using a large amount of lower alcohol having a low flash point, and there is no problem of complication of the process such as adding a hydrophilic agent to a module manufactured by using a dried film and drying it. It has the effect of simplifying the hydrophilization process.
　本発明の親水化方法は、ポリフッ化ビニリデン系多孔質分離膜に対し、親水化剤を接触させた後、水を接触させる工程（親水化工程Ａ）を有する。 The hydrophilization method of the present invention includes a step of contacting the polyvinylidene fluoride-based porous separation membrane with a hydrophilizing agent and then contacting water (hydrophilization step A).
　ポリフッ化ビニリデン系多孔質分離膜は、ポリフッ化ビニリデン系樹脂を含み、表面の平均孔径が１～２０ｎｍであり、表面と水との接触角が８０～１１０°である。 The polyvinylidene fluoride-based porous separation membrane contains a polyvinylidene fluoride-based resin, has an average pore diameter of 1 to 20 nm on the surface, and has a contact angle between the surface and water of 80 to 110 °.
　親水化剤は、界面活性剤を含み、表面張力が３０～４５ｍＮ／ｍであり、密度が１．０００～１．０１０ｇ／ｃｍ3である。 The hydrophilizing agent contains a surfactant, has a surface tension of 30 to 45 mN / m, and has a density of 1.000 to 1.010 g / cm 3 .
　親水化工程Ａは、平均孔径が２０ｎｍより大きいポリフッ化ビニリデン系多孔質分離膜、表面と水との接触角が８０°未満のポリフッ化ビニリデン系多孔質分離膜にも適用可能である。しかしながら、親水化工程Ａを、表面の平均孔径が１～２０ｎｍであり、表面と水との接触角が８０～１１０°であるポリフッ化ビニリデン系多孔質分離膜に用いることで、他の親水化剤では得られない効果が得られる。 The hydrophilization step A can also be applied to a polyvinylidene fluoride-based porous separation membrane having an average pore diameter of larger than 20 nm and a polyvinylidene fluoride-based porous separation membrane having a contact angle between the surface and water of less than 80 °. However, by using the hydrophilic step A for a polyvinylidene fluoride-based porous separation membrane having an average pore diameter of 1 to 20 nm on the surface and a contact angle between the surface and water of 80 to 110 °, other hydrophilicization is performed. An effect that cannot be obtained with an agent can be obtained.
　本発明において、ポリフッ化ビニリデン系樹脂とは、フッ化ビニリデンホモポリマーおよびフッ化ビニリデン共重合体のうちの少なくとも１つを含有する樹脂を意味する。ポリフッ化ビニリデン系樹脂は、複数の種類のフッ化ビニリデン共重合体を含有してもよい。 In the present invention, the polyvinylidene fluoride-based resin means a resin containing at least one of a vinylidene fluoride homopolymer and a vinylidene fluoride copolymer. The polyvinylidene fluoride-based resin may contain a plurality of types of vinylidene fluoride copolymers.
　フッ化ビニリデン共重合体とは、フッ化ビニリデン残基構造を有するポリマーであり、典型的にはフッ化ビニリデンモノマーとそれ以外のフッ素系モノマーなどとの共重合体である。このような共重合体としては、例えば、フッ化ビニル、四フッ化エチレン、六フッ化プロピレン、三フッ化塩化エチレンから選ばれた１種類以上のモノマーとフッ化ビニリデンとの共重合体が挙げられる。 The vinylidene fluoride copolymer is a polymer having a vinylidene fluoride residue structure, and is typically a copolymer of a vinylidene fluoride monomer and another fluorine-based monomer or the like. Examples of such a copolymer include a copolymer of one or more types of monomers selected from vinyl fluoride, ethylene tetrafluoroethylene, propylene hexafluoride, and ethylene trifluoride, and vinylidene fluoride. Be done.
　また、本発明の効果を損なわない程度に、前記フッ素系モノマー以外の例えばエチレンなどのモノマーが共重合されていてもよい。 Further, a monomer other than the fluorine-based monomer such as ethylene may be copolymerized to the extent that the effect of the present invention is not impaired.
　また、本発明で用いるポリフッ化ビニリデン系樹脂の重量平均分子量は、要求される多孔質分離膜の強度と透水性能によって適宜選択すればよいが、重量平均分子量が大きくなると透水性能が低下し、重量平均分子量が小さくなると強度が低下する。このため、ポリフッ化ビニリデン系樹脂の重量平均分子量は５万以上１００万以下が好ましい。ポリフッ化ビニリデン系多孔質分離膜が薬液洗浄に晒される水処理用途の場合、ポリフッ化ビニリデン系樹脂の重量平均分子量は１０万以上７０万以下が好ましく、さらに１５万以上６０万以下が好ましい。 Further, the weight average molecular weight of the polyvinylidene fluoride resin used in the present invention may be appropriately selected depending on the required strength and water permeability of the porous separation membrane, but as the weight average molecular weight increases, the water permeability deteriorates and the weight The smaller the average molecular weight, the lower the strength. Therefore, the weight average molecular weight of the polyvinylidene fluoride-based resin is preferably 50,000 or more and 1 million or less. For water treatment applications in which the polyvinylidene fluoride-based porous separation membrane is exposed to chemical washing, the weight average molecular weight of the polyvinylidene fluoride-based resin is preferably 100,000 or more and 700,000 or less, and more preferably 150,000 or more and 600,000 or less.
　ポリフッ化ビニリデン系多孔質分離膜は、ポリフッ化ビニリデン系樹脂を主成分として含有することが好ましい。ポリフッ化ビニリデン系多孔質分離膜においてポリフッ化ビニリデン系樹脂が占める割合は、８０質量％以上が好ましく、９０質量％以上がより好ましく、９５質量％以上であることが更に好ましい。また、ポリフッ化ビニリデン系多孔質分離膜は、ポリフッ化ビニリデン系樹脂のみで構成されていてもよい。 The polyvinylidene fluoride-based porous separation membrane preferably contains a polyvinylidene fluoride-based resin as a main component. The proportion of the polyvinylidene fluoride-based resin in the polyvinylidene fluoride-based porous separation membrane is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. Further, the polyvinylidene fluoride-based porous separation membrane may be composed of only a polyvinylidene fluoride-based resin.
　ポリフッ化ビニリデン系多孔質分離膜は、親水性樹脂をさらに含有することにより、純水透過性能および耐汚れ性が向上する。そのため、ポリフッ化ビニリデン系樹脂と親水性樹脂をブレンドすることも好適に実施される。ここで、親水性樹脂とは水と親和性の高いポリマーのことであり、水に溶解するか、または、水に対する接触角がポリフッ化ビニリデン系樹脂よりも小さいポリマーを指す。 The polyvinylidene fluoride-based porous separation membrane further contains a hydrophilic resin to improve pure water permeation performance and stain resistance. Therefore, blending a polyvinylidene fluoride resin and a hydrophilic resin is also preferably performed. Here, the hydrophilic resin is a polymer having a high affinity with water, and refers to a polymer that is soluble in water or has a contact angle with water smaller than that of a polyvinylidene fluoride resin.
