[go: up one dir, main page]

WO2007125709A1 - Membrane poreuse de traitement de l'eau faite d'une resine a base de fluorure de vinylidene avec une faible contamination et son procede de production - Google Patents

Membrane poreuse de traitement de l'eau faite d'une resine a base de fluorure de vinylidene avec une faible contamination et son procede de production Download PDF

Info

Publication number
WO2007125709A1
WO2007125709A1 PCT/JP2007/056363 JP2007056363W WO2007125709A1 WO 2007125709 A1 WO2007125709 A1 WO 2007125709A1 JP 2007056363 W JP2007056363 W JP 2007056363W WO 2007125709 A1 WO2007125709 A1 WO 2007125709A1
Authority
WO
WIPO (PCT)
Prior art keywords
membrane
porous
water
treatment
hollow fiber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2007/056363
Other languages
English (en)
Japanese (ja)
Inventor
Toshiya Mizuno
Yasushi Ebihara
Yasuhiro Tada
Kenichi Suzuki
Takeo Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kureha Corp
Original Assignee
Kureha Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kureha Corp filed Critical Kureha Corp
Publication of WO2007125709A1 publication Critical patent/WO2007125709A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0088—Physical treatment with compounds, e.g. swelling, coating or impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • 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
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/02—Hydrophilization
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/24—Mechanical properties, e.g. strength
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/28—Degradation or stability over time
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/30—Chemical resistance

