WO2011027878A1 - Porous vinylidene fluoride resin membrane and process for producing same - Google Patents
Porous vinylidene fluoride resin membrane and process for producing same Download PDFInfo
- Publication number
- WO2011027878A1 WO2011027878A1 PCT/JP2010/065205 JP2010065205W WO2011027878A1 WO 2011027878 A1 WO2011027878 A1 WO 2011027878A1 JP 2010065205 W JP2010065205 W JP 2010065205W WO 2011027878 A1 WO2011027878 A1 WO 2011027878A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- vinylidene fluoride
- fluoride resin
- porous membrane
- plasticizer
- hollow fiber
- Prior art date
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- 229950006800 prenderol Drugs 0.000 description 1
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- 239000011164 primary particle Substances 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
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Images
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
- 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
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
- B29C48/08—Flat, e.g. panels flexible, e.g. films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
- B29C48/885—External treatment, e.g. by using air rings for cooling tubular films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/02—Details relating to pores or porosity of the membranes
- B01D2325/022—Asymmetric membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
- B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
- B29K2027/16—PVDF, i.e. polyvinylidene fluoride
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/755—Membranes, diaphragms
Definitions
- the present invention relates to a porous membrane made of vinylidene fluoride resin having performance suitable as a separation porous membrane, particularly a (filter) water treatment membrane, and a method for producing the same.
- the present inventors also melt-extruded a vinylidene fluoride resin having a specific molecular weight characteristic into a hollow fiber shape together with a plasticizer and a good solvent of the vinylidene fluoride resin, and then perform extraction removal and stretching of the plasticizer.
- a plasticizer and a good solvent of the vinylidene fluoride resin
- Patent Documents 7 to 11 and others there is a strong demand for further improvement with respect to the overall performance including the filtration performance and mechanical performance required when the porous membrane is used as a filtration permeation membrane.
- MF microfiltration
- the average pore size is 0.25 ⁇ m or less, and there is little contamination (clogging) with organic substances during continuous filtration operation of turbid water, and a high water permeability is maintained. It is desirable.
- the porous membrane disclosed in the following Patent Document 6 has an excessive average pore diameter
- the hollow fiber porous membrane disclosed in the following Patent Document 8 has a problem in maintaining the amount of water permeation in the continuous filtration operation of muddy water. Remain.
- JP-A 63-296939 JP-A 63-296940 Japanese Patent Laid-Open No. 3-215535 JP 7-173323 A WO01 / 28667 Publication WO02 / 070115A WO2005 / 099879A WO2007 / 010932A WO2008 / 117740A WO2010 / 082437A Specification of PCT / JP2010 / 051425
- the present invention provides a porous vinylidene fluoride resin that has a surface pore size, water permeability and mechanical strength suitable for separation applications, particularly (filtered) water treatment, and exhibits good water permeability maintenance performance even during continuous filtration of muddy water.
- An object of the present invention is to provide a film and a method for producing the same.
- the ratio between the converted value Q to% (m / day) and the fourth power value P1 4 ( ⁇ m 4 ) of the surface pore diameter P1 of the one surface, Q / P1 4 is 5 ⁇ 10 4 (m / day ⁇ ⁇ m 4 )more than.
- the present inventors have made continuous filtration performance of muddy water on various vinylidene fluoride resin hollow fiber porous membranes including those disclosed in Patent Documents 7 to 11 above.
- continuous filtration test (details will be described later) by the MBR method (membrane separation activated sludge method) is performed, and the differential pressure increase in the 2-hour membrane filtration treatment is 0.133 kPa or less
- the critical filtration flux determined as the filtration flux (flux) is evaluated as a practical evaluation standard for the ability to maintain water permeability, and the evaluation is correlated with the outer surface and internal pore size distribution, porosity, etc. of the porous membrane. I investigated.
- porous membrane of vinylidene fluoride resin according to the Patent Document 11 the dense layer is relatively thick, therefore, heading is difficulty Q / P1 4 showing the permeability ability in terms of maintaining the fine particle removal performance is degraded (Comparative Examples 1 to 3 described later).
- the present invention is, while maintaining the characteristics of the film in Patent Document 11 described above, to prevent the thickening of the dense layer, in which succeeded in achieving an improvement in Q / P1 4.
- a film-like product formed by melting and kneading with a high molecular weight vinylidene fluoride resin using a relatively large amount of a polyester plasticizer that gives a crystallization temperature Tc ′ (° C.) is cooled and solidified from one side, and then the plasticizer is added. It was considered that it is preferable to form an asymmetric reticulated resin porous membrane by extraction. Moreover, in order to promote uniform mixing of the film raw material resin and the plasticizer, a large amount of a good solvent of vinylidene fluoride resin used in Patent Documents 7 to 10 and the like and compatible with the cooling liquid is melted.
- Tc ′ of the melt-kneaded material almost equivalent to Tc maintains a high difference Tc′ ⁇ Tq from the coolant temperature Tq, and a relatively large amount of plasticizer is densely placed near the membrane surface by phase separation during cooling.
- Tc′ the melt-kneaded material
- Tq the coolant temperature
- plasticizer is densely placed near the membrane surface by phase separation during cooling.
- This is based on the idea of forming a dense solidified layer of vinylidene fluoride resin dispersed in the resin.
- the cooling effect from the outer surface reaches the inside of the film at the same time, leading to thickening of the dense solidified layer.
- the plasticizer is preferably one that gives a lower Tc 'than Tc. According to further studies by the present inventors, even a melt-kneaded product having a Tc ′ lower than Tc gives the solidified product a large crystal melting enthalpy on the basis of the mass of the vinylidene fluoride resin. Then, it has been found that it is possible to form a dense solidified layer (dense layer) of vinylidene fluoride resin in which a relatively large amount of plasticizer is densely dispersed in the vicinity of the above-described film surface.
- the plasticizer further has a porosity of the dense layer finally formed by extruding the plasticizer once dispersed in the dense solidified layer by phase separation to the adjacent inner layer that has not been sufficiently solidified. It has also been found that it is preferable to have a certain degree of viscosity so as not to cause a decrease in the viscosity.
- the method for producing a vinylidene fluoride resin porous membrane of the present invention is based on such knowledge, and more specifically, a melt-kneaded product of a vinylidene fluoride resin and a plasticizer is extruded from a die into a film shape,
- a method of producing a porous film comprising a step of forming a film to be cooled and solidified, and a step of extracting a plasticizer, wherein the plasticizer is compatible with the vinylidene fluoride resin at the formation temperature of the melt-kneaded product, and further It is characterized by satisfying the following conditions (i) to (iii): (I) A crystallization temperature Tc ′ (° C.) lower by 6 ° C.
- a polyester plasticizer in which the end of a (poly) ester composed of an aliphatic dibasic acid and glycol is sealed with a monovalent aromatic carboxylic acid is used.
- the schematic explanatory drawing of the apparatus used in order to evaluate the water permeability of the hollow fiber porous membrane obtained by the Example and the comparative example The schematic explanatory drawing of the apparatus used in order to evaluate the critical filtration flux by the MBR method of the hollow fiber porous membrane obtained by the Example and the comparative example.
- the porous membrane of the present invention can be formed on either a flat membrane or a hollow fiber membrane, but it can be formed as a hollow fiber membrane that can easily increase the membrane area per filtration device, particularly in the case of filtered water treatment. preferable.
- the vinylidene fluoride resin as the main film raw material is a homopolymer of vinylidene fluoride, that is, polyvinylidene fluoride, a copolymer with other monomers copolymerizable with vinylidene fluoride, or a mixture thereof. And those having a weight average molecular weight of 600,000 to 1,200,000, more preferably 650,000 to 1,000,000, particularly preferably 700,000 to 900,000 are preferably used.
- the monomer copolymerizable with vinylidene fluoride one or more of ethylene tetrafluoride, hexafluoropropylene, ethylene trifluoride, ethylene trifluoride chloride, vinyl fluoride and the like can be used.
- the vinylidene fluoride resin preferably contains 70 mol% or more of vinylidene fluoride as a structural unit. Among these, it is preferable to use a homopolymer composed of 100 mol% of vinylidene fluoride because of its high chemical resistance and mechanical strength.
- the relatively high molecular weight vinylidene fluoride resin as described above can be obtained by emulsion polymerization or suspension polymerization, particularly preferably suspension polymerization.
- the vinylidene fluoride resin has a relatively large molecular weight of 600,000 or more as well as the resin's original melting point Tm2 (° C) and crystallization temperature Tc (° C) by DSC measurement.
- the difference Tm2 ⁇ Tc is preferably 32 ° C. or less, more preferably 30 ° C. or less, still more preferably 28 ° C. or less, and most preferably less than 25 ° C.
- the original melting point Tm2 (° C.) of the resin is distinguished from the melting point Tm1 (° 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. It is. That is, generally-available vinylidene fluoride resins exhibit a melting point Tm1 (° C.) different from the original melting point Tm2 (° C.) due to the heat and mechanical history received during the manufacturing process or thermoforming process.
- the original melting point Tm2 (° C.) of the resin is found again in the DSC temperature raising process after the obtained sample resin is once subjected to a predetermined heating and cooling cycle to remove heat and mechanical history. It is defined as the melting point (endothermic peak temperature accompanying crystal melting), and the details of the measurement method will be described prior to the description of Examples described later.
- the above-mentioned vinylidene fluoride resins satisfying the condition of Tm2-Tc ⁇ 32 ° C. preferably have a weight average molecular weight of 450,000 to 1,000,000, preferably selected from the above-mentioned vinylidene fluoride resin species as a raw material, 490,000 to 900,000, more preferably 600,000 to 800,000 medium high molecular weight vinylidene fluoride resin for matrix (PVDF-I) 25 to 98% by weight, preferably 50 to 95% by weight, more preferably 60 Crystal characteristic modification with ultra high molecular weight of ⁇ 90% by weight and a weight average molecular weight of 1.4 times or more of PVDF-I and less than 1.5 million, preferably less than 1.4 million, more preferably less than 1.3 million Vinylidene fluoride resin (PVDF-II) for use as a mixture with 2 to 75% by weight, preferably 5 to 50% by weight, more preferably 10 to 40% by weight It is.
- PVDF-II
- the medium high molecular weight component functions as a matrix resin component, which keeps the molecular weight level of the entire vinylidene fluoride resin high and gives a hollow fiber porous membrane excellent in strength and water permeability.
- the ultrahigh molecular weight component is combined with the medium high molecular weight component to increase the crystallization temperature Tc of the raw material resin (generally about 140 ° C. for vinylidene fluoride homopolymer) and has a high plasticizer content. Nevertheless, by increasing the viscosity of the melt-kneaded composition and reinforcing it, stable extrusion in the form of a hollow fiber becomes possible.
- a gradient pore size distribution in the film thickness direction is formed by a cooling rate gradient in which the cooling surface is rapidly cooled and the opposite surface from the inside is gradually cooled. It will be.
- the use of a plasticizer that lowers the Tc ′ of the melt-kneaded product maintains the cooling temperature necessary for obtaining the desired surface pore diameter on the small pore diameter surface side (without change) while maintaining the film thickness. Thickening of the dense layer is prevented by delaying crystallization in most of the directions.
- spherulites of vinylidene fluoride resin are formed on the opposite surface from the inside of the film that is gradually cooled, which may cause a decrease in mechanical strength, a decrease in water permeability, and a decrease in stretchability. Even under such slow cooling conditions, the formation of spherulites can be effectively suppressed by the addition of the ultrahigh molecular weight component.
- the ultrahigh molecular weight component is considered to act as a crystal nucleating agent, and the characteristics as the crystal nucleating agent appear as an increase in the crystallization temperature Tc of the vinylidene fluoride resin alone, but the relative relationship between the cooling surface and the inside of the film This is not inconsistent with the use of a plasticizer that lowers the Tc ′ of the melt-kneaded product for the purpose of extending the crystallization delay range.
- Tc is preferably 143 ° C. or higher, more preferably 145 ° C. or higher and most preferably higher than 148 ° C.
- the Tc of the vinylidene fluoride resin used does not substantially change during the production process of the hollow fiber membrane. Therefore, the obtained hollow fiber porous membrane can be measured as a sample by the DSC method described later.
- the Mw of the ultra high molecular weight vinylidene fluoride resin (PVDF-II) is less than 1.4 times the Mw of the medium high molecular weight resin (PVDF-I), it is difficult to sufficiently suppress the formation of spherulites. If it is 10,000 or more, it is difficult to uniformly disperse it in the matrix resin.
- any of the above-mentioned medium and ultra high molecular weight vinylidene fluoride resins can be obtained by emulsion polymerization or suspension polymerization, particularly preferably suspension polymerization.
- the amount of the ultra high molecular weight vinylidene fluoride resin is less than 2% by weight, the effect of suppressing spherulite and the effect of thickening and reinforcing the melt-kneaded composition are not sufficient, while if it exceeds 75% by weight, the vinylidene fluoride is added. There is a tendency that the phase separation structure of the base resin and the plasticizer becomes excessively fine, and the water permeability of the resulting porous membrane decreases, and further, stable film formation becomes difficult due to the occurrence of melt fracture during processing. .
- a plasticizer is added to the above-mentioned vinylidene fluoride resin to form a raw material composition for film formation.
- the hollow fiber porous membrane of the present invention is mainly formed from the above-mentioned vinylidene fluoride resin, but in addition to the above-mentioned vinylidene fluoride resin, at least the plasticizer is used as a pore-forming agent for the production. It is preferable.
- the plasticizer in the present invention those having compatibility with the vinylidene fluoride resin at the melt kneading temperature and the following characteristics (i) to (iii) are preferably used:
- the melt-kneaded product with the vinylidene fluoride resin is 6 ° C. or more lower than the crystallization temperature Tc (° C.) of the vinylidene fluoride resin alone, preferably 9 ° C. or more, more preferably 12 ° C. or more lower. Giving a crystallization temperature Tc ′ (° C.), (Ii) As the crystal melting enthalpy ⁇ H ′ (J / g) based on the vinylidene fluoride resin mass standard when measured with a differential scanning calorimeter (DSC), the molded product obtained by cooling and solidifying the melt-kneaded product, Plasticity measured at a temperature of 25 ° C.
- DSC differential scanning calorimeter
- the viscosity of the agent alone is 200 mPa ⁇ s to 1000 Pa ⁇ s, preferably 400 mPa ⁇ s to 100 Pa ⁇ s, more preferably 500 mPa ⁇ s to 10 Pa ⁇ s or less.
- plasticizers having the above-described properties include (poly) esters composed of aliphatic dibasic acids and glycols, that is, polyesters or esters (mono- or diglycol esters of aliphatic dibasic acids, preferably A polyester plasticizer having both ends sealed with a monovalent aromatic carboxylic acid is used.
- the aliphatic dibasic acid component constituting the (poly) ester at the center of the polyester plasticizer is preferably an aliphatic dibasic acid having 4 to 12 carbon atoms.
- Examples of such an aliphatic dibasic acid component include succinic acid, maleic acid, fumaric acid, glutamic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid.
- aliphatic dibasic acids having 6 to 10 carbon atoms are preferable in terms of obtaining a polyester plasticizer having good compatibility with vinylidene fluoride resins, and adipic acid is particularly preferable from the viewpoint of industrial availability. .
- These aliphatic dibasic acids may be used alone or in combination of two or more.
- the glycol component constituting the (poly) ester at the center of the polyester plasticizer is preferably a glycol having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, and 1,2-butanediol. 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 2,2-diethyl-1, 3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2-butyl-2 -Aliphatic dihydric alcohols such as ethyl-1,5-propanediol, 1,12-octadecane
- the above-mentioned polyester plasticizer is preferably sealed at its molecular chain end with an aromatic monovalent carboxylic acid.
- aromatic monovalent carboxylic acids include benzoic acid, toluic acid, dimethyl aromatic monocarboxylic acid, ethyl aromatic monocarboxylic acid, cumic acid, tetramethyl aromatic monocarboxylic acid, naphthoic acid, biphenyl carboxylic acid, and furic acid.
- monocyclic or bicyclic aromatic monovalent carboxylic acids are used, and these may be used alone or in combination of two or more.
- benzoic acid is preferable because of industrial availability.
- a monomeric resin as long as the plasticizer (components other than the vinylidene fluoride resin in the melt-kneaded product) satisfies the above characteristics (i) to (iii).
- a plasticizer or a water-insoluble solvent can be used in combination.
- a preferred example of such a monomeric plasticizer is a dibenzoate monomeric plasticizer comprising glycol and an aromatic monovalent carboxylic acid. As the glycol and aromatic monovalent carboxylic acid contained, those similar to those contained in the above-mentioned polyester plasticizer are used.
- water-insoluble solvent for example, a solvent that is immiscible with water such as propylene carbonate and has a solubility of, for example, 0.1 g / ml or more at 200 ° C. with respect to vinylidene fluoride resin.
- the degree of polymerization of the polyester plasticizer is preferably 10,000 or less, more preferably 5000 or less, and most preferably 2000 or less as the number average molecular weight. If the number average molecular weight is more than 10,000, when the molten mixture is cooled and solidified, crystallization of the vinylidene fluoride resin is hindered and ⁇ H ′ is lowered, and the phase separation property at low temperature may be lowered.
- a viscosity measured at a temperature of 25 ° C. in accordance with JIS K7117-2 (cone-flat plate viscometer used) is often used, preferably 1000 Pa. ⁇ S or less, more preferably 100 Pa ⁇ s or less, and most preferably 10 Pa ⁇ s or less.
- plasticizer By selecting such a preferable plasticizer, it becomes possible to add a large amount of the plasticizer to the vinylidene fluoride resin having the preferable molecular weight characteristics as described above, and the molded product solidified by cooling after melt extrusion is fluorinated. After separating the vinylidene resin phase and the plasticizer phase and removing the plasticizer phase in the subsequent extraction step, a high dense layer porosity is obtained.
- the polyester plasticizer used in the present invention is such that a melted mixture can be obtained by melting and kneading with a vinylidene fluoride resin in an extruder so as to obtain a clear (that is, without leaving a dispersion that can be visually recognized with the naked eye).
- a clear that is, without leaving a dispersion that can be visually recognized with the naked eye.
- it is compatible with the vinylidene fluoride resin.
- the formation of the melt-kneaded product in the extruder includes factors other than the properties derived from the raw materials, such as mechanical conditions, and in the sense of eliminating these factors, the compatibility determination method described later in the present invention. To determine compatibility.
- the plasticizer is 50 to 80% by weight, preferably 60 to 75% by weight relative to 20 to 50% by weight, preferably 25 to 40% by weight, of the vinylidene fluoride resin. % Is good to mix.
- the monomeric ester plasticizer, water-insoluble solvent, and the like added as necessary are used in such a manner that a part of the plasticizer is replaced in consideration of the melt viscosity of the raw material composition under melt kneading.
- plasticizer or the like the whole of the components other than the vinylidene fluoride resin constituting the melt mixture including these optional components may be referred to as “plasticizer or the like” hereinafter.
- the amount of the plasticizer is too small, it is difficult to obtain an increase in the porosity of the dense layer that is the object of the present invention. If the amount is too large, the melt viscosity is excessively reduced, and in the case of hollow fibers, the yarn tends to be crushed. Moreover, there exists a possibility that the mechanical strength of the porous film obtained may fall.
- the addition amount of the plasticizer is adjusted within the above range so that the Tc ′ of the melt-kneaded product with the vinylidene fluoride resin is 120 to 140 ° C., more preferably 125 to 139 ° C., and further preferably 130 to 138 ° C. Is done. If it is less than 120 ° C., the crystal melting enthalpy ⁇ H ′ of the melt-kneaded product is lowered, and the porosity A1 of the dense layer is lowered, or in the case of a hollow fiber, solidification in the cooling bath is insufficient and the yarn is crushed. May occur. If it exceeds 140 ° C., the thickening prevention effect of the dense layer is insufficient.
- a biaxial kneading extruder is used, and the vinylidene fluoride resin (preferably comprising a mixture of a main resin and a crystal characteristic modifying resin) is The plasticizer and the like are supplied from the upstream side of the extruder, supplied downstream, and 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 axis direction, and appropriate temperature adjustment is made according to the contents of the passing material at each site.
- the melt-extruded hollow fiber membrane is converted into a vinylidene fluoride resin having a temperature Tq of 50 to 140 ° C., more preferably 55 to 130 ° C., and even more preferably 60 to 110 ° C., lower than the crystallization temperature Tc ′.
- the cooling bath which consists of a liquid (preferably water) which is inactive (namely, non-solvent and non-reactive), preferentially cools from the outer surface, and solidifies into a film.
- Tc′ ⁇ Tq When Tc′ ⁇ Tq is less than 50 ° C., it is difficult to form a porous film having a small pore size distribution with a small pore size on the surface of the water to be treated, which is the object of the present invention.
- the cooling bath temperature Tq is preferably 0 to 90 ° C., more preferably 5 to 80 ° C., and further preferably 25 to 70 ° C.
- a hollow fiber membrane having an enlarged diameter is obtained by cooling while injecting an inert gas such as air or nitrogen into the hollow portion.
- an inert gas such as air or nitrogen
- This is advantageous for obtaining a hollow fiber porous membrane having a small decrease in the amount of water per area (WO 2005 / 03700A).
- cooling from one side by a chill roll is also used in addition to a cooling bath shower.
- the elapsed time from the melt extrusion until entering the cooling bath Is generally in the range of 0.3 to 10.0 seconds, particularly 0.5 to 5.0 seconds.
- the cooled and solidified film-like material is then introduced into an extraction liquid bath and subjected to extraction and removal of a plasticizer and the like.
- the extraction liquid is not particularly limited as long as it does not dissolve the polyvinylidene fluoride resin and can dissolve the plasticizer and the like.
- a solvent having a boiling point of about 30 to 100 ° C. is suitable for alcohols such as methanol and isopropyl alcohol, and for a halogen-based solvent such as dichloromethane and 1,1,1-trichloroethane.
- the halogen-based solvent is swellable with respect to the vinylidene fluoride resin and has a large plasticizer extraction effect. However, due to its swelling property, when the extracted film-like material is transferred to the drying process as it is, the pores formed by the extraction of the plasticizer tend to shrink. Therefore, for the solidified film after melt extrusion and cooling, after extracting the plasticizer with a halogen-based solvent, the halogen-based solvent is removed by immersing in a solvent that does not swell with respect to the vinylidene fluoride resin. It is preferable to dry after substitution. Whether the solvent is swellable with respect to the vinylidene fluoride resin can be evaluated as follows. Examples of non-swellable solvents include, for example, isopropyl alcohol, ethanol, hexane and the like, but are not limited thereto as long as the following evaluation criteria are satisfied.
- Extraction rinse method that is, the vinylidene fluoride resin film-like molded article containing a halogen-based solvent in the pores is once immersed in a solvent that does not swell with respect to the vinylidene fluoride resin.
- a method of substituting (rinsing) a halogen-based solvent with, for example, and then drying is performed by, for example, a thermally induced phase separation method using a halogenated solvent as an extraction solvent or a non-solvent using a halogenated solvent as a non-solvent
- a film-like molded body (b) of vinylidene fluoride resin containing a halogenated solvent is formed in its pores by induced phase separation, it can be applied to both the formation of flat membranes and hollow fiber membranes. Is possible.
- a film-shaped molded article (b) containing a halogenated solvent is formed by a thermally induced phase separation method that requires the use of a halogenated solvent in order to efficiently extract an organic liquid.
- a thermally induced phase separation method that requires the use of a halogenated solvent in order to efficiently extract an organic liquid.
- it is preferably used for forming a hollow fiber membrane in which the membrane area per filtration device can be easily increased.
- the stretching is generally performed after extraction of the organic liquid with a halogenated solvent, but can also be performed before extraction of the organic liquid with a halogenated solvent.
- the draw ratio is preferably 1.4 to 5.0 times, more preferably 1.6 to 4.0 times, and most preferably about 1.8 to 3.0 times.