　親水性樹脂としては、ポリビニルピロリドン系樹脂、ポリエチレングリコール、ポリビニルアルコール、アクリル系樹脂（ポリアクリル酸、ポリメタクリル酸メチルなど）、セルロースエステル系樹脂、ポリアクリロニトリル、ポリスルホンなどが好ましい例として挙げられる。またエチレン、プロピレン、フッ化ビニリデンなどのオレフィン系モノマーと親水基を共重合した親水化ポリオレフィン系樹脂も親水性樹脂として使用することができる。これらの中でもとりわけ、ポリビニルピロリドン系樹脂、アクリル系樹脂およびセルロースエステル系樹脂から選ばれる少なくとも１種以上を含有させることが耐汚れ性の向上の点で好ましい。 Preferred examples of the hydrophilic resin include polyvinylpyrrolidone-based resin, polyethylene glycol, polyvinyl alcohol, acrylic-based resin (polyacrylic acid, polymethylmethacrylate, etc.), cellulose ester-based resin, polyacrylonitrile, polysulfone, and the like. Further, a hydrophilic polyolefin resin obtained by copolymerizing an olefin monomer such as ethylene, propylene or vinylidene fluoride with a hydrophilic group can also be used as the hydrophilic resin. Among these, it is preferable to contain at least one selected from polyvinylpyrrolidone-based resin, acrylic-based resin, and cellulose ester-based resin from the viewpoint of improving stain resistance.
　本発明の親水化方法が適用されるポリフッ化ビニリデン系多孔質分離膜は、表面の平均孔径が１～２０ｎｍで、表面と水との接触角が８０～１１０°である。 The polyvinylidene fluoride-based porous separation membrane to which the hydrophilization method of the present invention is applied has an average pore diameter of 1 to 20 nm on the surface and a contact angle between the surface and water of 80 to 110 °.
　ポリフッ化ビニリデン系多孔質分離膜の表面の平均孔径は、小さい方が除去対象物の除去率が高く、透水性が低くなる傾向にあるが、除去率と透水性のバランスから３～２０ｎｍが好ましく、５～２０ｎｍがより好ましく、８～２０ｎｍがさらに好ましく、１０～２０ｎｍが特に好ましい。
　ポリフッ化ビニリデン系多孔質分離膜の表面と水との接触角は、８５～１０５°が好ましく、８８～１０２°がより好ましい。 The smaller the average pore size of the surface of the polyvinylidene fluoride-based porous separation membrane, the higher the removal rate of the object to be removed and the lower the water permeability, but 3 to 20 nm is preferable from the balance between the removal rate and the water permeability. 5 to 20 nm is more preferable, 8 to 20 nm is further preferable, and 10 to 20 nm is particularly preferable.
The contact angle between the surface of the polyvinylidene fluoride-based porous separation membrane and water is preferably 85 to 105 °, more preferably 88 to 102 °.
　平均孔径及び水との接触角は、実施例に記載の方法で測定できる。 The average pore size and contact angle with water can be measured by the method described in Examples.
　このポリフッ化ビニリデン系多孔質分離膜の製造方法は特に制限されないが、膜表面の平均細孔径を小さく制御するため、熱誘起相分離法、非溶媒誘起相分離法、あるいはそれらの複合プロセスが好ましい。その中でも、非溶媒誘起相分離法が精密な細孔径制御が可能となるため、特に好ましい。具体的なポリフッ化ビニリデン系多孔質分離膜の製造方法としては、日本国特開２００６－２６３７２１号公報や国際公開第２０１０／０３２８０８号で開示されている公知の方法をそのまま用いることができる。 The method for producing this polyvinylidene fluoride-based porous separation membrane is not particularly limited, but a heat-induced phase separation method, a non-solvent-induced phase separation method, or a composite process thereof is preferable in order to control the average pore diameter on the membrane surface to be small. .. Among them, the non-solvent-induced phase separation method is particularly preferable because it enables precise pore size control. As a specific method for producing a polyvinylidene fluoride-based porous separation membrane, a known method disclosed in Japanese Patent Application Laid-Open No. 2006-263721 or International Publication No. 2010/032808 can be used as it is.
　また、本発明の親水化方法が適用されるポリフッ化ビニリデン系多孔質分離膜の表面粗さは３０ｎｍ以下が好ましい。一般的にポリフッ化ビニリデンのような疎水性材料の多孔質分離膜においては、表面粗さが大きくなるほど膜表面と水との接触角が大きくなるためである。ポリフッ化ビニリデン系多孔質分離膜の表面粗さを３０ｎｍ以下とすることで、本発明の親水化方法の効果を高く維持できる。 Further, the surface roughness of the polyvinylidene fluoride-based porous separation membrane to which the hydrophilization method of the present invention is applied is preferably 30 nm or less. This is because, in general, in a porous separation membrane of a hydrophobic material such as polyvinylidene fluoride, the larger the surface roughness, the larger the contact angle between the membrane surface and water. By setting the surface roughness of the polyvinylidene fluoride-based porous separation membrane to 30 nm or less, the effect of the hydrophilization method of the present invention can be maintained high.
　本発明においてポリフッ化ビニリデン系多孔質分離膜は、中空糸膜および平膜のいずれの形態でも用いることができるが、中空糸膜は効率良くモジュールに充填することが可能であり、単位体積当たりの有効膜面積を増大させることができるため好ましく用いられる。 In the present invention, the polyvinylidene fluoride-based porous separation membrane can be used in either a hollow fiber membrane or a flat membrane, but the hollow fiber membrane can be efficiently filled in a module and per unit volume. It is preferably used because it can increase the effective film area.
　本発明のポリフッ化ビニリデン系多孔質分離膜の親水化方法は、ポリフッ化ビニリデン系多孔質分離膜を親水化剤に接触させた後、水を接触させる工程（親水化工程Ａ）を有する。 The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane of the present invention includes a step of contacting the polyvinylidene fluoride-based porous separation membrane with a hydrophilizing agent and then contacting it with water (hydrophilization step A).
　親水化工程Ａは具体的に、
　　ステップ１：ポリフッ化ビニリデン系多孔質分離膜の細孔表面に親水化剤が接触する。
　　ステップ２：細孔内に親水化剤が浸透する。
　　ステップ３：細孔内に充填された親水化剤が水を呼び込み置換する。
の３ステップを有する。 Specifically, the hydrophilization step A
Step 1: The hydrophilic agent comes into contact with the pore surface of the polyvinylidene fluoride-based porous separation membrane.
Step 2: The hydrophilic agent penetrates into the pores.
Step 3: The hydrophilizing agent filled in the pores attracts and replaces water.
It has 3 steps of.
　ステップ１の細孔表面に親水化剤が接触する段階において、細孔表面に親水化剤を効率よく接触させるためには、ポリフッ化ビニリデン系多孔質分離膜表面と親水化剤の界面における濡れ性が重要となってくる。濡れ性を定量化したものが接触角であり、接触角はヤングの式（１）で示される。 In order to efficiently bring the hydrophilic agent into contact with the pore surface at the stage of contacting the hydrophilic agent with the pore surface in step 1, the wettability at the interface between the polyvinylidene fluoride-based porous separation membrane surface and the hydrophilic agent Becomes important. The contact angle is a quantification of the wettability, and the contact angle is represented by Young's equation (1).
