WO2007123004A1 - Membrane poreuse en fibres creuses de résine de fluorure de vinylidène et procédé destiné à produire ladite membrane - Google Patents

Membrane poreuse en fibres creuses de résine de fluorure de vinylidène et procédé destiné à produire ladite membrane Download PDF

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Publication number
WO2007123004A1
WO2007123004A1 PCT/JP2007/057684 JP2007057684W WO2007123004A1 WO 2007123004 A1 WO2007123004 A1 WO 2007123004A1 JP 2007057684 W JP2007057684 W JP 2007057684W WO 2007123004 A1 WO2007123004 A1 WO 2007123004A1
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WIPO (PCT)
Prior art keywords
hollow fiber
porous membrane
vinylidene fluoride
membrane
fiber porous
Prior art date
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PCT/JP2007/057684
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English (en)
Japanese (ja)
Inventor
Takeo Takahashi
Masayuki Hino
Yasuhiro Tada
Toshiya Mizuno
Takaaki Mukumoto
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Kureha Corporation
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Publication of WO2007123004A1 publication Critical patent/WO2007123004A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/08—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of halogenated hydrocarbons
    • D01F6/12—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of halogenated hydrocarbons from polymers of fluorinated hydrocarbons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B01D63/02—Hollow fibre modules
    • B01D63/021—Manufacturing thereof
    • B01D63/022—Encapsulating hollow fibres
    • B01D63/023—Encapsulating materials
    • 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
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/12—Activated sludge processes
    • C02F3/1236—Particular type of activated sludge installations
    • C02F3/1268—Membrane bioreactor systems
    • C02F3/1273—Submerged membrane bioreactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/42—Details of membrane preparation apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/20—Specific permeability or cut-off range
    • 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
    • B01D2325/34—Molecular weight or degree of polymerisation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