- the stretching temperature is the same as in the case of stretching after extraction.
- the method for producing a vinylidene fluoride resin porous membrane including the generalized “extraction rinsing method” is characterized by the following (1) to (8).
- a film-like molded body (a) of a mixture of a vinylidene fluoride resin and an organic liquid is immersed in a halogenated solvent to extract and remove the organic liquid, and the halogenated solvent is left in the voids of the trace.
- the said film-shaped molded object (a) has 5 J / g or more as a crystal-melting enthalpy on the basis of vinylidene fluoride resin mass measured by differential operation calorimetry (DSC), as described in (2) above Production method.
- the mixing ratio of the organic liquid in the mixture of the vinylidene fluoride resin and the organic liquid forming the film-shaped molded body (a) is 200 parts by volume or more with respect to 100 parts by volume of the vinylidene fluoride resin.
- the extracted film-like material is then subjected to stretching to increase the porosity and pore diameter and improve the strength.
- stretching it is possible to selectively wet from the outer surface of the film-like material after extraction (porous membrane) to a certain depth and stretch in this state (hereinafter referred to as “partial wet stretching”). It is preferable for obtaining a high dense layer porosity A1. More specifically, prior to stretching, 5 ⁇ m or more from the outer surface of the porous membrane, preferably 7 ⁇ m or more, more preferably 10 ⁇ m or more, and 1 ⁇ 2 or less, preferably 1 / or less, more preferably 1 / 1 / of the film thickness.
- a depth of 4 or less is selectively wetted.
- the wet depth is less than 5 ⁇ m, the increase in the dense layer porosity A1 is not sufficient, and when it exceeds 1/2, when the dry heat is relaxed after stretching, the drying of the wetting liquid becomes uneven, and the heat treatment or relaxation Processing may be uneven.
- Partial wet stretching method basically has a main feature of a stretching step applied to a resin porous membrane that has already been formed in a dry state. Is not subject to essential constraints.
- the porous membrane is applicable regardless of whether it is a flat membrane or a hollow fiber membrane.
- the resin forming the porous film can be either a hydrophilic resin or a hydrophobic resin, and either a natural resin or a synthetic resin can be used. However, considering durability such as when the liquid to be treated when used as a separation membrane is an aqueous liquid, it is preferable that the resin be insoluble in water.
- polyolefin resins eg JP46-40119B, JP50-2176B
- polyvinylidene fluoride resins eg JP63-296940A, JP03-215535A, WO99 / 47593A, WO03 / 031038A, WO2004 / 081109A, WO2005 / 099879A, JP2001-179062A, JP2003-210954A
- polytetrafluoroethylene resin polysulfone resin, polyethersulfone resin (WO02 / 058828A1)
- polyvinyl chloride resin polyarylene sulfide system Resin
- polyacrylonitrile-based resin cellulose acetate resin (JP2003-31133A), etc.
- a vinylidene fluoride resin porous membrane is obtained by cooling a mixture of (A) a vinylidene fluoride resin and an organic liquid material that is compatible at least at an elevated temperature, and thereby fluorinating the organic liquid material.
- a method of obtaining a porous film by causing phase separation from vinylidene resin and removing the organic liquid from the film-like molded body of vinylidene fluoride resin containing the organic liquid separated by phase extraction (thermally induced phase separation method) WO99 / 47593A, WO03 / 031038A, WO2004 / 081109A, WO2005 / 099879A, JP2001-179062A), or (B) a film-like molded body of a mixture of the vinylidene fluoride resin and the organic liquid, and the phase of the organic liquid Contact with a non-solvent of the soluble vinylidene fluoride resin, and replace the organic liquid with the non-solvent.
- a method of forming a film-like molded body of a vinylidene fluoride resin containing a non-solvent by causing phase separation between the organic liquid and the vinylidene fluoride resin (non-solvent induced phase separation method; JP63-296940A and JP2003) 210954A) or (C) a vinylidene fluoride resin, an organic liquid incompatible with the resin, and a mechanical kneaded product of the inorganic fine powder into a film, and then the organic liquid from the film
- it is manufactured by a method (JP03-215535A) for extracting a body and inorganic fine powder to obtain a porous membrane, but the method of the present invention can be applied to a porous membrane obtained through any of the above methods. is there.
- the partial wet stretching method can be formed on either a flat membrane or a hollow fiber membrane.
- the method for producing a stretched resin porous membrane including the generalized “partial wet stretching method” is characterized by the following (1) to (14): (1) A stretched resin porous membrane, wherein the resin porous membrane is stretched in a state of being selectively wetted with a wetting liquid to a depth of 5 ⁇ m or more and 1/2 or less of the film thickness from the outer surface. Manufacturing method.
- a solvent for wetting vinylidene fluoride resin such as methanol or ethanol or its aqueous solution
- a wettability improving liquid having a surface tension of 25 to 45 mN / m (including the case of immersion). If the surface tension is less than 25 mN / m, it may be difficult to selectively apply the wettability improving liquid to the outer surface because the penetration rate into the PVDF porous membrane is too fast.
- a surfactant solution obtained by adding a surfactant to water that is, an aqueous solution or an aqueous homogeneous dispersion of a surfactant
- the type of the surfactant is not particularly limited.
- a carboxylate type such as an aliphatic monocarboxylate, a sulfonate type such as an alkylbenzene sulfonate, a sulfate ester type such as an alkyl sulfate, Phosphate ester type such as alkyl phosphate salt; amine salt type such as alkylamine salt for cationic surfactant, quaternary ammonium salt type such as alkyltrimethylammonium salt; glycerin fatty acid for nonionic surfactant Ester type such as ester, ether type such as polyoxyethylene alkylphenyl ether, ester ether type such as polyethylene glycol fatty acid ester; for amphoteric surfactant, carboxybetaine type such as N, N-dimethyl-N-alkylaminoacetic acid betaine 2-alkyl-1-hydroxyl Le - such as glycine type and the like, such as carboxymethyl imidazo
- the surfactant preferably has an HLB (hydrophilic / lipophilic balance) of 8 or more. When the HLB is less than 8, the surfactant is not finely dispersed in water, and as a result, uniform wettability improvement becomes difficult.
- Particularly preferably used surfactants include nonionic surfactants having an HLB of 8 to 20, and further 10 to 18, or ionic (anionic, cationic and amphoteric) surfactants. A surfactant is preferred.
- the wettability improving liquid to the outer surface of the porous membrane by batch or continuous immersion of the porous membrane.
- This dipping process is a double-sided coating process for flat membranes and a single-sided coating process for hollow fiber membranes.
- the flat membrane batch dipping treatment is carried out by dipping the hollow fiber membranes bundled by bobbin winding or casserole winding by dipping the layers cut into appropriate sizes.
- the continuous treatment is performed by continuously immersing a long porous membrane in the treatment liquid.
- a surfactant having a relatively high HLB within the above range more specifically 8-20, more preferably 10-18, may be used to form relatively small emulsion particles. preferable.
- the penetration speed can be lowered moderately by increasing the wettability improving liquid to a high viscosity, or penetrating with a low viscosity. It is possible to increase the speed.
- the permeation rate can be moderately slowed by lowering the wettability improving liquid or the permeation at a high temperature. It is possible to increase the speed.
- the viscosity and temperature of the wettability improving liquid act in opposite directions, and can be complementarily controlled for adjusting the penetration rate of the wettability improving liquid.
- the stretching of the hollow fiber membrane is generally preferably performed as uniaxial stretching 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 strength and elongation of the vinylidene fluoride resin hollow fiber porous membrane of the present invention, the stretched fibril (fiber) portion and the unstretched node (node) portion are arranged along the stretching direction. This is because it has been found that a microstructure that appears alternately is preferable.
- the draw ratio is about 1.1 to 4.0 times, particularly about 1.2 to 3.0 times, and most preferably about 1.4 to 2.5 times. When the draw ratio is excessive, the tendency of the hollow fiber membrane to break becomes large.
- 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. On the other hand, if the stretching temperature is too high, it is difficult to increase the porosity even if the stretching ratio is increased. In the case of a flat membrane, sequential or simultaneous biaxial stretching is also possible.
- the crystallinity is increased by heat treatment 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. It is also preferable.
- the hollow fiber porous membrane of vinylidene fluoride resin obtained as described above is subjected to at least one stage, more preferably at least two stages of relaxation or constant length heat treatment in a non-wetting atmosphere (or medium).
- the non-wetting atmosphere is a non-wetting liquid having a surface tension (JIS K6768) larger than the wetting tension of vinylidene fluoride resin near room temperature, typically water or air. Gas is used.
- the relaxation treatment of the uniaxially stretched porous membrane such as the hollow fiber is carried out by first performing the above-described non-wetting, preferably heated atmosphere, disposed between the upstream roller and the downstream roller, where the peripheral speed gradually decreases. It is obtained by passing the obtained stretched porous membrane.
- the relaxation rate determined by (1 ⁇ (downstream roller peripheral speed / upstream roller peripheral speed)) ⁇ 100 (%) is preferably in the range of 0% (constant length heat treatment) to 50%, particularly 1 to 20 % Relaxation heat treatment is preferable.
- a relaxation rate exceeding 20% depends on the stretching ratio in the previous step, but is not preferable because it is difficult to achieve or even if realized, the effect of improving the water permeability is saturated or decreases.
- the first-stage constant length or relaxation heat treatment temperature is preferably 0 to 100 ° C., particularly 50 to 100 ° C.
- the treatment time may be short or long as long as the desired heat setting effect and relaxation rate are obtained. Generally, it is about 5 seconds to 1 minute, but it is not necessary to be within this range.
- the post-stage constant length or relaxation heat treatment temperature is preferably 80 to 170 ° C., more preferably 120 to 160 ° C., so that a relaxation rate of 1 to 20% can be obtained.
- the effect of the relaxation treatment described above is a remarkable effect that the substantial membrane fractionation performance is maintained in a sharp state and the water permeability of the obtained porous membrane is increased. Moreover, performing the above-mentioned one-stage and two-stage treatment under a constant length is a heat setting operation after stretching.
- the porous membrane of the present invention obtained through the above series of steps is substantially a single layer membrane of vinylidene fluoride resin, but has a dense layer that has a small pore size and governs separation performance on one surface side thereof.
- the porosity A1 (%) is 60% or more, preferably 65% or more, more preferably 70% or more (the upper limit is not particularly limited, but generally it is difficult to exceed 85%),
- the surface pore diameter P1 of the one surface is 0.30 ⁇ m or less, preferably 0.25 ⁇ m or less, more preferably 0.20 ⁇ m or less, most preferably 0.15 ⁇ m or less (the lower limit is not particularly limited, but less than 0.01 ⁇ m)
- the converted value Q (m) of the water permeability at the test length L 200 mm measured under the conditions of the differential pressure of 100 kPa and the water temperature of 25 ° C.
- Q / P1 4 is 5 ⁇ 10 4 (m / day ⁇ ⁇ m 4 ) or more, preferably 7 ⁇ 10 4 (m / day ⁇ ⁇ m 4 ) or more, more preferably 1 ⁇ 10 5 (m / day ⁇ ⁇ m 4 ) or more (the upper limit is not particularly limited, but it exceeds 5 ⁇ 10 5 (m / day ⁇ ⁇ m 4 )) Difficult) More preferably, (d) the ratio A1 / P1 with the surface pore diameter P1 ( ⁇ m) of the treated water is 400 or more, preferably 550 or more, more preferably 500 or more (the upper limit is not particularly limited).
- the ratio A1 / A2 between A1 and the total layer porosity A2 is 0.80 or more, preferably 0.85 or more, more preferably 0.90 or more (the upper limit is generally difficult to exceed 1.0) )
- the dense layer thickness is generally 7 ⁇ m or more, but 40 ⁇ m or less, preferably 30 ⁇ m or less, more preferably 20 ⁇ m or less, most preferably 15 ⁇ m or less
- the ratio P2 / P1 of the surface pore diameter P1 ( ⁇ m) on the one surface and the surface pore diameter P2 ( ⁇ m) on the opposite surface is preferably 2.0 to 10. It is represented by being 0.
- the porosity A1 of the dense layer is 60% or more means that the dense layer that governs the separation performance of the porous membrane of the present invention has a high porosity
- the average pore diameter Pm is generally 0.25 ⁇ m or less, preferably 0.20 to 0.01 ⁇ m, more preferably 0.15 to 0.05 ⁇ m, and the maximum pore diameter Pmax is generally 0.70 to 0.03 ⁇ m, preferably 0 .40 to 0.06 ⁇ m; Properties with a tensile strength of 7 MPa or more, preferably 8 MPa or more, and a breaking elongation of 70% or more, preferably 100% or more can be obtained.
- the thickness is usually in the range of about 50 to 800 ⁇ m, preferably 50 to 600 ⁇ m, particularly preferably 150 to 500 ⁇ m.
- the outer diameter of the hollow fiber is about 0.3 to 3 mm, particularly about 1 to 3 mm.
- the pure water permeation amount at a test length of 200 mm, a water temperature of 25 ° C., and a differential pressure of 100 kPa is 20 m / day or more, preferably 30 m / day or more, more preferably 40 m / day or more, and the total layer porosity is 80%.
- the converted water permeability Q is 20 m / day or more, preferably 30 m / day or more, and more preferably 40 m / day or more.
- Crystal melting point Tm1, Tm2 and crystallization temperature Tc, Tc ′ Using a differential scanning calorimeter “DSC7” manufactured by PerkinElmer Co., Ltd., 10 mg of the sample resin was set in the measurement cell, and the temperature was increased from 30 ° C. to 250 ° C. at a rate of 10 ° C./min in a nitrogen gas atmosphere. Then, after holding at 250 ° C. for 1 minute, the temperature was lowered from 250 ° C. to 30 ° C. at a temperature lowering rate of 10 ° C./min to obtain a DSC curve.
- DSC7 differential scanning calorimeter
- the endothermic peak speed in the temperature rising process was the melting point Tm1 (° C.), and the exothermic peak temperature in the temperature lowering process was the crystallization temperature Tc (° C.).
- the temperature was raised again from 30 ° C. to 250 ° C. at a rate of 10 ° C./min, and the DSC curve was measured.
- the endothermic peak temperature in this reheated DSC curve was the original resin melting point Tm2 (° C.) that defines the crystal characteristics of the vinylidene fluoride resin of the present invention.
- the crystallization temperature Tc ′ (° C.) of the mixture of vinylidene fluoride resin as a film raw material and a plasticizer is 10% of the cooled and solidified product of the melt-kneaded product and subjected to the same heating and cooling cycle as described above. An exothermic peak temperature detected during the temperature lowering process after obtaining a curve.
- the crystallization temperature Tc of the vinylidene fluoride-based resin does not substantially change throughout the manufacturing process of the porous film according to the method of the present invention, but in the present specification, typically, the film after film formation, that is, the extraction process, If necessary, the DSC curve is obtained by subjecting 10 mg of the film finally obtained through the stretching process and the relaxation process to the same heating and cooling cycle as described above, and the measured value of the exothermic peak temperature detected in the cooling process is obtained. It is described.
- Crystal melting enthalpy ⁇ H ′ of the cooled and solidified product of the melt-kneaded product The crystal melting enthalpy ⁇ H ′ of a mixture of vinylidene fluoride resin as a film raw material and a plasticizer was measured as follows: A DSC curve is obtained by subjecting 10 mg of the cooled and solidified product of the melt-kneaded product to the same temperature raising and lowering cycle as the measurement of the crystallization temperature Tc ′, and the total mass of the cooled and solidified product of the melt-kneaded product from the endothermic peak area at the first temperature increase. The reference crystal melting enthalpy ⁇ H0 (J / g) was determined.
- ⁇ H ′ ⁇ H0 / (W / W0)
- ⁇ H ′ ⁇ H0 / (W / W0)
- the compatibility of the plasticizer (etc.) with the vinylidene fluoride resin was determined by the following method: A slurry-like mixture is obtained by mixing 23.73 g of vinylidene fluoride resin and 46.27 g of a plasticizer at room temperature. Next, the barrel of “Lab Plast Mill” (mixer type: “R-60”) manufactured by Toyo Seiki Co., Ltd. is 10 ° C. higher than the melting point of the vinylidene fluoride resin (for example, about 17 to 37 ° C. higher). The temperature is adjusted, and the slurry mixture is charged and preheated for 3 minutes, and then melt-kneaded at a mixer rotation speed of 50 rpm.
- the plasticizer is based on vinylidene fluoride resin. Determined to be compatible.
- the viscosity of the melt-kneaded material is high, it may appear cloudy due to entrapment of bubbles, and in that case, it is determined by deaeration appropriately by a method such as hot pressing. Once it has cooled and solidified, it is heated again to be in a molten state, and then it is determined whether or not it is clarified.
- the porosity A0 (%) of the whole layer of the unstretched film measured by the same method for the film after extraction and before stretching, and the ratio RB (% by weight) of the plasticizer (and solvent) mixture B in the melt extrusion mixture
- the approximate number of the ratio A0 / RB is considered to indicate the pore formation efficiency of the mixture B.
- the hole formation efficiency was determined by the ratio A0 / RL between the total layer porosity A0 and RL.
- the first intermediate formed body before extraction in the examples and comparative examples described later is cut out to a length of about 300 mm, the pre-extraction yarn length L0 (mm), the pre-extraction outer diameter OD0 (mm), the pre-extraction inner diameter ID0 (mm), and the extraction
- the previous film thickness T0 (mm) was measured.
- predetermined operations of extraction, replacement, and drying are performed, and the thread length L1 (mm) after drying, the outer diameter OD1 (mm) after drying, the inner diameter ID1 (mm) after drying, and the film thickness T1 (mm) after drying are obtained. It was measured.
- Average pore size Based on ASTM F316-86 and ASTM E1294-89, average pore size Pm ( ⁇ m) was measured by a half dry method using “Palm Porometer CFP-200AEX” manufactured by Porous Materials, Inc. Perfluoropolyester (trade name “Galwick”) was used as a test solution.
- the average pore diameter P1 of the treated water side surface (outer surface in hollow fiber) and the average pore diameter P2 of the permeated water side surface (inner surface in hollow fiber) were determined by SEM method. Measured (SEM average pore diameter).
- SEM average pore diameter the measurement method will be described by taking a hollow fiber porous membrane sample as an example. SEM photography is performed on the outer surface and inner surface of the hollow fiber membrane sample at an observation magnification of 15,000 times, respectively. Next, for each SEM photograph, the hole diameter is measured for everything that can be recognized as a hole.
- the arithmetic average of the measured pore diameters is obtained and set as the outer surface average pore diameter P1 and the inner surface average pore diameter P2.
- the photograph image may be divided into four equal parts, and the above-mentioned hole diameter measurement may be performed for one area (1 ⁇ 4 screen). .
- the number of measurement holes is approximately 200 to 300.
- the thickness of the dense and continuous layer having a substantially uniform pore diameter from the surface to be treated is measured by cross-sectional observation using an SEM.
- the measurement method will be described by taking a hollow fiber porous membrane sample as an example.
- the hollow fiber porous membrane material is immersed in isopropyl alcohol (IPA), the pores are impregnated with IPA, then immediately immersed in liquid nitrogen and frozen, and while being frozen, the hollow fiber membrane is folded and broken, A cross section perpendicular to the longitudinal direction is exposed.
- IPA isopropyl alcohol
- the hole diameter is measured for all the 3 ⁇ m ⁇ 3 ⁇ m square regions centered on a point of 1.5 ⁇ m from the outer surface that can be recognized as holes.
- the arithmetic average of the measured pore diameter is obtained, and this is defined as the sectional pore diameter X 1.5 ( ⁇ m) at a depth of 1.5 ⁇ m.
- the arithmetic average pore diameter is obtained in the same manner as described above for the 3 ⁇ m ⁇ 3 ⁇ m square region centered on the point shifted to the inner surface side sequentially at an interval of about 3 ⁇ m.
- the cross-sectional hole diameter X d ( ⁇ m) at an arbitrary depth d ( ⁇ m) is obtained from the outer surface. If the condition of X d / X 1.5 ⁇ 1.2 is satisfied, the hole diameter is assumed to be uniform, and the dense layer thickness having a uniform hole diameter is defined as the maximum depth d ( ⁇ m) that satisfies the condition.
- a flat membrane or hollow fiber-like porous membrane sample is impregnated with a porosity A1 (%) (hereinafter referred to as “dense layer porosity A1”) of a portion having a thickness of 5 ⁇ m in contact with the surface to be treated of the dense layer. Measure by the method.
- VL (W ⁇ W0) / ( ⁇ s ⁇ 1000)
- ⁇ s is the specific gravity of the test solution and is 1.261 (g / ml).
- the dense layer porosity A1 (%) is calculated by the following formula.
- A1 VL / V ⁇ 100.
- the mini module is formed by vertically fixing two hollow fiber porous membrane samples between the upper header and the lower header so that the effective filtration length per one becomes 500 mm.
- the upper header is an upper insertion port to be fixed with the upper end of the hollow fiber membrane being opened on the lower side, an internal space (flow path) for filtrate water communicating with the upper insertion port, and suction on the upper side. It has a filtrate outlet for discharging filtrate to the pump.
- the lower header has a lower insertion port for fixing the hollow fiber membrane on its upper side with its lower end closed, and an aeration nozzle that does not communicate with the lower insertion port (diameter 1 mm ⁇ 10) And an internal space (supply path) for supplying air to the aeration nozzle and an air supply port for supplying air from the air pump to the internal space.
- the upper and lower ends of the two hollow fiber membrane samples are each inserted and fixed to the upper insertion port by epoxy resin so that the upper header is liquid-tightly connected, and the lower header is inserted so that the lower header is closed. It is inserted into the mouth and fixed.
- This modularized hollow fiber membrane sample was dipped in ethanol for 15 minutes and then wetted by replacement with pure water. Then, the bottom area was approximately 30 cm 2 and the height of the water surface was approximately 600 mm. Soak the hollow fiber vertically.
- MLSS floating substance concentration
- DOC total organic concentration after filtration through a 1 ⁇ m glass filter
- 7 to 9 mg / L of activated sludge water is supplied at a rate of 0.2 L / min by a pump, and the overflow is circulated to the raw water tank. Further, air is supplied from the lower header at a rate of 5 L / min, and is constantly bubbled into the activated sludge water in the test water tank.
- the suction filtration operation is performed for 13 minutes with a constant amount of filtrate, and the filtration is stopped for 2 minutes. While repeating the cycle, the suction filtration is performed for 2 hours, and the change with time of the differential pressure inside and outside the hollow fiber porous membrane is measured.
- the constant amount of filtered water is initially 0.3 m / day as the filtration flux (m / day) and increases by 0.1 m / day every 2 hours, and the differential pressure increase rate becomes higher than 0.133 kPa / 2 hours.
- polyester plasticizer polymer of dibasic acid and glycol whose ends are sealed with benzoic acid; “W-83” manufactured by DIC Corporation, number average molecular weight of about 500, JIS K7117-2 (cone-flat plate) The viscosity measured at 25 ° C. with a mold rotational viscometer (750 mPa ⁇ s) was used.
- the mixture A is supplied from the powder supply unit, and the barrel temperature is 220 ° C.
- the mixture was fed and kneaded at a barrel temperature of 220 ° C., and the mixture was extruded into a hollow fiber shape from a nozzle (190 ° C.) having a circular slit having an outer diameter of 6 mm and an inner diameter of 4 mm. At this time, the inner diameter was adjusted by injecting air into the hollow portion of the hollow fiber from the vent provided in the center of the nozzle.
- the extruded mixture is kept in a molten state, is maintained at a temperature of 50 ° C., and has a water surface at a position 280 mm away from the nozzle (that is, an air gap of 280 mm). (Retention time in cooling bath: about 6 seconds) After taking up at a take-up speed of 3.8 m / min, this was wound around a bobbin to obtain a first intermediate molded body.