　　γS＝γLｃｏｓθ＋γLS・・・（１）
　θ：接触角、γS：固体の表面張力、γL：液体の表面張力、γLS：液体／固体間の界面張力 γ S = γ L cos θ + γ LS・ ・ ・ (1)
θ: Contact angle, γ S : Surface tension of solid, γ L : Surface tension of liquid, γ LS : Interfacial tension between liquid / solid
　液体の表面張力が小さい程、接触角は小さくなり、濡れ性が良好になるため、ステップ１における親水化剤としては表面張力の小さいものが好ましい。 The smaller the surface tension of the liquid, the smaller the contact angle and the better the wettability. Therefore, the hydrophilic agent in step 1 preferably has a small surface tension.
　ステップ２の細孔内に親水化剤が浸透する段階は、ポリフッ化ビニリデン系多孔質分離膜の細孔を毛細管（キャピラリー）と見なすと、下記の毛細管現象の式（２）で表現することができる。 The step in which the hydrophilic agent permeates into the pores in step 2 can be expressed by the following equation (2) of the capillary phenomenon, assuming that the pores of the polyvinylidene fluoride-based porous separation membrane are capillaries. it can.
　　ｈ＝２γLｃｏｓθ／ρｇｒ・・・（２）
　ｈ：毛細管の液面高さ、γL：液体の表面張力、θ：接触角、ρ：液体の密度、ｇ：重力加速度、ｒ：管の半径 h = 2γ L cos θ / ρgr ... (2)
h: Capillary liquid level height, γ L : Liquid surface tension, θ: Contact angle, ρ: Liquid density, g: Gravity acceleration, r: Tube radius
　ここで、毛細管の液面高さｈは、ポリフッ化ビニリデン系多孔質分離膜の細孔内部への浸透深さと見なせる。すなわち、ステップ２において細孔への親水化剤の浸透深さを大きくするためには、親水化剤の表面張力を大きくし、親水化剤とポリフッ化ビニリデン系多孔質分離膜表面の接触角を小さくし、親水化剤の密度を小さくすることが重要である。 Here, the liquid level h of the capillary can be regarded as the penetration depth into the pores of the polyvinylidene fluoride-based porous separation membrane. That is, in order to increase the penetration depth of the hydrophilic agent into the pores in step 2, the surface tension of the hydrophilic agent is increased, and the contact angle between the hydrophilic agent and the surface of the polyvinylidene fluoride-based porous separation membrane is adjusted. It is important to make it smaller and reduce the density of the hydrophilic agent.
　ステップ１でポリフッ化ビニリデン系多孔質分離膜と親水化剤の接触性を高めるためには、親水化剤の表面張力を小さくすることが好ましく、ステップ２でポリフッ化ビニリデン系多孔質分離膜の細孔内部にまで親水化剤を浸透させるためには、表面張力を大きくすることが好ましいため、ポリフッ化ビニリデン系多孔質分離膜の親水化工程においては、バランスの良い表面張力を有する親水化剤の選定が重要である。 In order to improve the contact between the polyvinylidene-based porous separation membrane and the hydrophilic agent in step 1, it is preferable to reduce the surface tension of the hydrophilic agent, and in step 2, the fineness of the polyvinylidene-based porous separation membrane is fine. In order to allow the hydrophilizing agent to penetrate into the pores, it is preferable to increase the surface tension. Therefore, in the hydrophilization step of the polyvinylidene fluoride-based porous separation membrane, the hydrophilizing agent having a well-balanced surface tension Selection is important.
　さらに、ステップ３の親水化剤が水を呼び込み置換する段階においては、効率的に置換を進めるために親水化剤と水との相溶性が重要となる。相溶性の指標としては、例えば親水化剤が親水性樹脂の水溶液である場合は、親水性樹脂の溶解度を使用でき、親水化剤が界面活性剤の水溶液である場合は、ＨＬＢ値を使用できる。 Further, at the stage where the hydrophilic agent in step 3 calls in and replaces water, the compatibility between the hydrophilic agent and water is important in order to proceed with the replacement efficiently. As an index of compatibility, for example, when the hydrophilic agent is an aqueous solution of a hydrophilic resin, the solubility of the hydrophilic resin can be used, and when the hydrophilic agent is an aqueous solution of a surfactant, an HLB value can be used. ..
　ここでＨＬＢ値とは、親水性と親油性のバランスを示す指標であって、例えば「界面活性剤入門」〔２００７年三洋化成工業株式会社発行、藤本武彦著〕２１２頁に記載されている小田法によって、有機化合物の有機性の値と無機性の値との比率から計算された値である。 Here, the HLB value is an index showing the balance between hydrophilicity and lipophilicity. For example, Oda described in "Introduction to Surfactants" [published by Sanyo Chemical Industries, Ltd. in 2007, by Takehiko Fujimoto] on page 212. It is a value calculated from the ratio of the organic value and the inorganic value of the organic compound by the method.
　　ＨＬＢ値＝１０×（無機性の値）／（有機性の値）
　ＨＬＢ値を導き出すための有機性の値及び無機性の値については前記「界面活性剤入門」２１３頁に記載の表の値を用いて算出できる。 HLB value = 10 x (inorganic value) / (organic value)
The organic value and the inorganic value for deriving the HLB value can be calculated using the values in the table described on page 213 of the above-mentioned "Introduction to Surfactants".
　親水化剤の選定においては、ポリフッ化ビニリデン系多孔質分離膜以外の部材への影響も考慮する必要がある。通常、ポリフッ化ビニリデン系多孔質分離膜を水処理用途で用いる場合は、透過水への原水の漏洩を防ぐために、ポリフッ化ビニリデン系多孔質分離膜の一部を接着剤や樹脂で封止した、いわゆるモジュールやエレメントといった形状に加工される。 When selecting a hydrophilizing agent, it is necessary to consider the effect on members other than the polyvinylidene fluoride-based porous separation membrane. Normally, when a polyvinylidene fluoride-based porous separation membrane is used for water treatment, a part of the polyvinylidene fluoride-based porous separation membrane is sealed with an adhesive or resin in order to prevent leakage of raw water to permeated water. , So-called modules and elements are processed into shapes.
　上述の接着剤および樹脂はポリフッ化ビニリデン系多孔質分離膜内に含浸させた後に固化させる必要があるため、多くの場合は主剤と硬化剤を混合して徐々に硬化する熱架橋性樹脂のエポキシ樹脂やウレタン樹脂が用いられる。 Since the above-mentioned adhesives and resins need to be impregnated in a polyvinylidene-based porous separation film and then solidified, in many cases, a thermosetting resin epoxy that is gradually cured by mixing a main agent and a curing agent. Resin or urethane resin is used.
　しかしながら、これら混合系の熱硬化性樹脂は、その全量が反応することはなく樹脂内には未反応物が残存する。このため、本発明の親水化方法で用いる親水化剤の表面張力が小さく、濡れ性が高すぎる場合、これら樹脂からの未反応物の溶出が促進されて、樹脂の強度劣化やポリフッ化ビニリデン系多孔質分離膜との接着性の低下を引き起こす。よって、適切な表面張力の親水化剤を選定する必要がある。 However, the entire amount of these mixed thermosetting resins does not react, and unreacted substances remain in the resin. Therefore, when the surface tension of the hydrophilizing agent used in the hydrophilization method of the present invention is small and the wettability is too high, the elution of unreactants from these resins is promoted, resulting in deterioration of the strength of the resin and polyvinylidene fluoride. Causes a decrease in adhesiveness with the porous separation membrane. Therefore, it is necessary to select a hydrophilic agent having an appropriate surface tension.