  • Vinylidene fluoride resin hollow fiber porous membrane and method for producing the same
  • the present invention relates to a hollow fiber porous membrane (hollow fiber porous membrane) made of vinylidene fluoride resin having both (filter) water treatment performance and durability, and a method for producing the same.
  • the present inventors also melt-extruded vinylidene fluoride resin having specific molecular weight characteristics into a hollow fiber shape together with a plasticizer and a good solvent of the polyvinylidene fluoride resin.
  • the method of extracting and removing the post plasticizer to make it porous is effective for the formation of a porous vinylidene fluoride resin porous membrane having fine pores of appropriate size and distribution and excellent mechanical strength.
  • Patent Document 4 proposes to further improvements in the overall performance including the filtration performance and mechanical performance required when using a hollow fiber porous membrane as a filtration membrane.
  • a membrane separation activated sludge method that combines activated sludge method and membrane treatment is adopted in the fields of sewage and wastewater treatment. This involves immersing the membrane directly in an activated sludge tank and performing solid-liquid separation by suction filtration. At this time, an aeration treatment is performed using a blower, which combines oxygen supply for biological treatment and membrane surface cleaning by vibrating the membrane surface, and is always in operation. Therefore, it is effective for suppressing film fouling, but if the film itself is weak, there is a greater risk of thread breakage. Therefore, in the MBR method, a film having high strength (high resistance against load under load) is particularly required.
  • Patent Document 7 proposes to increase the strength by including reinforcing fibers in the hollow fiber film thickness.
  • the membrane permeation resistance and flow resistance increase and the water permeation rate tends to decrease because the film thickness is inevitably large and it is difficult to increase the inner diameter. There is a point.
  • Patent Document 8 "A plasticizer and a vinylidene fluoride-based resin with respect to 100 parts by weight of a vinylidene fluoride resin having a weight average molecular weight of 300,000 or more.
  • the total amount of the good solvent for the resin is 100 to 300 parts by weight, and the proportion of the good solvent is 8 to 22% by weight, and the resulting composition is melt extruded into a hollow fiber, and the hollow part is not melted.
  • a method for producing a vinylidene fluoride-based rosin porous hollow fiber characterized by injecting an active gas into an inert liquid, cooling and solidifying, and then extracting a plasticizer to recover a porous hollow fiber ”Is proposed.
  • the hollow fiber porous membrane (porous hollow fiber) formed in this way has the characteristics that the flow resistance in the hollow fiber is small due to expansion and the length dependency of the water permeability is small. Yes. However, it still does not have high durability (high strength) enough to withstand the MBR method (see Comparative Examples 1 and 2 below).
  • Patent Document 1 Japanese Patent Laid-Open No. 63-296939
  • Patent Document 2 WO02 / 070115A Publication
  • Patent Document 3 Japanese Patent Laid-Open No. 2003-210954
  • Patent Document 4 WO 2004/081109 A Publication
  • Patent Document 5 Japanese Patent No. 2899903
  • Patent Document 6 WO02 / 070115A Publication
  • Patent Document 7 Japanese Unexamined Patent Application Publication No. 2002-166141
  • Patent Document 8 WO2005Z032700A.
  • the main object of the present invention is to provide a highly durable polyvinyl biliary fluorinated hollow fiber porous membrane having a high durability capable of withstanding the MBR method and having a high particulate removal performance and a high water permeability. It aims at providing the manufacturing method.
  • the polyvinylidene fluoride based hollow fiber porous membrane of the present invention has been developed to achieve the above-mentioned object, and more specifically has a weight average molecular weight of 200,000 to 600,000. It is made of a vinylidene fluoride resin and has the following characteristics (A) and (B): (A) One end of the resin is covered with an epoxy resin with a hardness of 98 g.
  • the hollow fiber porous membrane having such characteristics (A) and (B) is further added with a stretching step in the method of Patent Document 4 or 8,
  • a stretching step in the method of Patent Document 4 or 8
  • the melt extrusion rate the residence time after extrusion and the draw ratio, and forming a hollow fiber porous membrane having an outer diameter of 1.50 to 3,000 mm and a wall thickness of 0.30 to 0.75 mm
  • the resulting high cross-sectional area ⁇ hollow fiber membrane can be effectively manufactured by increasing the thickness and further preferably expanding the diameter.
  • the method for producing a hollow hollow fiber membrane comprises a plasticizer and a good solvent for vinylidene fluoride resin for 100 parts by weight of vinylidene fluoride resin having a weight average molecular weight of 200,000 to 600,000. The total amount is 100 to 300 parts by weight, and the proportion of the good solvent is 12.5 to 35% by weight.
  • the resulting composition is melt extruded into a hollow fiber and introduced into an inert liquid from the outside.
  • the hollow fiber porous membrane When the hollow fiber porous membrane is produced by drawing after cooling and solidification and further extracting the plasticizer, the melt extrusion speed, the inert liquid bath temperature, the residence time to the bath after the extrusion, and the elongation By adjusting the magnification, a hollow fiber porous membrane having an outer diameter of 1.50 to 3.OO mm and a wall thickness of 0.30 to 0.75 mm is formed.
  • the hollow fiber membrane produced by such a method causes the crystallization of the vinylidene fluoride resin to be finer on the outer side and larger on the inner side by cooling the outer force of the melt-extruded hollow fiber membrane.
  • it has a feature that it has an inclined hole diameter distribution (asymmetric hole diameter distribution) with a small hole diameter on the outer surface (near) and a large hole diameter on the inner surface (near).
  • the effective filtration layer thickness having an average pore size Pm that governs fine particle removal performance and membrane permeation resistance is relatively small, and the hollow fiber membranes that have been made thick overall This part contributes to an increase in mechanical strength such as bending resistance, but does not contribute so much to an increase in the effective filtration layer thickness (and hence an increase in membrane permeation resistance).
  • the hollow fiber membrane having an inclined pore size distribution provides greater bending flexibility than a hollow fiber membrane having a uniform pore size distribution. It is understood that these factors contribute synergistically to realize the characteristics (A) and (B) of the hollow fiber porous membrane of the present invention.