- the plasticizer was extracted by immersing this first intermediate molded body in dichloromethane at room temperature for 30 minutes. At this time, the extraction was performed while rotating the bobbin so that the dichloromethane was evenly distributed over the yarn. Next, the operation of replacing the dichloromethane with a new one and extracting again under the same conditions was repeated, and extraction was performed three times in total.
- the first intermediate molded body containing dichloromethane is immersed in isopropyl alcohol (IPA) at room temperature for 30 minutes without being substantially dried (that is, in a state where no whitening is visually recognized in the first intermediate molded body). Then, the dichloromethane impregnated in the first intermediate molded body was replaced with IPA. At this time, the replacement was performed while rotating the bobbin so that the IPA was evenly distributed over the yarn. Subsequently, the operation of replacing the IPA with a new one and replacing the same under the same conditions was repeated, and the replacement was performed twice in total.
- IPA isopropyl alcohol
- IPA was removed by air drying at room temperature for 24 hours, followed by heating in an oven at a temperature of 120 ° C. for 1 hour to remove IPA and heat treatment to obtain a second intermediate molded body. At this time, the shrinkage stress of the yarn was relaxed so that the diameter of the bobbin was freely contracted.
- the second intermediate molded body is pulled out while rotating the bobbin, the first roll speed is set to 20.0 m / min, and the second roll is passed through a 60 ° C. water bath.
- the film was stretched 1.75 times in the longitudinal direction by setting the speed to 35.0 m / min.
- it is passed through a hot water bath controlled at a temperature of 90 ° C., the first stage relaxation rate is relaxed at 8%, and further passed through a dry heat tank controlled at a spatial temperature of 140 ° C., and the second stage relaxation rate is 1.5%. And relaxed.
- Example 2 A polyvinylidene fluoride hollow fiber porous membrane of the present invention was obtained in the same manner as in Example 1 except that the cooling water bath temperature Tq after melt extrusion was changed to 70 ° C.
- Example 2 A polyvinylidene fluoride hollow fiber porous membrane was obtained essentially by the method of Example 7 of Patent Document 11.
- a polyvinylidene fluoride hollow fiber porous membrane of the present invention was obtained in the same manner as in Comparative Example 1 except that 8% relaxation was performed in a water bath and then 2% relaxation treatment was performed in air at 140 ° C.
- Example 3 A polyvinylidene fluoride-based hollow fiber porous membrane was obtained essentially by the method of Example 8 of Patent Document 11.
- a polyvinylidene fluoride hollow fiber porous membrane of the present invention was obtained in the same manner as in Comparative Example 2 except that the cooling water bath temperature Tq after melt extrusion was changed to 85 ° C.
- PVDF-I PVDF mixture A in which PVDF-I and PVDF-II were mixed at a ratio of 95% by weight and 5% by weight using polyvinylidene fluoride having Mw of 4.1 ⁇ 10 5 was used.
- Adipic acid polyester plasticizer as a plasticizer polyester of adipic acid and 1,2-propylene glycol whose ends are sealed with octyl alcohol; “PN150” manufactured by ADEKA Corporation, number average molecular weight of about 1000, viscosity of 500 mPa ⁇ s) And N-methylpyrrolidone (NMP) in a proportion of 82.5 wt% / 17.5 wt% with stirring and mixing at room temperature; used plasticizer / solvent mixture B; Supply at a ratio of 4% by weight / 61.6% by weight; water cooling bath temperature at 40 ° C .; no extraction rinse with IPA Except that the draw ratio was 1.85 times; as the heat treatment after stretching, 8% relaxation was performed in a 90 ° C. water bath, and then 3% relaxation treatment was performed in air at 140 ° C .; A polyvinylidene fluoride porous membrane was obtained in the same manner as in Example 1.
- PVDF-I PVDF mixture A in which PVDF-I and PVDF-II were mixed at a ratio of 75% by weight and 25% by weight using polyvinylidene fluoride having Mw of 4.1 ⁇ 10 5 was used.
- a plasticizer / solvent mixture B mixed at a ratio of 0.6 wt% and the solvent N-methylpyrrolidone (NMP) 31.4 wt% was used.
- the mixture was fed at a ratio of 2 (weight) and kneaded at a barrel temperature of 220 ° C., and the kneaded product was extruded into a hollow fiber form from a nozzle (temperature 150 ° C.) having a circular slit having an outer diameter of 6 mm and an inner diameter of 4 mm. At this time, air was injected into the air-conditioning section of the hollow fiber from the vent hole provided in the center of the nozzle to adjust the inner diameter.
- the extruded molten mixture is cooled at a cooling water bath temperature of 15 ° C., extracted by dichloromethane and then stretched 1.1 times, and further passed through a hot water bath at 90 ° C. and a dry heat bath controlled at a space temperature of 140 ° C.
- a polyvinylidene fluoride hollow fiber porous membrane was obtained.
- PVDF-I a mixture containing PVDF-I and PVDF-II of 95% by weight and 5% by weight using polyvinylidene fluoride having an Mw of 4.1 ⁇ 10 5 was used.
- an adipic acid-based polyester plasticizer as a plasticizer, polyester of adipic acid and 1,2-butanediol whose ends are sealed with isononyl alcohol; “D620N” manufactured by J.
- Mixture A is supplied from the powder supply section, and mixture B is heated to 160 ° C. from the liquid supply section provided at a position 480 mm from the most upstream part of the cylinder.
- Mixture A / mixture B 38.4 / 61.
- the mixture was fed at a ratio of 6 (weight) and kneaded at a barrel temperature of 220 ° C., and the kneaded product was extruded into a hollow fiber shape from a nozzle having a circular slit having an outer diameter of 7 mm and an inner diameter of 5 mm. At this time, air was injected into the air-conditioning section of the hollow fiber from the vent hole provided in the center of the nozzle to adjust the inner diameter.
- the extruded molten mixture is cooled at a cooling water bath temperature of 70 ° C.
- the mixture B is extracted with dichloromethane, dried at 50 ° C. for 1 hour, stretched 2.4 times at 85 ° C., and further heated at a 90 ° C. hot water bath.
- the polyvinylidene fluoride hollow fiber porous membrane was obtained by relaxing 1% in the solution and further relaxing 1% in a dry heat bath controlled at a space temperature of 140 ° C.
- Example 7 Extrusion was performed in the same manner as in Example 1 except that polyvinylidene fluoride having a Mw of 4.1 ⁇ 10 5 was used as PVDF-I. However, the yarn could not be formed because the yarn was crushed in the cooling water bath after melt extrusion.
- Example 8 Extrusion was carried out in the same manner as in Example 1 except that the cooling water bath temperature Tq after melt extrusion was changed to 85 ° C. However, the yarn could not be formed because the yarn was crushed in the cooling water bath after melt extrusion.
- Example 9 A dibenzoate-type monomeric plasticizer (“PB-10” manufactured by DIC Corporation, number average molecular weight of about 300, viscosity of 81 mPa ⁇ s) was used as the plasticizer; 26.9 wt% / 73 of the mixture A and the mixture B A polyvinylidene fluoride hollow fiber porous membrane was obtained in the same manner as in Example 1 except that the cooling water bath temperature Tq after melt extrusion was changed to 60 ° C.
- PB-10 dibenzoate-type monomeric plasticizer manufactured by DIC Corporation, number average molecular weight of about 300, viscosity of 81 mPa ⁇ s
- PVDF-I Polyvinylidene fluoride
- Mw weight average molecular weight
- PVDF-II polyvinylidene fluoride for modifying crystal properties having a Mw of 9.7 ⁇ 10 5 (PVDF-II) ) (Powder) at a ratio of 75 wt% and 25 wt%, respectively, was mixed using a Henschel mixer to obtain a PVDF mixture having an Mw of 6.1 ⁇ 10 5 .
- a polyester plasticizer polymer of adipic acid and 1,2-butanediol whose ends are sealed with isononyl alcohol; “D623N” manufactured by J Plus Co., Ltd., number average molecular weight of about 1800, JIS K7117- 2 (cone-flat-plate rotational viscometer) measured viscosity at 25 ° C. 3000 mPa ⁇ s, specific gravity 1.090 g / ml) and monoisonic ester plasticizer diisononyl adipate (“DINA” manufactured by J. Plus) And a plasticizer mixture obtained by stirring and mixing at a normal temperature of 88% / 12% by weight.
- the mixture was fed and kneaded at a barrel temperature of 220 ° C., and the mixture was extruded into a hollow fiber shape from a nozzle (190 ° C.) having a circular slit having an outer diameter of 6 mm and an inner diameter of 4 mm. At this time, the inner diameter was adjusted by injecting air into the hollow portion of the hollow fiber from the vent provided in the center of the nozzle.
- the plasticizer was extracted by immersing the first intermediate molded body in dichloromethane at room temperature for 30 minutes. At this time, the extraction was performed while rotating the bobbin so that the dichloromethane was evenly distributed over the yarn. Next, the operation of replacing the dichloromethane with a new one and extracting again under the same conditions was repeated, and extraction was performed three times in total.
- the first intermediate molded body containing dichloromethane is immersed in isopropyl alcohol (IPA) at room temperature for 30 minutes without substantially drying (that is, no whitening is visually recognized in the first intermediate molded body).
- IPA isopropyl alcohol
- the dichloromethane impregnated in the first intermediate molded body was replaced with IPA.
- the replacement was performed while rotating the bobbin so that the IPA was evenly distributed over the yarn.
- the operation of replacing the IPA with a new one and replacing the same under the same conditions was repeated, and the replacement was performed twice in total.
- IPA was removed by air drying at room temperature for 24 hours, followed by heating in an oven at a temperature of 120 ° C. for 1 hour to remove IPA and heat treatment to obtain a second intermediate molded body.
- the bobbin diameter was freely contracted, and drying and heat treatment were performed without restricting the contraction of the yarn.
- the second intermediate formed body is pulled out while rotating the bobbin, the first roll speed is set to 20.0 m / min, and the second roll is passed through the 60 ° C. water bath.
- the film was stretched 1.75 times in the longitudinal direction by setting the speed to 35.0 m / min.
- it is passed through a hot water bath controlled at a temperature of 90 ° C., the first stage relaxation rate is relaxed at 8%, and further passed through a dry heat tank controlled at a spatial temperature of 140 ° C., and the second stage relaxation rate is 1.5%. And relaxed. This was wound up to obtain a vinylidene fluoride resin hollow fiber porous membrane.
- Example A2 A vinylidene fluoride resin porous membrane was obtained in the same manner as in Example A1, except that the cooling water bath temperature Tq after melt extrusion was changed to 30 ° C .; the draw ratio was changed to 1.85 times.
- W-83 manufactured by DIC Corporation, number average molecular weight of about 500, JIS K7117-2 (cone- A viscosity measured at 25 ° C. by a flat plate type viscometer (750 mPa ⁇ s, specific gravity 1.155 g
- PB-10 monomeric ester plasticizer
- an unstretched vinylidene fluoride resin porous membrane was obtained according to the method disclosed in Patent Document 4, and then the unstretched yarn was partially wetted and then stretched. That is, hydrophobic silica (“Aerosil R-972” manufactured by Nippon Aerosil Co., Ltd., primary particle average diameter 16 nanometer, specific surface area 110 m 2 / g) 14.8% by volume, dioctyl phthalate (DOP) 48.5% by volume %, Dibutyl phthalate (DBP) 4.4% by volume is mixed with a Henschel mixer, and 32.3% by volume of polyvinylidene fluoride (powder) having a weight average molecular weight (Mw) of 2.4 ⁇ 10 5 is mixed therewith. Added and mixed again with a Henschel mixer.
- hydrophobic silica (“Aerosil R-972” manufactured by Nippon Aerosil Co., Ltd., primary particle average diameter 16 nanometer, specific surface area 110 m 2
- a hollow fiber was extruded from a nozzle (temperature 240 ° C.) having a circular slit with a diameter of 6 mm and an inner diameter of 4 mm. At this time, the inner diameter was adjusted by injecting air into the hollow portion of the hollow fiber from the vent provided in the center of the nozzle.
- the extruded mixture is kept in a molten state, maintained at a temperature of 70 ° C., and has a water surface at a position 140 mm away from the nozzle (ie, the air gap is 140 mm). (Residence time in the cooling bath: about 9 seconds) was taken at a take-up speed of 2.5 m / min to obtain a first intermediate molded body having an outer diameter of 2.87 mm and an inner diameter of 1.90 mm.
- the plasticizer was extracted by immersing this first intermediate molded body in dichloromethane at room temperature for 30 minutes. Next, the operation of replacing the dichloromethane with a new one and extracting again under the same conditions was repeated, and extraction was performed four times in total. Next, it was dried in a vacuum dryer at a temperature of 30 ° C. for 24 hours to remove dichloromethane.
- the hollow fiber was wetted by immersing in 50% ethanol aqueous solution for 30 minutes and further immersing in pure water for 30 minutes. Further, after removing the hydrophobic silica by immersing in a 20% aqueous sodium hydroxide solution at 70 ° C. for 1 hour, it is washed with water to remove the sodium hydroxide, and then dried in a vacuum dryer at a temperature of 30 ° C. for 24 hours. A molded body was obtained. In addition, during a series of operations from extraction to drying, both ends of the hollow fiber were not contracted and were freely contracted.
- Example A1 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A1, except that partial wetting was not performed prior to stretching.
- Example A2 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A2 except that partial wetting was not performed prior to stretching.
- Example A4 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A3 except that partial wetting was not performed prior to stretching.
- Example A5 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A4 except that partial wetting was not performed prior to stretching.
- Example A6 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A5 except that partial wetting was not performed prior to stretching.
- Example B1 Polyvinylidene fluoride (PVDF-I) for matrix having a weight average molecular weight (Mw) of 4.9 ⁇ 10 5 (powder) and polyvinylidene fluoride for modifying crystal properties having a Mw of 9.7 ⁇ 10 5 (PVDF-II) ) (Powder) at a ratio of 75 wt% and 25 wt%, respectively, was mixed using a Henschel mixer to obtain a PVDF mixture having an Mw of 6.1 ⁇ 10 5 .
- a polyester plasticizer polymer of dibasic acid and glycol whose ends are sealed with a monohydric alcohol; “W-4010” manufactured by DIC Corporation, number average molecular weight of about 4000, JIS K7117-2 (cone -Viscosity measured at 25 ° C by a flat plate type viscometer), specific gravity 1.113 g / ml), and diisononyl adipate, a monomeric ester plasticizer ("DINA” manufactured by Jay Plus Co., Ltd.) K7117-2 (cone-flat plate viscometer) measured at 25 ° C.
- DINA monomeric ester plasticizer manufactured by Jay Plus Co., Ltd.
- the mixture A is supplied from the powder supply unit, and the barrel temperature is 220 ° C.
- the mixture was fed at a ratio and kneaded at a barrel temperature of 220 ° C., and the mixture was extruded into a hollow fiber shape from a nozzle (190 ° C.) having a circular slit having an outer diameter of 6 mm and an inner diameter of 4 mm.
- the inner diameter was adjusted by injecting air into the hollow portion of the hollow fiber from the vent provided in the center of the nozzle.
- the extruded mixture is kept in a molten state, maintained at a temperature of 12 ° C., and has a water surface at a position 280 mm away from the nozzle (that is, an air gap of 280 mm). (Retention time in the cooling bath: about 6 seconds) After being taken up at a take-up speed of 3.8 m / min, this was wound up on a bobbin (core diameter: 220 mm) to a length of 500 m to obtain an outer diameter of 1.80 mm, A first intermediate molded body having an inner diameter of 1.20 mm (vinylidene fluoride resin hollow fiber porous membrane containing an organic liquid) was obtained.
- this first intermediate molded body was cut out to a length of 300 mm, and the organic liquid was extracted by immersing in dichloromethane as an extraction solvent at room temperature for 30 minutes without fixing both ends. At this time, extraction was carried out while stirring the dichloromethane so that the dichloromethane was evenly distributed over the yarn. Next, the operation of replacing the dichloromethane with a new one and extracting again under the same conditions was repeated, and extraction was performed three times in total.
- the first intermediate molded body containing dichloromethane is rinsed without substantially drying (that is, in a state where no whitening is observed in the first intermediate molded body by visual observation) and without fixing both ends.
- Dichloromethane impregnated in the first intermediate molded body by being immersed in ethanol (swelling ratio of 0.5% relative to the raw material vinylidene fluoride resin) at room temperature for 30 minutes was replaced with ethanol as a rinsing liquid. At this time, the substitution was performed while stirring the ethanol so that the ethanol was evenly distributed over the yarn. Subsequently, the operation of replacing the ethanol with a new one and substituting again under the same conditions was repeated, and the replacement was performed twice in total.
- the ethanol was removed by air drying at room temperature for 24 hours, followed by heating in an oven at a temperature of 120 ° C. for 1 hour to remove the ethanol and a heat treatment, followed by fluorination.
- a vinylidene resin hollow fiber porous membrane was obtained.
- Example B2 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as B1, except that isopropyl alcohol (swelling rate 0.2% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B3 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1, except that hexane (swelling ratio of 0.0% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B4 After substituting with ethanol as the rinsing liquid, the second rinsing liquid, water (swelling ratio 0.0% of the raw material vinylidene fluoride resin) is further obtained without substantially drying the hollow fiber porous membrane containing ethanol.
- the vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1 except that it was replaced with a).
- Example B1 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1 except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B2 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1, except that methanol (swelling ratio of 1.8% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B3 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1 except that acetone (swelling ratio of 5.0% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B4 A vinylidene fluoride system was used in the same manner as in Example B1 except that a heptafluorocyclopentane-based solvent (“Zeorolla HTA” manufactured by Nippon Zeon Co., Ltd., a swelling ratio of 3.4% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- a resin hollow fiber porous membrane was obtained.
- Example B5 As an organic liquid, a polyester plasticizer (polyester of adipic acid and 1,2-butanediol whose ends are sealed with isononyl alcohol; “D623N” manufactured by J Plus Co., Ltd., number average molecular weight of about 1800, JIS K7117- 2 (cone-flat-plate rotational viscometer) measured viscosity at 25 ° C. 3000 mPa ⁇ s, specific gravity 1.090 g / ml) and monoisonic ester plasticizer diisononyl adipate (“DINA” manufactured by J.
- D623N polyisonic ester plasticizer diisononyl adipate
- Example B2 except that the cooling water bath temperature Tq after melt extrusion was changed to 45 ° C. In the same manner, a vinylidene fluoride resin hollow fiber porous membrane was obtained.
- Example B5 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B5, except that dichloromethane (swelling ratio of 5.7% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B6 Polyvinylidene fluoride resin as a matrix polyvinylidene fluoride (PVDF-I) (powder) with a weight average molecular weight (Mw) of 6.6 ⁇ 10 5 and crystal property modification with Mw of 9.7 ⁇ 10 5
- PVDF-II polyvinylidene fluoride
- Example B6 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B6 except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B7 As an organic liquid, alkylene glycol dibenzoate, a monomeric ester plasticizer (“PB-10” manufactured by DIC Corporation, number average molecular weight of about 300, JIS K7117-2 (cone-flat plate viscometer) at 25 ° C.) A measured viscosity of 81 mPa ⁇ s and a specific gravity of 1.147 g / ml); a vinylidene fluoride resin porous membrane in the same manner as in Example B6 except that the cooling water bath temperature Tq after melt extrusion was changed to 60 ° C. Got.
- PB-10 monomeric ester plasticizer
- Example B7 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B7, except that dichloromethane (swelling ratio of 5.7% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
- Example B and Comparative Example B described above extraction (and subsequent rinsing) was performed on the separated single-filamentary first intermediate molded body (vinylidene fluoride hollow fiber membrane containing an organic liquid after phase separation).
- first intermediate molded body vinylene fluoride hollow fiber membrane containing an organic liquid after phase separation.
- bobbin extraction is performed by reducing the dimensional shrinkage rate according to the method of the present invention. And the film characteristics by subsequent stretching were evaluated.
- Example B8 The first intermediate molded body (length: 500 m) wound on the bobbin (core diameter: 220 mm) in Example B5 was immersed in dichloromethane for 30 minutes at room temperature while being wound on the bobbin, and the plasticizer was extracted. At this time, the extraction was performed while rotating the bobbin so that the dichloromethane was evenly distributed over the yarn. Next, the operation of replacing the dichloromethane with a new one and extracting again under the same conditions was repeated, and extraction was performed three times in total.
- IPA isopropyl alcohol
- IPA was removed by air drying at room temperature for 24 hours, followed by heating in an oven at a temperature of 120 ° C. for 1 hour to remove IPA and heat treatment to obtain a second intermediate molded body.
- the bobbin diameter was freely contracted, and drying and heat treatment were performed without restricting the contraction of the yarn.
- the second intermediate formed body is pulled out while rotating the bobbin, the first roll speed is set to 20.0 m / min, and the second roll is passed through the 60 ° C. water bath.
- the film was stretched 1.75 times in the longitudinal direction by setting the speed to 35.0 m / min.
- it is passed through a hot water bath controlled at a temperature of 90 ° C., the first stage relaxation rate is relaxed at 8%, and further passed through a dry heat tank controlled at a spatial temperature of 140 ° C., and the second stage relaxation rate is 1.5%. And relaxed. This was wound up to obtain a vinylidene fluoride resin hollow fiber porous membrane.
- Example B9 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B8, except that the first intermediate molded body (length: 500 m) wound on a bobbin in Example B6 was used.
- Example B10 A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B8, except that the first intermediate molded body (length: 500 m) wound around the bobbin in Example B7 was used.
- Example B8 Bobbin extraction was performed in the same manner as in Example B8, except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
- dichloromethane swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin
- Example B9 Bobbin extraction was performed in the same manner as in Example B9, except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
- dichloromethane swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin
- Example B10 Bobbin extraction was performed in the same manner as in Example B10, except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
- dichloromethane swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin
- Example B11 The first intermediate molded body (length: 500 m) wound up in Example B6 was pulled out from the bobbin, passed through a 60 ° C. water bath at a first roll speed of 20.0 m / min, and a second roll speed. The film was stretched 2.5 times in the longitudinal direction at a speed of 50 m / min. Next, it is passed through a hot water bath controlled at a temperature of 90 ° C., the first stage relaxation rate is relaxed at 8%, and further passed through a dry heat tank controlled at a spatial temperature of 140 ° C., and the second stage relaxation rate is 1.5%. Was relaxed and wound on a bobbin to obtain a drawn yarn.
- the drawn liquid was wound around a bobbin and immersed in dichloromethane at room temperature for 30 minutes to extract an organic liquid.
- the extraction was performed while rotating the bobbin so that the dichloromethane was evenly distributed over the yarn.
- the operation of replacing the dichloromethane with a new one and extracting again under the same conditions was repeated, and extraction was performed three times in total.
- the drawn yarn is immersed in isopropyl alcohol (IPA), which is a rinse solution, at room temperature for 30 minutes for drawing.
- IPA isopropyl alcohol
- Dichloromethane impregnated in the yarn was replaced with IPA.
- the replacement was performed while rotating the bobbin so that the IPA was evenly distributed over the yarn.
- the operation of replacing the IPA with a new one and replacing the same under the same conditions was repeated, and the replacement was performed twice in total.
- IPA was removed by air drying at room temperature for 24 hours, followed by heating in an oven at 120 ° C. for 1 hour to remove IPA and heat treatment to obtain a vinylidene fluoride resin hollow fiber porous membrane.
- the bobbin diameter was freely contracted, and drying and heat treatment were performed without restricting the contraction of the yarn.
- Example B11 Bobbin extraction was performed in the same manner as in Example B11, except that dichloromethane (swelling ratio of 5.7% with respect to the raw vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, the yarn was bitten and the yarn was crimped due to the tightening of the yarn, and could not be recovered as a hollow fiber porous membrane having a uniform shape.