　本発明者らは、これらのステップで構成されるポリフッ化ビニリデン系多孔質分離膜の親水化工程、および水処理用途における他部材への影響を考慮して鋭意検討を行った結果、表面の平均孔径が１～２０ｎｍ、表面と水との接触角が８０～１１０°のポリフッ化ビニリデン系多孔質分離膜に対しては、界面活性剤を含み、表面張力が３０～４５ｍＮ／ｍで、密度が１．０００～１．０１０ｇ／ｃｍ3の親水化剤に浸漬した後、水に接触させることでポリフッ化ビニリデン系多孔質分離膜が良好に親水化されることを見出した。 The present inventors have conducted a diligent study in consideration of the hydrophilization step of the polyvinylidene fluoride-based porous separation membrane composed of these steps and the influence on other members in water treatment applications. For a polyvinylidene fluoride-based porous separation membrane having a pore size of 1 to 20 nm and a contact angle between the surface and water of 80 to 110 °, a surfactant is contained, the surface tension is 30 to 45 mN / m, and the density is high. It has been found that the polyvinylidene-based porous separation membrane is satisfactorily hydrophilized by being immersed in a hydrophilic agent of 1,000 to 1.010 g / cm 3 and then contacting with water.
　親水化剤の表面張力が３０ｍＮ／ｍ未満の場合は、ポリフッ化ビニリデン系多孔質分離膜表面の濡れ性が良くすぐに馴染み始めるが、ポリフッ化ビニリデン系多孔質分離膜内部への浸透が遅く、結果的に親水化効果が小さくなる。親水化剤の表面張力が４５ｍＮ／ｍを超える場合は、ポリフッ化ビニリデン系多孔質分離膜との濡れ性が悪いため親水化効果が小さくなる。 When the surface tension of the hydrophilic agent is less than 30 mN / m, the surface of the polyvinylidene fluoride-based porous separation membrane has good wettability and begins to become familiar immediately, but the penetration into the inside of the polyvinylidene fluoride-based porous separation membrane is slow. As a result, the hydrophilic effect is reduced. When the surface tension of the hydrophilizing agent exceeds 45 mN / m, the wettability with the polyvinylidene fluoride-based porous separation membrane is poor, and the hydrophilicizing effect is reduced.
　親水化剤の表面張力は、３３～４３ｍＮ／ｍが好ましく、３５～３９ｍＮ／ｍがより好ましい。
　親水化剤の密度は、１．０００～１．００８ｇ／ｃｍ3が好ましく、１．００１～１．００５ｇ／ｃｍ3がより好ましい。 The surface tension of the hydrophilic agent is preferably 33 to 43 mN / m, more preferably 35 to 39 mN / m.
Density of hydrophilizing agent is preferably 1.000 ~ 1.008g / cm 3, more preferably 1.001 ~ 1.005g / cm 3.
　表面張力及び密度は、実施例に記載の方法で測定できる。 The surface tension and density can be measured by the method described in the examples.
　本発明における親水化剤は、具体的にはＨＬＢ値が１４以上２０未満の非イオン性界面活性剤の水溶液が好ましい。ＨＬＢ値は、界面活性剤の水と油との親和性程度を表す値であり、親水基を持たないパラフィン等はＨＢＬ＝０、親水基だけを持つポリエチレングリコール等はＨＬＢ＝２０と、１～２０の範囲で設定される。本発明においては、ＨＬＢ値が１４未満の場合、界面活性剤と水との相溶性が低くなり、特に親水化効果が低くなる。 Specifically, the hydrophilic agent in the present invention is preferably an aqueous solution of a nonionic surfactant having an HLB value of 14 or more and less than 20. The HLB value is a value indicating the degree of affinity between water and oil of a surfactant. HBL = 0 for paraffins having no hydrophilic group, HLB = 20 for polyethylene glycol having only a hydrophilic group, and 1 to 1 to It is set in the range of 20. In the present invention, when the HLB value is less than 14, the compatibility between the surfactant and water becomes low, and the hydrophilicity effect becomes particularly low.
　非イオン性界面活性剤のＨＬＢ値は、１４以上１９未満がより好ましく、１４．５以上１８未満がさらに好ましい。 The HLB value of the nonionic surfactant is more preferably 14 or more and less than 19, and even more preferably 14.5 or more and less than 18.
　本発明における親水化剤は、上記非イオン性界面活性剤を３～１０質量％含む水溶液であることが好ましい。非イオン性界面活性剤の濃度が３質量％未満の場合は本発明における親水化効果が小さく、イオン性界面活性剤の濃度が１０質量％を超える場合は親水化剤の密度が高くなりすぎて、ステップ３の水への置換に時間を要するようになる。 The hydrophilic agent in the present invention is preferably an aqueous solution containing 3 to 10% by mass of the above nonionic surfactant. When the concentration of the nonionic surfactant is less than 3% by mass, the hydrophilic effect in the present invention is small, and when the concentration of the ionic surfactant exceeds 10% by mass, the density of the hydrophilic agent becomes too high. , It takes time to replace with water in step 3.
　また、非イオン性界面活性剤の引火点は、安全性と取扱性の観点から、２５０℃以上が好ましく、２６０～３００℃がより好ましい。 Further, the flash point of the nonionic surfactant is preferably 250 ° C. or higher, more preferably 260 to 300 ° C., from the viewpoint of safety and handleability.
　本発明における親水化剤においては、比較的高濃度（例えば、３～１０質量％）の界面活性剤を用いることが好ましい。通常、界面活性剤は水溶液中で特定の濃度以上になるとミセルを形成する。この濃度は臨界ミセル濃度と呼ばれ、それ以上濃度を高くしても表面張力はほとんど変化しないため、高濃度の界面活性剤水溶液が好んで使用されることは少ない。 In the hydrophilic agent in the present invention, it is preferable to use a relatively high concentration (for example, 3 to 10% by mass) of a surfactant. Surfactants usually form micelles above a certain concentration in aqueous solution. This concentration is called the critical micelle concentration, and since the surface tension hardly changes even if the concentration is higher than that, a high-concentration aqueous surfactant solution is rarely used.
　また、高濃度の界面活性剤水溶液は密度が高くなるため、親水化工程Ａのステップ２において浸透し難くなり、ステップ３において水に置換し難くなるため、本発明のポリフッ化ビニリデン系多孔質分離膜の親水化工程に積極的に使用されることはなかった。 Further, since the high-concentration aqueous surfactant solution has a high density, it becomes difficult to permeate in step 2 of the hydrophilic step A, and it becomes difficult to replace it with water in step 3. Therefore, the polyvinylidene fluoride-based porous separation of the present invention is difficult. It was not actively used in the process of hydrophilizing the membrane.