Definitions

  • the present invention relates to the resistance of water treatment membranes made of polyvinylidene fluoride resin used as microfiltration membranes for sterilization of water and sewage, contamination purification, aqueous chemical treatment, or pure water production. Concerning improvement of pollution.
  • porous membranes used as water treatment membranes have an appropriate porosity, pore size and pore size distribution suitable for removal and separation of fine particles to be removed, and a sufficient breaking point for mechanical strength during use. It is required to have stress, pressure resistance, elongation at break, chemical resistance to the liquid to be treated or backwashing after use and ozone treatment.
  • vinylidene fluoride resin is excellent in weather resistance, chemical resistance, heat resistance, strength, etc., application to these water treatment membranes is being studied.
  • the vinylidene fluoride resin has the above-mentioned excellent characteristics, it is a hydrophobic resin, so that during the drainage operation, organic matter contained in the treated water is
  • a polyvinylidene fluoride-based porous resin membrane can be hydrophilized by treating it with an alkali solution (Patent Document 1) or by further treating with ozone after the alkali solution treatment (Patent Document 2). Proposed.
  • an alkali solution Patent Document 1
  • Patent Document 2 the hydrophilic property of the polyvinylidene fluoride resin porous membrane is improved with certainty, but at the same time, there is a drawback that mechanical properties such as high elongation are remarkably lowered.
  • a polyvinylidene fluoride-based porous resin membrane is formed by dissolving a hydrophilic resin such as polybutyl alcohol. It has also been proposed to make it hydrophilic by immersing it in a liquid and forming a coating film (Patent Document 3), or by subjecting a hydrophilic monomer to a draft polymerization (Patent Document 4).
  • the hydrophilic resin coating film or graft film formed in this way does not necessarily have good adhesion to the polyvinylidene fluoride resin porous film, and physical washing such as backwashing and air scrubbing is not possible. Poor durability for cleaning, low chemical resistance, poor durability including regeneration treatment, and formation of paint film or graft membrane reduces pore size, or pore connectivity If it is hindered and the water permeability capacity decreases, there is a drawback.
  • a hydrophilic resin such as polybulualcohol is mixed with a vinylidene fluoride resin to make the matrix resin itself forming a porous film hydrophilic (patent).
  • a porous membrane made of a matrix resin mixed with a hydrophilic resin which has a poor affinity for the vinylidene fluoride resin, which is a hydrophobic resin, prevents a decrease in mechanical strength.
  • the chemical resistance of the hydrophilic resin is small, the durability against chemical cleaning (drug cleaning durability) also decreases.
  • the conventional fluoride fluoride has been improved satisfactorily as a hydrophobic coagulant by hydrophilization while maintaining durability and mechanical properties including regeneration treatment with chemicals and the like.
  • the reality is that a porous water treatment membrane made of redene-based rosin has not been obtained.
  • Patent Document 1 Japanese Patent Publication No. 62-17614
  • Patent Document 2 Japanese Patent No. 3242983
  • Patent Document 3 Japanese Patent Laid-Open No. 3-178429
  • Patent Document 4 Japanese Patent Laid-Open No. 2003-268152
  • Patent Document 5 Japanese Patent No. 3200095.
  • the main objects of the present invention are (i) low membrane contamination during filtration operation (low contamination), and (mouth) maintained after chemical cleaning in which low contamination is repeated ( High (drug washing durability) and (c) Good mechanical strength (Polyvinylidene fluoride resin porous membrane retains the original mechanical strength well), Vinylidene fluoride resin porous water treatment membrane And to provide an efficient manufacturing method.
  • the low-contamination porous water treatment membrane of the present invention is a flat film made of vinylidene fluoride resin. It is a porous membrane in the form of a membrane or a hollow fiber membrane, and its outer surface is selectively hydrophilized.
  • the outer surface of the porous film refers to at least one of the two main surfaces facing each other across the film thickness, and the surface (inner surface) of the fine pores distributed in the film thickness. This is an exception. However, it does not completely eliminate the surface of micropores that exist from the outer surface to a limited depth.
  • the degree of selectivity of hydrophilization on the outer surface is defined by the thickness of the hydrophilization layer (preferably, the wetting index) described later.
  • hydrophobic hydrophobic resin porous membranes have been considered to easily adhere to membrane dirt components because they have a small electrical repulsive force with membrane dirt components. Attempts have been made to increase the electric repulsive force with the film dirt component to reduce the film dirt.
  • membrane dirt components contained in raw water are deposited on the outer surface of the membrane on the raw water supply side (forming a cake layer) and adhered to the surface of micropores distributed in the film thickness, reducing the pore size. Some of them cause clogging of pores, all of which are thought to cause an increase in filtration resistance (decrease in water permeability). For this reason, even in the case of aiming at low contamination, the hydrophilization treatment to the hydrophobic resin porous membrane has been carried out exclusively on the entire surface including the microporous surface (for example, Patent Document 5).
  • the inventors of the present invention have fundamentally studied a membrane fouling mechanism as a water treatment membrane of a polyvinylidene fluoride resin porous membrane, and as a result, a change in filtration characteristics over time (due to reduction and regeneration). For the recovery of filtration characteristics, etc., the pores distributed in the thickness direction that form the porous membrane do not contribute uniformly, but deposit mainly on the outer surface of the raw water supply side and the outer surface. We found that the cake layer was dominant.
  • the present inventors have determined that the outer surface of the polyvinylidene fluoride-based rosin porous membrane does not uniformly hydrophilize the outer surface and the inner microporous surface. If selectively hydrophilized, porous water treatment made of polyvinylidene fluoride resin, a hydrophilic resin that does not cause problems such as a decrease in mechanical strength due to uniform hydrophilization. We have found that many of the membrane problems can be improved and have reached the present invention.
  • the inventors of the present invention for efficient production of the above-described low-contamination porous water treatment membrane, used a contact treatment liquid for hydrophilization as a polyvinylidene fluoride resinous porous membrane. It has also been found that it is effective to selectively act on the outer surface of the film. That is, in the method for producing a low-contamination porous water treatment membrane of the present invention, a flat membrane or hollow fiber membrane-like porous membrane made of a vinylidene fluoride resin is hydrophilized by contact with a hydrophilization treatment liquid. In this case, the outer surface of the porous membrane is selectively hydrophilized.
  • FIG. 1 is a schematic explanatory view of a water permeability measuring device used for evaluating the water treatment performance of hollow fiber porous membranes obtained in Examples and Comparative Examples.
  • the low-contamination water treatment membrane of the present invention is generally produced by treating the outer surface of a hydrophobic polyvinylidene fluoride resin porous membrane produced by various production methods according to the method of the present invention. Can be built. For example, the method of selectively hydrophilizing the outer surface according to the present invention is applied to a flat membrane or hollow fiber membrane porous membrane made of vinylidene fluoride resin formed by the following method. A low-contamination porous water treatment membrane can be obtained.
  • An organic liquid such as decyl phthalate and hydrophobic silica are mixed as inorganic fine powder with vinylidene fluoride resin, and after melt molding, the organic liquid and hydrophobic silica are extracted.
  • a method for producing a vinylidene fluoride resin porous membrane that forms pores after extraction JP-A-3-215535, etc.).
  • the polyvinylidene fluoride resin porous membrane to which selective hydrophilization is applied is applied.
  • the membrane has an inclined pore size distribution in the thickness direction, and it is preferable to use a polyvinylidene fluoride-based resin porous membrane obtained by the method (3).
  • a porous membrane having an inclined pore size distribution whether the feed surface of the raw water is large or small, and the side of the raw water is different from that of the dirt component or fine particles to be removed is determined. It is arbitrarily determined empirically or experimentally after considering factors such as chemical composition, particle size (ie, raw water quality), filtration conditions, and washing conditions (ie, operating conditions).
  • the pore size is small in river water, lake water, ground water, or raw water (including MBR: activated sludge membrane filtration method) that is biologically treated from sewage, industrial wastewater, or livestock wastewater! It is preferable to supply raw water from the side.
  • the selective hydrophilization of the outer surface is effective in the part where membrane contamination is most likely to occur.
  • the hole on the outer surface to which water is supplied has a small hole diameter!
  • a porous membrane having a slanted pore size distribution when supplying side force raw water having a small pore size, it is inevitably effective to selectively hydrophilicize the outer surface on the side having a small pore size.
  • factors such as the quality of the raw water and the operating conditions should be taken into consideration to determine whether the outer surface is selectively hydrophilized to the gap between the large and small pores.
  • the empirical above is arbitrarily determined experimentally.
  • the outer surface to which raw water is supplied is selectively hydrophilized.
  • the hollow fiber-like low-contamination porous material is obtained by selectively hydrophilizing the outer surface subsequent to each step of the method for producing a vinylidene fluoride-based porous resin membrane by the method (3).
