WO2015041286A1 - Porous hollow fiber membrane and method for manufacturing same - Google Patents
Porous hollow fiber membrane and method for manufacturing same Download PDFInfo
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- WO2015041286A1 WO2015041286A1 PCT/JP2014/074680 JP2014074680W WO2015041286A1 WO 2015041286 A1 WO2015041286 A1 WO 2015041286A1 JP 2014074680 W JP2014074680 W JP 2014074680W WO 2015041286 A1 WO2015041286 A1 WO 2015041286A1
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- hollow fiber
- fiber membrane
- porous
- porous hollow
- film
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Images
Classifications
-
- 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
- B01D69/10—Supported membranes; Membrane supports
- B01D69/107—Organic support material
- B01D69/1071—Woven, non-woven or net mesh
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/08—Hollow fibre membranes
-
- 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
- B01D69/10—Supported membranes; Membrane supports
-
- 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
- B01D2325/021—Pore shapes
-
- 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
- B01D2325/021—Pore shapes
- B01D2325/0212—Symmetric or isoporous membranes
-
- 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
- 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
- B01D2325/0231—Dense layers being placed on the outer side of the cross-section
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/40—Fibre reinforced membranes
Definitions
- the present invention relates to a porous hollow fiber membrane having excellent anti-fouling performance, which is mainly used for removing bacteria, viruses, SS components and the like in water. Specifically, the present invention relates to a porous hollow fiber membrane that is excellent in stable membrane performance over a long period of time and excellent in recoverability of membrane performance by washing. The present invention also relates to a porous hollow fiber membrane suitable for water treatment such as water purification treatment that can be used as a microfiltration membrane or an ultrafiltration membrane, and a method for producing the same.
- This application claims priority based on Japanese Patent Application No. 2013-193213 filed in Japan on September 18, 2013 and Japanese Patent Application No. 2013-193214 filed on September 18, 2013 in Japan. Is hereby incorporated by reference.
- the seawater supplied to the reverse osmosis membrane is subjected to a turbidity treatment in advance by a pretreatment such as coagulation sedimentation or sand filtration, and then supplied to the reverse osmosis membrane to be removed.
- Salt treatment is performed.
- turbidity by membrane filtration is employed instead of coagulation sedimentation or sand filtration or in combination with other water treatment techniques.
- Examples of the required characteristics required for the porous hollow fiber membrane used for membrane separation include the following points. (1) The removability of the substance to be removed is high. (2) The permeability of the permeable substance is high. (3) The permeability of the processing fluid is high. (Hereinafter, (1), (2), and (3) are collectively referred to as membrane separation characteristics.) (4) The rupture strength against tension or the like is sufficiently high, and it is difficult to break or leak. (5) The fractionation characteristics are unlikely to deteriorate over time. (6) The permeability of the processing fluid is difficult to decrease over time. (Hereinafter, (5) and (6) are collectively referred to as retention of membrane separation characteristics.) (7) Excellent recovery of fractionation characteristics by washing. (8) It is excellent in recovering permeability by washing. (Hereinafter, (7) and (8) are collectively referred to as recoverability of membrane separation characteristics.)
- a membrane made of a hydrophobic polymer is first formed, and then various surface treatments are performed to coat the surface of the hydrophobic polymer membrane with a hydrophilic polymer, thereby improving fouling resistance.
- various surface treatments are performed to coat the surface of the hydrophobic polymer membrane with a hydrophilic polymer, thereby improving fouling resistance.
- These methods have many practical problems such as a complicated manufacturing process and difficulty in controlling the process as compared with a method of forming a film by mixing a hydrophilic polymer in a film forming stock solution.
- Patent Documents 1 and 2 can be cited as examples referring to the relationship between the shape of the membrane surface and the membrane separation characteristics.
- Patent Document 1 discloses an invention related to a composite reverse osmosis membrane having a polyamide-based skin layer. By making the specific surface area of the membrane surface on the side to which raw water is supplied into a specific range, It has been shown that water permeability is improved.
- Patent Document 2 discloses an invention related to a composite reverse osmosis membrane having a polyamide-based skin layer as well, and the average value X of the horizontal distance between adjacent vertices of the surface irregularities on the membrane surface on the raw water supply side is disclosed. It is disclosed that a composite reverse osmosis membrane exhibiting high blocking performance can be obtained when the average value Z of the unevenness difference between the apex adjacent to each other and the bottom side satisfies a specific relationship.
- neither of Patent Documents 1 and 2 is a study on a composite reverse osmosis membrane, and further, no mention is made regarding improvement of fouling resistance.
- filtration membranes made of polysulfone, polyacrylonitrile, cellulose acetate, or polyvinylidene fluoride manufactured by a wet or dry wet spinning method are known as filtration membranes having excellent water permeability. These filtration membranes are manufactured by microphase-separating a polymer solution and then coagulating the polymer solution in a non-solvent, and have a high porosity and an asymmetric structure.
- polyvinylidene fluoride resin is suitably used as a material for separation membranes because it is excellent in chemical resistance and heat resistance.
- many of the proposed filtration membranes made of polyvinylidene fluoride hollow fiber membranes are not sufficient in any one of separation characteristics, filtration stability, and mechanical strength, and those satisfying all of them There was a problem that the manufacturing method was complicated.
- Patent Document 3 a separation membrane in which a hollow braid is used as a support and a porous layer is provided on the surface has been proposed.
- this porous layer has a large macro void inside the membrane structure due to its production method, and there is a problem that the separation characteristics are liable to be deteriorated due to damage to the outer surface of the membrane due to external factors.
- a polyvinylidene fluoride resin and a plasticizer are melt-kneaded, extruded, cooled and solidified, then the plasticizer is extracted to obtain a porous hollow fiber membrane, and then the outer surface dense layer is stretched in a wet state
- a separation membrane has been proposed in which the porosity of the surface dense layer is increased to make it less likely to be contaminated by turbid water (Patent Document 5).
- the separation membrane of this technique has a high porosity, but the pore diameter of the dense layer is almost uniform, so that the problem that microscopic objects and soluble organic polymers that have passed through the surface are easily clogged inside the dense layer still remains.
- there is a problem that it is difficult to combine with a support because the manufacturing method substantially requires stretching, and it is difficult to achieve both mechanical strength.
- the problem of the present invention is that it can be used in the treatment of various aqueous fluids such as water purification treatment, beverage treatment, or seawater turbidity, and has excellent fractionation characteristics and permeability,
- An object of the present invention is to provide a porous hollow fiber membrane in which a decrease is suppressed and the membrane separation property recoverability by washing is excellent.
- Another object of the present invention is to solve the above problems and provide a porous hollow fiber membrane having excellent separation characteristics, filtration stability, and mechanical strength.
- the average pore diameter P2 of the layer from the outer surface to the depth of 10 ⁇ m in the cross-sectional structure is 0.1 to 5.0 ⁇ m, and the open area ratio A2 is 10 to 50%, as described in (1) or (2)
- Porous hollow fiber membrane (4)
- the structure from the outer surface to a depth of 5 ⁇ m is a three-dimensional network structure in which the pore diameter gradually increases in the direction away from the outer surface (1) to (3) Porous hollow fiber membrane.
- the average pore diameter of the porous layer from the outer surface to a depth of 5 ⁇ m is smaller than the average pore diameter of the porous layer existing at a position farther from the outer surface than the depth of 5 ⁇ m (1) to (4)
- the porous hollow fiber membrane according to any one of the above.
- the porous hollow fiber membrane according to (10) or (11), wherein the hollow fiber-shaped support is a hollow knitted string.
- a film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, and then the discharged film-forming resin solution is used as a component of the film-forming resin solution to saturate a non-solvent.
- a method for producing a porous hollow fiber membrane which is brought into contact with steam and then solidified by being immersed in a coagulating liquid to form a porous hollow fiber membrane, wherein the spinning nozzle is a single or double tubular nozzle And the said porous hollow fiber membrane is a manufacturing method of the porous hollow fiber membrane which forms the site
- the embodiment of the present invention has the following aspects.
- the first gist of the present embodiment that solves the above-mentioned problems is a porous hollow fiber membrane having an outer surface open area ratio of 15 to 65%.
- the second gist of the present embodiment is a method for evaluating a porous hollow fiber membrane having the following steps. Step (1): A step of observing a cross section of the porous hollow fiber membrane with a scanning electron microscope and measuring an area of each hole appearing on the surface of the cross section. Step (2): Area of each hole measured in step (1) Of calculating the average pore diameter index for the holes corresponding to 50% of the total area
- this embodiment is a porous hollow fiber membrane having a porous layer made of a thermoplastic resin at least on the outer surface and in the vicinity thereof, and the average pore diameter Ad from the surface in the cross-sectional structure to the depth of 1 ⁇ m is the depth.
- the porous hollow fiber membrane has a mean pore diameter Bd of 2 ⁇ m to 3 ⁇ m that is 1/2 or less.
- a film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, immediately after being brought into contact with a non-solvent saturated vapor of the film-forming resin, and then into a coagulating liquid. This is a method for producing a porous hollow fiber membrane that is solidified by dipping.
- the embodiment of the present invention has the following aspects.
- (1A) A porous hollow fiber membrane in which at least the outer surface side is composed of a porous layer, and the porosity of the outer surface is 15 to 65%.
- (2A) The porous hollow fiber membrane according to (1A), wherein the outer surface has an average pore diameter index P1 of 0.05 to 1.0 ( ⁇ m).
- (3A) As described in (1A) or (2A), the dense layer has a dense layer up to 10 ⁇ m near the outer surface, and the average pore diameter index P2 ( ⁇ m) of the dense layer is in the range of 0.1 to 5.0 ( ⁇ m).
- Porous hollow fiber membrane 4A) The porous hollow fiber membrane according to (3A), wherein the open area ratio A2 (%) of the dense layer is 10 to 50%.
- (7A) A method for evaluating a porous hollow fiber membrane comprising the following steps, wherein the outer surface side is a porous layer. Step 1: A step of observing the cross section of the porous hollow fiber membrane with a scanning electron microscope and measuring the area of each hole appearing on the surface of the cross section. Step 2: The area value of each hole measured in Step 1 is small. Step of calculating the average pore diameter index using the holes corresponding to 50% of the total area
- the embodiment of the present invention further has the following aspects.
- (1B) A porous hollow fiber membrane having a porous layer made of a thermoplastic resin at least on the outer surface and in the vicinity thereof, wherein the average pore diameter Ad from the surface to the depth of 1 ⁇ m in the cross-sectional structure is from the depth of 2 ⁇ m to 3 ⁇ m A porous hollow fiber membrane having a mean pore diameter Bd of 1 ⁇ 2 or less.
- the porous hollow fiber membrane according to (7B), wherein the hollow fiber-shaped support is a hollow knitted string.
- (10B) The porous hollow fiber membrane according to (8B) or (9B), wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
- (11B) A film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, then contacted with a non-solvent saturated vapor of the film-forming resin, and then immersed in a coagulation liquid.
- a method for producing a porous hollow fiber membrane which is solidified by the method.
- (12B) The production of the porous hollow fiber membrane according to (11B), wherein the spinning nozzle is a single or double or more tubular nozzle, and at least 4 ⁇ m in depth is formed from the outer surface with the same membrane-forming resin solution.
- the porous hollow fiber membrane of the present invention is a porous hollow fiber membrane having a porous layer containing a thermoplastic resin at least on the outer surface and in the vicinity of the outer surface, and is in the thickness direction of the porous hollow fiber membrane.
- the size of the average pore diameter (Ad) from the surface to the depth of 1 ⁇ m in the cross-sectional structure is not more than 0.6 in terms of the ratio of the average pore diameter (Bd) from the depth of 2 ⁇ m to 3 ⁇ m.
- a porous hollow fiber membrane having a porous layer at least on the outer surface side and a porosity of 15 to 65% on the outer surface Since the structure has an inclined structure coarser than the surface, it is considered that there is no clogging inside and the cleaning recovery is high. Moreover, a porous hollow fiber membrane excellent in retention and recovery of membrane separation characteristics can be obtained.
- the porous hollow fiber membrane of the present invention can be used in the treatment of various aqueous fluids such as water purification membranes, beverage treatment membranes and seawater turbidity membranes, and provides a porous hollow fiber membrane particularly suitable for water purification treatments. Can do.
- the porous hollow fiber membrane of the present application has sufficient membrane strength that does not cause breakage or leakage during module molding or actual use, while having excellent fractionation characteristics and permeability. In this way, it is possible to suppress the deterioration of the characteristics of the film over time, and it is excellent in recovering the membrane separation characteristics by washing.