　しかしながら、本発明者らは鋭意検討した結果、表面の平均孔径が１～２０ｎｍと小さく、表面と水との接触角が８０～１１０°と疎水性の高いポリフッ化ビニリデン系多孔質分離膜に対しては、表面張力が変化せず、密度も高い高濃度の界面活性剤水溶液の方が、低濃度の界面活性剤水溶液よりも親水化効果が高くなることを見出した。 However, as a result of diligent studies, the present inventors have found that the average pore size of the surface is as small as 1 to 20 nm, and the contact angle between the surface and water is 80 to 110 °, which is a highly hydrophobic polyvinylidene fluoride-based porous separation membrane. It was found that a high-concentration surfactant aqueous solution having a high surface tension and a high density has a higher hydrophilic effect than a low-concentration surfactant aqueous solution.
　ポリフッ化ビニリデン系多孔質分離膜表面に対する濡れ性も変化せず、高密度化のためにポリフッ化ビニリデン系多孔質分離膜細孔内に浸透し難くなる高濃度界面活性剤で親水化効果が高くなる理由は不明だが、親水化工程Ａ（ステップ１～３）のバランスが良いためと考えられる。 The wettability to the surface of the polyvinylidene fluoride-based porous separation membrane does not change, and the hydrophilicity is high with a high-concentration surfactant that makes it difficult for the polyvinylidene fluoride-based porous separation membrane to penetrate into the pores due to high density. The reason for this is unknown, but it is considered that the hydrophilization step A (steps 1 to 3) is well-balanced.
　本発明においては、上述のとおり、ＨＬＢ値が１４以上２０未満の非イオン性界面活性剤の３～１０質量％水溶液を親水化剤として用いることで良好な親水化効果が得られるが、その中でも特にＨＬＢ値が１６以上２０未満のポリオキシエチレンソルビタン脂肪酸エステルを主成分とする界面活性剤の水溶液を用いることがより好ましい。 In the present invention, as described above, a good hydrophilic effect can be obtained by using a 3 to 10% by mass aqueous solution of a nonionic surfactant having an HLB value of 14 or more and less than 20 as a hydrophilic agent. In particular, it is more preferable to use an aqueous solution of a surfactant containing a polyoxyethylene sorbitan fatty acid ester having an HLB value of 16 or more and less than 20 as a main component.
　親水化剤中のＨＬＢ値が１６以上２０未満のポリオキシエチレンソルビタン脂肪酸エステルの濃度は、３～８質量％が好ましく、３～５質量％がより好ましい。
　ポリオキシエチレンソルビタン脂肪酸エステルのＨＬＢ値は、１６．３以上１８未満が好ましく、１６．５以上１７未満がより好ましい。 The concentration of the polyoxyethylene sorbitan fatty acid ester having an HLB value of 16 or more and less than 20 in the hydrophilizing agent is preferably 3 to 8% by mass, more preferably 3 to 5% by mass.
The HLB value of the polyoxyethylene sorbitan fatty acid ester is preferably 16.3 or more and less than 18, and more preferably 16.5 or more and less than 17.
　ポリオキシエチレンソルビタン脂肪酸エステルは、ＨＬＢ値が１６以上で水との親和性が高いことで、高濃度においても水溶液が懸濁することなく均質な状態となり親水化剤としての効果がより高くなる。また、ポリオキシエチレンソルビタン脂肪酸エステルは、水との親和性が高いことにより、上記ステップ３の水置換工程においても良好な置換効率を有すると考えられる。 Polyoxyethylene sorbitan fatty acid ester has an HLB value of 16 or more and has a high affinity with water, so that the aqueous solution does not suspend even at a high concentration and becomes a homogeneous state, and the effect as a hydrophilic agent becomes higher. Further, the polyoxyethylene sorbitan fatty acid ester is considered to have a good substitution efficiency even in the water substitution step of the above step 3 because of its high affinity with water.
　本発明では、実施例で算出した親水化剤の透水性能発現率は、実使用を想定した場合、９０％以上であることが好ましい。 In the present invention, the water permeability performance expression rate of the hydrophilic agent calculated in the examples is preferably 90% or more, assuming actual use.
　以下に実施例によって本発明をさらに詳細に説明するが、本発明はこれらの実施例によって何ら限定されるものではない。 The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.
　実施例及び比較例における測定、評価は次のとおり行った。結果を表１～６に示す。 Measurements and evaluations in Examples and Comparative Examples were performed as follows. The results are shown in Tables 1-6.
　（１）多孔質分離膜表面の平均孔径測定
　多孔質分離膜の表面を電子顕微鏡（ＨＩＴＡＣＨＩ製；Ｓ－５５００）を用いて、３万～１０万倍の倍率で観察し、無作為に選択した孔３００個の面積をそれぞれ測定した。各孔の面積から、孔が円であったと仮定したときの直径を孔径としてそれぞれ算出し、それらの平均値を表面平均孔径とした。 (1) Measurement of average pore size on the surface of the porous separation membrane The surface of the porous separation membrane was observed with an electron microscope (manufactured by HITACHI; S-5500) at a magnification of 30,000 to 100,000 times, and was randomly selected. The area of each of the 300 holes was measured. From the area of each hole, the diameter when the hole was assumed to be a circle was calculated as the hole diameter, and the average value thereof was taken as the surface average hole diameter.
（２）多孔質分離膜表面と水との接触角測定
　室温２５℃、相対湿度５０％の雰囲気において多孔質分離膜表面と水の接触角を自動接触角計（協和界面科学株式会社製、ＤＭ５００）を用いて測定した。接触角の測定は、θ／２法にて静的接触角をコンピュータでの画像解析により自動算出した。なお、液適量は１．０μｌとし、蒸留水の多孔質分離膜表面への着滴開始から１０秒後に接触角を測定した。 (2) Measurement of contact angle between the surface of the porous separation membrane and water Automatic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., DM500) measures the contact angle between the surface of the porous separation membrane and water in an atmosphere at room temperature of 25 ° C and relative humidity of 50%. ) Was used for measurement. For the measurement of the contact angle, the static contact angle was automatically calculated by image analysis with a computer by the θ / 2 method. The appropriate amount of the liquid was 1.0 μl, and the contact angle was measured 10 seconds after the start of dropletation of distilled water on the surface of the porous separation membrane.
　（３）親水化剤の表面張力測定
　室温２５℃、相対湿度５０％の雰囲気において親水化剤の表面張力を自動接触角計（協和界面科学株式会社製、ＤＭ５００）を用いて測定した。親水化剤の表面張力は懸滴法によって６回測定した平均値を採用した。 (3) Measurement of surface tension of hydrophilic agent The surface tension of the hydrophilic agent was measured using an automatic contact angle meter (DM500, manufactured by Kyowa Interface Science Co., Ltd.) in an atmosphere at room temperature of 25 ° C. and relative humidity of 50%. For the surface tension of the hydrophilic agent, the average value measured 6 times by the suspension method was adopted.