  • mode of this invention method which manufactures a water treatment membrane is demonstrated sequentially.
  • a vinylidene fluoride resin having a weight average molecular weight (Mw) of 200,000 to 600,000 as the main film material.
  • Mw weight average molecular weight
  • the Mw is 200,000 or less
  • the mechanical strength of the obtained porous film becomes small.
  • the Mw is 600,000 or more
  • the phase separation structure between the vinylidene fluoride resin and the plasticizer becomes excessively fine, and the water permeability when the obtained hollow fiber porous membrane is used as a microfiltration membrane is small. descend.
  • the vinylidene fluoride-based resin homopolymers of vinylidene fluoride, that is, poly (vinylidene fluoride) and other copolymerizable with vinylidene fluoride can be used. Copolymers with monomers or mixtures thereof are used. As the monomer copolymerizable with vinylidene fluoride, one or two or more of tetrafluoroethylene, hexafluoropropylene, trifluoride styrene, trifluoride salt, ethylene, butyl fluoride, etc. may be used. it can.
  • the vinylidene fluoride resin preferably contains 70 mol% or more of vinylidene fluoride as a structural unit. Among them, it has a high mechanical strength and is composed of 100% by mole of vinylidene fluoride. It is preferable to use a polymer.
  • the above-described relatively high molecular weight vinylidene fluoride resin can be obtained by emulsion polymerization or suspension polymerization, particularly preferably suspension polymerization.
  • the vinylidene fluoride resin forming the hollow fiber porous membrane of the present invention has a DSC measurement.
  • the difference between the original melting point Tm2 (° C) and the crystallization temperature Tc (° C) due to Tm2—Tc is less than 32 ° C, preferably less than 30 ° C. At this time, it is preferable to have crystal characteristics that suppress the growth of spherical crystals and promote the formation of a network structure.
  • the original melting point Tm2 (° C) of the resin is the melting point Tml (° C) measured by subjecting the obtained sample resin or the resin forming the porous film to the temperature rising process by DSC as it is. C) is distinct.
  • generally available vinylidene fluoride-based resin has a melting point Tml (different from the original melting point Tm2 (° C) due to the heat and mechanical history received during its production process or thermoforming process.
  • the melting point Tm2 (° C) of the above-described fluoride-redene resin is determined by subjecting the obtained sample resin to a predetermined temperature increase / decrease cycle. And the melting point (endothermic peak temperature associated with crystal melting) found again in the DSC temperature rise process after removing the mechanical history, and details of the measurement method are described in the description of Examples below. List in advance.
  • Tm 2-1 ⁇ ⁇ 32 which represents the crystallization temperature of vinylidene fluoride resin preferably used in the present invention
  • Tm 2-1 ⁇ ⁇ 32 which represents the crystallization temperature of vinylidene fluoride resin preferably used in the present invention
  • Tm 2-1 ⁇ ⁇ 32 which represents the crystallization temperature of vinylidene fluoride resin preferably used in the present invention
  • Mw weight average molecular weight
  • the Mw was 1.8 times or more, preferably 2 times or more and 1.2 million or less, obtained by adding 2 to 30% by weight of a high molecular weight vinylidene fluoride resin for crystal property modification.
  • a vinylidene fluoride-based resin mixture is used.
  • the crystallization temperature Tc can be significantly increased without changing the crystal melting point of the matrix resin alone (preferably represented by Tm2 within the range of 170 to 180 ° C.). More specifically, by increasing Tc, the outer surface force of the hollow fiber membrane formed by melt extrusion is preferential.
  • Tc is preferably 143 ° C or higher.
  • the Mw of the high molecular weight vinyl fluoride-redene resin is less than 1.8 times the Mw of the matrix resin, it is difficult to sufficiently suppress the formation of the spherical particle structure. In some cases, it is difficult to disperse uniformly in the matrix resin.
  • the amount of the high molecular weight vinylidene fluoride resin is less than 2% by weight, the effect of suppressing the formation of the spherical particle structure is not sufficient. On the other hand, if it exceeds 30% by weight, the vinylidene fluoride type resin is added. There is a tendency that the phase separation structure of the resin and the plasticizer becomes excessively fine and the water permeability of the membrane decreases.
  • a raw material for film formation is obtained by adding a plasticizer and a good solvent of vinylidene fluoride resin to the above-mentioned vinylidene fluoride resin. Form a composition.
  • the hollow fiber porous membrane of the present invention is mainly formed of the above-mentioned vinylidene fluoride resin, but for its production, in addition to the above-mentioned vinylidene fluoride resin, at least its plastics are used. It is preferable to use an agent as a pore-forming agent.
  • an aliphatic polyester including a dibasic acid and a glycolic acid for example, an adipic acid-based polyester such as adipic acid monopropylene glycol-based, adipic acid 1,3-butylene glycol-based, or the like; And azelaic acid polyesters such as azelaic acid-propylene glycol type and azelaic acid 1,3 butylene glycol type.
  • a good solvent of vinylidene fluoride resin in addition to the plasticizer.
  • a solvent capable of dissolving vinylidene fluoride resin in a temperature range of 20 to 250 ° C. is used.
  • N-methylpyrrolidone dimethylformamide, dimethylacetamide, dimethylsulfoxide, methylethyl Ketone, acetone, tetrahydrofuran, dioxane, ethyl acetate, propylene carbonate, cyclohexane, methyl isobutyl ketone , Dimethyl phthalate, and mixed solvents thereof.
  • NMP N-methylpyrrolidone
  • the raw material composition for forming a hollow fiber membrane is preferably 100 to 300 parts by weight of a plasticizer and a good solvent for vinylidene fluoride resin in a total amount of 100 parts by weight of vinylidene fluoride resin. Parts by weight, more preferably 140 to 220 parts by weight, and the ratio of the good solvent is 12.5 to 35% by weight, more preferably 15.0 to 32.5% by weight and mixed. Can be obtained.
  • the raw material composition for producing the hollow fiber membrane used in the present invention contains various stabilizers and a small amount of additives such as a granular filler in addition to the plasticizer and good solvent described above. However, it is preferable not to include a fibrous reinforcing material. Including fibrous reinforcing material, in addition to unstable mixing and melt extrusion, the control of inner and outer diameters and wall thickness controls the strength and balances water permeability and microfiltration performance. This is because it becomes difficult to obtain a hollow fiber porous membrane.
  • substantially only the strength of vinylidene fluoride-based resin means that the porous film is not only in the form of polyvinylidene-based resin.
  • optional stabilizers or small amounts of granular filler may be included, but no fibrous reinforcement is included.
  • the melt-extruded composition is generally formed into a film by extrusion through a hollow nozzle cover at a temperature of 140 to 270 ° C, preferably 150 to 200 ° C. Therefore, as long as a homogeneous composition in the above temperature range is finally obtained, the mixture of the vinylidene fluoride resin, the plasticizer and the good solvent is mixed.
  • the molten form is arbitrary. According to one preferred embodiment for obtaining such a composition, a biaxial kneading extruder is used (preferably also having a mixture power of the main resin and the crystal characteristic modifying resin).
  • the redene-based resin is supplied from the upstream side of the extruder, and a mixture of a plasticizer and a good solvent is supplied downstream and is made into a homogeneous mixture before being discharged through the extruder.
  • This twin-screw extruder can be controlled independently by dividing it into a plurality of blocks along its longitudinal direction, and appropriate temperature adjustment is made according to the contents of the passing material at each part.
  • it is effective to increase the melt extrusion speed, which is the raw material discharge amount per length (m) of the melt-extruded material.
  • the melt extrusion speed is preferably 2.0 to 0. OgZm, more preferably 2.5 to 9.
  • OgZm and particularly preferably 2.5 to 6. OgZm. 2. If it is less than OgZm, the durability of the resulting film will be reduced, and if it exceeds 10. OgZm, the melt-extruded product may be crushed, making it impossible to form a hollow part.
  • the melt-extruded hollow fiber membrane is introduced into a cooling bath, and the outer surface force is preferentially cooled to solidify and form a film.
  • a hollow fiber membrane having an expanded diameter is obtained by cooling while injecting an inert gas such as air or nitrogen into the hollow portion of the hollow fiber membrane material.
  • an inert gas such as air or nitrogen
  • obtaining a hollow fiber membrane whose diameter has been expanded by blowing an inert gas into the hollow portion is larger than that of simply increasing the thickness of the hollow fiber membrane to be produced. And is preferable for obtaining a hollow fiber membrane having good bending resistance.
  • the inert gas injection rate as the feed rate per length (m) of the melt-extruded material is 0.7 to 6.8 ml / m, more preferably 1.2 to 3. Oml / m, especially 1 4 to 2.
  • the cooling liquid a liquid that is inert (that is, non-solvent and non-reactive) with respect to vinylidene fluoride-based resin, preferably water, is generally used.
  • a good solvent for vinylidene fluoride resin similar to that contained in the melt-extruded composition described above
  • an inert liquid preferably NMP compatible with water
  • the pore diameter on the outer surface side of the finally obtained hollow fiber porous membrane is increased, and air scrubbing It is also possible to obtain a hollow fiber porous membrane having a minimum pore size layer inside the membrane which is advantageous for regeneration (WO2004Z081109A1 report).
  • the temperature after cooling is 0 to 120 ° C, and a wide temperature range force can be selected, but it is preferably 5 to 100 ° C, particularly preferably 10 to 80 ° C.
  • the cooled and solidified film is then introduced into the extract bath and subjected to extraction removal of the plasticizer and good solvent.