  • the hollow fiber membrane of the present invention has a constant stress (0.136 MPa) as a result of the large cross-sectional area represented by diameter expansion and thickening as described above. It is noted that even under the conditions, the bending resistance is improved (the number of bending breaks is increased) (see Table 1 showing the results of Examples and Comparative Examples described later).
  • FIG. 1 is a schematic explanatory view of a hollow fiber porous membrane sample used for a bending resistance test.
  • FIG. 3 is a schematic explanatory diagram of a water permeability measuring device used for evaluating the water treatment performance of the hollow fiber porous membranes obtained in Examples and Comparative Examples.
  • the vinylidene fluoride based hollow fiber porous membrane of the present invention will be sequentially described according to the production method of the present invention which is a preferred production method thereof.
  • 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, ie, poly (vinylidene fluoride) and other copolymerizable with vinylidene fluoride are 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 is preferable to use a homopolymer composed of 100% by mole of vinylidene fluoride because of its high mechanical strength.
  • the above-mentioned relatively high molecular weight vinylidene fluoride-based resin can be preferably 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 relatively large molecular weight of 200,000 to 600,000 as described above.
  • 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 resin is produced by heat and mechanical history received during its production process or thermoforming process. It shows a melting point Tml (° C) different from the original melting point Tm2 (° C) of the resin, and the melting point Tm2 (° C) of the above-mentioned fluoride-redene resin is the sample obtained.
  • melting point endothermic peak temperature associated with crystal melting
  • Tm 2-1 ⁇ ⁇ 32 that represents the crystallization temperature of vinylidene fluoride resin preferably used in the present invention can be achieved even if the reduction of 13 ⁇ 412 is caused by copolymerization, for example. However, in this case, there is a case where the chemical resistance of the resulting porous film tends to be lowered. Accordingly, in a preferred embodiment of the present invention, 70 to 98% by weight of a vinylidene fluoride resin having a weight average molecular weight (Mw) of 150,000 to 600,000 is used as a matrix (mainly) resin.
  • 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 preferentially cooling the outer surface force of a hollow fiber membrane formed by melt extrusion by increasing Tc, the vinylidene fluoride system from the inside of the membrane to the inside surface is slower to cool than the membrane surface. It is possible to speed up the solidification of the coconut and to suppress the growth of spherical particles.
  • 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 forming a film by adding a plasticizer and a good solvent for the 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
  • ketones include ketones, 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 is difficult to achieve the object of the present invention to obtain a hollow fiber porous membrane.
  • substantially only the strength of the vinylidene fluoride resin also means that the porous membrane is not only the vinylidene fluoride resin.
  • optional stabilizers or small granular fillers 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, mixing of the vinylidene fluoride resin, the plasticizer and the good solvent, and the molten form are 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 amount of raw material discharged 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 will be crushed and hollow parts will be formed. May be impossible.
  • 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 inert gas into the hollow portion is larger than the case of simply increasing the thickness of the hollow fiber membrane produced by the present invention.
  • the inert gas injection rate as the feed rate per length (m) of the melt-extruded material is 0.7 to 6.8 mlZm, more preferably 1.2 to 3. Oml / m, especially 1.4 to 2.
  • the range of OmlZm is preferred. If it is less than 7 mlZm, the inner diameter of the hollow portion becomes small, and the water permeability decreases due to flow resistance. If it exceeds 6.8 mlZm, the melt-extruded membrane may be punctured.
  • the cooling liquid generally a liquid which is inert (that is, non-solvent and non-reactive) to vinylidene fluoride-based resin, preferably water is 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 advantageous for regeneration (WO2006Z087963A1).
  • the temperature of the cooling bath is 0 to 120 ° C., a force that can select a force in a wide temperature range, preferably 5 to 100 ° C., particularly preferably 10 to 80 ° C. [0034] (Extraction)
  • 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 hollow fiber membrane having a large cross-sectional area 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 (PCTZJP2006Z318028 specification).
  • the non-wetting atmosphere has a surface tension (JIS K6768) that is greater than the wetting tension of vinylidene fluoride resin near room temperature. It is composed of a non-wetting liquid, typically water or almost any gas including air, especially a non-condensable gas near room temperature, or the vapor 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 where the peripheral speed 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%.
  • step relaxation rate exceeds 20%, or the total relaxation rate exceeds 30%, it is difficult to achieve the force depending on the draw ratio in the previous process, or is the water permeability improvement effect saturated even if realized? It is preferable because it is lowered.
  • 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 multistage relaxation treatment described above is a remarkable effect 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 be slightly lowered. .
  • the thickness of the hollow fiber membrane slightly increases, and the inner diameter and outer diameter tend to increase.
  • a heat treatment with a relaxation rate of 0% that is, a heat setting treatment may be performed.
  • One characteristic of the hollow fiber porous membrane of the present invention obtained by force is that it has a large number of bending breaks. It is characterized by having excellent bending resistance (characteristic (A)) as represented.
  • the property (A) (number of bending breaks) described in the present specification is basically based on a value measured in accordance with ASTM-D2176. More specifically, a hollow fiber porous membrane sample was cut to a length of 100 mm, and its lower end was sealed with about 10 mm by heat sealing, and then the lower end was epoxy resin (manufactured by SUNREC Co., Ltd. RN5 ”) and cured completely, then the epoxy resin was cut off, and the bottom edge was measured with a type A durometer (length 10mm x width 20mm x height 8mm according to J IS K6253) A bending line fracture sample as shown in Fig. 1 fixed with an epoxy resin having an A hardness of 98 was obtained.
  • a durometer length 10mm x width 20mm x height 8mm according to J IS K6253