　（４）親水化剤の密度測定
　比重測定キット（ＡＤ－１６５３－ＧＭ、エーアンドディー（株）製）を用いて、室温２５℃、相対湿度５０％の雰囲気でアルキメデス法にて親水化剤の密度の測定を行った。測定はｎ＝３で行い、その平均値を親水化剤の密度（ｇ/ｃｍ3）とした。 (4) Density measurement of hydrophilic agent Using a specific gravity measurement kit (AD-1653-GM, manufactured by A & D Co., Ltd.), the hydrophilic agent was prepared by the Archimedes method in an atmosphere at room temperature of 25 ° C. and relative humidity of 50%. The density was measured. The measurement was performed at n = 3, and the average value was taken as the density of the hydrophilic agent (g / cm 3 ).
　（５）多孔質表面の表面粗さＲａ
　多孔質分離膜表面が上になるようにサンプル台に接着し、ＡＦＭ（Ｂｒｕｋｅｒ　ＡＸＳ社製；Ｄｉｍｅｎｓｉｏｎ　ＦａｓｔＳｃａｎ）にて、表面粗さ（算術平均粗さ）Ｒａを測定した。具体的な測定条件は以下のとおりとした。なお、シリコンカンチレバーは測定前に都度校正をした。 (5) Surface roughness Ra of the porous surface
It was adhered to the sample table so that the surface of the porous separation membrane was on top, and the surface roughness (arithmetic mean roughness) Ra was measured by AFM (manufactured by Bruker AXS; Dimension FastScan). The specific measurement conditions are as follows. The silicon cantilever was calibrated before each measurement.
　走査モード：ＳｃａｎＡｓｙｓｔ
　探針：シリコンカンチレバー（Ｂｒｕｋｅｒ　ＡＸＳ社製；ＳｃａｎＡｓｙｓｔ－Ａｉｒ）
　走査範囲：２．５μｍ×２．５μｍ
　走査速度：０．５Ｈｚ
　ピクセル数：２５６×２５６
　測定温度：２５℃ Scan mode: ScanAsyst
Probe: Silicon cantilever (manufactured by Bruker AXS; ScanAsyst-Air)
Scanning range: 2.5 μm x 2.5 μm
Scanning speed: 0.5Hz
Number of pixels: 256 x 256
Measurement temperature: 25 ° C
　（６）親水化剤による親水化効果の確認
　多孔質分離膜の表面を、親水化剤に２時間接触させた後に、親水化剤を純水に置換し、その後、純水中で２４時間静置することで多孔質分離膜を親水化した。 (6) Confirmation of hydrophilizing effect by the hydrophilizing agent After contacting the surface of the porous separation membrane with the hydrophilizing agent for 2 hours, the hydrophilizing agent was replaced with pure water, and then the mixture was allowed to stand in pure water for 24 hours. By placing it, the porous separation membrane was made hydrophilic.
　親水化した多孔質分離膜の純水透水性を下記の方法で測定し、純水透水性Ａを算出した。 The pure water permeability of the hydrophilized porous separation membrane was measured by the following method, and the pure water permeability A was calculated.
〔純水透水性Ａ〕
　多孔質分離膜が平膜状の場合には、有効膜面積３０ｃｍ2に対して評価を行った。また、多孔質分離膜が中空糸膜状の場合には、有効膜面積１４ｃｍ2に対して評価を行った。 [Pure water permeability A]
When the porous separation membrane was flat, evaluation was performed for an effective membrane area of 30 cm 2. In addition, when the porous separation membrane was in the form of a hollow fiber membrane, an evaluation was performed for an effective membrane area of 14 cm 2.
　多孔質分離膜に、温度２５℃、ろ過差圧１０ｋＰａの条件で、１時間にわたって蒸留水を供給して全量ろ過し、得られた透過水量（ｍ3）を測定し、単位時間（ｈ）及び単位膜面積（ｍ2）当たりの数値に換算し、さらに圧力（５０ｋＰａ）換算して算出した。なお、多孔質分離膜に加えて支持体を備える複合膜については、支持体を含めた複合膜全体について評価を行った。 Distilled water was supplied to the porous separation membrane at a temperature of 25 ° C. and a filtration differential pressure of 10 kPa for 1 hour to filter the entire amount, and the obtained permeated water amount (m 3 ) was measured for a unit time (h) and. It was calculated by converting it into a numerical value per unit film area (m 2 ) and further converting it into a pressure (50 kPa). As for the composite membrane having a support in addition to the porous separation membrane, the entire composite membrane including the support was evaluated.
〔純水透水性Ｂ〕
　次に、親水化した多孔質分離膜を純エタノールに３０分接触させ、純エタノールを純水に置換し、その後、純水中で１２時間静置することで多孔質分離膜を完全に親水化した。完全に親水化した多孔質分離膜を純水透水性Ａの測定方法に準じた方法で測定し、純水透水性Ｂを算出した。 [Pure water permeability B]
Next, the hydrophilic separation membrane was brought into contact with pure ethanol for 30 minutes, the pure ethanol was replaced with pure water, and then the porous separation membrane was allowed to stand in pure water for 12 hours to completely hydrophilize the porous separation membrane. did. The completely hydrophilic porous separation membrane was measured by a method according to the method for measuring pure water permeability A, and pure water permeability B was calculated.
〔透水性能発現率〕
　さらに、下式を用いて親水化剤の透水性能発現率を算出した。
　　親水化剤の透水性能発現率＝（純水透水性Ａ／純水透水性Ｂ）×１００ [Permeability expression rate]
Furthermore, the water permeability performance expression rate of the hydrophilic agent was calculated using the following formula.
Water permeability performance expression rate of hydrophilic agent = (pure water permeability A / pure water permeability B) x 100
（実施例１）
　重量平均分子量４１．７万のフッ化ビニリデンホモポリマーとγ－ブチロラクトンとを、それぞれ３８質量％と６２質量％の割合で１７０℃の温度で溶解し、高分子溶液を得た。この高分子溶液をγ－ブチロラクトンを中空部形成液体として随伴させながら口金から吐出し、温度２０℃のγ－ブチロラクトン８０質量％水溶液からなる冷却浴中で固化して球状構造からなる中空糸膜Ｍ１０を作製した。 (Example 1)
A vinylidene fluoride homopolymer having a weight average molecular weight of 417,000 and γ-butyrolactone were dissolved at a temperature of 170 ° C. at a ratio of 38% by mass and 62% by mass, respectively, to obtain a polymer solution. This polymer solution is discharged from the mouthpiece with γ-butyrolactone as a hollow part-forming liquid, and solidified in a cooling bath consisting of an 80% by mass aqueous solution of γ-butyrolactone at a temperature of 20 ° C. to form a hollow fiber membrane M10 having a spherical structure. Was produced.
　次いで、重量平均分子量２８．４万のフッ化ビニリデンホモポリマーを１２質量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５－７５Ｓ）を７．２質量％、Ｎ－メチル－２－ピロリドンを８０．８質量％の割合で９５℃の温度で混合溶解して高分子溶液を調製した。この高分子溶液を中空糸膜Ｍ１０の表面に均一に塗布し、すぐに、水１００％からなる２５℃の凝固浴中で凝固させて球状構造層の上に三次元網目構造層を形成させた中空糸膜Ｍ１１を作製した。 Next, 12% by mass of vinylidene fluoride homopolymer having a weight average molecular weight of 284,000, 7.2% by mass of cellulose acetate (Eastman Chemical Company, CA435-75S), and 80.8% of N-methyl-2-pyrrolidone. A polymer solution was prepared by mixing and dissolving at a temperature of 95 ° C. at a ratio of mass%. This polymer solution was uniformly applied to the surface of the hollow fiber membrane M10, and immediately coagulated in a coagulation bath of 100% water at 25 ° C. to form a three-dimensional network structure layer on the spherical structure layer. A hollow fiber membrane M11 was produced.