- the porous hollow fiber membrane of the present invention has a so-called dense layer because the average pore diameter Ad from the surface to the depth of 1 ⁇ m in the cross-sectional structure is 1 ⁇ 2 or less of the average pore diameter Bd from the depth of 2 ⁇ m to 3 ⁇ m. As a result, a porous hollow fiber membrane excellent in separation characteristics, filtration stability and mechanical strength is obtained.
- 2 is a cross-sectional photograph of a porous layer of a porous hollow fiber membrane obtained in Reference Example 1.
- 4 is a cross-sectional photograph of a porous layer of a porous hollow fiber membrane obtained in Reference Example 2.
- 4 is a cross-sectional photograph of a porous layer of a porous hollow fiber membrane obtained in Reference Example 3.
- 4 is a cross-sectional photograph of a porous layer of a porous hollow fiber membrane obtained in Reference Example 4.
- 2 is a cross-sectional photograph of a porous layer of a porous hollow fiber membrane obtained in Reference Comparative Example 1.
- 2 is a cross-sectional photograph of the porous layer in the vicinity of the outer surface portion of the porous hollow fiber membrane obtained in Reference Example 1.
- 4 is a cross-sectional photograph of the porous layer in the vicinity of the outer surface portion of the porous hollow fiber membrane obtained in Reference Example 2.
- 4 is a cross-sectional photograph of the porous layer in the vicinity of the outer surface portion of the porous hollow fiber membrane obtained in Reference Example 3.
- 4 is a cross-sectional photograph of the porous layer in the vicinity of the outer surface portion of the porous hollow fiber membrane obtained in Reference Example 4.
- 2 is a cross-sectional photograph of a porous layer in the vicinity of an outer surface portion of a porous hollow fiber membrane obtained in Reference Comparative Example 1.
- It is a graph which shows the time-dependent change of the differential pressure
- It is a schematic diagram which shows the manufacturing apparatus used for manufacture of the porous hollow fiber membrane which concerns on one Embodiment of this invention.
- It is a bottom view which shows the ventilation nozzle which comprises the manufacturing apparatus of the hollow porous membrane of FIG.
- the porous hollow fiber membrane of the present embodiment is a porous hollow fiber membrane in which at least the outer surface side of the present embodiment is composed of a porous layer, and the porosity of the outer surface is from 15 to the total area of the outer surface. It is a porous hollow fiber membrane that is 60%.
- the outer surface refers to the surface on the side facing the outer periphery of the cylinder when the membrane is formed into a hollow fiber shape (cylindrical shape) to form a porous hollow fiber membrane.
- the surface on the side facing the inner periphery of the cylinder is defined as the inner surface.
- the porous layer refers to a layer having pores having the properties described later in a form dispersed in almost the entire layer.
- the open area ratio means that the outer surface of the porous hollow fiber membrane is observed with a microscope or the like, the area of the holes is measured by image analysis or the like, and the total area of all the holes is totaled. It is a value obtained as the sum of the areas of all the holes / the area of the entire observed outer surface (film area in the field of view).
- a porous hollow fiber membrane having a porous layer at least on the outer surface side, and the porosity of the outer surface is 15 to 60% with respect to the entire area of the outer surface. It becomes an excellent porous hollow fiber membrane.
- the porosity of the outer surface is preferably 20% or more and 60% or less, and more preferably 25% or more and 55% or less with respect to the entire area of the outer surface.
- the average pore diameter index (or average pore diameter P1) of each pore of the porous layer of the porous hollow fiber membrane of the present embodiment may be 0.05 to 1.0 ( ⁇ m). Thereby, it becomes a porous hollow fiber membrane excellent in recoverability.
- the average pore diameter index of the porous hollow fiber membrane is preferably 0.06 to 0.9 ( ⁇ m), more preferably 0.75 to 0.8 ( ⁇ m).
- the average pore size index refers to the pore size calculated by performing arithmetic processing on the pore size read from the micrograph using image analysis software. As a result, there is an effect of excluding minute noise due to the density of pixels.
- the outer surface of the porous hollow fiber membrane is photographed with a microscope, and the average value of the pore diameters in the photograph is measured.
- the average pore diameter P2 of the layer from the surface to the depth of 10 ⁇ m in the cross-sectional structure is 0.1 to 5.0 ( ⁇ m It is preferable that the porosity A2 in this layer is 10 to 50%. If it is this range, there exists an effect which can make clogging-proof property and intensity
- the porous membrane layer constituting the porous hollow fiber membrane of the present embodiment preferably has a thickness of 200 ⁇ m or less. This is because when the thickness of the porous membrane layer is 200 ⁇ m or less, the permeation resistance at the time of membrane separation is reduced, and excellent water permeability is obtained. This is because the coagulation time when forming the membrane layer can be shortened, and it is effective in suppressing macrovoids (defects), and excellent productivity tends to be obtained. More preferably, the thickness of the porous membrane layer is 150 ⁇ m or less. Moreover, in the porous membrane layer which comprises the porous hollow fiber membrane of this embodiment, it is preferable that the thickness is 100 micrometers or more.
- the porous membrane layer has a dense layer at least near the outer surface.
- the vicinity of the outer surface refers to a portion adjacent to the outer surface of the porous membrane layer (inside the porous membrane layer) at a portion inside the porous membrane layer.
- the dense layer refers to a region in which fine pores having smaller pore diameters are gathered in the porous membrane layer.
- the water permeability and separation of the porous hollow fiber membrane are used.
- the average pore diameter index is preferably in the range of 0.01 to 1 ⁇ m.
- the thickness of the dense layer in this embodiment is preferably in the range of 10 to 125 ⁇ m from the viewpoints of both improving the stability of separation characteristics and improving water permeability.
- the thickness is more preferably in the range of 25 to 100 ⁇ m from the viewpoint of improving the stability of the separation characteristics. More preferably, the dense layer has a thickness in the range of 40 to 75 ⁇ m.
- the position of the dense layer in the vicinity of the outer surface is preferably present at a position within 20 ⁇ m from the outer surface of the porous membrane layer from the viewpoint of avoiding an increase in water permeability resistance inside the membrane. Furthermore, it is particularly preferred that this dense layer constitutes the outer surface of the porous membrane layer.
- the porous membrane layer preferably has a sponge layer having an average pore diameter index of 2 ⁇ m or more inside the dense layer near the outer surface (a portion further away from the outer surface and a portion deeper when viewed from the outer surface). . Since this intermediate porous layer contributes to the water permeability in the porous hollow fiber membrane of this embodiment in particular, the larger the pore diameter, the better. However, if it is too large, it becomes a macrovoid and reduces its mechanical strength. . Therefore, the average pore diameter index is preferably 8 ⁇ m or less, and more preferably substantially no pores of 10 ⁇ m or more are present. More preferably, it is in the range of 3 to 5 ⁇ m.
- this intermediate porous layer is directed away from the dense layer near the outer surface toward the outer surface, that is, near the inner surface. It is preferable to have an inclined structure in which the hole diameter gradually increases.
- the intermediate porous layer preferably has a three-dimensional network structure in which the pores sterically intersect with each other.
- the average pore diameter of the porous layer from the outer surface to a depth of 5 ⁇ m is smaller than the average pore diameter of the porous layer existing at a site deeper than the depth of 5 ⁇ m from the outer surface.
- the average pore diameter of the porous layer existing at a site deeper than 5 ⁇ m from the outer surface is 10 ⁇ m or less.
- the porous layer described so far may be discontinuously divided into a plurality of layers (for example, a dense layer and a layer other than the dense layer) depending on the material and the average pore diameter.
- the average value of the diameter gradually changes according to the distance from the surface).
- the layer may be referred to as a part (for example, a dense part and other parts).
- the porous hollow fiber membrane of the present embodiment includes an annular nozzle and a first membrane undiluted solution and a second membrane undiluted solution containing the material and solvent for the porous membrane layer on the outer peripheral surface of the hollow support.
- the film-forming stock solution can be continuously applied and laminated, and these film-forming stock solutions can be coagulated at the same time.
- the solidification may be from only one side, and an integral porous membrane structure can be obtained from two types of film-forming stock solutions by this method.
- a double annular nozzle as shown in FIG. 1 of Patent Document 7 is used, a hollow support (knitted string) is passed through the support passage, and the first film is formed from the first supply port.
- the stock solution inner layer side film forming stock solution
- the second film forming stock solution outer layer side film forming stock solution
- the second film-forming stock solution is applied onto the coating layer of the first film-forming stock solution.
- the hollow knitted string coated with the film-forming stock solution is idled for a predetermined time, and then immersed in a coagulation liquid to solidify the film-forming stock solution, washed with water, and dried, so that the porous hollow specified in this embodiment is used.
- a thread membrane structure can be obtained.
- the first film-forming stock solution and the second film-forming stock solution can be combined in the nozzle in advance, and these can be simultaneously discharged from the nozzle surface and applied to the hollow support.
- a triple annular nozzle having a central part, an inner part and an outer part, while passing a hollow support through the central part, the first film-forming stock solution from the inner part and the second film-forming stock solution from the outer part Can be simultaneously discharged to apply the film-forming stock solution to a hollow support.
- each of the first film-forming stock solution and the second film-forming stock solution can be uniformly applied, and the first film-forming stock solution and the second film-forming stock solution are laminated.
- the first film-forming stock solution and the second film-forming stock solution may be applied in sequence. In this case, when the first film-forming stock solution and the second film-forming stock solution are applied, the first film-forming stock solution and the second film-forming solution may be applied either continuously or at intervals. In order to prevent bubbles from being generated between the layers when laminating the membrane stock solution, it is preferably performed continuously.
- two types of film-forming stock solutions are used, both of which contain a polymer resin, an additive, and an organic solvent.
- the polymer resin used in these film-forming stock solutions include polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyvinylidene fluoride resin, polyacrylonitrile resin, polyimide resin, polyamideimide resin, or polyesterimide resin. be able to. These can be appropriately selected and used as necessary, but among these, polyvinylidene fluoride resin is preferred because of its excellent chemical resistance.
- a hydrophilic polymer resin such as monool, diol, triol, or polyvinylpyrrolidone represented by polyethylene glycol is used. be able to. These can be appropriately selected and used as necessary, and among them, polyvinylpyrrolidone is preferred because of its excellent thickening effect.
- the organic solvent is not particularly limited as long as it can dissolve the above-described polymer resin and additives, and for example, dimethyl sulfoxide, dimethylacetamide, or dimethylformamide can be used.
- composition of the two types of film-forming stock solutions described above is not particularly limited, and the same film-forming stock solution or different film-forming stock solutions may be used. However, from the viewpoint of preventing delamination and improving mechanical strength, it is preferable that the solvent and polymer resin used are the same type in order to form an integral structure from two types of film-forming stock solutions during solidification.
- the viscosity of the first membrane forming stock solution that is the inner layer side membrane forming stock solution is higher than that of the second membrane forming stock solution that is the outer layer side membrane forming stock solution. It is preferable to increase the height. This is because the first membrane-forming solution having a higher viscosity is applied to the outer peripheral surface of the hollow support, thereby preventing the membrane-forming stock solution from excessively penetrating into the hollow support, This is because blockage of the hollow portion of the yarn membrane can be prevented. In order to achieve this, the first film-forming stock solution needs to have a sufficient viscosity, and the viscosity at 40 ° C.
- the viscosity of the first film forming stock solution at 40 ° C. is in the range of 5 to 250,000 mPa ⁇ sec
- the viscosity of the second film forming stock solution at 40 ° C. is in the range of 100,000 to 300,000 mPa ⁇ sec. It is.
- the method for adjusting the viscosity of the film-forming stock solution described above is not particularly limited.
- the viscosity can be changed by changing the molecular weight of the polymer resin or changing the concentration of the polymer resin.
- a method of changing the molecular weight of the polymer resin a method of blending two kinds of polymer resins having different molecular weights can also be used.
- the viscosity adjustment of the film-forming stock solution can be appropriately selected as described above.
- adjusting the concentration of the polymer resin and increasing the concentration is a slow coagulation rate.
- the inner layer is also preferred because it tends to suppress the generation of macrovoids. Further, it is preferable because the structural stability of the entire porous layer can be improved by increasing the concentration of the first film-forming stock solution.
- the second membrane forming undiluted solution it is preferable to adjust the molecular weight of the polymer resin because the porosity of the outer surface of the porous membrane layer tends to be maintained high.
- a porous structure is formed by phase separation.
- various structures can be obtained depending on the film forming conditions, but as a typical porous structure, a sponge structure derived from a sea-island structure in which the polymer resin is on the sea side, and the polymer resin is on the island side.
- the porous structure can be appropriately selected from these structures, but the particle aggregate structure tends to be a structure in which the polymer resin layer is aggregated and tends to be inferior in mechanical strength. It is preferable to adopt a sponge structure or a three-dimensional network structure.