  • the hollow fiber porous membrane of the present invention has a number of bending breaks of 100 times or more, preferably 1000 times or more, more preferably 5000 times or more, more preferably 48 times or less under a load of 48 g measured as described above. Is characterized in that the number of bending breaks under a constant stress of 0.136 MPa is 10 times or more, more preferably 50 times or more, and still more preferably 100 times or more.
  • the hollow fiber porous membrane of the present invention shows a large amount of water permeability despite the small average pore diameter.
  • the hole has good communication.
  • Pm mean pore diameter
  • the water permeability force S (average) is proportional to the fourth power of the pore diameter, while the number of holes is 2 of the average pore diameter. Therefore, the water permeability is proportional to the square of the (average) pore diameter. According to the present inventors, this square law does not hold when the porosity (V) is different, but since an experimental result in which the water permeability is proportional to the porosity is obtained, a constant porosity is obtained.
  • the hollow fiber porous membrane of the present invention preferably has an average pore diameter Pm of 0.05-0.20 ⁇ m, particularly 0.08 to 0.18 / zm by a half dry method. If the average pore size Pm is less than 0.05 m, the water permeability of the membrane will decrease. On the other hand, if it exceeds 0.20 m, the ability of the membrane to remove fine particles (contaminants or bacteria) may decrease. Similarly, the maximum diameter Pmax force by the bubble point method SO. 15 to 0.50 111, especially 0.20 to 0.40 m, is preferable. If the maximum pore size Pmax is less than 0.15 m, the water permeability of the membrane will decrease. On the other hand, if it exceeds 0.50 / zm, the membrane's ability to remove fine particles (contaminants or bacteria) may decrease.
  • Other general characteristics of the hollow fiber porous membrane obtained by the present invention include an outer diameter of 1.50 to 3.00 mm, preferably 1.75 to 2.5 mm, and a wall thickness. ⁇ 0. 75 mm, preferably 0. 35-0. 60 mm, empty mosquito larva and rate (v) power 55-90 0/0, preferably ⁇ or 60 to 85 0/0, particularly preferably ⁇ or 65-80%, tensile Properties with a strength of 6 MPa or more and a breaking elongation of 5% or more can be obtained.
  • the hollow fiber porous membrane of the present invention obtained through the stretching process has a fine structure in which a crystal orientation part and a crystal non-orientation part (random orientation part) are recognized by an X-ray diffraction method. It is understood that this corresponds to the stretched fibril part and the unstretched node part, respectively.
  • the hollow fiber porous membrane of the present invention obtained by cooling from the outside of a hollow fiber-like melt-extruded product of vinylidene fluoride resin having an appropriate crystallinity is made of vinylidene fluoride resin. Finer crystallization occurs on the outside and larger on the inside. As a result, it has an asymmetrical hole size distribution in which the inner outer surface has a larger hole diameter than the outer outer surface hole diameter, and the outer outer surface (near) has a smaller hole diameter and the inner outer surface (near) has a larger hole diameter. It has a feature.
  • the preferred graded pore size distribution is such that the ratio of the inner outer surface average pore size to the outer outer surface average pore size measured by the method described later is 1.5 or more, particularly about 1.5 to 5.0. It is expressed by that.
  • 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.
  • DSC7 a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., set sample oil lOmg in the measuring cell, and in a nitrogen gas atmosphere at a temperature increase rate of 30 ° C to 10 ° CZ at 250 ° C. Then, the temperature was maintained at 250 ° C for 1 minute, and then the temperature was decreased from 250 ° C to 30 ° C at a rate of 10 ° CZ to obtain a DSC curve.
  • the endothermic peak velocity in the temperature rising process was defined as the melting point Tml (° C)
  • Tc crystallization temperature
  • 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.
  • Sample length L 200mm or 800mm hollow sample porous fiber membrane is immersed in ethanol for 15 minutes, then immersed in pure water for 15 minutes, wetted, water temperature 25 ° C, differential pressure 100k Pa
  • 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).
  • Wet flow curve and dry flow curve The hole diameter determined from the air pressure at the line coincidence point was determined as the minimum hole diameter (Pin gm).
  • 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.
  • the outer and inner outer surfaces of the hollow fiber porous membrane were photographed at an observation magnification of 5000 times.
  • the obtained SEM photograph (observation range is about 19 m square) was binarized using the “nexusNewQube Version4.01” manufactured by Nexus Co., Ltd.
  • the reason why the voids having D less than the minimum pore size Pmin by the half dry method are excluded is that these are not effective voids for filtration forming the communication holes (for example, unevenness of the rosin phase). It is.
  • 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 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) according to the method of the present invention.
  • the obtained polyvinylidene fluoride hollow fiber porous membrane has an outer diameter of 2.023 mm, an inner diameter of 1.218 mm, a film thickness of 0.402 mm, a porosity of 73.1%, and a differential pressure.
  • l Pure water permeation rate at OOkPa F (L, 100kPa) i, test length L 200mm
  • the air volume is the same as in Example 1 except that the discharge amount of the nozzle force is 21.6 gZ, the air flow rate of the vent hole force provided at the center of the nozzle is 11. lmlZ, and the take-up speed is 8. OmZ. A thread porous membrane was obtained.
  • Discharge amount of nozzle force is 10.3gZ
  • water bath temperature is 70 ° C
  • air flow rate from the air vent provided in the center of the nozzle is 4.6mlZ
  • take-up speed is 3.OmZ
  • draw ratio 2.4 times A hollow fiber porous membrane was obtained in the same manner as in Example 1 except that the one-step relaxation ratio was changed to 12%.
  • the mixing ratio of adipic acid-based polyester plasticizer (“PN-150” manufactured by Asahi Denki Kogyo Co., Ltd.) and N-methylpyrrolidone (NMP) is 72.5 / 27.5 (weight ratio).
  • Discharge rate is 8.5gZ
  • water bath temperature is 50 ° C
  • air flow rate from the vent in the center of the nozzle is 5.
  • Oml Z min, take-up speed is 5.
  • OmZ min, draw ratio is 2.0 times, one step A hollow fiber porous membrane was obtained in the same manner as in Example 1 except that the relaxation ratio was 10% and the two-stage relaxation temperature was changed to 110 ° C.
  • Porous membranes have (A) significantly improved flex resistance and (B) excellent fine particle removal performance, but have a large amount of water permeability and are particularly suitable for MBR (filter) water treatment membranes. I can understand that.