　得られた中空糸膜Ｍ１１を２５℃真空乾燥機中で２４時間乾燥させ、本発明に適用する多孔質分離膜を得た。 The obtained hollow fiber membrane M11 was dried in a vacuum dryer at 25 ° C. for 24 hours to obtain a porous separation membrane applied to the present invention.
　次いで、界面活性剤イオネットＴ－２０Ｃ（ポリオキシエチレンソルビタン脂肪酸エステル系の非イオン性界面活性剤、主成分：ポリオキシエチレン（２０）ソルビタンモノラウレート、ＨＬＢ値１６．７、引火点２９７℃）の５質量％水溶液からなる親水化剤を調製した。この親水化剤は、淡黄色の透明溶液で不溶成分はなかった。 Next, the surfactant Ionet T-20C (polyoxyethylene sorbitan fatty acid ester-based nonionic surfactant, main component: polyoxyethylene (20) sorbitan monolaurate, HLB value 16.7, ignition point 297 ° C.) A hydrophilizing agent consisting of a 5% by mass aqueous solution of the above was prepared. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
（実施例２）
　界面活性剤レオドールＴＷ－Ｌ１２０（ポリオキシエチレンソルビタン脂肪酸エステル系の非イオン性界面活性剤、主成分：ポリオキシエチレン（２０）ソルビタンモノラウレート、ＨＬＢ値１６．７、引火点２９７℃）の３質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、淡黄色の透明溶液で不溶成分はなかった。 (Example 2)
Surfactant Leodor TW-L120 (polyoxyethylene sorbitan fatty acid ester-based nonionic surfactant, main component: polyoxyethylene (20) sorbitan monolaurate, HLB value 16.7, ignition point 297 ° C) 3 The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a mass% aqueous solution was used. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
（実施例３）
　界面活性剤イオネットＴ－６０Ｖ（ポリオキシエチレンソルビタン脂肪酸エステル系の非イオン性界面活性剤、主成分：ステアリン酸ポリオキシエチレンソルビタン、ＨＬＢ値１４．９、引火点２７７℃）の５質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、白濁した懸濁溶液で不溶成分を含んでいた。 (Example 3)
From a 5% by mass aqueous solution of the surfactant Ionet T-60V (polyoxyethylene sorbitan fatty acid ester-based nonionic surfactant, main component: polyoxyethylene sorbitan stearate, HLB value 14.9, ignition point 277 ° C) The same operation as in Example 1 was carried out except that the hydrophilic agent was used. This hydrophilizing agent contained an insoluble component in a cloudy suspension solution.
（実施例４）
　界面活性剤ナロアクティーＣＬ４００（合成アルコール系の非イオン性界面活性剤、主成分：ポリオキシエチレンアルキルエーテル、ＨＬＢ値１７．８、引火点２６２℃）の１０質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、無色の透明溶液で不溶成分はなかった。 (Example 4)
Uses a hydrophilic agent consisting of a 10% by mass aqueous solution of the surfactant Naroacty CL400 (synthetic alcohol-based nonionic surfactant, main component: polyoxyethylene alkyl ether, HLB value 17.8, flash point 262 ° C). The same operation as in Example 1 was performed except that there was a problem. This hydrophilic agent was a colorless transparent solution with no insoluble components.
（実施例５）
　界面活性剤ニューポールＰＥ－６８（プルロニック系の非イオン性界面活性剤、主成分：ポリオキシエチレンポリオキシプロピレン　ブロックポリマー、ＨＬＢ値１５．６、引火点２７９℃）の１０質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、無色の透明溶液で不溶成分はなかった。 (Example 5)
Hydrophile consisting of 10% by mass aqueous solution of surfactant New Pole PE-68 (pluronic nonionic surfactant, main component: polyoxyethylene polyoxypropylene block polymer, HLB value 15.6, ignition point 279 ° C) The same operation as in Example 1 was carried out except that the agent was used. This hydrophilic agent was a colorless transparent solution with no insoluble components.
（実施例６）
　実施例１と同様の方法で、中空糸膜Ｍ１０を作製した。 (Example 6)
A hollow fiber membrane M10 was produced in the same manner as in Example 1.
　次いで、重量平均分子量２８．４万のフッ化ビニリデンホモポリマーを１３質量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５－７５Ｓ）を４質量％、Ｎ－メチル－２－ピロリドンを７７質量％、界面活性剤イオネットＴ－２０Ｃを３質量％、水を３質量％の割合で９５℃の温度で混合溶解して高分子溶液を調製した。この高分子溶液を中空糸膜Ｍ１０の表面に均一に塗布し、すぐに２５℃の３０質量％Ｎ－メチル－２－ピロリドン水溶液中で凝固させて球状構造層の上に三次元網目構造層を形成させた中空糸膜Ｍ６１を作製した。 Next, 13% by mass of vinylidene fluoride homopolymer having a weight average molecular weight of 284,000, 4% by mass of cellulose acetate (Eastman Chemical Co., Ltd., CA435-75S), 77% by mass of N-methyl-2-pyrrolidone, and an interface. A polymer solution was prepared by mixing and dissolving the activator ionet T-20C at a ratio of 3% by mass and water at a ratio of 3% by mass at a temperature of 95 ° C. This polymer solution is uniformly applied to the surface of the hollow fiber membrane M10 and immediately coagulated in a 30 mass% N-methyl-2-pyrrolidone aqueous solution at 25 ° C. to form a three-dimensional network structure layer on the spherical structure layer. The formed hollow fiber membrane M61 was produced.
　得られた中空糸膜Ｍ６１を水洗して界面活性剤とＮ－メチル－２－ピロリドンを除去した後、２５℃真空乾燥機中で２４時間乾燥させ、本発明に適用する多孔質分離膜を得た。 The obtained hollow fiber membrane M61 was washed with water to remove the surfactant and N-methyl-2-pyrrolidone, and then dried in a vacuum dryer at 25 ° C. for 24 hours to obtain a porous separation membrane applied to the present invention. It was.
　次いで、界面活性剤イオネットＴ－２０Ｃの１０質量％水溶液からなる親水化剤を調製した。この親水化剤は、淡黄色の透明溶液で不溶成分はなかった。 Next, a hydrophilic agent composed of a 10% by mass aqueous solution of the surfactant Ionet T-20C was prepared. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
（実施例７）
　実施例１と同様の方法で、中空糸膜Ｍ１０を作製した。 (Example 7)
A hollow fiber membrane M10 was produced in the same manner as in Example 1.