- the sponge structure tends to be a homogeneous structure in which the pore diameter does not change greatly in the film thickness direction, and is a structure suitable for improving the stability of the separation characteristics.
- the three-dimensional network structure tends to be a structure having a higher degree of communication between pores than the sponge structure, and is a structure suitable for improving the permeation performance.
- the composition of the first film-forming stock solution that is the inner-layer side film-forming stock solution can be appropriately selected according to the film structure to be formed.
- the conditions for obtaining the sponge structure from the first film-forming stock solution are the same, and the composition is not particularly limited, but the mass ratio of the additive to the polymer resin in the film-forming stock solution (additive / polymer resin) ) Is 0.45 or less, more preferably 0.40 or less. By setting the mass ratio to 0.45 or less, the homogeneous structure tends to be densified, and macrovoids tend not to occur easily.
- this mass ratio is preferably 0.3 or more.
- the composition of the film-forming stock solution include 20-30% by weight of polyvinylidene fluoride resin, 5-12% by weight of polyvinylpyrrolidone, 60-85% by weight of dimethylacetamide, and polyvinyl There may be mentioned those having a mass ratio of pyrrolidone to polyvinylidene fluoride resin (polyvinylpyrrolidone / polyvinylidene fluoride resin) in the range of 0.3 to 0.45.
- the conditions for obtaining the three-dimensional network structure of the porous layer from the first film-forming stock solution are not particularly limited, but the mass ratio of the additive to the polymer resin in the film-forming stock solution (additive / polymer resin) ) Is 0.45 or more, more preferably 0.51 or more. Moreover, it is preferable that the ratio of an organic solvent shall be 68 mass% or less with respect to the whole mass of a film-forming stock solution. This is because the generation of macrovoids tends to be suppressed, and the structural stability of the entire porous layer tends to be improved. More preferably, it is 60% by weight or less based on the total mass of the film-forming stock solution.
- composition of the film-forming stock solution examples include 20-30% by weight of polyvinylidene fluoride resin, 10-20% by weight of polyvinylpyrrolidone, 55-68% by weight of dimethylacetamide, and polyvinyl The thing whose mass ratio (polyvinyl pyrrolidone / polyvinylidene fluoride resin) of a pyrrolidone and a polyvinylidene fluoride resin is 0.45 or more can be mentioned.
- the gradient structure has a dense layer near the outer surface of the porous membrane layer and the pore diameter gradually increases toward the inner surface of the porous membrane layer. If it can form by this, it will not specifically limit.
- the composition of the second membrane forming stock solution can be appropriately selected according to the target membrane structure, but from the viewpoint that the surface porosity of the porous membrane layer can be increased, the ratio of the organic solvent is 70% by mass or more. It is preferable to do. Moreover, since there exists a tendency which can form the inclination structure without a big macrovoid, it is preferable that mass ratio of an additive / polymer resin is 0.45 or more.
- composition of the film forming stock solution examples include 15 to 25% by weight of polyvinylidene fluoride resin, 5 to 15% by weight of polyvinylpyrrolidone, 70 to 80% by weight of dimethylacetamide, and (polyvinylpyrrolidone / polyvinylidene fluoride resin) The thing which is 0.45 or more can be mentioned.
- the thickness at the time of application of each of the outer layer and the inner layer can be set as appropriate, but if the outer layer tends to have a higher ratio of organic solvent, macro voids tend to occur during film formation,
- the thickness of the outer layer is preferably 150 ⁇ m or less. More preferably, it is 100 micrometers or less, More preferably, it is 80 micrometers or less. On the other hand, the lower limit of the thickness of the outer layer is 5 ⁇ m.
- the support When a hollow knitted string is used as the support, the support may be previously impregnated with a non-solvent for the film-forming stock solution in order to prevent excessive infiltration of the film-forming stock solution into the support.
- a non-solvent for the film-forming stock solution in order to prevent excessive infiltration of the film-forming stock solution into the support.
- An example of the non-solvent in the case of using the film-forming stock solution having the above composition is glycerin.
- non-solvents with too high coagulation ability for the film-forming stock solution to be used and non-solvents with too high viscosity hinder the penetration of the porous membrane layer into the support and greatly reduce the peel resistance. Absent.
- polyvinylpyrrolidone when used as an additive, it is preferable to perform chemical cleaning of the porous hollow fiber membrane using sodium hypochlorite or the like in the cleaning after the formation of the membrane structure from coagulation.
- porous membrane examples of the material for the porous membrane layer include polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyvinyl pyrrolidone, and polyethylene glycol. From the viewpoint of chemical resistance and heat resistance, polyvinylidene fluoride, or polyvinylidene fluoride and polyvinyl A combination with pyrrolidone is preferred.
- the porous membrane layer may be a single layer composed of any one of these constituent materials, or may be a composite porous membrane layer formed by laminating two or more of these single layers.
- the hollow porous hollow fiber membrane of this embodiment has an average pore diameter Ad of a layer from the surface to a depth of 1 ⁇ m (hereinafter referred to as porous layer A) in the cross-sectional structure when cut and observed in the thickness direction.
- porous layer A a porous layer whose ratio to the size of a layer having a depth of 2 to 3 ⁇ m (hereinafter referred to as porous layer B) Bd is 0.6 or less, preferably 1 ⁇ 2 or less (0.5 or less) It is in a hollow fiber membrane.
- the porous hollow fiber membrane of the present embodiment has a membrane having the smallest pore diameter in the porous layer A forming the outer surface, which is substantially less than 1 ⁇ m.
- a soluble organic polymer has a characteristic that it is difficult to be clogged inside the film.
- porous hollow fiber membrane porous layer A of the present embodiment and a structure in which the pore diameter gradually increases to a layer having a depth of 4 ⁇ m to 5 ⁇ m are more preferable.
- porous layer C a structure in which the pore diameter gradually increases to a layer having a depth of 4 ⁇ m to 5 ⁇ m.
- the pore diameter Bd of the porous layer B may be 5/3 or more (that is, Ad / Bd is 0.6 or less) with respect to the pore diameter Ad of the porous layer A forming the outer surface.
- Bd is preferably 2 times or more (Ad / Bd is 0.5 or less) with respect to Ad, more preferably 3 times or more (Ad / Bd is 0.33 or less), and 4 times or more (Ad / B). More preferably, Bd is 0.25 or less. When the separation characteristics can be maintained, it is more preferable that the separation characteristic is 5 times or more (Ad / Bd is 0.2 or less).
- the porous layer B preferably means a layer adjacent to the porous layer A constituting the outer surface with one layer interposed therebetween.
- the pore size Ad substantially determines the filtration characteristics and is appropriately selected depending on the material to be filtered.
- 0.01 to The range is preferably 1 ⁇ m, more preferably 0.02 to 0.5 ⁇ m, and still more preferably 0.04 to 0.2 ⁇ m.
- the pore diameter from the porous layer C to the layer forming the inner surface is larger than the pore diameter from the porous layer A to the porous layer C.
- the pore diameter from the porous layer C to the layer forming the inner surface becomes smaller, the microscopic matter and the soluble organic polymer that have passed through the porous layer C tend to be clogged inside the membrane.
- the pore diameter from the porous layer C to the layer forming the inner surface is appropriately selected according to the purpose. If the system is prioritized for water permeability, the larger one is preferable, and if the system is prioritized for separation characteristics, it is preferable to maintain a pore diameter close to Cd. In many separation membranes, separation characteristics are given priority. In that case, the pore diameter from the porous layer C to the layer forming the inner surface is preferably 8 ⁇ m or less, and there are substantially no pores of 10 ⁇ m or more. Is more preferable. More preferably, it is 5 ⁇ m or less.
- the layers from the porous layer A to the porous layer C are preferably formed from one dope. That is, it includes the same constituent material, more specifically, a thermoplastic resin of the same compound that substantially constitutes the layer, and other film constituent additives. If a multi-layer structure is used, an interfacial structure will be generated between the layers, which may cause clogging of microscopic objects and soluble organic polymers that have passed through the outer surface, and the strength of each layer will decrease, causing a peeling problem. This is because there is a possibility of occurrence.
- the porous hollow fiber membrane in the present embodiment does not have a defect site called a macrovoid having a pore diameter of 10 ⁇ m or more.
- a defect site called a macrovoid having a pore diameter of 10 ⁇ m or more.
- the dope viscosity is greatly reduced.
- macro voids are likely to occur near the outer surface at the same time. Separation characteristics are greatly reduced. Therefore, in this embodiment, it is preferable that the macro void or part of the macro void is not provided between the porous layer A and the porous layer C.
- the porous layer from the outer surface to the layer having a depth of 10 ⁇ m does not contain a macro void having a pore diameter exceeding 10 ⁇ m and a part thereof, and the macro void is observed over the entire cross section when the cross-sectional structure is observed. It is further preferable not to contain.
- “including a macro void and a part thereof from the outer surface to a layer having a depth of 10 ⁇ m” means that a part of the macro void is outside the outer surface by a depth of 10 ⁇ m (near the outer surface). It is also included when it is hung.
- the hollow porous hollow fiber membrane of the present embodiment may be composed only of the above-mentioned porous layer, but since excellent mechanical strength is obtained, the porous porous fiber membrane is formed on the hollow support. Those having a layer are particularly preferred. Here, in order to clarify the positional relationship between the porous layer and the support, it is expressed as on the support, but the porous layer may be impregnated inside the support through the gap of the support. . In the present embodiment, the porous layer is formed on the outer surface side of the hollow fiber support.
- the support is not particularly limited as long as it has high mechanical strength and can be integrated with the porous layer, and is not particularly limited. Knitted cords are preferable because they can achieve both the stability and shape stability (roundness) of the cross section and are excellent in adhesion to the porous layer. Among these, a hollow knitted string obtained by circularly knitting a single yarn made of multifilament is preferable.
- the constituent material of the support is preferably a polyester fiber, an acrylic fiber, a polyvinyl alcohol fiber, a polyamide fiber, a polyolefin fiber, or a polyvinyl chloride fiber from the viewpoint of excellent chemical resistance, a polyester fiber, Acrylic fibers or polyvinyl chloride fibers are particularly preferred.
- the support is preferably heat-treated at a temperature higher than the thermal deformation temperature of the fiber and lower than the melting temperature of the fiber while regulating the outer diameter.
- the porous layer and the support do not necessarily need to be in close contact with each other. However, if their adhesiveness is low, they are separated when the hollow fiber membrane is pulled, Layers can escape. Therefore, in the hollow porous hollow fiber membrane of the present embodiment, a part of the porous layer is infiltrated into the knitted string through the stitch of the hollow knitted string, and the porous layer and the hollow knitted string are integrated. It is preferable to make it. In order to provide sufficient adhesion between the porous layer and the support, it is more preferable that the porous layer penetrates 50% or more of the thickness of the hollow knitted string.
- the porous layers that have penetrated 50% or more through different stitches are connected to each other and wrap around a part of the support.
- a portion that wraps a part of the support is connected in the fiber axis direction because the peel resistance is further increased.
- the connection in the fiber axis direction is spiral, it is more preferable because the peel resistance is remarkably improved.
- the above-described film thickness in the present embodiment means the thickness of the portion exposed on the support.
- the porous layer is formed of a film-forming resin.
- a thermoplastic resin can be used as described above, for example, polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyfluorinated vinylidene resin, polyacrylonitrile resin, polyimide resin, polyamideimide resin. Or polyesterimide resin.
- polyvinylidene fluoride resin is preferable because of excellent chemical resistance.
- the porous hollow fiber membrane of this embodiment is preferably formed by a non-solvent phase separation method.
- the non-solvent phase separation method is a method for making a porous layer that induces phase separation by incorporating a non-solvent (water or the like).
- a non-solvent water or the like.
- the thermally induced phase separation method in which phase separation is induced by heat, since the heat propagation speed is high, it is difficult to form a structure in which the pore diameter of the porous layer gradually increases toward the inside.
- a homogeneous structure is formed in terms of the production method.
- the non-solvent phase separation method has an effect of easily forming a structure that gradually increases toward the inside because the diffusion rate of the non-solvent into the inside is slow.
- the porous hollow fiber membrane of this embodiment is formed by applying a film-forming resin containing a porous layer material and a solvent to the outer surface of a hollow support using an annular nozzle. After forming the resin layer, it can be produced by bringing saturated water vapor (conditions such as temperature will be described later) into contact with the surface of the film-forming resin layer and then coagulating with a coagulating liquid.
- FIG. 12 shows the manufacturing apparatus of this embodiment.
- the manufacturing apparatus 1g of the present embodiment is for scavenging a spinning nozzle 10, a processing container 20A disposed on the downstream side of the spinning nozzle 10, a coagulating tank 30 for storing the coagulating liquid B, and a discharge surface 10a of the spinning nozzle.