  • the extract is not particularly limited as long as it does not dissolve the polyvinylidene fluoride-based resin but can dissolve the plasticizer or good solvent.
  • polar solvents having a boiling point of about 30 to 100 ° C. such as methanol and isopropyl alcohol for alcohols and dichloromethane and 1,1,1-trichloroethane for chlorinated hydrocarbons are suitable.
  • the hollow fiber membrane is preferably stretched uniaxially in the longitudinal direction of the hollow fiber membrane by a pair of rollers having different peripheral speeds. This is because, in order to harmonize the porosity and the strong elongation of the vinylidene fluoride resin hollow fiber porous membrane of the present invention, the stretched fibril (fiber) portion and the unstretched node ( This is because it has been found that a fine structure in which sections) appear alternately is preferable.
  • Stretching is a powerful means for adjusting the thickness when obtaining a large cross-sectional area hollow fiber membrane according to the present invention, and is also effective for obtaining a high-strength hollow fiber membrane.
  • the draw ratio is suitably about 1.2 to 4.0 times, particularly about 1.4 to 3.0 times. If the draw ratio is too low, the relaxation ratio cannot be increased, and it is difficult to obtain the effect of improving the water permeability due to the relaxation. On the other hand, when the draw ratio is excessive, the tendency of the hollow fiber membrane to break increases.
  • the stretching temperature is preferably 25 to 90 ° C, particularly 45 to 80 ° C. . If the stretching temperature is too low, the stretching becomes non-uniform and the hollow fiber membrane is easily broken.
  • heat treatment is performed in advance at a temperature in the range of 80 to 160 ° C., preferably 100 to 140 ° C. for 1 second to 18000 seconds, preferably 3 seconds to 3600 seconds, to improve the crystallinity. Also preferred to increase.
  • the hollow fiber membrane after the stretching treatment is preferably subjected to relaxation treatment.
  • the relaxation is preferably performed in at least two stages in a non-wetting atmosphere with respect to the vinylidene fluoride resin (PCTZJP2006Z318026 specification).
  • the non-wetting atmosphere is a non-wetting liquid, typically water or air, that has a surface tension (JIS K6768) that is greater than the wetting tension of vinylidene fluoride resin near room temperature. It is composed of almost all gases, especially non-condensable gases near room temperature, or vapors of the non-wetting liquid.
  • treatment with a non-wetting liquid with a large heat capacity and heat transfer coefficient is preferably used, but if the relaxation treatment temperature is raised, A treatment in a heated gas (or steam) (dry heat treatment) is also preferably used. 25 ⁇ 100 ° C, especially 50 ⁇ 100 ° C underwater heat treatment and Z or 80 ⁇ 160 ° C in terms of giving good permeability and good working environment through a large relaxation rate Dry heat treatment with air (or water vapor) is preferably used.
  • a two-stage relaxation treatment in which the first-stage relaxation is a wet heat treatment in water and the second-stage relaxation is a wet heat treatment in water or a dry heat treatment in air (or water vapor) is preferably used.
  • the relaxation treatment in each stage is performed by stretching the previously obtained non-wetting, preferably heated atmosphere, disposed between the upstream roller and the downstream roller, the peripheral speed of which is gradually reduced. It is obtained by passing through a hollow fiber porous membrane.
  • the relaxation rate determined by X 100 (%) is preferably 2 to 20% at each stage, and the total relaxation rate is preferably about 4 to 30%. If the relaxation rate at each stage is less than 2%, it is difficult to obtain the desired effect of improving water permeability, which means that the meaning of multistage relaxation is insufficient. The same applies when the total relaxation rate is less than 4%.
  • each stage relaxation rate exceeding 20%, or total relaxation rate exceeding 30% is difficult to achieve the force depending on the draw ratio in the previous process, or even if realized, the water permeability can be improved. It is preferable because the fruit is saturated or is reduced.
  • the relaxation processing time in each stage may be short or long as long as a desired relaxation rate is obtained.
  • the force is about 5 seconds to 1 minute.
  • the effect of the above-described multistage relaxation treatment is a remarkable effect in that the water permeability of the obtained hollow fiber porous membrane is increased, but the pore size distribution does not change so much and the porosity tends to slightly decrease. .
  • the thickness of the hollow fiber membrane slightly increases, and the inner diameter and outer diameter tend to increase.
  • heat treatment with a relaxation rate of 0% that is, heat setting treatment may be performed.
  • the outer surface of the polyvinylidene fluoride resin porous membrane obtained as described above (in the above, the manufacturing method is detailed for hollow fiber membranes, but flat membranes are of course! /) Is selectively hydrophilized (that is, preferential hydrophilization of the outer surface and the inner pore surface of the porous membrane with respect to the outer surface).
  • Selective hydrophilization of the outer surface can be basically achieved by any method as long as a desired effect is obtained.
  • the outer surface is oxidized on the outer surface, or is exposed to an outer surface such as ultraviolet rays or electron beams. Irradiation and the like are conceivable, but in order to impart a higher degree of hydrophilicity to the outer surface, a method of selectively acting a hydrophilization treatment liquid on the outer surface of the porous membrane is preferred according to the method of the present invention.
  • the hydrophilization treatment liquid examples include an organic solvent solution of a water-insoluble hydrophilic resin such as polyvinyl alcohol having a low saponification degree, or an organic solvent-based graft reaction liquid containing a hydrophilic monomer such as hydroxypropyl acrylate.
  • a water-insoluble hydrophilic resin such as polyvinyl alcohol having a low saponification degree
  • an organic solvent-based graft reaction liquid containing a hydrophilic monomer such as hydroxypropyl acrylate.
  • an aqueous hydrophilization treatment solution such as an alkaline aqueous solution alone as employed in Patent Documents 1 and 2 alone, more preferably an aqueous hydrophilization treatment solution such as an alkaline aqueous solution and an oxidant are sequentially treated. Is adopted.
  • the aqueous polyvinylidene fluoride resin porous membrane is aqueous.
  • Hydrophilic treatment It is necessary to give wettability to the liquid.
  • immersion treatment in a water-miscible liquid such as ethanol that makes the polyvinylidene fluoride-based porous membrane wettable with the alkaline aqueous solution is performed.
  • the wettability is improved on the outer surface of the porous membrane by the hydrophilic treatment liquid prior to the contact with the hydrophilic treatment liquid of the vinylidene fluoride-based rosin porous membrane.
  • Specific methods include selective oxidation of the outer surface of the above-mentioned polyvinylidene fluoride resin porous membrane; irradiation with ultraviolet rays; irradiation with ionizing radiation such as an electron beam; ethanol, N-methylbidonidone (NMP) It is also possible to selectively apply a water-miscible liquid that wets the vinylidene fluoride-based resin, such as, to the outer surface of the porous membrane.
  • a wettability improving liquid having a surface tension of 25 to 45 mNZm is preferable in order to give selective coating properties to the outer surface of the biridene fluoride resin porous membrane. If the surface tension is less than 25 mNZm, it may be difficult to selectively apply the wettability improving liquid to the outer surface because the penetration rate into the P VDF porous membrane is too high. If the surface tension exceeds 45 mNZm, It may be difficult to evenly apply the wettability improving liquid to the outer surface due to galling (insufficient wettability or permeability to the PVDF porous membrane).
  • a surfactant solution obtained by adding a surfactant to water is preferred as a wettability improving solution.
  • a surfactant solution obtained by adding a surfactant to water that is, an aqueous solution of a surfactant or an aqueous homogeneous dispersion
  • a surfactant solution obtained by adding a surfactant to water is preferred as a wettability improving solution.
  • a surfactant for ionic surfactants, carboxylic acid types such as aliphatic monocarboxylates, sulfonic acid types such as alkylbenzene sulfonates, sulfuric acids such as alkyl sulfates, etc.
  • amine salt type such as alkylamine salt, quaternary ammonium salt type such as alkyltrimethyl ammonium salt;
  • ester type such as glycerin fatty acid ester, ether type such as polyoxyethylene alkyl ether, ester ether type such as polyethylene glycol fatty acid ester;
  • amphoteric surfactant N, N dimethyl-N —Carboxybetaine type such as alkylaminoacetic acid betaine, 2-alkyl 1 hydroxyethyl carbo Examples include glycine type such as xymethylimidazolium-umbetaine.
  • the surfactant preferably has an HLB (hydrophilic / lipophilic balance) of 8 or more. If the HLB is less than 8, the surfactant does not disperse in water, resulting in uniform wettability improvement and And hydrophilic treatment becomes difficult.
  • Particularly preferably used surfactants include nonionic surfactants having an HLB of 8 to 20, and further 10 to 18 or ionic (cion, cationic and amphoteric) surfactants. However, nonionic surfactants are preferred.
  • the wettability improving liquid and the hydrophilization treatment liquid described later
  • This immersion treatment is a double-sided coating treatment for flat membranes and a single-sided coating treatment for hollow fiber membranes.
  • the flat membrane batch dipping treatment is performed by dipping the layers cut into appropriate sizes, and the hollow fiber membrane batch dipping treatment is performed by dipping the hollow fiber membrane bundled by bobbin winding or caulking.
  • the continuous treatment is performed by continuously immersing a long porous membrane in the treatment liquid.
  • the temperature of the wettability improving liquid! / there is no particular limitation on the temperature of the wettability improving liquid! /, but depending on the method of applying the wettability improving liquid, the permeation rate is moderately slowed by lowering the wettability improving liquid, Alternatively, the permeation rate can be increased by increasing the temperature. In this way, the viscosity and temperature of the wettability improving liquid act in opposite directions, and can be controlled complementarily to adjust the penetration rate of the wettability improving liquid.