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  • Textile Engineering (AREA)
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Abstract

La présente invention concerne une membrane poreuse en fibres creuses qui comprend une résine de fluorure de vinylidène présentant un poids moléculaire moyen pondéral de 200 000 à 600 000 et possède les propriétés (A) et (B) suivantes : (A) lorsqu'une extrémité de la membrane est recouverte d'une résine époxy présentant une dureté de 98, la durée de vie à la flexion telle que mesurée sous une charge de 48 g est égale ou supérieure à 100; et (B) le ratio de la valeur (F) obtenue en convertissant la perméabilité de l'eau, telle que mesurée à une longueur test (L) de 200 mm dans les conditions de pression différentielle égale à 100 kPa et à température de l'eau de 25 °C, à une valeur correspondant à une porosité (v) de 70 % (L = 200 mm; v = 70 %) (m/jour), rapporté au carré (Pm2) d'un diamètre de pore moyen (Pm) (µm) tel que mesuré par le procédé moitié-sec, c'est-à-dire F (L = 200 mm, v = 70 %)/Pm2, est égal ou supérieur à 2 000 (µm2 •m/jour). La membrane poreuse en fibres creuses présente non seulement une excellente résistance à la flexion (A), mais également une haute perméabilité à l'eau (B), en dépit de l'efficacité satisfaisante du rejet des microparticules (bactéries) en raison des micropores. Cette membrane poreuse en fibres creuses de fluorure de vinylidène est particulièrement adaptée pour être utilisée dans la filtration de l'eau par le procédé de traitement par les boues activées de séparation de membrane (procédé MBR). La membrane poreuse en fibres creuses est produite par un procédé de production de membrane poreuse en fibres creuses dans lequel diverses conditions de production sont régulées de manière à entraîner une augmentation du diamètre externe et une augmentation de l'épaisseur des parois.
PCT/JP2007/057684 2006-04-18 2007-04-05 Membrane poreuse en fibres creuses de résine de fluorure de vinylidène et procédé destiné à produire ladite membrane WO2007123004A1 (fr)