- Scavenging means 40A for scavenging gas.
- the processing container 20A contains a gas containing a non-solvent of the film-forming resin (hereinafter referred to as “processing gas”), and brings the filament A ′ discharged from the spinning nozzle 10 into contact with the processing gas.
- processing gas a gas containing a non-solvent of the film-forming resin
- the container is configured as described above.
- the non-solvent refers to a solvent that does not have the ability to dissolve the film-forming resin under the reaction conditions in this step (for example, the solubility is less than 1% by mass at room temperature).
- water alcohols such as ethanol, acetone, toluene, ethylene glycol, or a mixture of water and a good solvent used for the film-forming resin solution can be used. Of these, water is particularly preferred.
- the processing container 20A used in the present embodiment is a cylindrical body having a flat ceiling portion 21, a flat bottom portion 22 and a cylindrical side portion 23, and the filament A ′ is introduced into the ceiling portion 21.
- the first opening 21a is formed, and the bottom 22 is formed with a second opening 22a into which the filament A ′ is introduced.
- the openings of the first opening 21a and the second opening 22a are the same, or more processing gas in the processing container 20A flows out of the first opening 21a than the second opening 22a due to thermal buoyancy.
- the opening diameter of the second opening 22a may be made larger than the opening diameter of the first opening 21a.
- the second opening 22 a is disposed above the liquid level of the coagulating liquid B in the coagulating tank 30. That is, in the present embodiment, the processing container 20A and the coagulation liquid B in the coagulation tank are separated from each other, and the second opening 22a is not closed with the coagulation liquid B.
- the filament A ′ is introduced from the first opening 21a, and the filament A ′ brought into contact with the processing gas in the processing container 20A is exposed to the outside from the second opening 22a.
- the processing gas supplied from the gas supply pipe 24 passes through the inside of the processing container 20A, and is then discharged from the first opening portion 21a and the second opening portion 22a.
- the scavenging means 40A is a gas removing means configured to replace the processing gas flowing out in the vicinity of the spinning nozzle 10 with the scavenging gas and remove it, and the scavenging nozzle 41 provided on the discharge surface 10a of the spinning nozzle 10. And a gas supply means 42 for supplying a scavenging gas to the scavenging nozzle 41.
- the scavenging nozzle 41 is formed of an annular member, and has a central circular opening 41a, a gas introduction chamber 41b that is connected to the gas supply means 42 and is formed of an annular space into which scavenging gas is introduced, and a circular opening 41a.
- annular gas discharge port 41c for discharging the scavenging gas supplied from the gas introduction chamber 41b toward the discharge surface 10a of the spinning nozzle 10 exposed.
- the circular opening 41a is arranged so that the center thereof coincides with the center of the support discharge port and the resin solution discharge port of the spinning nozzle 10. Accordingly, the filament A ′ passes through the circular opening 41a.
- the gas introduction chamber 41b is formed concentrically with the scavenging nozzle 41 on the outer peripheral side of the circular opening 41a. Since the gas discharge port 41c communicates with the gas introduction chamber 41b and opens toward the center of the circular opening 41a as shown in FIG. 123, the scavenging gas is centered from the outer peripheral side of the circular opening 41a. It discharges toward
- a protective cylinder 50 is provided on the lower surface of the scavenging nozzle 41 in the scavenging means 40A to cover and protect the filament A ′.
- the protective cylinder 50 is a cylindrical member and has a through hole 50a. Further, the upper end portion 51 of the protective cylinder 50 is closely fixed to the lower surface of the scavenging nozzle 41 so that the through hole 50 a communicates with the circular opening 41 a of the scavenging nozzle 41. The lower end portion 52 of the protective cylinder 50 is spaced apart from the processing container 20A, and a gap Q is formed between the protective cylinder 50 and the treatment container 20A.
- the opening area of the through-hole 50a and the opening area of the opening 52a on the lower end 52 side are small as long as the filament A ′ can pass without contacting.
- the smaller the cross-sectional area of the through-hole 50a the higher the flow rate can be achieved and the scavenging ability can be improved even if the supply amount of the scavenging gas is small.
- the opening area of the opening 52a on the lower end 52 side is smaller, the processing gas flowing out from the first opening 21a can be prevented from flowing into the through hole 50a.
- the flow rate of the scavenging gas from the lower end 52 side toward the first opening 21a is not made faster than necessary, and the opening area of the opening 52a on the lower end 52 side is not made smaller than necessary. .
- the flow rate of the scavenging gas toward the first opening 21a is excessively high, or the opening area of the opening 52a of the lower end 52 is excessively small, the scavenging gas passes through the first opening 21a. There is a risk of entering the processing container 20A and changing the temperature and humidity of the gas in the processing container 20A.
- the material of the protective cylinder 50 is preferably a material that is not corroded or attacked by the gas flowing out of the processing container 20A. Examples of materials that satisfy these requirements include polyethylene, polypropylene, fluororesin, stainless steel, aluminum, ceramic, and glass.
- the material of the protective cylinder 50 preferably has a low thermal conductivity in order to suppress heat dissipation of the scavenging gas flowing through the through hole 50a and temperature change of the scavenging gas due to heat received from the external atmosphere. Examples of the material having low thermal conductivity include polyethylene, polypropylene, fluorine-based resin, ceramic, or glass.
- the material of the protective cylinder 50 is preferably highly transparent because the state of the filament A ′ running through the through hole 50a can be observed from the outside.
- Highly transparent polyethylene, highly transparent polypropylene, transparent Particularly preferred is a highly fluoropolymer tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA) or glass.
- the protective cylinder 50 is preferably detachable from the scavenging nozzle. If the protective cylinder 50 is detachable, it can be removed from the scavenging nozzle 41, so that the hand can easily reach the vicinity of the discharge surface 10a, and the operability at the start of film formation can be improved.
- a mechanical attachment / detachment means such as a screw or a clamp, or a magnet adsorption attachment / detachment means using a magnet and a metal adsorbed to the magnet is simple and suitable.
- the filament A ′ discharged from the spinning nozzle 10 passes through the through hole 50a of the protective cylinder 50 after passing through the gas discharge port 41c. Further, the scavenging gas discharged from the gas discharge port 41c of the scavenging nozzle 41 flows from the upper end 51 toward the lower end 52 in parallel with the filament A 'passing through the through hole 50a. To do. And it discharges toward the process gas which flows out out of the 1st opening part 21a from the through-hole 50a. Thereafter, the scavenging gas flows outward in the gap Q so as to be separated from the first opening 21a together with the processing gas flowing out from the first opening 21a.
- the treatment gas flowing out from the first opening 21a can be replaced with the scavenging gas by the scavenging means 40A and removed from the vicinity of the ejection surface 10a, so that condensation on the ejection surface 10a due to a non-solvent can be prevented.
- precise control of the membrane surface structure of the obtained porous hollow fiber membrane A, uniformity of the membrane surface structure, and quality of the porous hollow fiber membrane A can be improved.
- dry air refers to a gas having a relative humidity (vapor pressure with respect to saturated vapor pressure) of 0 to 9%.
- a gas temperature adjusting means to be heated dry air, which is supplied to the scavenging nozzle 41. It is preferable to supply.
- the manufacturing method of the porous hollow fiber membrane A using the said manufacturing apparatus 1a is demonstrated.
- This manufacturing method has a spinning process, a scavenging process, and a coagulation process.
- the hollow string-like support A1 is discharged downward from the support discharge port of the spinning nozzle 10 while the film-forming resin solution is discharged downward from the resin solution discharge port, thereby forming the hollow string.
- a film A2 of a film-forming resin solution is formed on the outer peripheral surface of the support A1 to produce a hollow filamentous body A ′.
- the film-forming resin solution usually contains a film-forming resin, a hydrophilic resin, and a solvent for dissolving them.
- the film-forming resin solution may contain other additive components as necessary.
- the hydrophilic resin is added to adjust the viscosity of the film-forming resin solution to a range suitable for the formation of the hollow porous hollow fiber membrane A, and to stabilize the film-forming state.
- Glycol or polyvinyl pyrrolidone is preferably used. Among these, polyvinyl pyrrolidone or a copolymer obtained by copolymerizing other monomers with polyvinyl pyrrolidone from the viewpoint of controlling the pore diameter of the obtained hollow porous hollow fiber membrane and the strength of the hollow porous hollow fiber membrane. preferable.
- hydrophilic resin can also be mixed and used.
- a higher molecular weight hydrophilic resin when a higher molecular weight hydrophilic resin is used, a hollow porous hollow fiber membrane having a good membrane structure tends to be formed.
- a low molecular weight hydrophilic resin is preferable in that it is more easily removed from the hollow porous hollow fiber membrane A. Therefore, the same kind of hydrophilic resins having different molecular weights may be appropriately blended depending on the purpose.
- the solvent examples include N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, or N-methylmorpholine-N monooxide, and one or more of these can be used.
- a poor solvent or a non-solvent of the film-forming resin or the hydrophilic resin may be mixed and used as long as the solubility of the film-forming resin or the hydrophilic resin in the solvent is not impaired.
- the temperature of the film-forming resin solution is not particularly limited, but is usually 20 to 40 ° C.
- the viscosity of the film-forming resin solution at 40 ° C. is preferably 20,000 to 500,000 mPa ⁇ second, more preferably 50,000 to 300,000 mPa ⁇ second, and 70,000 to 250,000 mPa ⁇ second. More preferably it is. If the viscosity is too low, the phase separation rate increases, and Ad and Bd become too large, and the separation characteristics deteriorate. On the other hand, if the viscosity is too high, the speed of phase separation decreases, and it becomes difficult to make Bd sufficiently larger than Ad.
- the lower limit is preferably 10% by mass and more preferably 15% by mass with respect to the total mass of the film-forming resin solution.
- the upper limit is preferably 30% by mass, and more preferably 25% by mass with respect to the total mass of the film-forming resin solution.
- the film-forming resin may be in the range of 10 to 30% by mass, preferably 15 to 25% by mass, based on the total mass of the film-forming resin solution.
- the lower limit of the concentration of the hydrophilic resin is preferably 1% by mass, preferably 5% by mass with respect to the total mass of the film-forming resin solution in order to make it easier to form a hollow porous hollow fiber membrane. More preferred.
- the upper limit of the concentration of the hydrophilic resin is preferably 20% by mass and more preferably 12% by mass with respect to the total mass of the film-forming resin solution from the viewpoint of the handleability of the film-forming resin solution. Specifically, it may be in the range of 1 to 20% by mass, preferably 5 to 20% by mass with respect to the total mass of the film-forming resin solution.
- the composition of the film-forming resin solution is not particularly limited as long as the structure that gradually increases from the porous layer A to the porous layer C can be formed by phase separation, but the surface porosity of the porous layer can be increased. Therefore, the ratio of the solvent is preferably 68% by mass or more, more preferably 70% or more with respect to the total mass of the film-forming resin solution. Moreover, since there exists a tendency which can form the gradual increase structure without a big macrovoid, it is preferable that the mass ratio of hydrophilic resin / film-forming resin is 0.45 or more. Below this value, it tends to form macrovoids and tends to form a sea-island structure rather than a co-continuous structure, resulting in a decrease in surface porosity and formation of a homogeneous structure, It is not preferable.
- the scavenging step in the present embodiment is a step of feeding a scavenging gas to the discharge surface 10a of the spinning nozzle 10. Specifically, in the scavenging step, first, the scavenging gas supplied from the gas supply unit 432 is filtered by the gas filtering unit 43, the temperature and humidity are adjusted by the gas adjusting unit 44, and then supplied to the gas introduction chamber 41 b. At this time, since the condensation on the discharge surface 10a can be further spun, the scavenging gas is preferably adjusted by the gas adjusting means 44 so that the dew point is lower than the surface temperature of the discharge surface of the spinning nozzle 10.
- the scavenging gas In order to keep the temperature of the spinning nozzle 10 and the filament A ′ from changing from the set state, it is preferable to supply the scavenging gas at the same temperature as the set temperature of the spinning nozzle 10.
- the pressure distribution of the scavenging gas is made uniform by the resistance applying body 41d provided in the gas discharge port 41c.
- the scavenging gas in the gas introduction chamber 41b is discharged toward the center of the circular opening 41a through the resistance applying body 41d of the gas discharge port 41c, and the scavenging gas is sent to the discharge surface 10a.
- the scavenging gas discharged from the gas discharge port 41c flows from the upper end 51 toward the lower end 52 around the filament A ′ passing through the through hole 50a in parallel with the filament A ′. And it discharges toward the process gas which flows out out of the 1st opening part 21a from the through-hole 50a. Thereafter, the scavenging gas is discharged toward the outside in the gap Q together with the processing gas flowing out from the first opening 21a so as to be separated from the first opening 21a.