- dichloromethane swelling ratio of 5.7% with respect to the raw vinylidene fluoride resin
- Example B12 After using the first intermediate molded body (length: 500 m) wound around the bobbin in Example B1 and substituting with ethanol as the rinsing liquid, the hollow fiber porous membrane containing ethanol is substantially dried.
- a vinylidene fluoride resin hollow fiber porous membrane was prepared in the same manner as in Example B8, except that substitution was used for water (the swelling rate of 0.0% relative to the raw material vinylidene fluoride resin) as the second rinse liquid. Obtained.
- Example B12 Bobbin extraction was performed in the same manner as in Example B12 except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
- dichloromethane swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin
- the results in Table 6 are obtained by bobbing a long hollow fiber membrane-like vinylidene fluoride resin porous membrane for effective extraction, and then substituting with a non-swelling solvent after extraction with a halogenated solvent.
- the deformation of the hollow fiber membrane due to tightening is suppressed, the removal of the hollow fiber membrane is facilitated, and the vinylidene fluoride resin hollow fiber porous membrane having good water permeability despite the small pore diameter is formed.
- the highly permeable vinylidene fluoride resin porous membrane formed by the method of the present invention is not only suitable for drainage treatment, but also for concentrating bacteria and proteins, and collecting chemically aggregated particles of heavy metals.
- the vinylidene fluoride resin porous membrane obtained by the thermally induced phase separation method has a pore diameter continuously expanding in the film thickness direction, and a porosity is uniformly distributed in the film thickness direction.
- the dense layer that contributes to separation characteristics or selective permeation characteristics it has excellent separation characteristics or selective permeation characteristics while maintaining fluid separation or movement of ions, etc. The characteristic that there is little resistance is given. Such characteristics are particularly suitable for the separation applications described above in general.
- (filtration) has a surface pore diameter, water permeability and mechanical strength suitable for water treatment, and is represented by a large critical filtration flux.
- a vinylidene fluoride resin porous membrane that exhibits good water permeability maintaining performance even during continuous filtration of turbid water and has a large water permeability despite the small surface pore diameter of the water to be treated.
- the vinylidene fluoride resin porous membrane of the present invention is suitable for (filtered) water treatment as described above, but the pore diameter is continuously increased in the film thickness direction and the porosity is the film thickness. It has a characteristic of being uniformly distributed in the vertical direction.
- the porous membrane of the present invention is not limited to (filtered) water treatment, but can be used for concentration of bacteria, proteins, etc., recovery of chemically aggregated particles of heavy metals, separation membrane for oil-water separation and gas-liquid separation Also, it can be suitably used as a battery diaphragm such as a lithium ion secondary battery and a solid electrolyte support.
Abstract
Description
(a)前記緻密層の前記一表面から連続する厚さ5μmの部分の空孔率A1が60%以上、
(b)前記一表面の表面孔径P1が0.30μm以下、且つ
(c)差圧100kPa、水温25℃の条件で測定した試長L=200mmでの透水量の全層空孔率A2=80%への換算値Q(m/day)と、前記一表面の表面孔径P1の4乗値P14(μm4)との比、Q/P14が5×104(m/day・μm4)以上。 The vinylidene fluoride resin porous membrane of the present invention has been developed to achieve the above-mentioned object, and more specifically has two main surfaces sandwiching a certain thickness, and the pore diameter is on one surface side. It has a dense layer that is small and governs separation performance, has an asymmetric mesh-like inclined structure in which the pore diameter continuously increases from one surface to the opposite surface, and satisfies the following conditions (a) to (c) Is characterized by:
(A) The porosity A1 of a portion having a thickness of 5 μm continuous from the one surface of the dense layer is 60% or more,
(B) The total surface porosity A2 = 80 of the water permeability at the test length L = 200 mm measured under the condition that the surface pore diameter P1 of the one surface is 0.30 μm or less and (c) the differential pressure is 100 kPa and the water temperature is 25 ° C. The ratio between the converted value Q to% (m / day) and the fourth power value P1 4 (μm 4 ) of the surface pore diameter P1 of the one surface, Q / P1 4 is 5 × 10 4 (m / day · μm 4 )more than.
(i)フッ化ビニリデン系樹脂との溶融混練物に、フッ化ビニリデン系樹脂単独の結晶化温度Tc(℃)より6℃以上低い結晶化温度Tc′(℃)を与え、
(ii)前記溶融混練物を冷却した固化物に、示差走査熱量計(DSC)で測定したときのフッ化ビニリデン系樹脂質量基準での結晶融解エンタルピーΔH’(J/g)として53J/g以上を与え、且つ
(iii)JIS K7117-2(円すい-平板型回転粘度計使用)に準拠して温度25℃で測定した可塑剤単独の粘度が200mPa・s~1000Pa・s。本発明の好ましい態様によれば、上記可塑剤として、脂肪族二塩基酸とグリコールとからなる(ポリ)エステルの末端を一価の芳香族カルボン酸で封止したポリエステル系可塑剤が用いられる。 The method for producing a vinylidene fluoride resin porous membrane of the present invention is based on such knowledge, and more specifically, a melt-kneaded product of a vinylidene fluoride resin and a plasticizer is extruded from a die into a film shape, A method of producing a porous film comprising a step of forming a film to be cooled and solidified, and a step of extracting a plasticizer, wherein the plasticizer is compatible with the vinylidene fluoride resin at the formation temperature of the melt-kneaded product, and further It is characterized by satisfying the following conditions (i) to (iii):
(I) A crystallization temperature Tc ′ (° C.) lower by 6 ° C. or lower than the crystallization temperature Tc (° C.) of the vinylidene fluoride resin alone is given to the melt-kneaded product with the vinylidene fluoride resin.
(Ii) 53 J / g or more as crystal melting enthalpy ΔH ′ (J / g) based on the vinylidene fluoride resin mass standard when measured with a differential scanning calorimeter (DSC) on the solidified product obtained by cooling the melt-kneaded product And (iii) the viscosity of the plasticizer alone measured at a temperature of 25 ° C. in accordance with JIS K7117-2 (cone—using a flat plate type viscometer) is 200 mPa · s to 1000 Pa · s. According to a preferred aspect of the present invention, as the plasticizer, a polyester plasticizer in which the end of a (poly) ester composed of an aliphatic dibasic acid and glycol is sealed with a monovalent aromatic carboxylic acid is used.
本発明において、主たる膜原料であるフッ化ビニリデン系樹脂としては、フッ化ビニリデンの単独重合体、すなわちポリフッ化ビニリデン、フッ化ビニリデンと共重合可能な他のモノマーとの共重合体あるいはこれらの混合物で、重量平均分子量が60万~120万、より好ましくは65万~100万、特に好ましくは70万~90万、のものが好ましく用いられる。フッ化ビニリデンと共重合可能なモノマーとしては、四フッ化エチレン、六フッ化プロピレン、三フッ化エチレン、三フッ化塩化エチレン、フッ化ビニル等の一種又は二種以上を用いることができる。フッ化ビニリデン系樹脂は、構成単位としてフッ化ビニリデンを70モル%以上含有することが好ましい。なかでも耐薬品性と機械的強度の高さからフッ化ビニリデン100モル%からなる単独重合体を用いることが好ましい。
上記したような比較的高分子量のフッ化ビニリデン系樹脂は、好ましくは乳化重合あるいは懸濁重合、特に好ましくは懸濁重合により得ることができる。 (Vinylidene fluoride resin)
In the present invention, the vinylidene fluoride resin as the main film raw material is a homopolymer of vinylidene fluoride, that is, polyvinylidene fluoride, a copolymer with other monomers copolymerizable with vinylidene fluoride, or a mixture thereof. And those having a weight average molecular weight of 600,000 to 1,200,000, more preferably 650,000 to 1,000,000, particularly preferably 700,000 to 900,000 are preferably used. As the monomer copolymerizable with vinylidene fluoride, one or more of ethylene tetrafluoride, hexafluoropropylene, ethylene trifluoride, ethylene trifluoride chloride, vinyl fluoride and the like can be used. The vinylidene fluoride resin preferably contains 70 mol% or more of vinylidene fluoride as a structural unit. Among these, it is preferable to use a homopolymer composed of 100 mol% of vinylidene fluoride because of its high chemical resistance and mechanical strength.
The relatively high molecular weight vinylidene fluoride resin as described above can be obtained by emulsion polymerization or suspension polymerization, particularly preferably suspension polymerization.
(可塑剤)
本発明の中空糸多孔膜は、主として上記したフッ化ビニリデン系樹脂により形成されるが、その製造のためには上述したフッ化ビニリデン系樹脂に加えて、少なくともその可塑剤を孔形成剤として用いることが好ましい。本発明において可塑剤としては、溶融混練温度において、フッ化ビニリデン系樹脂と相溶性を有するとともに、下記(i)~(iii)の特性を有するものが好ましく用いられる: In the production method of the present invention, a plasticizer is added to the above-mentioned vinylidene fluoride resin to form a raw material composition for film formation.
(Plasticizer)
The hollow fiber porous membrane of the present invention is mainly formed from the above-mentioned vinylidene fluoride resin, but in addition to the above-mentioned vinylidene fluoride resin, at least the plasticizer is used as a pore-forming agent for the production. It is preferable. As the plasticizer in the present invention, those having compatibility with the vinylidene fluoride resin at the melt kneading temperature and the following characteristics (i) to (iii) are preferably used:
(ii)その溶融混練物を冷却して固化した成形物に、示差走査熱量計(DSC)で測定したときのフッ化ビニリデン系樹脂質量基準での結晶融解エンタルピーΔH’(J/g)として、53J/g以上、好ましくは55J/g、更に好ましくは58J/g、を与え、且つ
(iii)JIS K7117-2(円すい-平板型回転粘度計使用)に準拠して温度25℃で測定した可塑剤単独の粘度が200mPa・s~1000Pa・s、好ましくは400mPa・s~100Pa・s、更に好ましくは500mPa・s~10Pa・s以下。 (I) The melt-kneaded product with the vinylidene fluoride resin is 6 ° C. or more lower than the crystallization temperature Tc (° C.) of the vinylidene fluoride resin alone, preferably 9 ° C. or more, more preferably 12 ° C. or more lower. Giving a crystallization temperature Tc ′ (° C.),
(Ii) As the crystal melting enthalpy ΔH ′ (J / g) based on the vinylidene fluoride resin mass standard when measured with a differential scanning calorimeter (DSC), the molded product obtained by cooling and solidifying the melt-kneaded product, Plasticity measured at a temperature of 25 ° C. in accordance with (iii) JIS K7117-2 (cone-using a plate-type rotary viscometer), and more than 53 J / g, preferably 55 J / g, more preferably 58 J / g. The viscosity of the agent alone is 200 mPa · s to 1000 Pa · s, preferably 400 mPa · s to 100 Pa · s, more preferably 500 mPa · s to 10 Pa · s or less.
多孔膜形成用の原料組成物は、フッ化ビニリデン系樹脂20~50重量%、好ましくは、25~40重量%に対して、可塑剤が、50~80重量%、好ましくは、60~75重量%を混合するのが良い。必要に応じて添加するモノメリックエステル系可塑剤、非水溶性の溶媒等は、原料組成物の溶融混練下での溶融粘度等を考慮して、可塑剤の一部を置きかえる態様で用いられる。(可塑剤に加えて、これら任意成分を含めた、溶融混和物を構成するフッ化ビニリデン系樹脂以外の成分の全体を、以下「可塑剤等」と称することがある。) (Composition)
In the raw material composition for forming the porous film, the plasticizer is 50 to 80% by weight, preferably 60 to 75% by weight relative to 20 to 50% by weight, preferably 25 to 40% by weight, of the vinylidene fluoride resin. % Is good to mix. The monomeric ester plasticizer, water-insoluble solvent, and the like added as necessary are used in such a manner that a part of the plasticizer is replaced in consideration of the melt viscosity of the raw material composition under melt kneading. (In addition to the plasticizer, the whole of the components other than the vinylidene fluoride resin constituting the melt mixture including these optional components may be referred to as “plasticizer or the like” hereinafter.)
バレル温度180~250℃、好ましくは200~240℃で溶融混練された溶融押出組成物は、一般に150~270℃、好ましくは170~240℃、の温度で、Tダイあるいは中空ノズルから押出されて膜状化される。従って、最終的に、上記温度範囲の均質組成物が得られる限りにおいて、フッ化ビニリデン系樹脂と、可塑剤等の混合並びに溶融形態は任意である。このような組成物を得るための好ましい態様の一つによれば、二軸混練押出機が用いられ、(好ましくは主体樹脂と結晶特性改質用樹脂の混合物からなる)フッ化ビニリデン系樹脂は、該押出機の上流側から供給され、可塑剤等が、下流で供給され、押出機を通過して吐出されるまでに均質混合物とされる。この二軸押出機は、その長手軸方向に沿って、複数のブロックに分けて独立の温度制御が可能であり、それぞれの部位の通過物の内容により適切な温度調節がなされる。 (Mixing / melt extrusion)
A melt-extruded composition melt-kneaded at a barrel temperature of 180 to 250 ° C., preferably 200 to 240 ° C., is generally extruded from a T die or a hollow nozzle at a temperature of 150 to 270 ° C., preferably 170 to 240 ° C. Filmed. Therefore, as long as a homogeneous composition in the above temperature range is finally obtained, the mixing and melting forms of the vinylidene fluoride resin and the plasticizer are arbitrary. According to one preferred embodiment for obtaining such a composition, a biaxial kneading extruder is used, and the vinylidene fluoride resin (preferably comprising a mixture of a main resin and a crystal characteristic modifying resin) is The plasticizer and the like are supplied from the upstream side of the extruder, supplied downstream, and 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 axis direction, and appropriate temperature adjustment is made according to the contents of the passing material at each site.
次いで溶融押出された中空糸膜状物を、その結晶化温度Tc′より50~140℃、より好ましくは55~130℃、更に好ましくは60~110℃、低い温度Tqのフッ化ビニリデン系樹脂に対して不活性(すなわち非溶媒且つ非反応性)な液体(好ましくは水)からなる冷却浴中に導入して、その外側面から優先的に冷却して固化成膜させる。Tc′-Tqが50℃未満であると、本発明の目的とする被処理水側表面側孔径が小さく傾斜孔径分布を有する多孔膜の形成が困難となる。また140℃を超えるためには、冷却用液体温度を0℃未満とすることが一般的に必要となり、好ましい冷却液としての水性媒体の使用が困難となるので好ましくない。冷却浴温度Tqは、好ましくは0~90℃、より好ましくは5~80℃、更に好ましくは25~70℃である。その際、中空糸膜状物形成に際しては、その中空部に空気あるいは窒素等の不活性ガスを注入しつつ冷却することにより拡径された中空糸膜が得られ、長尺化しても単位膜面積当りの透水量の低下が少い中空糸多孔膜を得るのに有利である(WO2005/03700A公報)。平膜形成のためには、冷却浴のシャワーの外、チルロールによる片側面からの冷却も用いられる。溶融押出しされた中空糸膜状物の冷却浴中でのつぶれを防止するために、溶融押出後、冷却浴に入るまでの経過時間(エアギャップ通過時間=エアギャップ/溶融押出物引取り速度)は、一般に0.3~10.0秒、特に0.5~5.0秒の範囲が好ましい。 (cooling)
Next, the melt-extruded hollow fiber membrane is converted into a vinylidene fluoride resin having a temperature Tq of 50 to 140 ° C., more preferably 55 to 130 ° C., and even more preferably 60 to 110 ° C., lower than the crystallization temperature Tc ′. On the other hand, it introduce | transduces in the cooling bath which consists of a liquid (preferably water) which is inactive (namely, non-solvent and non-reactive), preferentially cools from the outer surface, and solidifies into a film. When Tc′−Tq is less than 50 ° C., it is difficult to form a porous film having a small pore size distribution with a small pore size on the surface of the water to be treated, which is the object of the present invention. In order to exceed 140 ° C., it is generally necessary to set the cooling liquid temperature to less than 0 ° C., which makes it difficult to use an aqueous medium as a preferable cooling liquid. The cooling bath temperature Tq is preferably 0 to 90 ° C., more preferably 5 to 80 ° C., and further preferably 25 to 70 ° C. At that time, in forming the hollow fiber membrane, a hollow fiber membrane having an enlarged diameter is obtained by cooling while injecting an inert gas such as air or nitrogen into the hollow portion. This is advantageous for obtaining a hollow fiber porous membrane having a small decrease in the amount of water per area (WO 2005 / 03700A). In order to form a flat film, cooling from one side by a chill roll is also used in addition to a cooling bath shower. In order to prevent the melt-extruded hollow fiber membrane from collapsing in the cooling bath, the elapsed time from the melt extrusion until entering the cooling bath (air gap passage time = air gap / melt extrudate take-off speed) Is generally in the range of 0.3 to 10.0 seconds, particularly 0.5 to 5.0 seconds.
冷却・固化された膜状物は、次いで抽出液浴中に導入され、可塑剤等の抽出除去を受ける。抽出液としては、ポリフッ化ビニリデン系樹脂を溶解せず、可塑剤等を溶解できるものであれば特に限定されない。例えばアルコール類ではメタノール、イソプロピルアルコールなど、ハロゲン系溶媒ではジクロロメタン、1,1,1-トリクロロエタンなど、の沸点が30~100℃程度の溶媒が適当である。 (Extraction)
The cooled and solidified film-like material is then introduced into an extraction liquid bath and subjected to extraction and removal of a plasticizer and the like. The extraction liquid is not particularly limited as long as it does not dissolve the polyvinylidene fluoride resin and can dissolve the plasticizer and the like. For example, a solvent having a boiling point of about 30 to 100 ° C. is suitable for alcohols such as methanol and isopropyl alcohol, and for a halogen-based solvent such as dichloromethane and 1,1,1-trichloroethane.
フッ化ビニリデン系樹脂を温度230℃で5分間加熱プレスした後、温度20℃の冷却プレスで冷却固化して厚さ0.5mmのプレスシートを作製する。このプレスシートを50mm四方に裁断して試験片とする。この試験片の重量W1を測定した後、室温で溶媒に120時間浸漬する。その後に試験片を取り出して表面に付着した溶媒をろ紙で拭き取り、試験片の重量W2を測定する。下式により膨潤率(%)を測定する。膨潤率が1%未満であれば膨潤性を有さない、1%以上であれば膨潤性を有すると評価する。
膨潤率(%)=(W2-W1)/W1×100。 <Swelling evaluation method>
A vinylidene fluoride resin is heated and pressed at a temperature of 230 ° C. for 5 minutes, and then cooled and solidified by a cooling press at a temperature of 20 ° C. to produce a press sheet having a thickness of 0.5 mm. This press sheet is cut into 50 mm squares to form test pieces. After measuring the weight W1 of this test piece, it is immersed in a solvent at room temperature for 120 hours. Thereafter, the test piece is taken out, the solvent adhering to the surface is wiped off with a filter paper, and the weight W2 of the test piece is measured. The swelling rate (%) is measured by the following formula. If the swelling rate is less than 1%, it does not have swelling property, and if it is 1% or more, it is evaluated as having swelling property.
Swell rate (%) = (W2−W1) / W1 × 100.
上述した、抽出リンス法(すなわち、空孔中にハロゲン系溶媒を含むフッ化ビニリデン系樹脂の膜状成形体を、一旦、フッ化ビニリデン系樹脂に対して膨潤性を有さない溶媒に浸漬する等によりハロゲン系溶媒を置換(リンス)した後、乾燥する方法)は、それに先立って、例えば抽出溶媒としてハロゲン化溶媒を用いる熱誘起相分離法により、あるいは非溶媒としてハロゲン化溶媒を用いる非溶媒誘起相分離法により、その空孔中にハロゲン化溶媒を含有するフッ化ビニリデン系樹脂の膜状成形体(b)が形成されていれば、平膜および中空糸膜のいずれの形成にも適用可能である。ただし、どちらかといえば、有機液状体を効率的に抽出するためにハロゲン化溶媒を用いる必要のある熱誘起相分離法によりハロゲン化溶媒を含有する膜状成形体(b)を形成する態様が好ましい。また、ろ水処理膜としての使用を考慮したときは、ろ過装置当りの膜面積を大きくすることが容易な中空糸膜の形成に用いることが好ましい。 << Extraction rinse method >>
The above-described extraction rinse method (that is, the vinylidene fluoride resin film-like molded article containing a halogen-based solvent in the pores is once immersed in a solvent that does not swell with respect to the vinylidene fluoride resin. For example, a method of substituting (rinsing) a halogen-based solvent with, for example, and then drying is performed by, for example, a thermally induced phase separation method using a halogenated solvent as an extraction solvent or a non-solvent using a halogenated solvent as a non-solvent If a film-like molded body (b) of vinylidene fluoride resin containing a halogenated solvent is formed in its pores by induced phase separation, it can be applied to both the formation of flat membranes and hollow fiber membranes. Is possible. However, if anything, there is an aspect in which a film-shaped molded article (b) containing a halogenated solvent is formed by a thermally induced phase separation method that requires the use of a halogenated solvent in order to efficiently extract an organic liquid. preferable. Moreover, when considering the use as a filtered water treatment membrane, it is preferably used for forming a hollow fiber membrane in which the membrane area per filtration device can be easily increased.
(1)フッ化ビニリデン系樹脂と有機液状体との混合物の膜状成形体(a)をハロゲン化溶媒に浸漬して有機液状体を抽出除去してその抜け跡の空孔中にハロゲン化溶媒を含有する膜状成形体(b)を形成し、これを実質的に乾燥させることなく、フッ化ビニリデン系樹脂に対して膨潤性を有さない溶媒に浸漬してハロゲン化溶媒を置換させ、その後、乾燥させることを特徴とするフッ化ビニリデン系樹脂多孔膜の製造方法。
(2)前記膜状成形体(a)が、フッ化ビニリデン系樹脂と有機液状体との溶融混練物を冷却することにより、フッ化ビニリデン系樹脂と有機液状体とを相分離させ、固化させた膜状成形体である上記(1)に記載の製造方法。
(3)前記膜状成形体(a)が、示差操作熱量測定(DSC)で測定したフッ化ビニリデン系樹脂質量基準での結晶融解エンタルピーとして5J/g以上を有する、上記(2)に記載の製造方法。
(4)膜状成形体(a)を形成するフッ化ビニリデン系樹脂と有機液状体との混合物中の有機液状体の混合割合がフッ化ビニリデン系樹脂100容量部に対して200容量部以上である上記(1)~(3)のいずれかに記載の製造方法。
(5)有機液状体がポリエステル系可塑剤である上記(1)~(4)のいずれかに記載の製造方法。
(6)ハロゲン化溶媒のフッ化ビニリデン系樹脂に対する膨潤率が2~20重量%である上記(1)~(5)のいずれかに記載の製造方法。
(7)膜状成形体(a)を形成するフッ化ビニリデン系樹脂と有機液状体との混合物中の有機液状体の容積割合に対する製品多孔膜中の空孔率として定める孔形成効率が0.85以上である上記(1)~(6)のいずれかに記載の製造方法。
(8)ハロゲン化溶媒による抽出前、またはフッ化ビニリデン系樹脂に対して膨潤性を有さない溶媒によるハロゲン化溶媒の置換および乾燥後、に延伸工程を含む上記(1)~(7)のいずれかに記載の製造方法。 Thus, the method for producing a vinylidene fluoride resin porous membrane including the generalized “extraction rinsing method” is characterized by the following (1) to (8).
(1) A film-like molded body (a) of a mixture of a vinylidene fluoride resin and an organic liquid is immersed in a halogenated solvent to extract and remove the organic liquid, and the halogenated solvent is left in the voids of the trace. Without forming a film-like molded body (b) containing, and substantially lysing it, immersing it in a solvent that does not swell with respect to the vinylidene fluoride resin to replace the halogenated solvent, Then, it is made to dry, The manufacturing method of the vinylidene fluoride resin porous membrane characterized by the above-mentioned.