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JP2013507485A (ja) * 2009-10-07 2013-03-04 アイエスピー インヴェストメンツ インコーポレイテッド 可塑化ポリマー組成物

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JP4863970B2 (ja) * 2007-11-16 2012-01-25 富士フイルム株式会社 結晶性ポリマー微孔性膜及びその製造方法、並びに濾過用フィルタ
JP4850814B2 (ja) * 2007-11-16 2012-01-11 富士フイルム株式会社 結晶性ポリマー微孔性膜及びその製造方法、並びに濾過用フィルタ
JP4850815B2 (ja) * 2007-11-16 2012-01-11 富士フイルム株式会社 精密ろ過フィルター及びその製造方法
JP4850816B2 (ja) * 2007-11-16 2012-01-11 富士フイルム株式会社 精密ろ過フィルター及びその製造方法
WO2011027878A1 (fr) * 2009-09-04 2011-03-10 株式会社クレハ Membrane poreuse en résine de fluorure de vinylidène et son procédé de production

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WO2004092257A1 (fr) * 2003-04-16 2004-10-28 Kureha Corporation Film poreux de resine de fluorure de vinylidene et son procede de production
WO2005013234A1 (fr) * 2003-08-05 2005-02-10 Thinkware Systems Corporation Procede et systeme fournissant des informations d'acheminement par des vehicules de transport public heterogenes
WO2005032700A1 (fr) * 2003-10-03 2005-04-14 Kureha Corporation Fil creux poreux compose de resine a base de fluorure de vinylidene
WO2005099879A1 (fr) * 2004-04-14 2005-10-27 Kureha Corporation Membrane de filtrage d’eau poresue de fibre creuse de resine de fluorure de vinylidene et procédé de fabrication de celle-ci
JP2006063095A (ja) * 2004-08-24 2006-03-09 Kureha Corp フッ化ビニリデン系樹脂多孔膜の製造方法
WO2007032331A1 (fr) * 2005-09-14 2007-03-22 Kureha Corporation Membrane poreuse de fibre creuse de résine de fluorure de vinylidène et procédé de fabrication idoine

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WO2004092257A1 (fr) * 2003-04-16 2004-10-28 Kureha Corporation Film poreux de resine de fluorure de vinylidene et son procede de production
WO2005013234A1 (fr) * 2003-08-05 2005-02-10 Thinkware Systems Corporation Procede et systeme fournissant des informations d'acheminement par des vehicules de transport public heterogenes
WO2005032700A1 (fr) * 2003-10-03 2005-04-14 Kureha Corporation Fil creux poreux compose de resine a base de fluorure de vinylidene
WO2005099879A1 (fr) * 2004-04-14 2005-10-27 Kureha Corporation Membrane de filtrage d’eau poresue de fibre creuse de resine de fluorure de vinylidene et procédé de fabrication de celle-ci
JP2006063095A (ja) * 2004-08-24 2006-03-09 Kureha Corp フッ化ビニリデン系樹脂多孔膜の製造方法
WO2007032331A1 (fr) * 2005-09-14 2007-03-22 Kureha Corporation Membrane poreuse de fibre creuse de résine de fluorure de vinylidène et procédé de fabrication idoine

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013507485A (ja) * 2009-10-07 2013-03-04 アイエスピー インヴェストメンツ インコーポレイテッド 可塑化ポリマー組成物

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