- the dew point of the non-solvent in the atmosphere in the vicinity of the spinning nozzle 10 is made lower than the surface temperature of the spinning nozzle 10.
- the dew point of the non-solvent in the atmosphere in the vicinity of the spinning nozzle 10 is equal to or higher than the spinning nozzle 10, spinning of condensation becomes difficult.
- the dew point of the non-solvent in the atmosphere means that when the amount of the non-solvent that the atmosphere can contain matches the amount of the non-solvent contained in the atmosphere and the ambient temperature decreases, This is the temperature at which the non-solvent that cannot be used begins to condense.
- the relative humidity of the non-solvent in the atmosphere near the spinning nozzle is less than 10%.
- “the relative humidity of the non-solvent in the atmosphere” It is a value (unit:%) determined by the amount of non-solvent contained in an atmosphere at a certain temperature / the amount of saturated non-solvent at that temperature ⁇ 100.
- the coagulation step is a step in which the film-forming resin solution discharged from the spinning nozzle 10 is immersed in the coagulation liquid B in the coagulation tank 30 after being brought into contact with the processing gas in the processing vessel 20A.
- the filament A ′ is brought into contact with the processing gas in the processing vessel 20A and the coagulation liquid B in the coagulation tank 30 to thereby form a coating film of the film-forming resin solution of the filament A ′.
- A2 is solidified to obtain a porous hollow fiber membrane A.
- the filament A ′ formed with the coating film A2 of the film-forming resin solution in the spinning process is introduced into the processing container 20A from the first opening 21a of the processing container 20A.
- the non-solvent component contained in the processing gas diffuses and enters the coating film A2 that has come into contact with the processing gas, and phase separation starts.
- examples of the processing gas include air in which the non-solvent is saturated, air in which the non-solvent is non-saturated, and saturated vapor of the non-solvent.
- a non-solvent saturated vapor is preferred.
- the film-forming resin is a hydrophobic polymer, water, alcohols such as ethanol, acetone, toluene, ethylene glycol, or the like can be used as the non-solvent, but water is particularly preferable.
- the processing gas is a non-solvent saturated vapor
- the entire periphery of the filament A ′ passing through the processing container 20A is filled with the non-solvent.
- characteristics when the processing gas is saturated water vapor at atmospheric pressure will be described.
- the temperature of the saturated water vapor under atmospheric pressure is about 100 ° C., and the space in the processing vessel 20A filled with the saturated water vapor is filled with 100% water molecules. Therefore, when saturated steam is used as the processing gas, the ambient temperature and humidity around the filament A ′ can be easily made uniform. Further, the saturated water vapor can increase the amount of water and the amount of heat supplied per unit time to the filament A ′ passing through the processing container 20A, as compared with gases containing other moisture.
- the amount of heat of condensation when water vapor condenses is extremely large, and the heat of condensation heat transfer is high, so that the temperature near the surface layer of the filament A ′ can be instantaneously raised to near 100 ° C. Therefore, the phase separation behavior is completely different from the case where the filament A ′ is passed through a gas containing water in an unsaturated state by water supply and heat supply in saturated steam condensation due to a temperature difference from the filament A ′. Can be generated.
- the outer surface of the membrane proceeds to solidification immediately after phase separation. Therefore, if the viscosity of the film-forming resin solution is adjusted to a relatively high value, a dense structure suitable for filtration can be obtained. It can be formed on the surface.
- a large amount of moisture immediately diffuses and penetrates to the inside of the membrane, and can cause up to phase separation of the surface layer portion of the filament A ′ while the filament A ′ is in the processing container 20A.
- the phase separation rate is very high, and thereby a structure sufficiently large with respect to the structure of the porous layer A is obtained.
- the porous layer A can be formed on the inner surface layer.
- the filament A ′ whose outer surface structure is fixed and the phase separation has proceeded to the inner surface layer in the processing vessel 20A is then introduced into the coagulation tank 30 and brought into contact with the coagulation liquid B. .
- the non-solvent component of the coagulation liquid B diffuses and penetrates into the coating film A2 of the film-forming resin solution. Since the coagulating liquid B is a liquid, a large amount of non-solvent rapidly enters even when compared with saturated water vapor, and solidifies through phase separation to the inside, so that the porous hollow fiber membrane A is obtained.
- the coagulation liquid B is a non-solvent for the film-forming resin and a good solvent for the hydrophilic resin, and examples thereof include water, techanol, methanol, and mixtures thereof. Among them, the coagulating liquid B is used for the film-forming resin solution.
- a mixed solution of a solvent and water is preferable from the viewpoints of safety and operation management.
- the concentration of the solvent is preferably in the range of 5 to 50% by mass with respect to the total mass of the solvent, water and the mixed solution. The range of 10 to 40% by mass is more preferable. Below this range, the rate of increase of the non-solvent increases and the internal structure may become too dense. Moreover, if it exceeds this range, a sufficient amount of non-solvent cannot enter and solidification may not be completed in the coagulation tank.
- the temperature of the coagulation liquid B is in the range of 30 to 95 ° C, preferably 40 to 85 ° C.
- the porous hollow fiber membrane A can be washed with hot water and then treated with an oxidant-containing liquid to decompose and remove the hydrophilic resin. preferable.
- the method for producing a porous hollow fiber membrane of the present embodiment and the hollow fiber membrane produced thereby can be applied mainly in the field of water treatment.
- it can be used in a method for producing a porous hollow fiber membrane of the present embodiment, a water purification treatment method using the hollow fiber membrane produced thereby, and other water treatment methods.
- the manufacturing method of the porous hollow fiber membrane of this embodiment and the hollow fiber membrane manufactured thereby can be used in a water purification device or the like provided with the structure, and used in the manufacturing method of the water purification device or the like. Can do.
- each of the configurations of the above-described embodiments can be used in appropriate combination.
- the outer surface of the obtained porous film is observed with a scanning electron microscope (SEM).
- SEM scanning electron microscope
- the porous membrane is a porous hollow fiber membrane
- a reference point on the outer surface of the porous hollow fiber membrane is determined, and this is set to 0 °, and SEM photographs are taken from four directions of 90 °, 180 °, and 270 °. To do.
- the observation magnification depends on the desired fractional pore diameter, it cannot be generally stated, but in the case of a microfiltration membrane, it is 10,000 to 100,000 times. When outside this range, the pore diameter on the outer surface cannot be sufficiently observed at 5000 times or less, and when it is 100,000 or more times, the number of holes in the field of view decreases, and the average pore diameter is May be difficult to say.
- the diameter of the hole recognized by the image analysis software is taken as the hole diameter, the hole diameter of all the holes in the SEM photograph is calculated, the hole diameter index is calculated from the average value, and the surface or cross-sectional structure of the porous membrane is calculated accordingly. Assess quantitatively.
- the data is arranged so that the calculated total holes are in descending order by area, the area is integrated from the upper holes, and the holes up to a place corresponding to an arbitrary ratio of 50% with respect to the total area are used. Calculate the pore size index. For example, although not limited, this arbitrary ratio A is assumed.
- the outer diameter of the support was measured by the following method. A sample to be measured was cut into approximately 10 cm, several bundles were bundled, and the whole was covered with a polyurethane resin. The polyurethane resin also entered the hollow part of the support. After the polyurethane resin was cured, a thin piece having a thickness (longitudinal direction of the film) of about 0.5 mm was sampled using a razor blade. Next, the sampled cross section of the support was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens magnification of 100 times. A mark (line) was aligned with the position of the outer surface in the X direction and Y direction of the cross section of the support being observed, and the outer diameter was read. This was measured three times to determine the average value of the outer diameter.
- the inner diameter of the support was measured by the following method.
- the sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
- the sampled cross section of the support was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens magnification of 100 times.
- a mark (line) was aligned with the position of the inner surface in the X direction and Y direction of the cross section of the support being observed, and the inner diameter was read. This was measured three times to determine the average inner diameter.
- the outer diameter of the porous hollow fiber membrane was measured by the following method. A sample to be measured was cut into approximately 10 cm, several bundles were bundled, and the whole was covered with a polyurethane resin. The polyurethane resin also entered the hollow part of the support. After the polyurethane resin was cured, a thin piece having a thickness (longitudinal direction of the film) of about 0.5 mm was sampled using a razor blade. Next, a cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times. A mark (line) was placed at the position of the outer surface in the X direction and Y direction of the cross section of the porous hollow fiber membrane being observed, and the outer diameter was read. This was measured three times to determine the average value of the outer diameter.
- the inner diameter of the porous hollow fiber membrane was measured by the following method.
- the sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
- a cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
- a mark (line) was aligned with the position of the inner surface of the support in the X and Y directions of the cross section of the porous hollow fiber membrane being observed, and the inner diameter was read. This was measured three times to determine the average inner diameter.
- the film thickness of the porous membrane layer in Examples and the like is the thickness from the surface of the support to the surface of the porous hollow fiber membrane, and was measured by the following method.
- the sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
- the cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
- the film thickness was read by aligning marks (lines) at the positions of the outer surface and inner surface of the film at the 3 o'clock position on the cross section of the porous hollow fiber membrane being observed.
- the film thickness was read in the order of 9 o'clock, 12 o'clock, and 6 o'clock. This was measured three times to determine the average inner diameter.
- Pore diameter of porous membrane layer The pore diameter of the porous layer was measured by the following method. The cross-sectional structure to be measured was photographed at a magnification of 10,000 using a scanning electron microscope, and the average pore diameter index of the structure was obtained by image analysis processing of the obtained photograph. As image analysis processing software, IMAGE-PRO PLUS version 5.0 of Media Cybernetics was used.
- the water permeability of the porous hollow fiber membrane was measured by the following method.
- the sample to be measured was cut into 4 cm, and one end face was sealed with a polyurethane resin at the hollow portion.
- the sample was decompressed in ethanol for 5 minutes or more and then immersed in pure water for replacement.
- Pure water 25 ° C.
- an air pressure of 200 kPa was applied to the container to measure the amount of pure water coming out of the sample for 1 minute. This was measured three times to obtain an average value. This value was divided by the surface area of the sample to determine the water permeability.
- Process (1) The cross-sectional surface of the porous hollow fiber membrane is observed with an SEM, and the area of the hole diameter of all the holes captured by an electron micrograph is measured.
- Step (2) In step (1), data are arranged so that the calculated hole diameters are in descending order by area, the areas are integrated from the upper holes, and up to a place corresponding to a specific ratio B (50%) with respect to the total area. Using the holes, the area is regarded as a perfect circle, and the diameter (hole diameter) is calculated as an average hole diameter index.
- Polyester fibers (polyethylene terephthalate (PET), fineness: 84 dtex, number of filaments: 36, false twisted yarn) were used as hollow reinforcing support yarns.
- As bobbins used for producing the hollow reinforcing support five pieces of polyester fiber wound around 5 kg are prepared.
- a circular knitting machine a table type string knitting machine (manufactured by Sonai Textile Machinery Co., Ltd., number of knitted needles: 12 needles, needle size: 16 gauge, spindle diameter: 8 mm) were used.
- a Nelson roll was used as the string supply device and the take-up device.
- the heating die As the heating die, a stainless steel die (outer diameter D: 5 mm, inner diameter d: 2.5 mm, length L: 300 mm) having heating means was used. Five polyester fibers drawn from the bobbin were combined into a single yarn (total fineness: 420 dtex), and then circular knitted by a circular knitting machine to form a hollow knitted string. The hollow knitted string was passed through a heating die at 210 ° C., and the heat-treated hollow knitted string was wound as a hollow reinforcing support using a winding device at a winding speed of 200 m / hour. The obtained hollow reinforcing support had an outer diameter of about 2.5 mm and an inner diameter of about 1.7 mm. The number of loops of the hollow braid constituting the hollow reinforcing support was 12 per round, and the maximum opening width of the stitch was about 0.1 mm. The length of the hollow reinforcing support was 12000 m.
- Polyvinylidene fluoride (Arkema, trade name: Kyner 301F) 11.5% by mass, Polyvinylidene fluoride (Arkema, trade name: Kyner 9000LD) 11.5% by mass and polyvinylpyrrolidone (Nippon Shokubai, trade name) K-80) was dissolved in 65% by mass of N, N-dimethylacetamide with stirring to prepare a first film-forming resin solution.
- the viscosity of this first film-forming resin solution at 40 ° C. was 210,000 mP ⁇ sec.
- a spinning nozzle As a spinning nozzle, a through hole for a support that allows a hollow reinforcing support to pass through, and a flow path for resin solutions of two types of film-forming resin solutions (first flow path for resin solution, second resin) A multi-annular nozzle formed with a solution flow path) was used.
- a support discharge port, a first resin solution discharge port, and a second resin solution discharge port are formed on the lower surface.