(2) The film-shaped molded body (a) causes the vinylidene fluoride resin and the organic liquid to phase separate and solidify by cooling the melt-kneaded product of the vinylidene fluoride resin and the organic liquid. The manufacturing method as described in said (1) which is a film-like molded object.
(3) The said film-shaped molded object (a) has 5 J / g or more as a crystal-melting enthalpy on the basis of vinylidene fluoride resin mass measured by differential operation calorimetry (DSC), as described in (2) above Production method.
(4) The mixing ratio of the organic liquid in the mixture of the vinylidene fluoride resin and the organic liquid forming the film-shaped molded body (a) is 200 parts by volume or more with respect to 100 parts by volume of the vinylidene fluoride resin. The production method according to any one of the above (1) to (3).
(5) The production method according to any one of (1) to (4), wherein the organic liquid is a polyester plasticizer.
(6) The production method according to any one of (1) to (5) above, wherein the swelling ratio of the halogenated solvent to the vinylidene fluoride resin is 2 to 20% by weight.
(7) The pore formation efficiency determined as the porosity in the product porous film with respect to the volume ratio of the organic liquid in the mixture of the vinylidene fluoride resin and the organic liquid forming the film-shaped molded body (a) is 0. The production method according to any one of the above (1) to (6), which is 85 or more.
(8) The above-mentioned (1) to (7) including a stretching step before extraction with a halogenated solvent, or after substitution and drying of a halogenated solvent with a solvent that does not swell to vinylidene fluoride resin The manufacturing method in any one.
抽出後の膜状物は、次いでこれを延伸に付し、空孔率および孔径の増大並びに強伸度の改善をすることが好ましい。特に、延伸に先立って、抽出後の膜状物(多孔膜)の外表面から一定の深さまで選択的に湿潤させ、この状態で延伸すること(以下、「部分湿潤延伸」と称する)ことが、高い緻密層空孔率A1を得る上で好ましい。より詳しくは、延伸に先立って多孔膜の外表面から5μm以上、好ましくは7μm以上、更に好ましくは10μm以上、かつ膜厚さの1/2以下、好ましくは1/3以下、更に好ましくは1/4以下の深さを選択的に湿潤するように行う。湿潤される深さが5μm未満では緻密層空孔率A1の増大が十分でなく、1/2を超えると延伸後に乾熱緩和する場合に、湿潤液の乾燥が不均一になり、熱処理あるいは緩和処理が不均一になる恐れがある。 (Stretching)
It is preferable that the extracted film-like material is then subjected to stretching to increase the porosity and pore diameter and improve the strength. In particular, prior to stretching, it is possible to selectively wet from the outer surface of the film-like material after extraction (porous membrane) to a certain depth and stretch in this state (hereinafter referred to as “partial wet stretching”). It is preferable for obtaining a high dense layer porosity A1. More specifically, prior to stretching, 5 μm or more from the outer surface of the porous membrane, preferably 7 μm or more, more preferably 10 μm or more, and ½ or less, preferably 1 / or less, more preferably 1 / 1 / of the film thickness. A depth of 4 or less is selectively wetted. When the wet depth is less than 5 μm, the increase in the dense layer porosity A1 is not sufficient, and when it exceeds 1/2, when the dry heat is relaxed after stretching, the drying of the wetting liquid becomes uneven, and the heat treatment or relaxation Processing may be uneven.
上記説明から理解されるように、「部分湿潤延伸法」は、基本的に、既に形成された乾燥状態にある樹脂多孔膜に施す延伸工程を主たる特徴とし、その樹脂多孔膜の種類ならびに形成方法には、本質的な制約は受けない。多孔膜が、平膜であると、中空糸膜であるとに拘わらず適用可能である。又、多孔膜を形成する樹脂も、親水性樹脂と疎水性樹脂のいずれも可能であり、天然樹脂と合成樹脂のいずれも用いることができる。但し、分離膜として用いる際の被処理液が水性液である場合等の耐久性を考慮すれば、水に不溶な樹脂であることが好ましいであろう。このような水に不溶な樹脂の代表例として、ポリオレフィン系樹脂(例えばJP46-40119B,JP50-2176B)、ポリフッ化ビニリデン系樹脂(例えばJP63-296940A,JP03-215535A,WO99/47593A,WO03/031038A,WO2004/081109A,WO2005/099879A,JP2001-179062A,JP2003-210954A)、ポリ4フッ化エチレン系樹脂、ポリスルホン系樹脂、ポリエーテルスルホン系樹脂(WO02/058828A1)、ポリ塩化ビニル系樹脂、ポリアリーレンスルフィド系樹脂、ポリアクリロニトリル系樹脂、酢酸セルロース樹脂(JP2003-311133A)、等が本発明でも好ましい樹脂材料として用いられる。 << Partial wet stretching method >>
As understood from the above description, the “partial wet stretching method” basically has a main feature of a stretching step applied to a resin porous membrane that has already been formed in a dry state. Is not subject to essential constraints. The porous membrane is applicable regardless of whether it is a flat membrane or a hollow fiber membrane. The resin forming the porous film can be either a hydrophilic resin or a hydrophobic resin, and either a natural resin or a synthetic resin can be used. However, considering durability such as when the liquid to be treated when used as a separation membrane is an aqueous liquid, it is preferable that the resin be insoluble in water. As typical examples of such water-insoluble resins, polyolefin resins (eg JP46-40119B, JP50-2176B), polyvinylidene fluoride resins (eg JP63-296940A, JP03-215535A, WO99 / 47593A, WO03 / 031038A, WO2004 / 081109A, WO2005 / 099879A, JP2001-179062A, JP2003-210954A), polytetrafluoroethylene resin, polysulfone resin, polyethersulfone resin (WO02 / 058828A1), polyvinyl chloride resin, polyarylene sulfide system Resin, polyacrylonitrile-based resin, cellulose acetate resin (JP2003-31133A), etc. are also used as preferred resin materials in the present invention.
(1)樹脂多孔膜を、その外表面から5μm以上、且つ膜厚さの1/2以下の深さまで選択的に湿潤液により湿潤させた状態で延伸することを特徴とする、延伸樹脂多孔膜の製造方法。
(2)外表面から7μm以上、且つ膜厚さの1/2以下の深さまで選択的に湿潤させた状態で延伸する、上記(1)に記載の製造方法。
(3)空孔率が50%以上である樹脂多孔膜を延伸する、上記(1)または(2)に記載の製造方法。
(4)樹脂多孔膜が、その主たる二表面の孔径が異なる非対称構造膜であって、孔径が小さい側の表面のみを湿潤させる、上記(1)~(3)のいずれかに記載の製造方法。
(5)延伸倍率が1.5倍以上である、上記(1)~(4)のいずれかに記載の製造方法。
(6)樹脂多孔膜が疎水性樹脂からなる、上記(1)~(5)のいずれかに記載の製造方法。
(7)樹脂多孔膜がフッ化ビニリデン系樹脂からなる、上記(1)~(5)のいずれかに記載の製造方法。
(8)湿潤液が水溶液である、上記(6)または(7)に記載の製造方法。
(9)湿潤液が界面活性剤水溶液である、上記(8)に記載の製造方法。
(10)湿潤液がポリグリセリン脂肪酸エステルの水溶液である、上記(8)に記載の製造方法。
(11)延伸後の樹脂多孔膜の孔径が小さい側の表面孔径が0.5μm以下である上記(1)~(10)のいずれかに記載の製造方法。
(12)延伸後の樹脂多孔膜のハーフドライ法平均孔径が0.5μm以下である上記(1)~(11)のいずれかに記載の製造方法。
(13)延伸温度が25~90℃である、上記(1)~(12)のいずれかに記載の製造方法。
(14)延伸後に樹脂多孔膜を湿潤させない液体または気体中での緩和工程を含む上記(1)~(13)のいずれかに記載の製造方法。 As described above, the partial wet stretching method can be formed on either a flat membrane or a hollow fiber membrane. However, in general, a hollow fiber in which the membrane area per filtration device can be easily increased in drainage treatment. It is preferably formed as a film, and a flat film shape is preferable for electrochemical element separators including batteries. The method for producing a stretched resin porous membrane including the generalized “partial wet stretching method” is characterized by the following (1) to (14):
(1) A stretched resin porous membrane, wherein the resin porous membrane is stretched in a state of being selectively wetted with a wetting liquid to a depth of 5 μm or more and 1/2 or less of the film thickness from the outer surface. Manufacturing method.
(2) The production method according to (1), wherein stretching is performed in a state of being selectively wetted from the outer surface to a depth of 7 μm or more and ½ or less of the film thickness.
(3) The production method according to the above (1) or (2), wherein a resin porous membrane having a porosity of 50% or more is stretched.
(4) The production method according to any one of (1) to (3), wherein the porous resin membrane is an asymmetric structure membrane having different pore diameters on its two main surfaces, and wets only the surface having the smaller pore diameter. .
(5) The production method according to any one of (1) to (4), wherein the draw ratio is 1.5 times or more.
(6) The production method according to any one of (1) to (5) above, wherein the resin porous membrane is made of a hydrophobic resin.
(7) The production method according to any one of (1) to (5) above, wherein the resin porous membrane is made of a vinylidene fluoride resin.
(8) The production method according to the above (6) or (7), wherein the wetting liquid is an aqueous solution.
(9) The production method according to (8), wherein the wetting liquid is an aqueous surfactant solution.
(10) The production method according to (8), wherein the wetting liquid is an aqueous solution of a polyglycerin fatty acid ester.
(11) The production method according to any one of the above (1) to (10), wherein the pore diameter of the resin porous membrane after stretching has a surface pore diameter of 0.5 μm or less.
(12) The production method according to any one of (1) to (11) above, wherein the resin porous membrane after stretching has an average pore diameter of 0.5 μm or less in a half dry method.
(13) The production method according to any one of (1) to (12) above, wherein the stretching temperature is 25 to 90 ° C.
(14) The production method according to any one of (1) to (13), comprising a relaxation step in a liquid or gas that does not wet the resin porous membrane after stretching.
上記のようにして得られたフッ化ビニリデン系樹脂の中空糸多孔膜を、非湿潤性の雰囲気(あるいは媒体)中で少なくとも一段階、より好ましくは少なくとも二段階の緩和または定長熱処理に付すことが好ましい。非湿潤性の雰囲気は、室温付近でフッ化ビニリデン系樹脂の濡れ張力よりも大きな表面張力(JIS K6768)を有する非湿潤性の液体、代表的には水、あるいは空気をはじめとするほぼ全ての気体が用いられる。中空糸のように一軸延伸された多孔膜の緩和処理は、周速が次第に低減する上流ローラと下流ローラの間に配置された上記した非湿潤性の好ましくは加熱された雰囲気中を、先に得られた延伸された多孔膜を送通することにより得られる。(1-(下流ローラ周速/上流ローラ周速))×100(%)で定まる緩和率は、合計で0%(定長熱処理)~50%の範囲とすることが好ましく、特に1~20%の範囲の緩和熱処理とすることが好ましい。20%を超える緩和率は、前工程での延伸倍率にもよるが、実現し難いか、あるいは実現しても透水量向上効果が飽和するか、あるいは却って低下するため好ましくない。 (Relaxation treatment)
The hollow fiber porous membrane of vinylidene fluoride resin obtained as described above is subjected to at least one stage, more preferably at least two stages of relaxation or constant length heat treatment in a non-wetting atmosphere (or medium). Is preferred. The non-wetting atmosphere is a non-wetting liquid having a surface tension (JIS K6768) larger than the wetting tension of vinylidene fluoride resin near room temperature, typically water or air. Gas is used. The relaxation treatment of the uniaxially stretched porous membrane such as the hollow fiber is carried out by first performing the above-described non-wetting, preferably heated atmosphere, disposed between the upstream roller and the downstream roller, where the peripheral speed gradually decreases. It is obtained by passing the obtained stretched porous membrane. The relaxation rate determined by (1− (downstream roller peripheral speed / upstream roller peripheral speed)) × 100 (%) is preferably in the range of 0% (constant length heat treatment) to 50%, particularly 1 to 20 % Relaxation heat treatment is preferable. A relaxation rate exceeding 20% depends on the stretching ratio in the previous step, but is not preferable because it is difficult to achieve or even if realized, the effect of improving the water permeability is saturated or decreases.
後段の定長または緩和熱処理温度は、80~170℃、特に120~160℃で、1~20%の緩和率が得られる程度が好ましい。 The first-stage constant length or relaxation heat treatment temperature is preferably 0 to 100 ° C., particularly 50 to 100 ° C. The treatment time may be short or long as long as the desired heat setting effect and relaxation rate are obtained. Generally, it is about 5 seconds to 1 minute, but it is not necessary to be within this range.
The post-stage constant length or relaxation heat treatment temperature is preferably 80 to 170 ° C., more preferably 120 to 160 ° C., so that a relaxation rate of 1 to 20% can be obtained.
上記一連の工程を通じて得られる本発明の多孔膜は、実質的にフッ化ビニリデン系樹脂の単一層膜であるが、その一表面側に孔径が小さく分離性能を支配する緻密層を有し、その一表面から逆側表面にかけて連続的に孔径が拡大する非対称の網目状傾斜構造を有するフッ化ビニリデン系樹脂多孔膜であり、且つ
(a)前記緻密層の前記一表面に接する厚さ5μmの部分の空孔率A1(%)が60%以上、好ましくは65%以上、より好ましくは70%以上(その上限は特に限定されないが一般に85%を超えることは困難)であり、
(b)前記一表面の表面孔径P1が0.30μm以下、好ましくは0.25μm以下、より好ましくは0.20μm以下、最も好ましくは0.15μm以下 (下限は特に限定されないが0.01μm未満とすることは困難)であり、且つ
(c)差圧100kPa、水温25℃の条件で測定した試長L=200mmでの透水量の全層空孔率A2=80%への換算値Q(m/day)と、前記一表面の表面孔径P1の4乗値P14(μm4)との比、Q/P14が5×104(m/day・μm4)以上、好ましくは7×104(m/day・μm4)以上、より好ましくは1×105(m/day・μm4)以上(上限は特に限定されないが5×105(m/day・μm4)を超えることは困難)
という特徴を有し、更に好ましくは
(d)被処理水側表面孔径P1(μm)との比A1/P1が400以上、好ましくは550以上、更に好ましくは500以上(その上限は特に限定されないが一般に1000を超えることは困難)の値を有し、
(e)A1と全層空孔率A2との比A1/A2が、0.80以上、好ましくは0.85以上、より好ましくは0.90以上(上限は一般に1.0を超えることは困難)であり、
(f)緻密層厚さは、一般に7μm以上であるが、40μm以下、好ましくは30μm以下、更に好ましくは20μm以下、最も好ましくは15μm以下であり、
(g)また本発明の多孔膜の傾斜孔径分布は、好ましくは前記一表面の表面孔径P1(μm)、逆側表面の表面孔径P2(μm)の比P2/P1が2.0~10.0であることで代表される。 (Vinylidene fluoride resin porous membrane)
The porous membrane of the present invention obtained through the above series of steps is substantially a single layer membrane of vinylidene fluoride resin, but has a dense layer that has a small pore size and governs separation performance on one surface side thereof. A vinylidene fluoride resin porous membrane having an asymmetric network-like gradient structure in which the pore diameter continuously increases from one surface to the opposite surface, and (a) a portion having a thickness of 5 μm in contact with the one surface of the dense layer The porosity A1 (%) is 60% or more, preferably 65% or more, more preferably 70% or more (the upper limit is not particularly limited, but generally it is difficult to exceed 85%),
(B) The surface pore diameter P1 of the one surface is 0.30 μm or less, preferably 0.25 μm or less, more preferably 0.20 μm or less, most preferably 0.15 μm or less (the lower limit is not particularly limited, but less than 0.01 μm) And (c) the converted value Q (m) of the water permeability at the test length L = 200 mm measured under the conditions of the differential pressure of 100 kPa and the water temperature of 25 ° C. to the total layer porosity A2 = 80%. / Day) to the fourth power value P1 4 (μm 4 ) of the surface pore diameter P1 of the one surface, Q / P1 4 is 5 × 10 4 (m / day · μm 4 ) or more, preferably 7 × 10 4 (m / day · μm 4 ) or more, more preferably 1 × 10 5 (m / day · μm 4 ) or more (the upper limit is not particularly limited, but it exceeds 5 × 10 5 (m / day · μm 4 )) Difficult)
More preferably, (d) the ratio A1 / P1 with the surface pore diameter P1 (μm) of the treated water is 400 or more, preferably 550 or more, more preferably 500 or more (the upper limit is not particularly limited). In general, it is difficult to exceed 1000)
(E) The ratio A1 / A2 between A1 and the total layer porosity A2 is 0.80 or more, preferably 0.85 or more, more preferably 0.90 or more (the upper limit is generally difficult to exceed 1.0) ) And
(F) The dense layer thickness is generally 7 μm or more, but 40 μm or less, preferably 30 μm or less, more preferably 20 μm or less, most preferably 15 μm or less,
(G) In addition, in the distribution of the inclined pore diameter of the porous membrane of the present invention, the ratio P2 / P1 of the surface pore diameter P1 (μm) on the one surface and the surface pore diameter P2 (μm) on the opposite surface is preferably 2.0 to 10. It is represented by being 0.
パーキンエルマー社製の示差走査熱量計「DSC7」を用いて、試料樹脂10mgを測定セルにセットし、窒素ガス雰囲気中で、温度30℃から10℃/分の昇温速度で250℃まで昇温し、ついで250℃で1分間保持した後、250℃から10℃/分の降温速度で30℃まで降温してDSC曲線を求めた。このDSC曲線における昇温過程における吸熱ピーク速度を融点Tm1(℃)とし、降温過程における発熱ピーク温度を結晶化温度Tc(℃)とした。引き続いて、温度30℃で1分間保持した後、再び30℃から10℃/分の昇温速度で250℃まで昇温してDSC曲線を測定した。この再昇温DSC曲線における吸熱ピーク温度を本発明のフッ化ビニリデン系樹脂の結晶特性を規定する本来の樹脂融点Tm2(℃)とした。 (Crystal melting point Tm1, Tm2 and crystallization temperature Tc, Tc ′)
Using a differential scanning calorimeter “DSC7” manufactured by PerkinElmer Co., Ltd., 10 mg of the sample resin was set in the measurement cell, and the temperature was increased from 30 ° C. to 250 ° C. at a rate of 10 ° C./min in a nitrogen gas atmosphere. Then, after holding at 250 ° C. for 1 minute, the temperature was lowered from 250 ° C. to 30 ° C. at a temperature lowering rate of 10 ° C./min to obtain a DSC curve. In the DSC curve, the endothermic peak speed in the temperature rising process was the melting point Tm1 (° C.), and the exothermic peak temperature in the temperature lowering process was the crystallization temperature Tc (° C.). Subsequently, after maintaining at a temperature of 30 ° C. for 1 minute, the temperature was raised again from 30 ° C. to 250 ° C. at a rate of 10 ° C./min, and the DSC curve was measured. The endothermic peak temperature in this reheated DSC curve was the original resin melting point Tm2 (° C.) that defines the crystal characteristics of the vinylidene fluoride resin of the present invention.
膜原料としてのフッ化ビニリデン系樹脂と可塑剤等との混合物の結晶融解エンタルピーΔH’は次のようにして測定した:
溶融混練物の冷却固化物の10mgを上記結晶化温度Tc′の測定と同様の昇降温サイクルにかけてDSC曲線を得、1回目の昇温における吸熱ピーク面積から溶融混練物の冷却固化物の全体質量基準での結晶融解エンタルピーΔH0(J/g)を求めた。また、これとは別に上記溶融混練物の冷却固化物の約1gを秤量して、その重量をW0(g)とし、次いでこの溶融混練物の冷却固化物を室温でジクロロメタンに浸漬して30分間超音波洗浄する操作を3回繰り返して可塑剤等を抽出し、温度120℃のオーブンで乾燥させて再度秤量した。その重量をW(g)として、次式により、フッ化ビニリデン系樹脂質量基準での溶融混練物の冷却固化物の結晶融解エンタルピーΔH’(J/g)を算出した。
ΔH’=ΔH0/(W/W0)
溶融混練物の冷却固化物としては、実際の方法により製造された溶融混練押出物の冷却固化膜で抽出処理前のもの(後記の実施例における第1中間成形体)を用いることが便宜である。 (Crystal melting enthalpy ΔH ′ of the cooled and solidified product of the melt-kneaded product)
The crystal melting enthalpy ΔH ′ of a mixture of vinylidene fluoride resin as a film raw material and a plasticizer was measured as follows:
A DSC curve is obtained by subjecting 10 mg of the cooled and solidified product of the melt-kneaded product to the same temperature raising and lowering cycle as the measurement of the crystallization temperature Tc ′, and the total mass of the cooled and solidified product of the melt-kneaded product from the endothermic peak area at the first temperature increase. The reference crystal melting enthalpy ΔH0 (J / g) was determined. Separately, about 1 g of the cooled and solidified product of the melt-kneaded product was weighed to make it W0 (g), and then the cooled and solidified product of the melt-kneaded product was immersed in dichloromethane at room temperature for 30 minutes. The operation of ultrasonic cleaning was repeated three times to extract the plasticizer, etc., dried in an oven at a temperature of 120 ° C., and weighed again. Using the weight as W (g), the crystal melting enthalpy ΔH ′ (J / g) of the cooled and solidified product of the melt-kneaded product based on the vinylidene fluoride resin mass standard was calculated by the following formula.
ΔH ′ = ΔH0 / (W / W0)
As the cooled and solidified product of the melt-kneaded product, it is convenient to use a cooled and solidified film of the melt-kneaded extrudate produced by an actual method and before extraction processing (first intermediate molded body in the examples described later). .
可塑剤(等)のフッ化ビニリデン系樹脂に対する相溶性は、次の方法により判定した:
フッ化ビニリデン系樹脂23.73gと、可塑剤46.27gとを、室温で混ぜ合わせてスラリー状混合物を得る。次に、東洋精機(株)製「ラボプラストミル」(ミキサータイプ:「R-60」)のバレルをフッ化ビニリデン系樹脂の融点より10℃以上高い(例えば約17~37℃高い)所定の温度に調整しておいて,上記スラリー状混合物を投入して3分間予熱し、続いてミキサー回転数50rpmで溶融混練する。混練開始後、10分以内に清澄な(すなわち目視で濁りの原因となる分散物のない程度に透明な)溶融混練物が得られる場合には、その可塑剤はフッ化ビニリデン系樹脂に対して相溶性であると判定する。なお、溶融混練物の粘度が高い場合などには気泡の抱きこみにより白濁して見えることがあるので、そのときは、適宜、熱プレスするなどの方法により脱気して判定する。一旦、冷却固化した場合には、再度加熱して溶融状態にしてから清澄か否かを判定する。 (Compatibility)
The compatibility of the plasticizer (etc.) with the vinylidene fluoride resin was determined by the following method:
A slurry-like mixture is obtained by mixing 23.73 g of vinylidene fluoride resin and 46.27 g of a plasticizer at room temperature. Next, the barrel of “Lab Plast Mill” (mixer type: “R-60”) manufactured by Toyo Seiki Co., Ltd. is 10 ° C. higher than the melting point of the vinylidene fluoride resin (for example, about 17 to 37 ° C. higher). The temperature is adjusted, and the slurry mixture is charged and preheated for 3 minutes, and then melt-kneaded at a mixer rotation speed of 50 rpm. When a melted and kneaded product that is clear (that is, transparent to the extent that there is no visible turbidity) is obtained within 10 minutes after the start of kneading, the plasticizer is based on vinylidene fluoride resin. Determined to be compatible. In addition, when the viscosity of the melt-kneaded material is high, it may appear cloudy due to entrapment of bubbles, and in that case, it is determined by deaeration appropriately by a method such as hot pressing. Once it has cooled and solidified, it is heated again to be in a molten state, and then it is determined whether or not it is clarified.