　次いで、重量平均分子量２８．４万のフッ化ビニリデンホモポリマーを１８質量％、セルロースアセテート（イーストマンケミカル社、ＣＡ４３５－７５Ｓ）を１２質量％、Ｎ－メチル－２－ピロリドンを７０質量％の割合で１２０℃の温度で混合溶解して高分子溶液を調製した。この高分子溶液を中空糸膜Ｍ１０の表面に均一に塗布し、すぐに、水１００％からなる５℃の凝固浴中で凝固させて球状構造層の上に三次元網目構造層を形成させた中空糸膜Ｍ７１を作製した。 Next, 18% by mass of vinylidene fluoride homopolymer having a weight average molecular weight of 284,000, 12% by mass of cellulose acetate (Eastman Chemical Company, CA435-75S), and 70% by mass of N-methyl-2-pyrrolidone. A polymer solution was prepared by mixing and dissolving at a temperature of 120 ° C. This polymer solution was uniformly applied to the surface of the hollow fiber membrane M10, and immediately coagulated in a coagulation bath of 100% water at 5 ° C. to form a three-dimensional network structure layer on the spherical structure layer. A hollow fiber membrane M71 was produced.
　得られた中空糸膜Ｍ７１を水洗して界面活性剤とＮ－メチル－２－ピロリドンを除去した後、２５℃真空乾燥機中で２４時間乾燥させ、本発明に適用する多孔質分離膜を得た。 The obtained hollow fiber membrane M71 was washed with water to remove the surfactant and N-methyl-2-pyrrolidone, and then dried in a vacuum dryer at 25 ° C. for 24 hours to obtain a porous separation membrane applied to the present invention. It was.
　次いで、界面活性剤イオネットＴ－２０Ｃの１０質量％水溶液からなる親水化剤を調製した。この親水化剤は、淡黄色の透明溶液で不溶成分はなかった。 Next, a hydrophilic agent composed of a 10% by mass aqueous solution of the surfactant Ionet T-20C was prepared. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
（比較例１）
　界面活性剤イオネットＴ－２０Ｃの１質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、淡黄色の透明溶液で不溶成分はなかった。 (Comparative Example 1)
The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 1% by mass aqueous solution of the surfactant Ionet T-20C was used. This hydrophilic agent was a pale yellow transparent solution with no insoluble components.
（比較例２）
　界面活性剤オルフィンＥＸＰ４０３６（ＨＬＢ値１３．０、引火点なし）の５質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、白濁した懸濁溶液で不溶成分を含んでいた。 (Comparative Example 2)
The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 5% by mass aqueous solution of the surfactant Orphine EXP4036 (HLB value 13.0, no flash point) was used. This hydrophilizing agent contained an insoluble component in a cloudy suspension solution.
（比較例３）
　界面活性剤オルフィンＥＸＰ４０３６（ＨＬＢ値１３．０、引火点なし）の１０質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、白濁した懸濁溶液で不溶成分を含んでいた。 (Comparative Example 3)
The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 10% by mass aqueous solution of the surfactant Orphine EXP4036 (HLB value 13.0, no flash point) was used. This hydrophilizing agent contained an insoluble component in a cloudy suspension solution.
（比較例４）
　ポリビニルピロリドンｋ－３０の３質量％水溶液からなる親水化剤を用いた以外は、実施例１と同様の操作を行った。この親水化剤は、無色の透明溶液で不溶成分はなかった。

(Comparative Example 4)
The same operation as in Example 1 was carried out except that a hydrophilic agent composed of a 3% by mass aqueous solution of polyvinylpyrrolidone k-30 was used. This hydrophilic agent was a colorless transparent solution with no insoluble components.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　表１～４の結果より、実施例１～７の方法でポリフッ化ビニリデン系多孔質分離膜の親水化すると、親水化効果が良好であることが分かった。 From the results in Tables 1 to 4, it was found that the hydrophilic effect was good when the polyvinylidene fluoride-based porous separation membrane was hydrophilized by the methods of Examples 1 to 7.
　本発明を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明らかである。本出願は２０１９年８月２９日出願の日本特許出願（特願２０１９－１５６６５４）に基づくものであり、その内容はここに参照として取り込まれる。 Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on August 29, 2019 (Japanese Patent Application No. 2019-156654), the contents of which are incorporated herein by reference.
　本発明のポリフッ化ビニリデン系多孔質分離膜の親水化方法は、飲料水製造、浄水処理、排水処理などの水処理分野、医薬品製造分野、食品工業分野、血液浄化用膜分野に利用することができる。 The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane of the present invention can be used in water treatment fields such as drinking water production, water purification treatment, and wastewater treatment, pharmaceutical manufacturing fields, food industry fields, and blood purification membrane fields. it can.

Claims (5)

  1. 　ポリフッ化ビニリデン系多孔質分離膜に対し、親水化剤を接触させた後、水を接触させる工程を有する、ポリフッ化ビニリデン系多孔質分離膜の親水化方法であって、
    　前記ポリフッ化ビニリデン系多孔質分離膜は、ポリフッ化ビニリデン系樹脂を含み、表面の平均孔径が１～２０ｎｍであり、表面と水との接触角が８０～１１０°であり、
    　前記親水化剤は、界面活性剤を含み、表面張力が３０～４５ｍＮ／ｍであり、密度が１．０００～１．０１０ｇ／ｃｍ3である、ポリフッ化ビニリデン系多孔質分離膜の親水化方法。     A method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane, which comprises a step of contacting a polyvinylidene fluoride-based porous separation membrane with a hydrophilic agent and then contacting water.
    The polyvinylidene fluoride-based porous separation membrane contains a polyvinylidene fluoride-based resin, has an average pore diameter of 1 to 20 nm on the surface, and has a contact angle between the surface and water of 80 to 110 °.
    The hydrophilic agent is a method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane, which contains a surfactant, has a surface tension of 30 to 45 mN / m, and has a density of 1.000 to 1.010 g / cm 3. ..
  2. 　前記ポリフッ化ビニリデン系多孔質分離膜の表面の平均孔径が５～２０ｎｍである、請求項１に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。 The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to claim 1, wherein the average pore size on the surface of the polyvinylidene fluoride-based porous separation membrane is 5 to 20 nm.
  3. 　前記親水化剤は、非イオン性界面活性剤を３～１０質量％含む水溶液であり、
    　前記非イオン性界面活性剤のＨＬＢ値が１４以上２０未満である、請求項１又は２に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。     The hydrophilic agent is an aqueous solution containing 3 to 10% by mass of a nonionic surfactant.
    The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to claim 1 or 2, wherein the HLB value of the nonionic surfactant is 14 or more and less than 20.
  4. 　前記非イオン性界面活性剤は、ポリオキシエチレンソルビタン脂肪酸エステルを主成分とし、ＨＬＢ値が１６以上２０未満である、請求項３に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。 The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to claim 3, wherein the nonionic surfactant contains a polyoxyethylene sorbitan fatty acid ester as a main component and has an HLB value of 16 or more and less than 20.
  5. 　前記非イオン性界面活性剤の引火点が２５０℃以上である、請求項３又は４に記載のポリフッ化ビニリデン系多孔質分離膜の親水化方法。 The method for hydrophilizing a polyvinylidene fluoride-based porous separation membrane according to claim 3 or 4, wherein the flash point of the nonionic surfactant is 250 ° C. or higher.
PCT/JP2020/032699 2019-08-29 2020-08-28 Method for hydrophilizing polyvinylidene fluoride-based porous separation membrane WO2021040001A1 (en)

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