  • the hydrophilic treatment solution is preferably an alkaline aqueous solution (preferably pH 9 to 13, particularly ⁇ 11 to 13), or more preferably an alkaline aqueous solution and an acidic agent.
  • the combination by processing is performed.
  • the alkali include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide; or alkali metal or alkaline earth Metal alkoxides; organic amines such as trimethylamine and triethylamine.
  • Oxidizing agents include potassium permanganate (KMnO), sodium hypochlorite (NaC10),
  • Examples include aqueous solutions of performic acid (HCOOOH) and concentrated sulfuric acid (H 2 SO 4).
  • HCOOOH performic acid
  • H 2 SO 4 concentrated sulfuric acid
  • aqueous solution in the range of 0.1 to 5% by weight for potassium permanganate, effective chlorine concentration of 12 to 12% by weight for sodium hypochlorite, and 20 to 97% by weight for concentrated sulfuric acid.
  • formic acid for example, 97% by weight of formic acid and 30% by weight of peroxyhydrogen water are mixed in a ratio of 20-80% formic acid and 80-20% by weight of peroxyhydrogen water. Then, a performic acid aqueous solution produced by the reaction can be used.
  • hydrophilization treatment liquids can change the hydrophilization effect, particularly the hydrophilization layer wetting index described later, by appropriately changing the temperature in the range of 5 to 80 ° C. Further, by raising the temperature, the treatment time (contact time) for obtaining the desired hydrophilization treatment effect can be shortened. That is, both the concentration and temperature of the hydrophilization treatment liquid have the effect of increasing the hydrophilization rate by increasing, and can be complementarily controlled.
  • red dye ("Cation Red” manufactured by Kiwa Chemical Industry Co., Ltd.) dissolved in 100 parts by weight
  • a dye solution was prepared.
  • a hollow fiber porous membrane cut to a length of 10 mm (or a flat porous membrane cut to a length of lOmm x width of 5 mm) is immersed for 1 minute, and then the porous membrane is taken out and immediately attached to the outer surface.
  • the sample was cut off with a filter paper, and then the sample was cut in a direction perpendicular to the length at a position approximately in the middle of the length.
  • the exposed sample cross-section was observed, and the outer surface force was also measured through a microscope for the distance that the dye solution entered.
  • the penetration distance was measured at 4 locations equally divided in the circumferential direction (or 4 locations equally divided in the width direction), and the average value was taken as the hydrophilic layer thickness.
  • a dye solution was prepared by dissolving 0.1 part by weight of a red dye ("Kiyu Thion Red” manufactured by Kiwa Chemical Industry Co., Ltd.) with respect to 100 parts by weight of the mixture.
  • the porous film was immersed in the same manner as in the method for measuring the thickness of the hydrophilic layer using the dye solution strength in which the water mixing ratio was 100% by weight, and the penetration distance of the dye solution was measured.
  • the mixing ratio of water when the infiltration distance is 50% or more of the hydrophilized layer thickness for the first time (that is, the maximum concentration of water that can wet the outer surface force of the hydrophilized layer more than half the thickness (wt% )) was measured as the hydrophilicity layer wetting index. If the water mixing ratio is 80% by weight or less, it will not be suitable as a test solution for measuring the degree of hydrophilicity because it will be hydrophilized and penetrate into the PVDF porous membrane.
  • the polyvinylidene fluoride-based porous membrane of the present invention has a hydrophilic layer thickness of 2 from the outer surface, which is the average outer surface pore diameter by SEM observation. It is characterized by being not less than twice, preferably not less than 5 times, more preferably not less than 10 times, and a film thickness of 1Z2 or less, preferably 1Z3 or less, more preferably 1Z4. If the hydrophilized layer thickness is less than twice the outer surface pore diameter, low contamination is not sufficiently exhibited. On the other hand, if the thickness exceeds 1Z2, the mechanical strength of the membrane decreases.
  • the absolute thickness of the hydrophilic layer is preferably 0.5 to 200; ⁇ ⁇ , more preferably 1 to: LOO / z m or 2 to 60 / ⁇ ⁇ .
  • the thickness of the hydrophilizing layer is in the range of 5 to 15 m.
  • a wettability improving liquid having a surface tension of 34 to 45 mNZm.
  • the optimum surface tension range of this wettability improving liquid is the value when the average pore diameter (SEM method) on the outer surface of the porous membrane to which the wettability improving liquid is to be applied is around 0.20 ⁇ m. In response to the decrease, each should be increased or decreased slightly.
  • the hydrophilic layer wetting index of the porous membrane of the present invention is preferably 90% by weight or more, more preferably 95% by weight or more, and most preferably 100% by weight. %. If the wetting index of the hydrophilic layer is less than 90% by weight, low contamination may not be sufficiently exhibited.
  • the hydrophilized vinylidene fluoride-based rosin porous membrane after contact with a hydrophilic treatment solution preferably an alkaline aqueous solution, more preferably an alkaline aqueous solution and an oxidizing agent solution, is further washed with water. By drying, the low-contamination porous water treatment membrane of the present invention is obtained.
  • the typical physical properties other than the outer surface selective hydrophilicity of the low-contamination vinylidene fluoride-based rosin porous water treatment membrane of the present invention are listed.
  • the film thickness is 0.05 to L: 5 mm, preferably 0.1 to: Lmm, more preferably 0.15 to 0.5 mm (in the case of a hollow fiber membrane, the outer diameter is 0.3 to 4 mm, preferably 0.6 to 3.5 mm, more preferably l to 3 mm)
  • the porosity (v) is 50 to 90%, preferably 60 to 85%, more preferably 65 to 80%, the tensile strength is 7 MPa or more, preferably 8 MPa or more, the elongation at break is 20% or more, Preferably 30% or more, the average pore diameter is 0.01 to 1 ⁇ m, preferably 0.5 to 0.5 / ⁇ ⁇ , more preferably 0.1 to 0.2 / ⁇ ⁇ , the maximum diameter 02 ⁇ 3 / zm, preferably 0.1 ⁇ 1 111
  • a GPC device “GPC-900” manufactured by JASCO Corporation was used, “Shode x KD—806M” manufactured by Showa Denko Co., Ltd. as a column, “Shodex KD—G” used as a precolumn, NMP as a solvent, and a temperature of 40.
  • the molecular weight was measured as a polystyrene-equivalent molecular weight by gel permeation chromatography (GPC) method at C, flow rate of lOmLZ.
  • the endothermic peak temperature in the reheated DSC curve was defined as the original resin melting point Tm2 (° C) that defines the crystal characteristics of the vinylidene fluoride resin of the present invention.
  • the apparent volume V (cm 3 ) of the porous membrane was calculated, the weight W (g) of the porous membrane was measured, and the porosity was calculated from the following formula:
  • bubble point Z half-dry method measurement method of maximum pore size Pmax and pore size distribution suitable for porous membranes, especially hollow fiber porous membranes as defined in ASTM-F316-86 and ASTM ⁇ E 1294-86. More specifically, in the bubble point method, pressurized air with gradually increasing pressure is fed into a hollow fiber porous membrane sample immersed in the test solution, and the first bubble generation point (bubble point) from the test solution is measured. Air pressure force Obtain the maximum pore size Pmax (m) of the sample membrane.
  • the wetting flow rate curve (WET FLOW CURVE) when the hollow fiber porous membrane sample is wet with the test solution and the dry flow rate curve (DRY FL OW CURVE) with a 1Z2 slope curve (HALF DRY) Calculate the average pore size Pm m) of the sample membrane from the air pressure at the point where it intersects with (CURVE).
  • the hole diameter obtained from the air pressure at the coincidence point between the wet flow curve and the dry flow curve was determined as the minimum hole diameter Pmin (m).
  • the values stated in this document are “Palm Porometer CFP-2000AEXJ” manufactured by Porous Materials, Inc. as the measuring instrument, and perfluoropolyester (trade name “Galwick”) as the test solution. Based on the measurement results of the hollow fiber membrane samples. [0078] (Measurement of outer surface average pore diameter by SEM observation)
  • the outer and inner outer surfaces of the hollow fiber porous membrane were photographed at an observation magnification of 5000 times.
  • Sample length L 800 mm sample hollow fiber porous membrane was immersed in ethanol for 15 minutes, then immersed in pure water for 15 minutes, wetted, and measured at a water temperature of 25 ° C and a differential pressure of lOOkPa for 1 day
  • the sample hollow fiber porous membrane After immersing the sample hollow fiber porous membrane in ethanol for 15 minutes, then in pure water for 15 minutes and then moistening, it contains sodium hypochlorite (NaCIO) at an effective chlorine concentration of 5000 ppm. It was immersed in an aqueous solution containing (NaOH) at a concentration of 1% by weight for 96 hours, and then washed with running water for 12 hours. The flux retention rate of this hollow fiber porous membrane was measured in the same manner as the measurement of the above-mentioned flatness retention rate, and it was evaluated whether the hydrophilization effect was maintained after immersion with the above mixed solution.
  • NaCIO sodium hypochlorite
  • the sample hollow fiber porous membrane was immersed in ethanol for 15 minutes, then immersed in pure water for 15 minutes and wetted, then immersed in an aqueous solution containing 3% by weight of citrate for 96 hours, and then with running water. Washed with water for 12 hours.
  • the flux maintenance factor of the hollow fiber porous membrane was measured in the same manner as the flux maintenance factor, and it was evaluated whether or not the hydrophilization effect was maintained even after immersion with the citrate aqueous solution.
  • the temperature is 23 ° C
  • the scattering angle is 90 degrees
  • the measurement time is 100 seconds
  • Z times the number of repetitions is 10
  • the analysis mode is the monodisperse mode.
  • the surfactant particle size distribution (range: 3 ⁇ ! To 3000 nm) in the surfactant solution was measured under the conditions, and the average particle size was defined as the surfactant dispersed particle size.