日本分光社製のGPC装置「GPC-900」を用い、カラムに昭和電工社製の「Shodex KD-806M」、プレカラムに「Shodex KD-G」、溶媒にNMPを使用し、温度40℃、流量10mL/分にて、ゲルパーミエーションクロマトグラフィー(GPC)法によりポリスチレン換算分子量として測定した。 (Weight average molecular weight (Mw))
Using a GPC device “GPC-900” manufactured by JASCO Corporation, “Shodex KD-806M” manufactured by Showa Denko Co., Ltd. as a column, “Shodex KD-G” used as a pre-column, NMP as a solvent, temperature 40 ° C., flow rate The molecular weight was measured in terms of polystyrene by gel permeation chromatography (GPC) at 10 mL / min.
平膜および中空糸膜を含む多孔膜の見掛け体積V(cm3)を算出し、更に多孔膜の重量W(g)を測定して次式より全層空孔率A2を求めた:
[数1]
全層空孔率A2(%)=(1-W/(V×ρ))×100
ρ:PVDFの比重(=1.78g/cm3)。
なお、抽出後且つ延伸前の膜について同様の方法により測定される未延伸膜全層空孔率A0(%)と溶融押出混合物中の可塑剤(および溶媒)混合物Bの割合RB(重量%)の比A0/RBの概数は、混合物Bの孔形成効率を示すものと考えられる。 (All layer porosity A2)
The apparent volume V (cm 3 ) of the porous membrane including the flat membrane and the hollow fiber membrane was calculated, and the weight W (g) of the porous membrane was measured to determine the total-layer porosity A2 from the following formula:
[Equation 1]
Total layer porosity A2 (%) = (1−W / (V × ρ)) × 100
ρ: Specific gravity of PVDF (= 1.78 g / cm 3 ).
In addition, the porosity A0 (%) of the whole layer of the unstretched film measured by the same method for the film after extraction and before stretching, and the ratio RB (% by weight) of the plasticizer (and solvent) mixture B in the melt extrusion mixture The approximate number of the ratio A0 / RB is considered to indicate the pore formation efficiency of the mixture B.
膜状成形体形成用のフッ化ビニリデン系樹脂(比重=1.78)との混合物中の有機液状体の容積混合比率RLを押出供給比率(重量%)と有機液状体の比重から算出した。孔形成効率は、全層空孔率A0とRLとの比A0/RLにより求めた。 (Hole formation efficiency)
The volume mixing ratio RL of the organic liquid in the mixture with the vinylidene fluoride resin (specific gravity = 1.78) for forming the film-shaped molded body was calculated from the extrusion supply ratio (% by weight) and the specific gravity of the organic liquid. The hole formation efficiency was determined by the ratio A0 / RL between the total layer porosity A0 and RL.
後記実施例、比較例における抽出前の第1中間成形体を長さ約300mmに切り出し、抽出前糸長L0(mm)、抽出前外径OD0(mm)、抽出前内径ID0(mm)、抽出前膜厚さT0(mm)を測定した。次いで所定の抽出、置換、乾燥の各操作を行い、乾燥後糸長L1(mm)、乾燥後外径OD1(mm)、乾燥後内径ID1(mm)、乾燥後膜厚さT1(mm)を測定した。下式により各寸法収縮率(%)を算出した:
長手収縮率(%)=100×(L0-L1)/L0
外径収縮率(%)=100×(OD0-OD1)/OD0
内径収縮率(%)=100×(ID0-ID1)/ID0
膜厚さ収縮率(%)=100×(T0-T1)/T0 (Dimension shrinkage)
The first intermediate formed body before extraction in the examples and comparative examples described later is cut out to a length of about 300 mm, the pre-extraction yarn length L0 (mm), the pre-extraction outer diameter OD0 (mm), the pre-extraction inner diameter ID0 (mm), and the extraction The previous film thickness T0 (mm) was measured. Then, predetermined operations of extraction, replacement, and drying are performed, and the thread length L1 (mm) after drying, the outer diameter OD1 (mm) after drying, the inner diameter ID1 (mm) after drying, and the film thickness T1 (mm) after drying are obtained. It was measured. Each dimensional shrinkage (%) was calculated by the following formula:
Longitudinal shrinkage (%) = 100 × (L0−L1) / L0
Outer diameter shrinkage (%) = 100 × (OD0−OD1) / OD0
Inner diameter shrinkage (%) = 100 × (ID0−ID1) / ID0
Film thickness shrinkage (%) = 100 × (T0−T1) / T0
ASTM F316-86およびASTM E1294-89に準拠し、Porous Materials, Inc.社製「パームポロメータCFP-200AEX」を用いてハーフドライ法により平均孔径Pm(μm)を測定した。試液はパーフルオロポリエステル(商品名「Galwick」)を用いた。 (Average pore diameter)
Based on ASTM F316-86 and ASTM E1294-89, average pore size Pm (μm) was measured by a half dry method using “Palm Porometer CFP-200AEX” manufactured by Porous Materials, Inc. Perfluoropolyester (trade name “Galwick”) was used as a test solution.
ASTM F316-86およびASTM E1294-89に準拠し、Porous Materials, Inc.社製「パームポロメータCFP-200AEX」を用いてバブルポイント法により最大孔径Pmax(μm)を測定した。試液はパーフルオロポリエステル(商品名「Galwick」)を用いた。 (Maximum hole diameter)
Based on ASTM F316-86 and ASTM E1294-89, the maximum pore size Pmax (μm) was measured by a bubble point method using “Palm Porometer CFP-200AEX” manufactured by Porous Materials, Inc. Perfluoropolyester (trade name “Galwick”) was used as a test solution.
平膜または中空糸状の多孔膜試料について、被処理水側表面(中空糸においては外表面)の平均孔径P1および透過水側表面(中空糸においては内表面)の平均孔径P2を、SEM法により測定した(SEM平均孔径)。以下、中空糸多孔膜試料を例にとって、測定法を説明する。中空糸膜試料の外表面および内表面について、それぞれ観察倍率1万5千倍でSEM写真撮影を行う。次に、それぞれのSEM写真について、孔と認識できるすべてのものについて孔径を測定する。孔径は各孔の長径と短径を測定し、孔径=(長径+短径)/2として求める。測定した孔径の算術平均を求め、外表面平均孔径P1および内表面平均孔径P2とする。なお写真内に観察される孔数が多すぎる場合には、写真画像を4等分して、その1つの区域(1/4画面)について、上記の孔径測定を行うことで簡略化してもよい。本発明の中空糸膜の外表面について1/4画面で測定する場合には、測定孔数は概ね200~300個となる。 (Treatment water side surface hole diameter P1 and permeate water side surface hole diameter P2)
For a flat membrane or hollow fiber-like porous membrane sample, the average pore diameter P1 of the treated water side surface (outer surface in hollow fiber) and the average pore diameter P2 of the permeated water side surface (inner surface in hollow fiber) were determined by SEM method. Measured (SEM average pore diameter). Hereinafter, the measurement method will be described by taking a hollow fiber porous membrane sample as an example. SEM photography is performed on the outer surface and inner surface of the hollow fiber membrane sample at an observation magnification of 15,000 times, respectively. Next, for each SEM photograph, the hole diameter is measured for everything that can be recognized as a hole. The hole diameter is obtained by measuring the long and short diameters of each hole and determining the hole diameter = (long diameter + short diameter) / 2. The arithmetic average of the measured pore diameters is obtained and set as the outer surface average pore diameter P1 and the inner surface average pore diameter P2. In addition, when there are too many holes observed in the photograph, the photograph image may be divided into four equal parts, and the above-mentioned hole diameter measurement may be performed for one area (¼ screen). . When the outer surface of the hollow fiber membrane of the present invention is measured on a ¼ screen, the number of measurement holes is approximately 200 to 300.
平膜または中空糸状の多孔膜試料について、被処理水側表面(中空糸においては外表面)から連続する緻密且つ孔径がほぼ均一な層の厚さを、SEMによる断面観察により測定する。以下、中空糸多孔膜試料を例にとって、測定法を説明する。まず中空糸多孔膜資料をイソプロピルアルコール(IPA)に浸漬して細孔にIPAを含浸させ、次いで直ちに液体窒素に浸漬して凍結させ、凍結したまま、中空糸膜を折り曲げて破断することにより、その長手方向と直交する断面を露出する。露出した断面を観察倍率1万5千倍で外表面側から内表面側に向けて順次SEM写真撮影を行う。次に、最も外表面側のSEM写真について外表面から1.5μmの点を中心とした3μm×3μm四方の領域について孔と認識できるすべてのものについて孔径を測定する。孔径は各孔の長径と短径を測定し、孔径=(長径+短径)/2として求める。測定した孔径の算術平均を求め、これを深さ1.5μmでの断面孔径X1.5(μm)とする。外表面から、更に約3μmの間隔で順次、内表面側にずらした点を中心とした3μm×3μm四方の領域について、上記と同様に算術平均孔径を求め、その結果に基づき、必要に応じて内挿を行うことにより、外表面から任意の深さd(μm)における断面孔径Xd(μm)を求める。Xd/X1.5≦1.2の条件が満たされれば孔径が均一であるとし、その条件が満たされる最大深さd(μm)をもって、孔径が均一な緻密層厚さとする。 (Dense layer thickness)
With respect to a flat membrane or hollow fiber-like porous membrane sample, the thickness of the dense and continuous layer having a substantially uniform pore diameter from the surface to be treated (the outer surface in the case of a hollow fiber) is measured by cross-sectional observation using an SEM. Hereinafter, the measurement method will be described by taking a hollow fiber porous membrane sample as an example. First, the hollow fiber porous membrane material is immersed in isopropyl alcohol (IPA), the pores are impregnated with IPA, then immediately immersed in liquid nitrogen and frozen, and while being frozen, the hollow fiber membrane is folded and broken, A cross section perpendicular to the longitudinal direction is exposed. SEM photography is sequentially performed on the exposed cross section at an observation magnification of 15,000 times from the outer surface side toward the inner surface side. Next, in the SEM photograph on the outermost surface side, the hole diameter is measured for all the 3 μm × 3 μm square regions centered on a point of 1.5 μm from the outer surface that can be recognized as holes. The hole diameter is obtained by measuring the long and short diameters of each hole and determining the hole diameter = (long diameter + short diameter) / 2. The arithmetic average of the measured pore diameter is obtained, and this is defined as the sectional pore diameter X 1.5 (μm) at a depth of 1.5 μm. From the outer surface, the arithmetic average pore diameter is obtained in the same manner as described above for the 3 μm × 3 μm square region centered on the point shifted to the inner surface side sequentially at an interval of about 3 μm. By performing interpolation, the cross-sectional hole diameter X d (μm) at an arbitrary depth d (μm) is obtained from the outer surface. If the condition of X d / X 1.5 ≦ 1.2 is satisfied, the hole diameter is assumed to be uniform, and the dense layer thickness having a uniform hole diameter is defined as the maximum depth d (μm) that satisfies the condition.
平膜または中空糸状の多孔膜試料について、緻密層の被処理水側表面に接する厚さ5μmの部分の空孔率A1(%)(以下、「緻密層空孔率A1」と称する)を含浸法により測定する。以下、中空糸多孔膜試料を例にとって、測定法を説明する。まず中空糸多孔膜試料を、長さL=約300mmに切り出し、加熱圧着もしくは接着剤により中空部の両端を封じ、重さW0(mg)を測定する。次に、この両端を封じた中空糸膜試料を、染料(紀和化学工業(株)製「Cation Red」)0.05重量%と、脂肪酸グリセリンエステル(阪本薬品化学工業(株)製「MO-7S」;HLB値=12.9)1.0重量%とを溶解したグリセリン(ライオン(株)製「精製グリセリンD」)からなる試験液に浸漬した後、取り出して表面の試験液をふき取り、再び重さW(mg)を測定する。ついで計量後の試料を剃刀で輪切りにし、光学顕微鏡(KEYENS社製「VQ-Z50」を使用して、試験液が含浸した部分(=染色部分)の厚さt(μm)を測定する。含浸厚さtは、試験液への浸漬時間および試験液中の脂肪族グリセリンエステル濃度を調整することで、t=5±1(μm)に調整する。上記試料の外径OD(mm)、長さL(mm)および含浸厚さt(μm)から試験液が含浸した試料の部分の体積V(ml)を、次式により算出する:
V=π×((OD/2)2-(OD/2-t/1000)2)×L/1000
浸漬前の試料の重さW0(mg)と浸漬後の試料の重さW(mg)の差から次式により含浸した試験液の体積VL(ml)を算出する:
VL=(W-W0)/(ρs×1000)
ここでρsは試験液の比重であり、1.261(g/ml)とする。
次式により、緻密層空孔率A1(%)を算出する。
A1=VL/V×100。 (Dense layer porosity)
A flat membrane or hollow fiber-like porous membrane sample is impregnated with a porosity A1 (%) (hereinafter referred to as “dense layer porosity A1”) of a portion having a thickness of 5 μm in contact with the surface to be treated of the dense layer. Measure by the method. Hereinafter, the measurement method will be described by taking a hollow fiber porous membrane sample as an example. First, a hollow fiber porous membrane sample is cut into a length L = about 300 mm, both ends of the hollow portion are sealed with thermocompression bonding or an adhesive, and the weight W0 (mg) is measured. Next, a hollow fiber membrane sample sealed at both ends was prepared by adding 0.05% by weight of a dye (“Cation Red” manufactured by Kiwa Chemical Industry Co., Ltd.) and “MO-” produced by fatty acid glycerin ester (Sakamoto Pharmaceutical Co., Ltd.). 7S "; HLB value = 12.9) 1.0% by weight and after being immersed in a test solution made of glycerin (" Purified Glycerin D "manufactured by Lion Corporation), the sample was taken out and wiped off the surface test solution. The weight W (mg) is measured again. Next, the sample after weighing is cut with a razor, and the thickness t (μm) of the portion impregnated with the test solution (= stained portion) is measured using an optical microscope (“VQ-Z50” manufactured by KEYENS). The thickness t is adjusted to t = 5 ± 1 (μm) by adjusting the immersion time in the test solution and the concentration of the aliphatic glycerin ester in the test solution. From the thickness L (mm) and the impregnation thickness t (μm), the volume V (ml) of the portion of the sample impregnated with the test liquid is calculated by the following formula:
V = π × ((OD / 2) 2 − (OD / 2−t / 1000) 2 ) × L / 1000
From the difference between the weight W0 (mg) of the sample before immersion and the weight W (mg) of the sample after immersion, the volume VL (ml) of the test solution impregnated is calculated by the following formula:
VL = (W−W0) / (ρs × 1000)
Here, ρs is the specific gravity of the test solution and is 1.261 (g / ml).
The dense layer porosity A1 (%) is calculated by the following formula.
A1 = VL / V × 100.
純水透水量Fの測定のためには、試長L(図1参照)=200mmの試料中空糸多孔膜をエタノールに15分間浸漬し、次いで純水に15分間浸漬して湿潤化した後、水温25℃、差圧100kPaで測定した1日当りの透水量(m3/day)を、中空糸多孔膜の膜面積(m2)(=外径×π×試長Lとして計算)で除して得た。測定値は、F(100kPa,L=200mm)と表記し、単位はm/day(=m3/m2/day)で表わす。
全層空孔率80%への換算純水透水量Qは、測定された全層空孔率A2(%)に基づき、Q=F×80/A2 の式で求めた。 (Water permeability F, converted water permeability Q)
In order to measure the pure water permeation amount F, a sample hollow fiber porous membrane having a test length L (see FIG. 1) = 200 mm was immersed in ethanol for 15 minutes, then immersed in pure water for 15 minutes, and then wetted. Divide the amount of water per day (m 3 / day) measured at a water temperature of 25 ° C. and a differential pressure of 100 kPa by the membrane area (m 2 ) of the hollow fiber porous membrane (= calculated as outer diameter × π × test length L). I got it. The measured value is expressed as F (100 kPa, L = 200 mm), and the unit is represented by m / day (= m 3 / m 2 / day).
The converted pure water permeation amount Q to the total layer porosity 80% was determined by the formula Q = F × 80 / A2 based on the measured total layer porosity A2 (%).
図2に示す試験装置を用い、中空糸多孔膜試料から形成した浸漬型ミニモジュールについて、2時間毎にろ過流束(m/day)を段階的に増加しながら、活性汚泥水の継続的ろ過を行い、各ろ過流束における平均の差圧上昇速度を測定する。差圧上昇速度が0.133kPa/2時間を越えない最大のろ過流束を、臨界ろ過流束(m/day)と定義して求める。 (Critical filtration flux by MBR method)
Using the test apparatus shown in FIG. 2, continuous filtration of activated sludge water is performed while increasing the filtration flux (m / day) stepwise every two hours for submerged mini modules formed from hollow fiber porous membrane samples. And measure the average differential pressure increase rate in each filtration flux. The maximum filtration flux at which the pressure increase rate does not exceed 0.133 kPa / 2 hours is defined as the critical filtration flux (m / day).
デュヌイ表面張力試験器を用いてJIS-K3362に従って輪環法により、温度25℃での湿潤処理液の表面張力を測定した。 (Surface tension measurement)
The surface tension of the wet treatment solution at a temperature of 25 ° C. was measured by a ring method according to JIS-K3362 using a Dunui surface tension tester.
水とエタノールの比率を変えて混合し、表面張力の異なる水溶液を用意した。エタノール濃度と表面張力の関係は化学工学便覧(丸善株式会社、改定第5版)の記載を参照した。前記透水量の測定において、エタノールによる多孔膜の湿潤に代えて、上記水溶液を使用して、純水透水量F’(m/day)(=m3/m2/day)を測定した。エタノール単独を用いて湿潤して測定した純水透水量Fとの比F’/Fが0.9以上となる最大の表面張力を、多孔膜の臨界表面張力と定義する。因みに、後記実施例A1~A5で形成したフッ化ビニリデン系樹脂中空糸多孔膜の臨界表面張力γcは38mN/mと測定された。 (Critical surface tension)
Water and ethanol were mixed at different ratios to prepare aqueous solutions with different surface tensions. The relationship between the ethanol concentration and the surface tension was referred to the description in the Chemical Engineering Handbook (Maruzen Co., Ltd., revised fifth edition). In the measurement of the water permeability, pure water permeability F ′ (m / day) (= m 3 / m 2 / day) was measured using the above aqueous solution instead of wetting the porous membrane with ethanol. The maximum surface tension at which the ratio F ′ / F to the pure water permeation amount F measured by wetting with ethanol alone is 0.9 or more is defined as the critical surface tension of the porous membrane. Incidentally, the critical surface tension γc of the vinylidene fluoride resin hollow fiber porous membrane formed in Examples A1 to A5 described later was measured to be 38 mN / m.
引っ張り試験機(東洋ボールドウィン社製「RTM-100」)を使用して、温度23℃、相対湿度50%の雰囲気中で初期試料長100mm、クロスヘッド速度200mm/分の条件下で測定した。 (Tensile test)
Using a tensile tester (“RTM-100” manufactured by Toyo Baldwin Co., Ltd.), measurement was performed in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50% under conditions of an initial sample length of 100 mm and a crosshead speed of 200 mm / min.
重量平均分子量(Mw)が6.6×105のマトリクス用ポリフッ化ビニリデン(PVDF-I)(粉体)とMwが9.7×105の結晶特性改質用ポリフッ化ビニリデン(PVDF-II)(粉体)を、それぞれ75重量%および25重量%となる割合で、ヘンシェルミキサーを用いて混合して、Mwが7.4×105であるPVDF混合物(混合物A;成膜後の結晶化温度Tc=148.3℃)を得た。 Example 1
Polyvinylidene fluoride (PVDF-I) for matrix having a weight average molecular weight (Mw) of 6.6 × 10 5 (powder) and polyvinylidene fluoride for modifying crystal properties having a Mw of 9.7 × 10 5 (PVDF-II) ) (Powder) at a ratio of 75% by weight and 25% by weight, respectively, using a Henschel mixer, a PVDF mixture (mixture A; crystals after film formation) having an Mw of 7.4 × 10 5 Temperature was obtained (Tc = 148.3 ° C.).
0.3)を濃度0.05重量%で純水に溶解したエマルジョン水溶液(表面張力=32.4mN/m)に常温で30分間浸漬した。 Next, in a state where the second intermediate molded body is wound around a bobbin, a polyglycerin fatty acid ester (“SY Glyster ML-310” manufactured by Sakamoto Pharmaceutical Co., Ltd., HLB = 1) is used as a surfactant.
0.3) was immersed in an emulsion aqueous solution (surface tension = 32.4 mN / m) dissolved in pure water at a concentration of 0.05% by weight at room temperature for 30 minutes.
上記実施例1の概容および得られたポリフッ化ビニリデン系中空糸多孔膜の物性を、以下の実施例、比較例の結果とまとめて、後記表1~2に記す。 Further, while the bobbin is immersed in the emulsion aqueous solution, the second intermediate molded body is pulled out while rotating the bobbin, the first roll speed is set to 20.0 m / min, and the second roll is passed through a 60 ° C. water bath. The film was stretched 1.75 times in the longitudinal direction by setting the speed to 35.0 m / min. Next, it is passed through a hot water bath controlled at a temperature of 90 ° C., the first stage relaxation rate is relaxed at 8%, and further passed through a dry heat tank controlled at a spatial temperature of 140 ° C., and the second stage relaxation rate is 1.5%. And relaxed. This was wound up to obtain a polyvinylidene fluoride hollow fiber porous membrane (third molded body) of the present invention. The time required to stretch all the second intermediate molded body wound around the bobbin was about 200 minutes.
The outline of the above Example 1 and the physical properties of the obtained polyvinylidene fluoride hollow fiber porous membrane are summarized in Tables 1 and 2 below together with the results of the following Examples and Comparative Examples.
溶融押出後の冷却水浴温度Tqを70℃に変更する以外は、実施例1と同様にして本発明のポリフッ化ビニリデン系中空糸多孔膜を得た。 (Example 2)
A polyvinylidene fluoride hollow fiber porous membrane of the present invention was obtained in the same manner as in Example 1 except that the cooling water bath temperature Tq after melt extrusion was changed to 70 ° C.
PVDF-IとしてMwが4.9×105のポリフッ化ビニリデンを用いてPVDF混合物A(結晶化温度Tc=147.9℃)を得、溶融押出後の冷却水浴温度Tqを30℃に変更する以外は、実施例1と同様にして本発明のポリフッ化ビニリデン系中空糸多孔膜を得た。 (Example 3)
A PVDF mixture A (crystallization temperature Tc = 147.9 ° C.) is obtained using polyvinylidene fluoride having a Mw of 4.9 × 10 5 as PVDF-I, and the cooling water bath temperature Tq after melt extrusion is changed to 30 ° C. Except for the above, a polyvinylidene fluoride hollow fiber porous membrane of the present invention was obtained in the same manner as in Example 1.
本質的に特許文献11の実施例1の方法によりポリフッ化ビニリデン系中空糸多孔膜を得た。
PVDF-Iとして、Mwが4.1×105のポリフッ化ビニリデンを用いてPVDF混合物A(結晶化温度Tc=150.4℃)を得たこと;可塑剤として、アジピン酸系ポリエステル系可塑剤(末端をイソノニルアルコールで封止したアジピン酸と1,2-ブタンジオールのポリエステル;株式会社ジェイ・プラス製「D623N」、数平均分子量約1800、JIS K7117-2(円すい-平板型回転粘度計)による25℃での測定粘度3000mPa・s)と、モノメリックエステル系可塑剤であるアジピン酸ジイソノニル(株式会社ジェイ・プラス製「DINA」)とを、88重量%/12重量%の割合で、常温にて攪拌混合した可塑剤混合物Bを用いたこと;混合物Aと混合物Bを27.9重量%/72.1重量%の割合で供給したこと;引取速度を5.0m/分としたこと;ジクロロメタンによる抽出後の、IPAによる抽出リンスを行わなかったこと;延伸後の熱処理として、温度90℃に制御した温水浴中を通過させ(すなわち第1段緩和率を0%)、さらに空間温度80℃に制御した乾熱槽を通過させて(すなわち第2段緩和率を0%)熱処理を行ったこと;以外は、実施例1と同様にしてポリフッ化ビニリデン系中空糸多孔膜を得た。 (Comparative Example 1)
A polyvinylidene fluoride-based hollow fiber porous membrane was obtained essentially by the method of Example 1 of Patent Document 11.