- the processing container was arranged above the coagulation tank so that a gap of 10 mm from the coagulation liquid surface was formed.
- the processing container and the protective cylinder were arranged such that a gap of 5 mm was formed between the lower end opening of the protective cylinder and the first opening of the processing container.
- the scavenging nozzle was arranged so that its upper surface and the lower surface of the spinning nozzle were bonded.
- the scavenging nozzle was supplied with dry air at a temperature of 32 ° C. and a relative humidity of less than 1% at 6 L / min. 100 degreeC saturated water vapor
- the supply amount of water vapor is a flow rate adjusting valve while monitoring the temperature of a thermocouple having a diameter of 0.5 mm inserted 5 mm from the first opening while supplying dry air to the scavenging nozzle at 6 L / min. was opened little by little and the lower limit flow rate at which the thermocouple temperature was stable at 100 ° C. for 10 minutes or more was set.
- the water vapor discharged from the flow rate adjusting valve is cooled and liquefied, and the mass of drain water obtained per unit time is measured and converted to a water vapor volume of 100 ° C., which is equivalent to about 5 NL / min. It was.
- the coagulation tank was filled with a coagulation liquid having a composition of 10% by mass of N, N-dimethylacetamide as a solvent component and 90% by mass of pure water as a non-solvent component.
- the coagulation tank was kept at 75 ° C.
- the film-forming resin solution 1 at 32 ° C. was supplied to the spinning nozzle at a supply rate of 23.2 cm 3 / min, and the film-forming resin solution 2 at 32 ° C. was supplied at 25.0 cm 3 / min.
- the film-forming resin solution 1 and the film-forming resin solution 2 are discharged concentrically from the resin solution discharge port, and a film is formed on the outer peripheral surface of the hollow knitted string support drawn from the support discharge port at 20 m / min.
- Resin solutions 1 and 2 were applied.
- a filament A ′ in which the film-forming resin solution was applied to the hollow knitted string support was obtained.
- the filament A ′ was passed through a scavenging nozzle, a processing container, and a coagulating liquid in this order to obtain a porous hollow fiber membrane.
- the obtained porous hollow fiber membrane was passed through hot water at 98 ° C. for 1 minute to remove the solvent.
- After immersing in a 30,000 mg / L sodium hypochlorite aqueous solution it was heat-treated in a steam bath at 98 ° C. for 2 minutes. Subsequently, it was washed in hot water at 98 ° C. for 15 minutes, dried at 110 ° C.
- Example 2 As the first and second film-forming resin solutions, 19% by mass of polyvinylidene fluoride (trade name Kyner 761A, manufactured by Arkema Co., Ltd.) and 12% by mass of polyvinyl pyrrolidone (trade name, K-80, manufactured by Nippon Shokubai Co., Ltd.) Using a film-forming resin solution dissolved in 69% by mass of N-dimethylacetamide with stirring, a composition containing 20% by mass of N, N-dimethylacetamide as a coagulating liquid and 80% by mass of pure water as a non-solvent component A porous hollow fiber membrane was obtained in the same manner as in Example 1 except that the coagulating liquid was used. The viscosity of this film-forming resin solution at 40 ° C. was 250,000 mP ⁇ sec. For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
- Example 3 As the first and second film-forming resin solutions, 15% by mass of polyvinylidene fluoride (trade name Kyner 761A, manufactured by Arkema Co., Ltd.) and 11% by mass of polyvinyl pyrrolidone (trade name, K-80, manufactured by Nippon Shokubai Co., Ltd.) A porous hollow fiber membrane was obtained in the same manner as in Example 6 except that the membrane-forming resin solution dissolved in 74% by mass of N-dimethylacetamide with stirring was used. The viscosity of this film-forming resin solution at 40 ° C. was 80,000 mP ⁇ sec. For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
- Example 1 The same first and second film-forming resin solutions as in Example 1 were used.
- the coagulation tank was filled with a coagulation liquid having a composition of 8% by mass of N, N-dimethylacetamide as a solvent component and 92% by mass of pure water as a non-solvent component.
- the coagulation tank was kept at 70 ° C.
- the film forming resin solution 1 at 32 ° C. was supplied to the spinning nozzle at a supply rate of 17.4 cm 3 / min, and the film forming resin solution 2 at 32 ° C. was supplied at 18.7 cm 3 / min.
- the film-forming resin solution 1 and the film-forming resin solution 2 are discharged concentrically from the resin solution discharge port, and a film is formed on the outer peripheral surface of the hollow knitted string support drawn from the support discharge port at 15 m / min. Resin solutions 1 and 2 were applied. As a result, a filament A ′ in which the film-forming resin solution was applied to the hollow knitted string support was obtained.
- the obtained filament A ′ was introduced into a cover for forming a high-temperature and high-humidity atmosphere whose interior was filled with steam of a coagulating liquid (temperature of 70 ° C.) and subjected to a high-temperature and high-humidity treatment.
- the distance that the filament A ′ travels in the high temperature and high humidity atmosphere in the high temperature and high humidity atmosphere forming cover was set to 67 mm.
- the filament A ′ subjected to the high-temperature and high-humidity treatment was passed through a coagulation liquid (temperature: 70 ° C.) in the coagulation tank.
- a coagulating liquid was adhered to the outer peripheral surface of the filament A ′, and the coating film of the film-forming resin solution was coagulated to obtain a porous hollow fiber membrane.
- the obtained porous hollow fiber membrane was washed and dried in the same manner as in Example 1.
- the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
- Example 2 For the porous hollow fiber membrane (ZeeWeed 500) manufactured by GE, the average pore size of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
- a porous hollow fiber membrane 1 was produced using a porous hollow fiber membrane production apparatus.
- Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at a mass ratio shown in Table 2 to prepare membrane-forming stock solutions (1) and (5).
- the film-forming rate is 20 m / min, the length of the 100% water vapor emphasis region is 5 mm, and the film-forming stock solution (1) is combined with the outer layer and the film-forming stock solution (5) is combined with the inner layer at a coagulation bath temperature of 75 ° C. Application and film formation were performed.
- the outer diameter of the obtained porous hollow fiber membrane 1 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 ⁇ m on average, and the bubble point (Pi)
- the water permeability was 210 m 3 / m 2 / h / MPa.
- the surface opening ratio A1 was 40%, and the pore diameter index P1 was 0.21 ⁇ m.
- the aperture ratio A2 in the inner dense layer was 27%, and the pore diameter index P2 was 0.46 ⁇ m.
- the film-forming speed is 20 m / Min
- the length of the 100% water vapor emphasis region is 5 mm
- the temperature of the coagulation bath is 75 ° C.
- the film-forming stock solution (2) is the outer layer
- the film-forming stock solution (5) is the inner layer.
- the outer diameter of the obtained porous hollow fiber membrane 2 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 ⁇ m on average, and the bubble point (Pi) Was 197 kPa, and the water permeability was 49 m 3 / m 2 / h / MPa.
- the surface opening ratio A1 was 41%, and the pore diameter index P1 was 0.23 ⁇ m.
- the aperture ratio A2 in the inner dense layer was 23%, and the pore diameter index P2 was 0.45 ⁇ m.
- a porous hollow fiber membrane 3 was produced in the same manner as in Reference Example 1 using a porous hollow fiber membrane production apparatus.
- Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at the mass ratio shown in Table 2 to prepare membrane-forming stock solutions (3) and (5).
- the film-forming speed is 20 m / Min, the length of the 100% water vapor emphasis region is 5 mm, and the temperature of the coagulation bath is 75 ° C. Application and film formation were performed.
- the outer diameter of the obtained porous hollow fiber membrane 3 is about 2.80 mm, the inner diameter is about 1.2 mm, the average thickness of the porous membrane layer 11 is about 150 ⁇ m, and the bubble point (Pi)
- the water permeability was 164 kPa and 98 m 3 / m 2 / h / MPa.
- the surface opening ratio A1 was 45%, and the pore diameter index P1 was 0.31 ⁇ m.
- the aperture ratio A2 in the inner dense layer was 25%, and the pore diameter index P2 was 0.67 ⁇ m.
- the film-forming speed is 20 m / min
- the length of the 100% water vapor emphasis region is 5 mm
- the film-forming stock solution (4) is the outer layer
- the film-forming stock solution (5) is the inner layer at a coagulation bath temperature of 75 ° C.
- Application and film formation were performed.
- the outer diameter of the obtained porous hollow fiber membrane 4 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 ⁇ m on average, and the bubble point (Pi)
- the water permeation performance was 91 kPa and 168 m 3 / m 2 / h / MPa.
- the surface opening ratio A1 was 50%, and the pore diameter index P1 was 0.36 ⁇ m.
- the aperture ratio A2 in the internal dense layer was 26%, and the pore diameter index P2 was 1.1 ⁇ m.
- the film forming speed is 12.5 m / min, the high humidity and high temperature region length is 63.5 mm, and the coagulation bath temperature is 75 ° C.
- the film forming stock solution (4) is combined with the outer layer and the film forming stock solution (5) is combined with the inner layer. The film was applied to form a film.
- the outer diameter of the obtained porous hollow fiber membrane 4 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 ⁇ m on average, and the bubble point (Pi)
- the water permeation performance was 170 m 3 / m 2 / h / MPa.
- the surface opening ratio A1 was 26%, and the pore diameter index P1 was 0.17 ⁇ m.
- the aperture ratio A2 in the inner dense layer was 5%, and the pore diameter index P2 was 0.13 ⁇ m.
- the present embodiment it can be used in the treatment of various aqueous fluids such as water purification treatment, beverage treatment, seawater turbidity, etc., and it has excellent fractionation characteristics and permeability, while the performance deterioration with time.
- a porous hollow fiber membrane excellent in recovery of membrane separation characteristics by washing, and an evaluation method thereof can be provided.
- the porous hollow fiber membrane of the present embodiment has a structure in which the pore diameter of the inner layer is sufficiently large relative to the pore diameter of the layer forming the outer surface and is not easily clogged. Therefore, the hollow porous hollow fiber membrane of this embodiment has high filtration stability, and is suitable as a filtration membrane used for water treatment such as water purification such as microfiltration and ultrafiltration.
Abstract
Provided is a porous hollow fiber membrane and a method for manufacturing same, the porous hollow fiber membrane being able to be used suitably in devices for processing various water-based fluids for use in applications such as water purification, drinking-water processing, and seawater clarification; having excellent fractionation characteristics and permeability with minimal decrease in performance over time; having excellent recovery in membrane separation characteristics by washing: and having excellent separation characteristics, filtration stability, and mechanical strength. The present invention is a porous hollow fiber membrane having a porous layer made of a thermoplastic resin in at least an outer surface and the vicinity thereof, the average pore diameter (Ad) at a depth of 1 μm from the surface as seen in cross-section being no more than 0.6 of the average pore diameter (Bd) from a depth of 2 to 3 μm, and a method for manufacturing said membrane.
Description
本発明は、主に水中の細菌、ウイルス、ＳＳ成分等の除去に使用される耐ファウリング性能に優れた多孔質中空糸膜に関する。詳しくは、長期間の安定した膜性能、洗浄による膜性能の回復性に優れた多孔質中空糸膜に関するものである。本発明はまた、精密濾過膜又は限外濾過膜として用いることができる浄水処理等の水処理に適した多孔質中空糸膜及びその製造方法に関する。
本願は、２０１３年９月１８日に日本に出願された特願２０１３－１９３２１３号及び２０１３年９月１８日に日本に出願された特願２０１３－１９３２１４号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a porous hollow fiber membrane having excellent anti-fouling performance, which is mainly used for removing bacteria, viruses, SS components and the like in water. Specifically, the present invention relates to a porous hollow fiber membrane that is excellent in stable membrane performance over a long period of time and excellent in recoverability of membrane performance by washing. The present invention also relates to a porous hollow fiber membrane suitable for water treatment such as water purification treatment that can be used as a microfiltration membrane or an ultrafiltration membrane, and a method for producing the same.
This application claims priority based on Japanese Patent Application No. 2013-193213 filed in Japan on September 18, 2013 and Japanese Patent Application No. 2013-193214 filed on September 18, 2013 in Japan. Is hereby incorporated by reference.
本願は、２０１３年９月１８日に日本に出願された特願２０１３－１９３２１３号及び２０１３年９月１８日に日本に出願された特願２０１３－１９３２１４号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a porous hollow fiber membrane having excellent anti-fouling performance, which is mainly used for removing bacteria, viruses, SS components and the like in water. Specifically, the present invention relates to a porous hollow fiber membrane that is excellent in stable membrane performance over a long period of time and excellent in recoverability of membrane performance by washing. The present invention also relates to a porous hollow fiber membrane suitable for water treatment such as water purification treatment that can be used as a microfiltration membrane or an ultrafiltration membrane, and a method for producing the same.