  • the surface tension of the wet treatment solution at a temperature of 25 ° C. was measured by a ring method in accordance with JIS-K3362 using a Duny surface tension tester.
  • PVDF Polyvinylidene fluoride
  • Mw weight average molecular weight
  • PVDF polyvinylidene fluoride
  • Adipic acid polyester plasticizer ("PN-150” manufactured by Asahi Denka Kogyo Co., Ltd.) as the aliphatic polyester and N-methylpyrrolidone (NMP) as the solvent, 82.5 wt. 0 / oZl 7
  • NMP N-methylpyrrolidone
  • the supplied powder supply force also supplies the PVDF mixture, and the cylinder uppermost flow force is the liquid supply (plasticizer + solvent) mixture heated to 160 ° C from the liquid supply provided at the position of 480mm.
  • Z liquid mixture 35. 7 / 64.3 (% by weight) is supplied and kneaded at a barrel temperature of 220 ° C.
  • the kneaded product is discharged from a nozzle with a circular slit with an outer diameter of 7 mm and an inner diameter of 5 mm. 16.
  • the extruded mixture is maintained in a molten state at a temperature of 40 ° C and from the nozzle 28 It was led into a water cooling bath with a water surface at a distance of Omm (ie, air gap of 280 mm), cooled and solidified (residence time in the cooling bath: about 2.7 seconds), and taken up at a take-up speed of l lmZ Thereafter, this was scraped off into a force force having a circumference of about lm to obtain a first intermediate molded body.
  • Omm air gap of 280 mm
  • the first intermediate molded body was immersed in dichloromethane at room temperature for 30 minutes while being vibrated, and then the dichloromethane was replaced with a new one and immersed again under the same conditions to remove the plasticizer and the solvent. Extraction was then performed in an oven at a temperature of 120 ° C. for 1 hour to remove dichloromethane and heat treatment was performed to obtain a second intermediate molded body.
  • the second intermediate compact is passed through a 60 ° C water bath with a first roll speed of 20. OmZ and a second roll speed of 37. OmZ.
  • the film was stretched 1.85 times in the longitudinal direction.
  • the sample was passed through a warm water bath controlled at a temperature of 90 ° C., and the third roll speed was lowered to 34. OmZ, thereby performing 8% relaxation treatment in warm water.
  • 4% relaxation treatment was performed in the dry heat bath by passing it through a dry heat bath (2. Om length) controlled at a space temperature of 140 ° C and dropping the fourth roll speed to 32.7 mZ. It was.
  • This was wound up to obtain a PVDF hollow fiber porous membrane (third molded body).
  • SEM scanning electron microscope
  • the same PVDF mixture and liquid agent (plasticizer + solvent) mixture as in Production Example 1 were supplied using the same co-rotating twining twin screw extruder as in Production Example 1, and the same as in Production Example 1. Furthermore, the take-off speed of the melt extrudate with nozzle force was reduced to 4.8 mZ and extruded into a hollow fiber shape. At this time, air with a vent hole provided at the center of the nozzle was injected into the middle of the yarn at a flow rate of 8. OmLZ.
  • the extruded mixture is maintained in a molten state, maintained at a temperature of 40 ° C, and has a water surface at a position 28 Omm away from the nozzle (that is, an air gap of 280 mm).
  • a water surface at a position 28 Omm away from the nozzle (that is, an air gap of 280 mm).
  • the first intermediate molded body was immersed in dichloromethane at room temperature for 30 minutes while being vibrated, and then the dichloromethane was replaced with a new one and immersed again under the same conditions to remove the plasticizer and the solvent. Extraction was then performed in an oven at a temperature of 120 ° C. for 1 hour to remove dichloromethane and heat treatment was performed to obtain a second intermediate molded body.
  • the second intermediate formed body was passed through a 60 ° C water bath with a first roll speed of 20. OmZ, and the second roll speed was 37. OmZ. Stretched 1.85 times in the longitudinal direction.
  • the sample was passed through a warm water bath controlled at a temperature of 90 ° C., and the third roll speed was reduced to 3 4. OmZ, thereby performing 8% relaxation treatment in warm water.
  • 4% relaxation treatment was performed in the dry heat tank by passing it through a dry heat tank (2. Om length) controlled to a space temperature of 140 ° C and dropping the fourth roll speed to 32.7 mZ. . This was wound up to obtain a polyvinylidene fluoride hollow fiber porous membrane (third molded body).
  • PVDF hollow fiber porous membranes obtained in Production Examples 1 and 2 are subjected to an outer surface selective hydrophilization treatment according to the present invention as follows, whereby the low-contamination porous membrane of the present invention is used.
  • a water treatment membrane was obtained, and a porous water treatment membrane for comparison was obtained, and physical properties, drainage performance, flux maintenance rate, etc. were evaluated.
  • the outline of the hydrophilization treatment and physical property measurement 'evaluation results are summarized in Table 2 (Examples) and Table 3 (Comparative Examples) below.
  • glycerin fatty acid ester as a surfactant
  • a PVDF hollow fiber membrane having a selectively hydrophilized outer surface was obtained in the same manner as in Example 1 except that a surfactant aqueous solution (surface tension 32.7 mNZm) having a concentration reduced to 0.1% by weight was used. .
  • a PVDF hollow fiber membrane having a selectively hydrophilized outer surface was obtained in the same manner as in Example 1 except that the immersion time in the alkaline aqueous solution was shortened to 2 hours.
  • a PVDF hollow fiber membrane having a selectively hydrophilized outer surface was obtained in the same manner as in Example 2 except that the immersion time in the alkaline aqueous solution was shortened to 2 hours.
  • a PVDF hollow fiber membrane having a selectively hydrophilized outer surface was obtained in the same manner as in Example 1 except that the hollow fiber membrane obtained in Production Example 2 was used.
  • a PVDF hollow fiber membrane having a selectively hydrophilized outer surface was obtained in the same manner as in Example 5 except that the immersion time in the alkaline aqueous solution was reduced to 30 minutes.
  • a PVDF hollow fiber membrane having an outer surface selectively hydrophilized was obtained in the same manner as in Example 6 except that the concentration of the aqueous alkali solution was increased to 30% by weight.
  • the hollow fiber membrane obtained in Production Example 1 was fed out at a line speed of 0.1 mZ, and surfactants (such as Lion's “Chaimmy V Quick”, sodium alkyl ether sulfate, etc.) 36% surfactant component) dissolved in pure water at a concentration of 0.5% by weight
  • surfactants such as Lion's “Chaimmy V Quick”, sodium alkyl ether sulfate, etc. 36% surfactant component
  • the solution is allowed to pass through a surfactant solution (bath time 25 minutes), then passed through a 5% aqueous sodium hydroxide solution maintained at a temperature of 85 ° C (bath time 25 minutes), It was passed through a washing bath (resting time 100 minutes) and scraped off with force.
  • the removed hollow fiber membrane was washed with running water for 1 hour and then dried for 12 hours in a vacuum dryer maintained at a temperature of 40 ° C. to obtain a PVDF hollow fiber membrane whose outer surface was selectively hydrophilized. .
  • the surfactant solution had a surface tension of 28.9 mN Zm, the surfactant solution was a transparent aqueous solution, and the surfactant dispersed particle size was below the measurement limit (3 nm).
  • a PVDF hollow fiber membrane having a selectively hydrophilized outer surface was obtained in the same manner as in Example 8 except that the bathing time of the surfactant solution was changed to 1 minute and the concentration of sodium hydroxide aqueous solution was changed to 20%. It was.
  • the line speed was 0.86 mZ
  • the surfactant solution bathing time was 3 minutes
  • the sodium hydroxide aqueous solution concentration was 40%
  • the sodium hydroxide aqueous solution bathing time was 3 minutes
  • the washing bath bathing time was 12 minutes.
  • a PVDF hollow fiber membrane having an outer surface selectively hydrophilized was obtained in the same manner as in Example 8 except that the time was changed to minutes.
  • the solution is allowed to pass through an aqueous solution of emeraldil dissolved in pure water at a concentration of 2% (resting time: 2.9 minutes), and then passed through a 40% strength by weight aqueous sodium hydroxide solution maintained at a temperature of 85 ° C (resting time 2). 9 minutes), then passed through a water bath (lag time 11.6 minutes) and wound onto a bobbin.
  • the wound bobbin-wound hollow fiber membrane was immersed in an aqueous solution of 12% by weight sodium hypochlorite at room temperature and immersed for 24 hours.
  • the removed hollow fiber membrane is washed with running water for 24 hours, and then dried for 12 hours in a vacuum dryer maintained at a temperature of 40 ° C to selectively select the outer surface.
  • a hydrophilic PVDF hollow fiber membrane was obtained.
  • the surfactant solution had a surface tension of 34.9 mNZm, and the surfactant solution was a cloudy emulsion-like aqueous solution.
  • a PVDF hollow fiber membrane having an outer surface selectively hydrophilized was obtained in the same manner as in Example 11 except that “SY Glyster MO 7SJ” manufactured by Sakamoto Pharmaceutical Co., Ltd. was used as the surfactant.
  • the HLB value of the agent was 12.9
  • the surface tension of the surfactant solution was 36.2 mN Zm
  • the surfactant solution was a cloudy emeraldion-like aqueous solution.
  • the PVDF hollow fiber membranes obtained in Production Examples 1 and 2 were evaluated as they were.
  • Example 1 the same treatment as in Example 1 was performed except that the surfactant emulsion was changed to an aqueous solution and immersed in ethanol (surface tension 22. OmNZm) for 15 minutes. As a result, a PVDF porous membrane in which all layers were hydrophilized was obtained.
  • Example 3 the surfactant was immersed in ethanol for 15 minutes instead of the emulsion aqueous solution, and the concentration of the sodium hydroxide aqueous solution was changed from 5% by weight to 1% by weight. The same treatment as in Example 3 was performed except that. As a result, a porous PVDF membrane was obtained in which all layers were hydrophilized.
  • the outer surface of the polyvinylidene fluoride resin porous membrane is selectively hydrophilized.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