PVDF mixture A (crystallization temperature Tc = 150.4 ° C.) was obtained by using polyvinylidene fluoride having a Mw of 4.1 × 10 5 as PVDF-I; an adipic acid polyester plasticizer as a plasticizer (Polyester of adipic acid and 1,2-butanediol whose ends are sealed with isononyl alcohol; “D623N” manufactured by J. Plus Co., Ltd., number average molecular weight of about 1800, JIS K7117-2 (cone-flat plate viscometer) ) And a measured viscosity of 3000 mPa · s at 25 ° C.) and diisononyl adipate (“DINA” manufactured by Jay Plus Co., Ltd.), which is a monomeric ester plasticizer, at a ratio of 88% by weight / 12% by weight, Use of plasticizer mixture B stirred and mixed at normal temperature; mixture A and mixture B were provided at a ratio of 27.9 wt% / 72.1 wt% The take-up speed was 5.0 m / min; the extraction rinse with IPA was not performed after extraction with dichloromethane; and the heat treatment after stretching was passed through a hot water bath controlled at a temperature of 90 ° C. (That is, the first stage relaxation rate is 0%), and heat treatment was performed by passing through a dry heat bath controlled to a space temperature of 80 ° C. (that is, the second stage relaxation rate was 0%); In the same manner as described above, a polyvinylidene fluoride hollow fiber porous membrane was obtained.
本質的に特許文献11の実施例7の方法によりポリフッ化ビニリデン系中空糸多孔膜を得た。
PVDF-Iとして、Mwが4.9×105のポリフッ化ビニリデンを用いてPVDF混合物A(結晶化温度Tc=149.3℃)を得たこと;混合物Aと混合物Bを27.1重量%/72.9重量%の割合で供給したこと;溶融押出後の冷却水浴温度Tqを70℃に変更したこと;引取速度を3.3m/分としたこと;延伸後の熱処理として、90℃の水浴中で8%の緩和、ついで140℃の空気中で2%の緩和処理を行ったこと;以外は、比較例1と同様にして本発明のポリフッ化ビニリデン系中空糸多孔膜を得た。 (Comparative Example 2)
A polyvinylidene fluoride hollow fiber porous membrane was obtained essentially by the method of Example 7 of Patent Document 11.
PVDF mixture A (crystallization temperature Tc = 149.3 ° C.) was obtained using polyvinylidene fluoride having a Mw of 4.9 × 10 5 as PVDF-I; 27.1% by weight of mixture A and mixture B Supply at a rate of 72.9% by weight; the cooling water bath temperature Tq after melt extrusion was changed to 70 ° C .; the take-up speed was 3.3 m / min; A polyvinylidene fluoride hollow fiber porous membrane of the present invention was obtained in the same manner as in Comparative Example 1 except that 8% relaxation was performed in a water bath and then 2% relaxation treatment was performed in air at 140 ° C.
本質的に特許文献11の実施例8の方法によりポリフッ化ビニリデン系中空糸多孔膜を得た。
溶融押出後の冷却水浴温度Tqを85℃に変更したこと以外は、比較例2と同様にして本発明のポリフッ化ビニリデン系中空糸多孔膜を得た。 (Comparative Example 3)
A polyvinylidene fluoride-based hollow fiber porous membrane was obtained essentially by the method of Example 8 of Patent Document 11.
A polyvinylidene fluoride hollow fiber porous membrane of the present invention was obtained in the same manner as in Comparative Example 2 except that the cooling water bath temperature Tq after melt extrusion was changed to 85 ° C.
本質的に特許文献7(WO2005/099879A)の方法によりポリフッ化ビニリデン系中空糸多孔膜を得た。
PVDF-Iとして、Mwが4.1×105のポリフッ化ビニリデンを用いて、PVDF-IとPVDF-IIをそれぞれ95重量%および5重量%となる割合で混合したPVDF混合物Aを用いたこと;可塑剤としてアジピン酸ポリエステル系可塑剤(末端をオクチルアルコールで封止したアジピン酸と1,2-プロピレングリコールのポリエステル;株式会社ADEKA製「PN150」、数平均分子量約1000、粘度500mPa・s)とN-メチルピロリドン(NMP)とを、82.5重量%/17.5重量%の割合で、常温にて攪拌混合した可塑剤・溶媒混合物Bを用いたこと;混合物Aと混合物Bを38.4重量%/61.6重量%の割合で供給したこと;水冷却浴温度を40℃にしたこと;IPAによる抽出リンスを行わなかったこと;延伸倍率を1.85倍としたこと;延伸後の熱処理として、90℃の水浴中で8%の緩和、ついで140℃の空気中で3%の緩和処理を行ったこと;以外は実施例1と同様にしてポリフッ化ビニリデン系多孔膜を得た。 (Comparative Example 4)
A polyvinylidene fluoride hollow fiber porous membrane was obtained essentially by the method of Patent Document 7 (WO2005 / 099879A).
As PVDF-I, PVDF mixture A in which PVDF-I and PVDF-II were mixed at a ratio of 95% by weight and 5% by weight using polyvinylidene fluoride having Mw of 4.1 × 10 5 was used. Adipic acid polyester plasticizer as a plasticizer (polyester of adipic acid and 1,2-propylene glycol whose ends are sealed with octyl alcohol; “PN150” manufactured by ADEKA Corporation, number average molecular weight of about 1000, viscosity of 500 mPa · s) And N-methylpyrrolidone (NMP) in a proportion of 82.5 wt% / 17.5 wt% with stirring and mixing at room temperature; used plasticizer / solvent mixture B; Supply at a ratio of 4% by weight / 61.6% by weight; water cooling bath temperature at 40 ° C .; no extraction rinse with IPA Except that the draw ratio was 1.85 times; as the heat treatment after stretching, 8% relaxation was performed in a 90 ° C. water bath, and then 3% relaxation treatment was performed in air at 140 ° C .; A polyvinylidene fluoride porous membrane was obtained in the same manner as in Example 1.
本質的に特許文献9(WO2008/117740A)の製法に従い、ポリフッ化ビニリデン系中空糸多孔膜を得た:
すなわち、PVDF-Iとして、Mwが4.1×105のポリフッ化ビニリデンを用いて、PVDF-IとPVDF-IIをそれぞれ75重量%および25重量%となる割合で混合したPVDF混合物Aを用い、可塑剤としてとしてアジピン酸系ポリエステル(末端をオクチルアルコールで封止したアジピン酸と1,2-プロピレングリコールとのポリエステル;(株)ADEKA製「PN-150」;数平均分子量=約1000)68.6重量%と溶媒N-メチルピロリドン(NMP)31.4重量%の割合で混合した可塑剤・溶媒混合物Bを用いた。 (Comparative Example 5)
A polyvinylidene fluoride-based hollow fiber porous membrane was obtained essentially according to the production method of Patent Document 9 (WO2008 / 117740A):
That is, as PVDF-I, PVDF mixture A in which PVDF-I and PVDF-II were mixed at a ratio of 75% by weight and 25% by weight using polyvinylidene fluoride having Mw of 4.1 × 10 5 was used. As a plasticizer, adipic acid-based polyester (polyester of adipic acid and 1,2-propylene glycol whose ends are sealed with octyl alcohol; “PN-150” manufactured by ADEKA Corporation; number average molecular weight = about 1000) 68 A plasticizer / solvent mixture B mixed at a ratio of 0.6 wt% and the solvent N-methylpyrrolidone (NMP) 31.4 wt% was used.
本質的に特許文献10の製法に従い、ポリフッ化ビニリデン系中空糸多孔膜を得た。
すなわち、PVDF-Iとして、Mwが4.1×105のポリフッ化ビニリデンを用いて、PVDF-IとPVDF-IIとをそれぞれ95重量%および5重量%とした混合物を用いた。また可塑剤としてアジピン酸系ポリエステル系可塑剤として、末端をイソノニルアルコールで封止したアジピン酸と1,2-ブタンジオールのポリエステル;株式会社ジェイ・プラス製「D620N」、数平均分子量約800、JIS K7117-2(円すい-平板型回転粘度計)による25℃での測定粘度200mPa・s)82.5重量%とN-メチルピロリドン(NMP)17.5重量%との可塑剤・溶媒混合物Bを用いた。 (Comparative Example 6)
A polyvinylidene fluoride hollow fiber porous membrane was obtained essentially according to the production method of Patent Document 10.
That is, as PVDF-I, a mixture containing PVDF-I and PVDF-II of 95% by weight and 5% by weight using polyvinylidene fluoride having an Mw of 4.1 × 10 5 was used. Further, as an adipic acid-based polyester plasticizer as a plasticizer, polyester of adipic acid and 1,2-butanediol whose ends are sealed with isononyl alcohol; “D620N” manufactured by J. Plus Co., number average molecular weight of about 800, Plasticizer / solvent mixture B of 82.5% by weight and viscosity of N-methylpyrrolidone (NMP) 17.5% by weight according to JIS K7117-2 (cone-plate type rotational viscometer) measured at 25 ° C. at 200 mPa · s) Was used.
PVDF-Iとして、Mwが4.1×105のポリフッ化ビニリデンを用いたこと以外は実施例1と同様にして押出を行った。しかし溶融押出後の冷却水浴中で糸がつぶれたため、製膜することが出来なかった。 (Comparative Example 7)
Extrusion was performed in the same manner as in Example 1 except that polyvinylidene fluoride having a Mw of 4.1 × 10 5 was used as PVDF-I. However, the yarn could not be formed because the yarn was crushed in the cooling water bath after melt extrusion.
溶融押出後の冷却水浴温度Tqを85℃に変更する以外は実施例1と同様にして押出を行った。しかし溶融押出後の冷却水浴中で糸がつぶれたため、製膜することが出来なかった。 (Comparative Example 8)
Extrusion was carried out in the same manner as in Example 1 except that the cooling water bath temperature Tq after melt extrusion was changed to 85 ° C. However, the yarn could not be formed because the yarn was crushed in the cooling water bath after melt extrusion.
可塑剤をジベンゾエート系モノメリック可塑剤(株式会社DIC製「PB-10」、数平均分子量約300、粘度81mPa・s)を用いたこと;混合物Aと混合物Bを26.9重量%/73.1重量%の割合で供給したこと;溶融押出後の冷却水浴温度Tqを60℃に変更したこと以外は、実施例1と同様にしてポリフッ化ビニリデン系中空糸多孔膜を得た。 (Comparative Example 9)
A dibenzoate-type monomeric plasticizer (“PB-10” manufactured by DIC Corporation, number average molecular weight of about 300, viscosity of 81 mPa · s) was used as the plasticizer; 26.9 wt% / 73 of the mixture A and the mixture B A polyvinylidene fluoride hollow fiber porous membrane was obtained in the same manner as in Example 1 except that the cooling water bath temperature Tq after melt extrusion was changed to 60 ° C.
重量平均分子量(Mw)が4.9×105のマトリクス用ポリフッ化ビニリデン(PVDF-I)(粉体)とMwが9.7×105の結晶特性改質用ポリフッ化ビニリデン(PVDF-II)(粉体)を、それぞれ75重量%および25重量%となる割合で、ヘンシェルミキサーを用いて混合して、Mwが6.1×105であるPVDF混合物を得た。 (Example A1)
Polyvinylidene fluoride (PVDF-I) for matrix having a weight average molecular weight (Mw) of 4.9 × 10 5 (powder) and polyvinylidene fluoride for modifying crystal properties having a Mw of 9.7 × 10 5 (PVDF-II) ) (Powder) at a ratio of 75 wt% and 25 wt%, respectively, was mixed using a Henschel mixer to obtain a PVDF mixture having an Mw of 6.1 × 10 5 .
0.3)を濃度0.05重量%で純水に溶解したエマルジョン水溶液(表面張力=32.4mN/m)に常温で30分間浸漬して部分湿潤を行った。 Next, in a state where the second intermediate molded body is wound around a bobbin, a polyglycerin fatty acid ester (“SY Glyster ML-310” manufactured by Sakamoto Pharmaceutical Co., Ltd., HLB = 1) is used as a surfactant.
0.3) was dissolved in pure water at a concentration of 0.05% by weight (surface tension = 32.4 mN / m) and immersed for 30 minutes at room temperature to perform partial wetting.
溶融押出後の冷却水浴温度Tqを30℃に変更したこと;延伸倍率を1.85倍に変更したこと以外は実施例A1と同様にしてフッ化ビニリデン系樹脂多孔膜を得た。 (Example A2)
A vinylidene fluoride resin porous membrane was obtained in the same manner as in Example A1, except that the cooling water bath temperature Tq after melt extrusion was changed to 30 ° C .; the draw ratio was changed to 1.85 times.
有機液状体として、ポリエステル系可塑剤(末端を安息香酸で封止した二塩基酸とグリコールとのポリエステル;株式会社DIC製「W-83」、数平均分子量約500、JIS K7117-2(円すい-平板型回転粘度計)による25℃での測定粘度750mPa・s、比重1.155g/ml)を用いたこと;フッ化ビニリデン系樹脂/可塑剤=26.9重量%/73.1重量%の割合で供給したこと;溶融押出後の冷却水浴温度Tqを50℃に変更したこと以外は実施例A1と同様にしてフッ化ビニリデン系樹脂多孔膜を得た。 (Example A3)
As an organic liquid, a polyester plasticizer (polyester of dibasic acid and glycol whose ends are sealed with benzoic acid; “W-83” manufactured by DIC Corporation, number average molecular weight of about 500, JIS K7117-2 (cone- A viscosity measured at 25 ° C. by a flat plate type viscometer (750 mPa · s, specific gravity 1.155 g / ml); vinylidene fluoride resin / plasticizer = 26.9 wt% / 73.1 wt% A vinylidene fluoride resin porous membrane was obtained in the same manner as in Example A1, except that the cooling water bath temperature Tq after melt extrusion was changed to 50 ° C.
有機液状体として、モノメリックエステル可塑剤であるアルキレングリコールジベンゾエート(株式会社DIC製「PB-10」、数平均分子量約300、JIS K7117-2(円すい-平板型回転粘度計)による25℃での測定粘度81mPa・s、比重1.147g/ml)を用いたこと;フッ化ビニリデン系樹脂/可塑剤=26.9重量%/73.1重量%の割合で供給したこと;溶融押出後の冷却水浴温度Tqを60℃に変更したこと第2段緩和率を1.5%に変更したこと以外は実施例A1と同様にしてフッ化ビニリデン系樹脂多孔膜を得た。 (Example A4)
As an organic liquid, alkylene glycol dibenzoate, a monomeric ester plasticizer (“PB-10” manufactured by DIC Corporation, number average molecular weight of about 300, JIS K7117-2 (cone-flat plate viscometer) at 25 ° C.) Measured viscosity of 81 mPa · s, specific gravity 1.147 g / ml); vinylidene fluoride resin / plasticizer = 26.9 wt% / 73.1 wt% supplied; after melt extrusion A vinylidene fluoride resin porous membrane was obtained in the same manner as in Example A1, except that the cooling water bath temperature Tq was changed to 60 ° C. and the second-stage relaxation rate was changed to 1.5%.
本質的に特許文献4に開示される方法に従って未延伸のフッ化ビニリデン系樹脂多孔膜を得て、次いでこの未延伸糸を部分湿潤した後に延伸を行った。
すなわち、疎水性シリカ(日本アエロジル株式会社製「アエロジルR-972」、一次粒子の平均径16ナノメートル、比表面積110m2/g)14.8容量%、フタル酸ジオクチル(DOP)48.5容量%、フタル酸ジブチル(DBP)4.4容量%を、ヘンシェルミキサーで混合し、これに重量平均分子量(Mw)が2.4×105のポリフッ化ビニリデン(粉体)32.3容量%を添加し、再度ヘンシェルミキサーで混合した。 (Example A5)
Essentially, an unstretched vinylidene fluoride resin porous membrane was obtained according to the method disclosed in Patent Document 4, and then the unstretched yarn was partially wetted and then stretched.
That is, hydrophobic silica (“Aerosil R-972” manufactured by Nippon Aerosil Co., Ltd., primary particle average diameter 16 nanometer, specific surface area 110 m 2 / g) 14.8% by volume, dioctyl phthalate (DOP) 48.5% by volume %, Dibutyl phthalate (DBP) 4.4% by volume is mixed with a Henschel mixer, and 32.3% by volume of polyvinylidene fluoride (powder) having a weight average molecular weight (Mw) of 2.4 × 10 5 is mixed therewith. Added and mixed again with a Henschel mixer.
延伸に先立って部分湿潤を行わなかった以外は実施例A1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example A1)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A1, except that partial wetting was not performed prior to stretching.
延伸に先立って部分湿潤を行わなかった以外は実施例A2と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example A2)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A2 except that partial wetting was not performed prior to stretching.
部分湿潤液としてアルキルエーテル硫酸エステルナトリウムを濃度0.05重量%で純水に溶解した水溶液(表面張力=28.9mN/m)を用いた以外は実施例A2と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example A3)
Vinylidene fluoride resin in the same manner as in Example A2, except that an aqueous solution (surface tension = 28.9 mN / m) of sodium alkyl ether sulfate ester dissolved in pure water at a concentration of 0.05% by weight was used as the partial wetting liquid. A hollow fiber porous membrane was obtained.
延伸に先立って部分湿潤を行わなかった以外は実施例A3と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example A4)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A3 except that partial wetting was not performed prior to stretching.
延伸に先立って部分湿潤を行わなかった以外は実施例A4と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example A5)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A4 except that partial wetting was not performed prior to stretching.
延伸に先立って部分湿潤を行わなかった以外は実施例A5と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example A6)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example A5 except that partial wetting was not performed prior to stretching.
上記表3~4に示す実施例Aおよび比較例Aの結果を対比すれば理解されるように、部分湿潤延伸法によれば、一旦形成された樹脂多孔膜について、表層近傍を選択的に部分湿潤してから延伸することにより、延伸中での表層近傍での空孔率の低下を防止し、結果的に分離性能を支配する表層近傍の緻密層の空孔率A1を高く且つ膜全体としての透液性を高く維持した樹脂多孔膜が得られる。特に、この結果は、分離性能を支配する小孔径側表面孔径P1が1μm程度と比較的大きい場合(実施例A5、比較例A6)に比べて、小孔径側表面孔径P1が0.2μm以下と小さい場合(実施例A1~A4、比較例A1~A5)において、特に顕著に認められる。
<<抽出リンス法実施例>> [Evaluation]
As can be understood by comparing the results of Example A and Comparative Example A shown in Tables 3 to 4 above, according to the partial wet stretching method, the surface of the porous resin membrane once formed is selectively partially in the vicinity of the surface layer. By stretching after wetting, the porosity in the vicinity of the surface layer during stretching is prevented, and as a result, the porosity A1 of the dense layer in the vicinity of the surface layer that governs the separation performance is increased and the entire membrane A porous resin membrane having a high liquid permeability can be obtained. In particular, this result shows that the small hole diameter side surface hole diameter P1 is 0.2 μm or less as compared with the case where the small hole diameter side surface hole diameter P1 governing the separation performance is relatively large as about 1 μm (Example A5, Comparative Example A6). In the case of small size (Examples A1 to A4, Comparative Examples A1 to A5), this is particularly noticeable.
<< Execution Rinse Method Example >>
重量平均分子量(Mw)が4.9×105のマトリクス用ポリフッ化ビニリデン(PVDF-I)(粉体)とMwが9.7×105の結晶特性改質用ポリフッ化ビニリデン(PVDF-II)(粉体)を、それぞれ75重量%および25重量%となる割合で、ヘンシェルミキサーを用いて混合して、Mwが6.1×105であるPVDF混合物を得た。 (Example B1)
Polyvinylidene fluoride (PVDF-I) for matrix having a weight average molecular weight (Mw) of 4.9 × 10 5 (powder) and polyvinylidene fluoride for modifying crystal properties having a Mw of 9.7 × 10 5 (PVDF-II) ) (Powder) at a ratio of 75 wt% and 25 wt%, respectively, was mixed using a Henschel mixer to obtain a PVDF mixture having an Mw of 6.1 × 10 5 .
リンス液としてイソプロピルアルコール(原料フッ化ビニリデン系樹脂に対する膨潤率0.2%)を用いた以外はB1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Example B2)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as B1, except that isopropyl alcohol (swelling rate 0.2% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
リンス液としてヘキサン(原料フッ化ビニリデン系樹脂に対する膨潤率0.0%)を用いた以外は実施例B1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Example B3)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1, except that hexane (swelling ratio of 0.0% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
リンス液としてエタノールを用いて置換した後、エタノールを含有した中空糸多孔膜を実質的に乾燥させることなく、更に第2リンス液である水(原料フッ化ビニリデン系樹脂に対する膨潤率0.0%)に置換した以外は実施例B1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Example B4)
After substituting with ethanol as the rinsing liquid, the second rinsing liquid, water (swelling ratio 0.0% of the raw material vinylidene fluoride resin) is further obtained without substantially drying the hollow fiber porous membrane containing ethanol. The vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1 except that it was replaced with a).
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example B1)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1 except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
リンス液としてメタノール(原料フッ化ビニリデン系樹脂に対する膨潤率1.8%)を用いた以外は実施例B1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example B2)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1, except that methanol (swelling ratio of 1.8% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
リンス液としてアセトン(原料フッ化ビニリデン系樹脂に対する膨潤率5.0%)を用いた以外は実施例B1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example B3)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B1 except that acetone (swelling ratio of 5.0% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
リンス液としてヘプタフルオロシクロペンタン系溶媒(日本ゼオン株式会社製「ゼオローラHTA」、原料フッ化ビニリデン系樹脂に対する膨潤率3.4%)を用いた以外は実施例B1と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example B4)
A vinylidene fluoride system was used in the same manner as in Example B1 except that a heptafluorocyclopentane-based solvent (“Zeorolla HTA” manufactured by Nippon Zeon Co., Ltd., a swelling ratio of 3.4% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid. A resin hollow fiber porous membrane was obtained.