This application claims priority based on Japanese Patent Application No. 2013-193213 filed in Japan on September 18, 2013 and Japanese Patent Application No. 2013-193214 filed on September 18, 2013 in Japan. Is hereby incorporated by reference.
河川水や湖沼水、地下水等の淡水水源から水道水を製造する上水分野の濾過処理においては、従来、砂濾過及び凝集沈殿と砂濾過の併用が広く利用されてきた。しかし、これらの処理においては、耐塩素性が高く濾過後の塩素滅菌では完全に無害化できない恐れの有るクリプトスポリジジウムに起因する水源汚染等の懸念がある。こうした背景の上で、より容易かつ精度良く濁質を除去できる膜濾過法が、単独、あるいは凝集沈殿や砂濾過等の他の水処理技術と組み合わせて、多く採用されているようになりつつある。一方、逆浸透膜による海水の淡水化に際しても、逆浸透膜に供給される海水は、あらかじめ凝集沈殿、砂濾過等の前処理によって除濁処理を施された後、逆浸透膜に供給され脱塩処理がなされる。これらの処理についても、凝集沈殿又は砂濾過に代わって、あるいは他の水処理技術と組み合わされて、膜濾過による除濁が採用される場合が増加しつつある。
Conventionally, sand filtration and combined use of coagulation sedimentation and sand filtration have been widely used in the filtration process in the water supply field, where tap water is produced from fresh water sources such as river water, lake water, and groundwater. However, in these treatments, there is a concern such as water source contamination due to Cryptosporidium which has high chlorine resistance and may not be completely rendered harmless by chlorine sterilization after filtration. Against this background, membrane filtration methods that can remove turbidity more easily and accurately are becoming more and more used alone or in combination with other water treatment technologies such as coagulation sedimentation and sand filtration. . On the other hand, when desalinating seawater using a reverse osmosis membrane, the seawater supplied to the reverse osmosis membrane is subjected to a turbidity treatment in advance by a pretreatment such as coagulation sedimentation or sand filtration, and then supplied to the reverse osmosis membrane to be removed. Salt treatment is performed. For these treatments, there is an increasing number of cases where turbidity by membrane filtration is employed instead of coagulation sedimentation or sand filtration or in combination with other water treatment techniques.
膜分離に使用される多孔質中空糸膜に求められる要求特性としては、例えば、次の各点が挙げられる。
（１）被除去物質の除去性が高いこと。
（２）透過物質の透過性が高いこと。
（３）処理流体の透過性が高いこと。
（以下、（１）、（２）、（３）をあわせて膜分離特性という。）
（４）引張り等に対する破断強度が十分に高く、破断やリークしにくいこと。
（５）分画特性が経時的に低下しにくいこと。
（６）処理流体の透過性が経時的に低下しにくいこと。
（以下、（５）、（６）をあわせて膜分離特性の保持性という。）
（７）洗浄による分画特性の回復に優れていること。
（８）洗浄による透過性の回復に優れていること。
（以下、（７）、（８）をあわせて膜分離特性の回復性という。） Examples of the required characteristics required for the porous hollow fiber membrane used for membrane separation include the following points.
(1) The removability of the substance to be removed is high.
(2) The permeability of the permeable substance is high.
(3) The permeability of the processing fluid is high.
(Hereinafter, (1), (2), and (3) are collectively referred to as membrane separation characteristics.)
(4) The rupture strength against tension or the like is sufficiently high, and it is difficult to break or leak.
(5) The fractionation characteristics are unlikely to deteriorate over time.
(6) The permeability of the processing fluid is difficult to decrease over time.
(Hereinafter, (5) and (6) are collectively referred to as retention of membrane separation characteristics.)
(7) Excellent recovery of fractionation characteristics by washing.
(8) It is excellent in recovering permeability by washing.
(Hereinafter, (7) and (8) are collectively referred to as recoverability of membrane separation characteristics.)
（１）被除去物質の除去性が高いこと。
（２）透過物質の透過性が高いこと。
（３）処理流体の透過性が高いこと。
（以下、（１）、（２）、（３）をあわせて膜分離特性という。）
（４）引張り等に対する破断強度が十分に高く、破断やリークしにくいこと。
（５）分画特性が経時的に低下しにくいこと。
（６）処理流体の透過性が経時的に低下しにくいこと。
（以下、（５）、（６）をあわせて膜分離特性の保持性という。）
（７）洗浄による分画特性の回復に優れていること。
（８）洗浄による透過性の回復に優れていること。
（以下、（７）、（８）をあわせて膜分離特性の回復性という。） Examples of the required characteristics required for the porous hollow fiber membrane used for membrane separation include the following points.
(1) The removability of the substance to be removed is high.
(2) The permeability of the permeable substance is high.
(3) The permeability of the processing fluid is high.
(Hereinafter, (1), (2), and (3) are collectively referred to as membrane separation characteristics.)
(4) The rupture strength against tension or the like is sufficiently high, and it is difficult to break or leak.
(5) The fractionation characteristics are unlikely to deteriorate over time.
(6) The permeability of the processing fluid is difficult to decrease over time.
(Hereinafter, (5) and (6) are collectively referred to as retention of membrane separation characteristics.)
(7) Excellent recovery of fractionation characteristics by washing.
(8) It is excellent in recovering permeability by washing.
(Hereinafter, (7) and (8) are collectively referred to as recoverability of membrane separation characteristics.)
一般的に、膜濾過プロセスにおいては、膜濾過操作時間の経過につれて、原水が供給される側の膜表面にファウリング物質が付着、蓄積し、膜濾過抵抗が増大して膜濾過効率が低下する現象が生じる。その時、膜表面に付着したファウリング物質を除去するために、洗浄やエアスクラブ、供給水の脱液、又は化学洗浄等の洗浄操作を行って膜濾過抵抗を回復させ、再度膜濾過を再開する。左記の膜濾過操作と洗浄操作を繰り返し、膜濾過プロセスは運用される。洗浄操作には電気、及び水等のユーティリティを必要とし、また洗浄操作を行っている期間は、生産水は得らないため、洗浄操作頻度は低く洗浄操作時間は短い方が好ましい。従って、膜濾過操作時間の経過につれて生じる膜濾過抵抗の増大が小さく、洗浄操作による膜濾過抵抗の回復が大きい分離膜を得ることができれば、非常に有用である。
In general, in the membrane filtration process, as the membrane filtration operation time elapses, fouling substances adhere and accumulate on the membrane surface on the side where raw water is supplied, and membrane filtration resistance increases and membrane filtration efficiency decreases. A phenomenon occurs. At that time, in order to remove the fouling substances adhering to the membrane surface, washing operation such as washing, air scrub, draining of feed water, or chemical washing is performed to restore membrane filtration resistance, and membrane filtration is resumed. . The membrane filtration process is operated by repeating the membrane filtration operation and the washing operation on the left. The washing operation requires utilities such as electricity and water, and during the washing operation, since production water is not obtained, the washing operation frequency is low and the washing operation time is preferably short. Therefore, it is very useful if a separation membrane can be obtained in which the increase in the membrane filtration resistance that occurs with the passage of the membrane filtration operation is small and the recovery of the membrane filtration resistance by the washing operation is large.
従来技術においては、膜表面を親水化して耐ファウリング性を向上させ、膜濾過操作中の濾過抵抗の増大を抑制する方向での技術開発が多数行われてきた。例えば、疎水性高分子からなる多孔質膜を得る際に用いる製膜原液にポリビニルピロリドン（ＰＶＰ）やポリビニルアルコール（ＰＶＡ）等の親水性高分子を混入し、製膜後もこれらの親水性高分子が残存し、膜表面の親水性を向上させて耐ファウリング性を向上させようというものである。この方法は製膜が簡便で膜の生産効率が高く、優れた方法であるが、いまだ、耐ファウリング性は十分ではない。
In the prior art, many technical developments have been made in the direction of improving the fouling resistance by hydrophilizing the membrane surface and suppressing the increase in filtration resistance during the membrane filtration operation. For example, a hydrophilic polymer such as polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA) is mixed in a film-forming stock solution used to obtain a porous film made of a hydrophobic polymer. The molecule remains, and the hydrophilicity of the film surface is improved to improve the fouling resistance. Although this method is simple and easy to form and has high production efficiency of the membrane, it is an excellent method, but the fouling resistance is still insufficient.
また、従来技術においては、疎水性高分子からなる膜をまず形成し、その後に各種の表面処理を行って疎水性高分子膜の表面を親水性高分子で被覆し、耐ファウリング性を向上させようとするものがある。これらの方法は、製膜原液に親水性高分子を混入して製膜する方法に比べて製造工程が複雑であり、また工程の制御が困難である等、実用上問題が多い。
In addition, in the prior art, a membrane made of a hydrophobic polymer is first formed, and then various surface treatments are performed to coat the surface of the hydrophobic polymer membrane with a hydrophilic polymer, thereby improving fouling resistance. There is something to try. These methods have many practical problems such as a complicated manufacturing process and difficulty in controlling the process as compared with a method of forming a film by mixing a hydrophilic polymer in a film forming stock solution.
上記技術は両者とも膜表面の化学的性質、化学的組成に着目し、膜表面の親水化により耐ファウリング性を向上させようとの技術思想が根底をなしている。これに対し、膜表面の形状と膜分離特性との関係に言及している例として、特許文献１及び２を挙げることができる。特許文献１には、ポリアミド系スキン層を有する複合逆浸透膜に関する発明が開示されており、原水の供給される側の膜表面の比表面積を特定の範囲とすることによって、複合逆浸透膜の透水性能が向上することが示されている。また、特許文献２には、やはりポリアミド系スキン層を有する複合逆浸透膜に関する発明が開示されており、原水の供給される側の膜表面の表面凹凸の隣接頂点間水平距離の平均値Ｘと互いに隣接する頂点と底辺の凹凸差の平均値Ｚとが特定の関係を満足する場合に高い阻止性能を示す複合逆浸透膜が得られることが開示されている。しかしながら、特許文献１及び２のいずれも、複合逆浸透膜に関する検討であり、さらに耐ファウリング性向上に関しては何ら言及されていない。
Both of these technologies focus on the chemical properties and chemical composition of the membrane surface, and the technical idea of improving the fouling resistance by making the membrane surface hydrophilic is fundamental. On the other hand, Patent Documents 1 and 2 can be cited as examples referring to the relationship between the shape of the membrane surface and the membrane separation characteristics. Patent Document 1 discloses an invention related to a composite reverse osmosis membrane having a polyamide-based skin layer. By making the specific surface area of the membrane surface on the side to which raw water is supplied into a specific range, It has been shown that water permeability is improved. Further, Patent Document 2 discloses an invention related to a composite reverse osmosis membrane having a polyamide-based skin layer as well, and the average value X of the horizontal distance between adjacent vertices of the surface irregularities on the membrane surface on the raw water supply side is disclosed. It is disclosed that a composite reverse osmosis membrane exhibiting high blocking performance can be obtained when the average value Z of the unevenness difference between the apex adjacent to each other and the bottom side satisfies a specific relationship. However, neither of Patent Documents 1 and 2 is a study on a composite reverse osmosis membrane, and further, no mention is made regarding improvement of fouling resistance.
一方、近年、環境汚染に対する関心の高まりと規制の強化とにより、分離の完全性やコンパクト性などに優れた濾過膜を用いた膜法による水処理が注目を集めている。このような水処理の用途において、濾過膜には優れた分離特性や透水性能、そして高い機械的強度が要求されている。
On the other hand, in recent years, due to increasing interest in environmental pollution and stricter regulations, water treatment by a membrane method using a filtration membrane having excellent separation completeness and compactness has attracted attention. In such water treatment applications, filtration membranes are required to have excellent separation characteristics, water permeability, and high mechanical strength.
従来、透水性能に優れた濾過膜として、湿式又は乾湿式紡糸法により製造される、ポリスルホン、ポリアクリロニトリル、セルロースアセテート、又はポリフッ化ビニリデン製などの濾過膜が知られている。これらの濾過膜は、高分子溶液をミクロ相分離させた後、同高分子溶液を非溶媒中で凝固させて製造するものであり、高空孔率で且つ非対称な構造を持つ。
Conventionally, filtration membranes made of polysulfone, polyacrylonitrile, cellulose acetate, or polyvinylidene fluoride manufactured by a wet or dry wet spinning method are known as filtration membranes having excellent water permeability. These filtration membranes are manufactured by microphase-separating a polymer solution and then coagulating the polymer solution in a non-solvent, and have a high porosity and an asymmetric structure.