La présente invention concerne une membrane poreuse de traitement de l'eau avec une faible contamination, laquelle est une membrane poreuse faite d'une résine à base de fluorure de vinylidène dont la surface externe a été rendue hydrophile de manière sélective. Cette membrane poreuse de traitement de l'eau faite d'une résine à base de fluorure de vinylidène est caractérisée par : (a) le fait de présenter une faible contamination de la membrane lors de la filtration (à savoir ayant un taux élevé de rétention d'écoulement) ; (b) les propriétés de faible contamination étant maintenues après des lavages répétés avec un produit chimique (à savoir, une forte tolérance au lavage avec un produit chimique) ; et (c) le fait d'avoir une résistance mécanique favorable.
PCT/JP2007/056363 2006-04-25 2007-03-27 Membrane poreuse de traitement de l'eau faite d'une resine a base de fluorure de vinylidene avec une faible contamination et son procede de production Ceased WO2007125709A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2006-120514 2006-04-25
JP2006120514 2006-04-25
JP2006-184079 2006-07-04
JP2006184079A JP2007313491A (ja) 2006-04-25 2006-07-04 低汚染性フッ化ビニリデン系樹脂多孔水処理膜およびその製造方法

Publications (1)

Publication Number Publication Date
WO2007125709A1 true WO2007125709A1 (fr) 2007-11-08