有機液状体として、ポリエステル系可塑剤(末端をイソノニルアルコールで封止したアジピン酸と1,2-ブタンジオールのポリエステル;株式会社ジェイ・プラス製「D623N」、数平均分子量約1800、JIS K7117-2(円すい-平板型回転粘度計)による25℃での測定粘度3000mPa・s、比重1.090g/ml)と、モノメリックエステル系可塑剤であるアジピン酸ジイソノニル(株式会社ジェイ・プラス製「DINA」)とを、88重量%/12重量%の割合で、常温にて攪拌混合した可塑剤混合物を用いたこと;溶融押出後の冷却水浴温度Tqを45℃に変更したこと以外は実施例B2と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Example B5)
As an organic liquid, a polyester plasticizer (polyester of adipic acid and 1,2-butanediol whose ends are sealed with isononyl alcohol; “D623N” manufactured by J Plus Co., Ltd., number average molecular weight of about 1800, JIS K7117- 2 (cone-flat-plate rotational viscometer) measured viscosity at 25 ° C. 3000 mPa · s, specific gravity 1.090 g / ml) and monoisonic ester plasticizer diisononyl adipate (“DINA” manufactured by J. Plus) )) Was used at a rate of 88% / 12% by weight at a normal temperature and mixed with a plasticizer mixture; Example B2 except that the cooling water bath temperature Tq after melt extrusion was changed to 45 ° C. In the same manner, a vinylidene fluoride resin hollow fiber porous membrane was obtained.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B5と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example B5)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B5, except that dichloromethane (swelling ratio of 5.7% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
フッ化ビニリデン系樹脂として、重量平均分子量(Mw)が6.6×105のマトリクス用ポリフッ化ビニリデン(PVDF-I)(粉体)とMwが9.7×105の結晶特性改質用ポリフッ化ビニリデン(PVDF-II)(粉体)を、それぞれ75重量%および25重量%となる割合で、ヘンシェルミキサーを用いて混合して、Mwが7.4×105であるPVDF混合物を用いたこと;可塑剤として、ポリエステル系可塑剤(末端を安息香酸で封止した二塩基酸とグリコールとのポリエステル;株式会社DIC製「W-83」、数平均分子量約500、JIS K7117-2(円すい-平板型回転粘度計)による25℃での測定粘度750mPa・s、比重1.155g/ml)を用いたこと;フッ化ビニリデン系樹脂/可塑剤=26.9重量%/73.1重量%の割合で供給したこと;溶融押出後の冷却水浴温度Tqを50℃に変更したこと以外は実施例B2と同様にしてフッ化ビニリデン系樹脂多孔膜を得た。 (Example B6)
Polyvinylidene fluoride resin as a matrix polyvinylidene fluoride (PVDF-I) (powder) with a weight average molecular weight (Mw) of 6.6 × 10 5 and crystal property modification with Mw of 9.7 × 10 5 Polyvinylidene fluoride (PVDF-II) (powder) was mixed at a ratio of 75% by weight and 25% by weight using a Henschel mixer, and a PVDF mixture having an Mw of 7.4 × 10 5 was used. As a plasticizer, a polyester plasticizer (polyester of dibasic acid and glycol whose ends are sealed with benzoic acid; “W-83” manufactured by DIC Corporation, number average molecular weight of about 500, JIS K7117-2 ( (Cone-plate-type rotational viscometer), measured viscosity at 25 ° C. 750 mPa · s, specific gravity 1.155 g / ml); vinylidene fluoride resin / plasticizer = 26. It was fed at a rate of weight% / 73.1 weight%; and except for changing the cooling bath temperature Tq after melt extrusion 50 ° C. in the same manner as in Example B2 obtain a porous membrane of vinylidene fluoride resin.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B6と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example B6)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B6 except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinse liquid.
有機液状体として、モノメリックエステル可塑剤であるアルキレングリコールジベンゾエート(株式会社DIC製「PB-10」、数平均分子量約300、JIS K7117-2(円すい-平板型回転粘度計)による25℃での測定粘度81mPa・s、比重1.147g/ml)を用いたこと;溶融押出後の冷却水浴温度Tqを60℃に変更したこと以外は実施例B6と同様にしてフッ化ビニリデン系樹脂多孔膜を得た。 (Example B7)
As an organic liquid, alkylene glycol dibenzoate, a monomeric ester plasticizer (“PB-10” manufactured by DIC Corporation, number average molecular weight of about 300, JIS K7117-2 (cone-flat plate viscometer) at 25 ° C.) A measured viscosity of 81 mPa · s and a specific gravity of 1.147 g / ml); a vinylidene fluoride resin porous membrane in the same manner as in Example B6 except that the cooling water bath temperature Tq after melt extrusion was changed to 60 ° C. Got.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B7と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Comparative Example B7)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B7, except that dichloromethane (swelling ratio of 5.7% relative to the raw material vinylidene fluoride resin) was used as the rinse liquid.
実施例B5においてボビン(巻芯直径:220mm)に巻き取った第1中間成形体(長さ500m)を、ボビンに巻いたままジクロロメタン中に室温で30分間浸漬して可塑剤を抽出した。この際ジクロロメタンが糸に満遍なく行き渡るようにボビンを回転させながら抽出を行った。次いでジクロロメタンを新しいものに取り替えて再び同条件にて抽出する操作を繰り返し、合計3回の抽出を行った。 (Example B8)
The first intermediate molded body (length: 500 m) wound on the bobbin (core diameter: 220 mm) in Example B5 was immersed in dichloromethane for 30 minutes at room temperature while being wound on the bobbin, and the plasticizer was extracted. At this time, the extraction was performed while rotating the bobbin so that the dichloromethane was evenly distributed over the yarn. Next, the operation of replacing the dichloromethane with a new one and extracting again under the same conditions was repeated, and extraction was performed three times in total.
実施例B6においてボビンに巻き取った第1中間成形体(長さ500m)を用いたこと以外は実施例B8と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Example B9)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B8, except that the first intermediate molded body (length: 500 m) wound on a bobbin in Example B6 was used.
実施例B7においてボビンに巻き取った第1中間成形体(長さ500m)を用いたこと以外は実施例B8と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Example B10)
A vinylidene fluoride resin hollow fiber porous membrane was obtained in the same manner as in Example B8, except that the first intermediate molded body (length: 500 m) wound around the bobbin in Example B7 was used.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B8と同様にしてボビン抽出を行い、次いで乾燥、熱処理を行った。しかし、糸の巻き締まりによる、糸同士の食い込みと糸縮れが生じて、延伸に供することが出来なかった。 (Comparative Example B8)
Bobbin extraction was performed in the same manner as in Example B8, except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B9と同様にしてボビン抽出を行い、次いで乾燥、熱処理を行った。しかし、糸の巻き締まりによる、糸同士の食い込みと糸縮れが生じて、延伸に供することが出来なかった。 (Comparative Example B9)
Bobbin extraction was performed in the same manner as in Example B9, except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B10と同様にしてボビン抽出を行い、次いで乾燥、熱処理を行った。しかし、糸の巻き締まりによる、糸同士の食い込みと糸縮れが生じて、延伸に供することが出来なかった。 (Comparative Example B10)
Bobbin extraction was performed in the same manner as in Example B10, except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
実施例B6において巻き取った第1中間成形体(長さ500m)をボビンから引き出し、第1のロール速度を20.0m/分にして、60℃の水浴中を通過させ、第2のロール速度を50m/分にすることで長手方向に2.5倍に延伸した。次いで温度90℃に制御した温水浴中を通過させ第1段緩和率を8%で緩和を行い、さらに空間温度140℃に制御した乾熱槽を通過させ第2段緩和率を1.5%で緩和を行い、ボビンに巻き取り延伸糸を得た。 (Example B11)
The first intermediate molded body (length: 500 m) wound up in Example B6 was pulled out from the bobbin, passed through a 60 ° C. water bath at a first roll speed of 20.0 m / min, and a second roll speed. The film was stretched 2.5 times in the longitudinal direction at a speed of 50 m / min. Next, it is passed through a hot water bath controlled at a temperature of 90 ° C., the first stage relaxation rate is relaxed at 8%, and further passed through a dry heat tank controlled at a spatial temperature of 140 ° C., and the second stage relaxation rate is 1.5%. Was relaxed and wound on a bobbin to obtain a drawn yarn.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B11と同様にしてボビン抽出を行い、次いで乾燥、熱処理を行った。しかし、糸の巻き締まりによる、糸同士の食い込みと糸縮れが生じて、均一な形状を有する中空糸多孔膜として回収することが出来なかった。 (Comparative Example B11)
Bobbin extraction was performed in the same manner as in Example B11, except that dichloromethane (swelling ratio of 5.7% with respect to the raw vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, the yarn was bitten and the yarn was crimped due to the tightening of the yarn, and could not be recovered as a hollow fiber porous membrane having a uniform shape.
実施例B1においてボビンに巻き取った第1中間成形体(長さ500m)を用いたこと、リンス液としてエタノールを用いて置換した後、エタノールを含有した中空糸多孔膜を実質的に乾燥させることなく、更に第2リンス液である水(原料フッ化ビニリデン系樹脂に対する膨潤率0.0%)に置換を用いたこと以外は実施例B8と同様にしてフッ化ビニリデン系樹脂中空糸多孔膜を得た。 (Example B12)
After using the first intermediate molded body (length: 500 m) wound around the bobbin in Example B1 and substituting with ethanol as the rinsing liquid, the hollow fiber porous membrane containing ethanol is substantially dried. In addition, a vinylidene fluoride resin hollow fiber porous membrane was prepared in the same manner as in Example B8, except that substitution was used for water (the swelling rate of 0.0% relative to the raw material vinylidene fluoride resin) as the second rinse liquid. Obtained.
リンス液としてジクロロメタン(原料フッ化ビニリデン系樹脂に対する膨潤率5.7%)用いた以外は実施例B12と同様にしてボビン抽出を行い、次いで乾燥、熱処理を行った。しかし、糸の巻き締まりによる、糸同士の食い込みと糸縮れが生じて、延伸に供することが出来なかった。 (Comparative Example B12)
Bobbin extraction was performed in the same manner as in Example B12 except that dichloromethane (swelling ratio of 5.7% with respect to the raw material vinylidene fluoride resin) was used as the rinsing liquid, followed by drying and heat treatment. However, due to the tightness of the yarn, the yarns bite and the yarn was crimped, and could not be used for drawing.
上記表5をみれば、ハロゲン化溶媒を含有するフッ化ビニリデン系樹脂多孔膜からハロゲン化溶媒を除去してフッ化ビニリデン系樹脂多孔膜を化し有するに際して、これを直接乾燥するのでなく、フッ化ビニリデン系樹脂のハロゲン化溶媒を非膨潤性溶媒で置換する工程を挿入することにより、空孔の収縮が抑制されて、高い孔形成効率でフッ化ビニリデン系樹脂多孔膜が得られることが分る。また表6の結果は、効果的な抽出を行うために長尺の中空糸膜状フッ化ビニリデン系樹脂多孔膜をボビン巻きした後、ハロゲン化溶媒で抽出後に非膨潤性溶媒で置換することにより、中空糸膜の巻き締りによる変形が抑制され、中空糸膜の取出しが容易化して、孔径が小さいにもかかわらず透水性の良好なフッ化ビニリデン系樹脂中空糸多孔膜が形成されることを示している。このようにして本発明法により形成される透液性の良いフッ化ビニリデン系樹脂多孔膜は、ろ水処理に適するだけでなく、細菌やたんぱく質等の濃縮、重金属類の化学凝集粒子の回収に利用できる分離膜、油水分離や気液分離用の分離膜、リチウムイオン二次電池等の電池隔膜および固体電解質支持体等としても、好適に使用することが出来る。特に、好ましい態様としての熱誘起相分離法により得られるフッ化ビニリデン系樹脂多孔膜は、孔径が膜厚さ方向に連続的に拡大し、かつ空孔率が膜厚さ方向に均一に分布する特性を有するとともに、特に分離特性あるいは選択透過特性に寄与する緻密層の空孔率が改善されたことにより、優れた分離特性あるいは選択透過特性を有しながら、流体の透過あるいはイオン等の移動に対する抵抗が少ないという特性を与えられる。このような特性は、上記した分離用途一般に、特に適したものである。 [Evaluation]
According to Table 5 above, when removing the halogenated solvent from the vinylidene fluoride resin porous membrane containing the halogenated solvent to form a vinylidene fluoride resin porous membrane, the resin is not directly dried but is fluorinated. By inserting a step of replacing the halogenated solvent of the vinylidene resin with a non-swellable solvent, it is understood that pore shrinkage is suppressed and a vinylidene fluoride resin porous film can be obtained with high hole formation efficiency. . In addition, the results in Table 6 are obtained by bobbing a long hollow fiber membrane-like vinylidene fluoride resin porous membrane for effective extraction, and then substituting with a non-swelling solvent after extraction with a halogenated solvent. The deformation of the hollow fiber membrane due to tightening is suppressed, the removal of the hollow fiber membrane is facilitated, and the vinylidene fluoride resin hollow fiber porous membrane having good water permeability despite the small pore diameter is formed. Show. Thus, the highly permeable vinylidene fluoride resin porous membrane formed by the method of the present invention is not only suitable for drainage treatment, but also for concentrating bacteria and proteins, and collecting chemically aggregated particles of heavy metals. It can also be suitably used as a usable separation membrane, a separation membrane for oil-water separation or gas-liquid separation, a battery membrane such as a lithium ion secondary battery, and a solid electrolyte support. In particular, the vinylidene fluoride resin porous membrane obtained by the thermally induced phase separation method as a preferred embodiment has a pore diameter continuously expanding in the film thickness direction, and a porosity is uniformly distributed in the film thickness direction. In addition to improving the porosity of the dense layer that contributes to separation characteristics or selective permeation characteristics in particular, it has excellent separation characteristics or selective permeation characteristics while maintaining fluid separation or movement of ions, etc. The characteristic that there is little resistance is given. Such characteristics are particularly suitable for the separation applications described above in general.
Claims (22)
- ある厚さを挟む主たる二表面を有し、その一表面側に孔径が小さく分離性能を支配する緻密層を有し、その一表面から逆側表面にかけて連続的に孔径が拡大する非対称の網目状傾斜構造を有し且つ下記(a)~(c)の条件を満たすことを特徴とする、フッ化ビニリデン系樹脂多孔膜:
(a)前記緻密層の前記一表面から連続する厚さ5μmの部分の空孔率A1が60%以上、
(b)前記一表面の表面孔径P1が0.30μm以下、且つ
(c)差圧100kPa、水温25℃の条件で測定した試長L=200mmでの透水量の全層空孔率A2=80%への換算値Q(m/day)と、前記一表面の表面孔径P1の4乗値P14(μm4)との比、Q/P14が5×104(m/day・μm4)以上。 An asymmetrical network with two main surfaces sandwiching a certain thickness, a dense layer that has a small pore size and governs separation performance on one surface side, and the pore diameter continuously increases from one surface to the opposite surface. A vinylidene fluoride resin porous membrane having an inclined structure and satisfying the following conditions (a) to (c):
(A) The porosity A1 of a portion having a thickness of 5 μm continuous from the one surface of the dense layer is 60% or more,
(B) The total surface porosity A2 = 80 of the water permeability at the test length L = 200 mm measured under the condition that the surface pore diameter P1 of the one surface is 0.30 μm or less and (c) the differential pressure is 100 kPa and the water temperature is 25 ° C. The ratio between the converted value Q to% (m / day) and the fourth power value P1 4 (μm 4 ) of the surface pore diameter P1 of the one surface, Q / P1 4 is 5 × 10 4 (m / day · μm 4 )more than. - 前記フッ化ビニリデン系樹脂が、重量平均分子量60万~120万を有する請求項1に記載の多孔膜。 The porous film according to claim 1, wherein the vinylidene fluoride resin has a weight average molecular weight of 600,000 to 1,200,000.
- 前記フッ化ビニリデン系樹脂が、重量平均分子量45万~100万のフッ化ビニリデン系樹脂(PVDF-I)25~98重量%と、重量平均分子量がPVDF-Iの1.4倍以上150万未満であるフッ化ビニリデン系樹脂(PVDF-II)2~75重量部の混合物からなる請求項2に記載の多孔膜。 The vinylidene fluoride resin is 25 to 98% by weight of vinylidene fluoride resin (PVDF-I) having a weight average molecular weight of 450,000 to 1,000,000, and the weight average molecular weight is 1.4 times or more and less than 1.5 million of PVDF-I. The porous membrane according to claim 2, comprising a mixture of 2 to 75 parts by weight of a vinylidene fluoride resin (PVDF-II) which is
- A1/P1が400以上、前記逆側表面の表面孔径P2(μm)とP1との比P2/P1が2.0~10.0である請求項1~3のいずれかに記載の多孔膜。 The porous membrane according to any one of claims 1 to 3, wherein A1 / P1 is 400 or more, and a ratio P2 / P1 of the surface pore diameter P2 (µm) to P1 on the opposite surface is 2.0 to 10.0.
- A1/A2が0.80以上である請求項1~4のいずれかに記載の多孔膜。 The porous membrane according to any one of claims 1 to 4, wherein A1 / A2 is 0.80 or more.
- 緻密層厚さが40μm以下であるである請求項1~5のいずれかに記載の多孔膜。 6. The porous membrane according to claim 1, wherein the dense layer has a thickness of 40 μm or less.
- 前記フッ化ビニリデン系樹脂が、DSC測定による樹脂本来の融点Tm2(℃)と結晶化温度Tc(℃)との差Tm2-Tcが32℃以下である請求項1~6のいずれかに記載の多孔膜。 7. The vinylidene fluoride resin according to claim 1, wherein a difference Tm2−Tc between a resin original melting point Tm2 (° C.) and a crystallization temperature Tc (° C.) by DSC measurement is 32 ° C. or less. Porous membrane.
- 結晶化温度Tcが143℃以上である請求項1~7のいずれかに記載の多孔膜。 The porous film according to any one of claims 1 to 7, wherein the crystallization temperature Tc is 143 ° C or higher.
- 前記フッ化ビニリデン系樹脂が全体としてフッ化ビニリデンの単独重合体からなる請求項1~8のいずれかに記載の多孔膜。 The porous membrane according to any one of claims 1 to 8, wherein the vinylidene fluoride resin as a whole is made of a homopolymer of vinylidene fluoride.
- 全体形状が中空糸状であり、外表面が前記一表面、内表面が前記逆側表面である請求項1~9のいずれかに記載の多孔膜。 The porous membrane according to any one of claims 1 to 9, wherein the overall shape is a hollow fiber shape, the outer surface is the one surface, and the inner surface is the opposite surface.
- 引張り強度が7MPa以上である請求項1~10のいずれかに記載の多孔膜。 The porous membrane according to any one of claims 1 to 10, which has a tensile strength of 7 MPa or more.
- 延伸されている請求項1~11のいずれかに記載の多孔膜。 The porous membrane according to any one of claims 1 to 11, which is stretched.
- 請求項1~12のいずれかに記載の多孔膜の前記一表面を被処理水側表面とし、前記逆側表面を透過水側表面として有するろ水処理膜。 A drainage treatment membrane having the one surface of the porous membrane according to any one of claims 1 to 12 as a surface to be treated water and the reverse surface as a permeate surface.
- フッ化ビニリデン系樹脂と可塑剤との溶融混練物をダイから膜状に押し出し、冷却固化する成膜する工程、および可塑剤を抽出する工程、を含む多孔膜の製造方法であり、前記可塑剤が溶融混練物の形成温度においてフッ化ビニリデン系樹脂と相溶性を有するとともに、更に下記(i)~(iii)の条件を満たすことを特徴とする、フッ化ビニリデン系樹脂多孔膜の製造方法:
(i)フッ化ビニリデン系樹脂との溶融混練物に、フッ化ビニリデン系樹脂単独の結晶化温度Tc(℃)より6℃以上低い結晶化温度Tc′(℃)を与え、
(ii)前記溶融混練物を冷却した固化物に、示差走査熱量計(DSC)で測定したときのフッ化ビニリデン系樹脂質量基準での結晶融解エンタルピーΔH’(J/g)として53J/g以上を与え、且つ
(iii)JIS K7117-2(円すい-平板型回転粘度計使用)に準拠して温度25℃で測定した可塑剤単独の粘度が200mPa・s~1000Pa・s。 A method for producing a porous film comprising a step of extruding a melt-kneaded product of a vinylidene fluoride resin and a plasticizer from a die into a film, cooling and solidifying the film, and a step of extracting the plasticizer, the plasticizer Has a compatibility with the vinylidene fluoride resin at the formation temperature of the melt-kneaded product, and further satisfies the following conditions (i) to (iii):
(I) A crystallization temperature Tc ′ (° C.) lower by 6 ° C. or lower than the crystallization temperature Tc (° C.) of the vinylidene fluoride resin alone is given to the melt-kneaded product with the vinylidene fluoride resin.
(Ii) 53 J / g or more as crystal melting enthalpy ΔH ′ (J / g) based on the vinylidene fluoride resin mass standard when measured with a differential scanning calorimeter (DSC) on the solidified product obtained by cooling the melt-kneaded product And (iii) the viscosity of the plasticizer alone measured at a temperature of 25 ° C. in accordance with JIS K7117-2 (cone—using a flat plate type viscometer) is 200 mPa · s to 1000 Pa · s. - 前記可塑剤が、脂肪族二塩基酸とグリコールとからなる(ポリ)エステルの末端を芳香族一価カルボン酸で封止したポリエステル系可塑剤からなる請求項14に記載の製造方法。 The manufacturing method according to claim 14, wherein the plasticizer comprises a polyester plasticizer in which a terminal of a (poly) ester composed of an aliphatic dibasic acid and glycol is sealed with an aromatic monovalent carboxylic acid.
- 前記フッ化ビニリデン系樹脂が、重量平均分子量45万~100万のフッ化ビニリデン系樹脂(PVDF-I)25~98重量%と、重量平均分子量がPVDF-Iの1.4倍以上150万未満であるフッ化ビニリデン系樹脂(PVDF-II)2~75重量部の混合物からなる請求項14または15に記載の製造方法。 The vinylidene fluoride resin is 25 to 98% by weight of vinylidene fluoride resin (PVDF-I) having a weight average molecular weight of 450,000 to 1,000,000, and the weight average molecular weight is 1.4 times or more and less than 1.5 million of PVDF-I. The production method according to claim 14 or 15, comprising a mixture of 2 to 75 parts by weight of a vinylidene fluoride resin (PVDF-II) which is
- 前記溶融混練物の膜状押出物を、その一表面側から優先的に不活性液体により冷却固化する請求項14~16のいずれかに記載の製造方法。 The production method according to any one of claims 14 to 16, wherein the melt-kneaded film-like extrudate is preferentially cooled and solidified with an inert liquid from one surface side thereof.
- 前記溶融混練物の中空糸膜状押出物を、その外側から優先的に不活性液体により冷却固化する請求項14~16のいずれかに記載の製造方法 The process according to any one of claims 14 to 16, wherein the hollow fiber membrane extrudate of the melt-kneaded product is cooled and solidified with an inert liquid preferentially from the outside thereof.
- 前記溶融混練物のTc′(℃)と前記冷却用不活性液体の温度Tq(℃)の差Tc′-Tqが50~140℃である請求項17または18に記載の製造方法。 The production method according to claim 17 or 18, wherein a difference Tc'-Tq between Tc '(° C) of the melt-kneaded product and temperature Tq (° C) of the cooling inert liquid is 50 to 140 ° C.
- 前記溶融混練物のTc′(℃)が120~140℃である請求項14~19のいずれかに記載の製造方法。 The method according to any one of claims 14 to 19, wherein Tc '(° C) of the melt-kneaded product is 120 to 140 ° C.
- 前記溶融混練物の膜状固化成形体をハロゲン系溶媒に浸漬して可塑剤を抽出した後、ハロゲン系溶媒を含有する膜状固化成形体を実質的に乾燥させることなく、フッ化ビニリデン系樹脂に対して膨潤性を有さない溶媒に浸漬してハロゲン系溶媒を置換した後、乾燥させる請求項14~20のいずれかに記載の製造方法。 The vinylidene fluoride-based resin is obtained without substantially drying the film-shaped solidified molded body containing the halogen-based solvent after the film-shaped solidified molded body of the melt-kneaded product is immersed in the halogen-based solvent to extract the plasticizer. The production method according to any one of claims 14 to 20, wherein the halogen-based solvent is substituted by immersion in a solvent that does not swell, and then dried.
- 可塑剤の抽出後の多孔膜を、その外表面から5μm以上、且つ膜厚さの1/2以下の深さまで選択的に湿潤させた状態で延伸する工程を含む請求項14~21のいずかに記載の製造方法。 The method according to any one of claims 14 to 21, further comprising a step of stretching the porous film after extraction of the plasticizer in a state of being selectively wetted from the outer surface to a depth of 5 µm or more and 1/2 or less of the film thickness. The manufacturing method of crab.
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CN201080039112.8A CN102548647B (en) | 2009-09-04 | 2010-09-06 | Porous vinylidene fluoride resin membrane and process for producing same |
KR1020127005700A KR101372056B1 (en) | 2009-09-04 | 2010-09-06 | Porous vinylidene fluoride resin membrane and process for producing same |
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JP2009237026A JP5552289B2 (en) | 2009-09-04 | 2009-10-14 | Method for producing vinylidene fluoride resin porous membrane |
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