Family

ID=38655245

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2007/056363 Ceased WO2007125709A1 (fr) 2006-04-25 2007-03-27 Membrane poreuse de traitement de l'eau faite d'une resine a base de fluorure de vinylidene avec une faible contamination et son procede de production

Country Status (2)

Country Link
JP (1) JP2007313491A (fr)
WO (1) WO2007125709A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021040001A1 (fr) * 2019-08-29 2021-03-04 東レ株式会社 Procédé d'hydrophilisation d'une membrane de séparation poreuse à base de fluorure de polyvinylidène

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101641148A (zh) 2007-03-23 2010-02-03 株式会社吴羽 1,1-二氟乙烯系树脂中空丝多孔膜及其制造方法
JP2010088996A (ja) * 2008-10-07 2010-04-22 Asahi Kasei Chemicals Corp 分離膜用保存液
US20120012521A1 (en) * 2009-01-15 2012-01-19 Takeo Takahashi Vinylidene fluoride resin hollow fiber porous membrane and process for producing same
WO2010090183A1 (fr) * 2009-02-05 2010-08-12 株式会社クレハ Film poreux en résine de fluorure de vinyldène, et procédé de fabrication correspondant
KR101362553B1 (ko) 2009-07-14 2014-02-13 가부시끼가이샤 구레하 불화비닐리덴계 수지 다공막, 그의 제조 방법 및 여과수의 제조 방법
JP5552289B2 (ja) * 2009-09-04 2014-07-16 株式会社クレハ フッ化ビニリデン系樹脂多孔膜の製造方法
JP2011236292A (ja) * 2010-05-07 2011-11-24 Kri Inc ポリフッ化ビニリデン多孔質体
WO2013146742A1 (fr) * 2012-03-26 2013-10-03 三菱レイヨン株式会社 Solution de conservation de film poreux

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5893734A (ja) * 1981-11-30 1983-06-03 Asahi Chem Ind Co Ltd 親水性ポリフツ化ビニリデン樹脂多孔膜の製造方法
JPS5968344A (ja) * 1982-10-12 1984-04-18 Agency Of Ind Science & Technol 非対称機能膜及びその製法
JPH05317663A (ja) * 1992-05-19 1993-12-03 Asahi Chem Ind Co Ltd フッ素系親水性微多孔膜及びそれを用いた水処理方法
WO2003026779A1 (fr) * 2001-08-01 2003-04-03 Asahi Kasei Kabushiki Kaisha Film microporeux multicouches
JP2004098027A (ja) * 2002-09-12 2004-04-02 Asahi Medical Co Ltd 高性能精密濾過膜
JP2004202438A (ja) * 2002-12-26 2004-07-22 Toray Ind Inc 多孔質膜
JP2005194461A (ja) * 2004-01-09 2005-07-21 Kuraray Co Ltd フッ化ビニリデン系樹脂多孔膜およびその製造方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5893734A (ja) * 1981-11-30 1983-06-03 Asahi Chem Ind Co Ltd 親水性ポリフツ化ビニリデン樹脂多孔膜の製造方法
JPS5968344A (ja) * 1982-10-12 1984-04-18 Agency Of Ind Science & Technol 非対称機能膜及びその製法
JPH05317663A (ja) * 1992-05-19 1993-12-03 Asahi Chem Ind Co Ltd フッ素系親水性微多孔膜及びそれを用いた水処理方法
WO2003026779A1 (fr) * 2001-08-01 2003-04-03 Asahi Kasei Kabushiki Kaisha Film microporeux multicouches
JP2004098027A (ja) * 2002-09-12 2004-04-02 Asahi Medical Co Ltd 高性能精密濾過膜
JP2004202438A (ja) * 2002-12-26 2004-07-22 Toray Ind Inc 多孔質膜
JP2005194461A (ja) * 2004-01-09 2005-07-21 Kuraray Co Ltd フッ化ビニリデン系樹脂多孔膜およびその製造方法

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021040001A1 (fr) * 2019-08-29 2021-03-04 東レ株式会社 Procédé d'hydrophilisation d'une membrane de séparation poreuse à base de fluorure de polyvinylidène
JPWO2021040001A1 (ja) * 2019-08-29 2021-09-13 東レ株式会社 ポリフッ化ビニリデン系多孔質分離膜の親水化方法
JP7004079B2 (ja) 2019-08-29 2022-01-21 東レ株式会社 ポリフッ化ビニリデン系多孔質分離膜の親水化方法
CN114269458A (zh) * 2019-08-29 2022-04-01 东丽株式会社 聚偏二氟乙烯系多孔质分离膜的亲水化方法
CN114269458B (zh) * 2019-08-29 2024-02-27 东丽株式会社 聚偏二氟乙烯系多孔质分离膜的亲水化方法

Also Published As

Publication number Publication date
JP2007313491A (ja) 2007-12-06

Similar Documents

Publication Publication Date Title
CN101370572B (zh) 聚偏氟乙烯基中空纤维型微孔膜及其制造方法
AU2002338039B2 (en) Hollow fiber film and method for production thereof
TWI301774B (en) Porous membrane and process for producing the same
US10406487B2 (en) Hydrophilised vinylidene fluoride-based porous hollow fibre membrane, and manufacturing method therefor
WO2007125709A1 (fr) Membrane poreuse de traitement de l'eau faite d'une resine a base de fluorure de vinylidene avec une faible contamination et son procede de production
JP5626269B2 (ja) 高分子多孔質膜及び高分子多孔質膜の製造方法
US11338253B2 (en) Porous hollow fiber membrane, method for producing same, and water purification method
KR20140116146A (ko) 고분자 다공질막
KR20110033729A (ko) 불소계 중공사막 및 그 제조 방법
WO2019066061A1 (fr) Membrane poreuse à fibres creuses et procédé pour sa production
WO2010082437A1 (fr) Membrane poreuse en fibres creuses de résine de fluorure de vinylidène, et procédé de fabrication associé
WO2007123004A1 (fr) Membrane poreuse en fibres creuses de résine de fluorure de vinylidène et procédé destiné à produire ladite membrane
KR20130040620A (ko) 친수화 개질 폴리불화비닐리덴 수지를 이용한 고강도 수처리용 중공사막의 제조방법
JPWO2009119373A1 (ja) 中空糸膜およびその製造方法
JP4931796B2 (ja) フッ化ビニリデン系樹脂中空糸多孔膜、それを用いる水の濾過方法およびその製造方法
JP2003320228A (ja) 微多孔膜の製造方法および微多孔膜
JP4864707B2 (ja) フッ化ビニリデン系樹脂多孔水処理膜の製造方法
KR20160079354A (ko) 친수성이 향상된 pvdf 중공사막 조성물 및 이를 이용한 pvdf 중공사막
KR101308996B1 (ko) 친수화 폴리불화비닐리덴 복합 수지를 이용한 고투과 수처리용 중공사막의 제조방법
WO2011027878A1 (fr) Membrane poreuse en résine de fluorure de vinylidène et son procédé de production
JP5620665B2 (ja) 延伸樹脂多孔膜の製造方法
JP2010075851A (ja) 多孔質膜およびその製造方法
JP2014200752A (ja) 高分子多孔質膜

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 07739801

Country of ref document: EP

Kind code of ref document: A1

DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 07739801

Country of ref document: EP

Kind code of ref document: A1

DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)