上記濾過膜素材の中でもポリフッ化ビニリデン樹脂は、耐薬品性、及び耐熱性に優れているので、分離膜の素材として好適に用いられている。しかしながらこれまでに提案されているポリフッ化ビニリデン中空糸膜からなる濾過膜は、分離特性・濾過安定性・及び機械的強度のうちいずれか１以上が十分でないものが多く、またすべてを満たすものは製造方法が複雑であるという問題があった。
Among the above filtration membrane materials, polyvinylidene fluoride resin is suitably used as a material for separation membranes because it is excellent in chemical resistance and heat resistance. However, many of the proposed filtration membranes made of polyvinylidene fluoride hollow fiber membranes are not sufficient in any one of separation characteristics, filtration stability, and mechanical strength, and those satisfying all of them There was a problem that the manufacturing method was complicated.
分離膜の機械的強度を上げるために、中空状組紐を支持体とし、その表面上に多孔質層が設けられた分離膜が提案されている（特許文献３）。しかしながら、この多孔質層には、その製法から膜構造内部に大きなマクロボイドを有しており、外的要因による膜外表面の損傷等による分離特性の低下を招きやすいという問題があった。
In order to increase the mechanical strength of the separation membrane, a separation membrane in which a hollow braid is used as a support and a porous layer is provided on the surface has been proposed (Patent Document 3). However, this porous layer has a large macro void inside the membrane structure due to its production method, and there is a problem that the separation characteristics are liable to be deteriorated due to damage to the outer surface of the membrane due to external factors.
これに対し、相分離の制御により、緻密層をある程度厚くし、同時にマクロボイドを抑制し分離特性を高めた分離膜が提案されている（特許文献４）。しかしながら、このように緻密層を厚くすると、極微小物や溶解性有機高分子が緻密層で詰まり、濾過安定性が低下する可能性があるという問題があった。
On the other hand, a separation membrane has been proposed in which the dense layer is made thick to some extent by controlling the phase separation, and at the same time, macrovoids are suppressed to improve the separation characteristics (Patent Document 4). However, when the dense layer is thickened in this way, there is a problem that ultrafine objects and soluble organic polymers are clogged with the dense layer, which may reduce the filtration stability.
これに対し、ポリフッ化ビニリデン樹脂と可塑剤を溶融混練して押し出し、冷却して固化した後可塑剤を抽出し多孔質中空糸膜を得た後、外表面緻密層を湿潤させた状態で延伸し、表面緻密層の空孔率を高くして、濁水によって汚染され難くする分離膜が提案されている（特許文献５）。しかしながら、この技術の分離膜は、空孔率は高いながらも緻密層の孔径がほぼ均一なことから、表面を通過した極微小物や溶解性有機高分子が緻密層内部で詰まりやすいという問題は依然として残り、また製法として実質的に延伸が必要なことから支持体と組み合わせることが難しく、機械的強度を両立しにくいという問題があった。
On the other hand, a polyvinylidene fluoride resin and a plasticizer are melt-kneaded, extruded, cooled and solidified, then the plasticizer is extracted to obtain a porous hollow fiber membrane, and then the outer surface dense layer is stretched in a wet state However, a separation membrane has been proposed in which the porosity of the surface dense layer is increased to make it less likely to be contaminated by turbid water (Patent Document 5). However, the separation membrane of this technique has a high porosity, but the pore diameter of the dense layer is almost uniform, so that the problem that microscopic objects and soluble organic polymers that have passed through the surface are easily clogged inside the dense layer still remains. In addition, there is a problem that it is difficult to combine with a support because the manufacturing method substantially requires stretching, and it is difficult to achieve both mechanical strength.
本発明の課題は、浄水処理、飲料処理、又は海水除濁等の種々の水性流体の処理において使用することができ、優れた分画特性、及び透過性を有しながら、経時的な性能の低下が抑制され、洗浄による膜分離特性の回復性に優れた多孔質中空糸膜を提供することにある。
The problem of the present invention is that it can be used in the treatment of various aqueous fluids such as water purification treatment, beverage treatment, or seawater turbidity, and has excellent fractionation characteristics and permeability, An object of the present invention is to provide a porous hollow fiber membrane in which a decrease is suppressed and the membrane separation property recoverability by washing is excellent.
また、本発明の他の目的は、かかる課題を解決し、分離特性・濾過安定性・及び機械的強度に優れた多孔質中空糸膜を提供することにある。
Another object of the present invention is to solve the above problems and provide a porous hollow fiber membrane having excellent separation characteristics, filtration stability, and mechanical strength.
上述の課題を解決するため、本発明は、以下のような実施態様を有する。
（１） 少なくとも外表面に多孔質層を有する多孔質中空糸膜であって、前記多孔質中空糸膜の断面構造における外表面から深さ１μｍまでの平均孔径（Ａｄ）が、深さ２μｍから３μｍまでの平均孔径（Ｂｄ）に対する比（Ａｄ／Ｂｄ）で０．６以下である多孔質中空糸膜。
（２） 外表面は、平均孔径Ｐ１が０．０５～１．０μｍであり、開孔率Ａ１が１５～６５％である（１）記載の多孔質中空糸膜。
（３） 断面構造における外表面から深さ１０μｍまでの層の平均孔径Ｐ２が０．１～５．０μｍであり、開孔率Ａ２が１０～５０％である（１）又は（２）に記載の多孔質中空糸膜
（４） 外表面から深さ５μｍまでの構造が、孔径が外表面から離れる方向に向けて漸増する三次元網目構造である（１）～（３）のいずれかに記載の多孔質中空糸膜。
（５） 外表面から深さ５μｍまでの多孔質層の平均孔径が、前記外表面から深さ５μｍよりも離れた部位に存在する多孔質層の平均孔径よりも小さい（１）～（４）のいずれかに記載の多孔質中空糸膜。
（６） 前記外表面から深さ５μｍよりも離れた部位に存在する多孔質層の平均孔径が、１０μｍ以下である（１）～（５）のいずれかに記載の多孔質中空糸膜。
（７） 外表面から深さ５μｍまでを構成する熱可塑性樹脂が同一の熱可塑性樹脂からなる（１）～（６）のいずれかに記載の多孔質中空糸膜。
（８） 外表面から深さ１０μｍよりも離れていない部位の多孔質層に、孔径１０μｍを超えるマクロボイド及びその一部を含有しない（１）～（７）いずれかに記載の多孔質中空糸膜。
（９） 非溶媒相分離法により形成されてなる（１）～（８）のいずれかに記載の多孔質中空糸膜。
（１０） 前記多孔質層が中空糸状の支持体の外表面側に形成されている（１）～（９）のいずれかに記載の多孔質中空糸膜。
（１１） 前記中空糸状の支持体が熱処理された支持体である（１０）記載の多孔質中空糸膜。
（１２） 前記中空糸状の支持体が中空編紐である（１０）又は（１１）に記載の多孔質中空糸膜。
（１３） 支持体が、マルチフィラメントからなる１本の糸を丸編した中空編紐である（１１）又は（１２）記載の多孔質中空糸膜。
（１４） 熱可塑性樹脂と親水性化合物とを含む膜形成性樹脂溶液を、紡糸ノズルから吐出させた後、前記吐出させた膜形成性樹脂溶液を膜形成性樹脂溶液の成分にとって非溶媒の飽和蒸気に接触させ、その後に凝固液に浸漬させることにより凝固させて多孔質中空糸膜とする、多孔質中空糸膜の製造方法であって、前記紡糸ノズルが１重又は２重以上の管状ノズルであって、前記多孔質中空糸膜は少なくとも外表面から深さ５μｍの部位を同一の膜形成性樹脂溶液により形成する多孔質中空糸膜の製造方法。
（１５） 前記非溶媒の飽和蒸気が、飽和水蒸気である、（１４）記載の多孔質中空糸膜の製造方法。
（１６） 紡糸ノズルを用いて、中空状の支持体の外周面に膜形成性樹脂溶液を塗布し膜形成性樹脂層とした後、前記膜形成性樹脂層を非溶媒の飽和蒸気に接触させる、（１４）又は（１５）に記載の多孔質中空糸膜の製造方法。
（１７） 前記支持体は熱処理された支持体を用いることを特徴とする、（１６）に記載の多孔質中空糸膜の製造方法。
（１８） 支持体が編紐であることを特徴とする、（１６）又は（１７）に記載の多孔質中空糸膜の製造方法。
（１９） 支持体が、マルチフィラメントからなる１本の糸を丸編した中空状編紐である（１７）又は（１８）に記載の多孔質中空糸膜の製造方法。 In order to solve the above-described problems, the present invention has the following embodiments.
(1) A porous hollow fiber membrane having a porous layer on at least an outer surface, wherein an average pore diameter (Ad) from the outer surface to a depth of 1 μm in a cross-sectional structure of the porous hollow fiber membrane is from a depth of 2 μm A porous hollow fiber membrane having a ratio (Ad / Bd) to an average pore diameter (Bd) of up to 3 μm of 0.6 or less.
(2) The porous hollow fiber membrane according to (1), wherein the outer surface has an average pore diameter P1 of 0.05 to 1.0 μm and an open area ratio A1 of 15 to 65%.
(3) The average pore diameter P2 of the layer from the outer surface to the depth of 10 μm in the cross-sectional structure is 0.1 to 5.0 μm, and the open area ratio A2 is 10 to 50%, as described in (1) or (2) Porous hollow fiber membrane (4) The structure from the outer surface to a depth of 5 μm is a three-dimensional network structure in which the pore diameter gradually increases in the direction away from the outer surface (1) to (3) Porous hollow fiber membrane.
(5) The average pore diameter of the porous layer from the outer surface to a depth of 5 μm is smaller than the average pore diameter of the porous layer existing at a position farther from the outer surface than the depth of 5 μm (1) to (4) The porous hollow fiber membrane according to any one of the above.
(6) The porous hollow fiber membrane according to any one of (1) to (5), wherein an average pore diameter of the porous layer existing at a part farther from the outer surface than a depth of 5 μm is 10 μm or less.
(7) The porous hollow fiber membrane according to any one of (1) to (6), wherein the thermoplastic resin constituting the depth of 5 μm from the outer surface is made of the same thermoplastic resin.
(8) The porous hollow fiber according to any one of (1) to (7), which does not contain a macrovoid exceeding 10 μm in pore diameter and a part thereof in the porous layer at a part not more than 10 μm deep from the outer surface. film.
(9) The porous hollow fiber membrane according to any one of (1) to (8), which is formed by a non-solvent phase separation method.
(10) The porous hollow fiber membrane according to any one of (1) to (9), wherein the porous layer is formed on the outer surface side of a hollow fiber-like support.
(11) The porous hollow fiber membrane according to (10), wherein the hollow fiber-shaped support is a heat-treated support.
(12) The porous hollow fiber membrane according to (10) or (11), wherein the hollow fiber-shaped support is a hollow knitted string.
(13) The porous hollow fiber membrane according to (11) or (12), wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
(14) A film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, and then the discharged film-forming resin solution is used as a component of the film-forming resin solution to saturate a non-solvent. A method for producing a porous hollow fiber membrane, which is brought into contact with steam and then solidified by being immersed in a coagulating liquid to form a porous hollow fiber membrane, wherein the spinning nozzle is a single or double tubular nozzle And the said porous hollow fiber membrane is a manufacturing method of the porous hollow fiber membrane which forms the site | part of 5 micrometers in depth from an outer surface with the same film forming resin solution.
(15) The method for producing a porous hollow fiber membrane according to (14), wherein the non-solvent saturated vapor is saturated water vapor.
(16) Using a spinning nozzle, a film-forming resin solution is applied to the outer peripheral surface of the hollow support to form a film-forming resin layer, and then the film-forming resin layer is brought into contact with a non-solvent saturated vapor. (14) The manufacturing method of the porous hollow fiber membrane as described in (15).
(17) The method for producing a porous hollow fiber membrane according to (16), wherein the support is a heat-treated support.
(18) The method for producing a porous hollow fiber membrane according to (16) or (17), wherein the support is a knitted string.
(19) The method for producing a porous hollow fiber membrane according to (17) or (18), wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
（１） 少なくとも外表面に多孔質層を有する多孔質中空糸膜であって、前記多孔質中空糸膜の断面構造における外表面から深さ１μｍまでの平均孔径（Ａｄ）が、深さ２μｍから３μｍまでの平均孔径（Ｂｄ）に対する比（Ａｄ／Ｂｄ）で０．６以下である多孔質中空糸膜。
（２） 外表面は、平均孔径Ｐ１が０．０５～１．０μｍであり、開孔率Ａ１が１５～６５％である（１）記載の多孔質中空糸膜。
（３） 断面構造における外表面から深さ１０μｍまでの層の平均孔径Ｐ２が０．１～５．０μｍであり、開孔率Ａ２が１０～５０％である（１）又は（２）に記載の多孔質中空糸膜
（４） 外表面から深さ５μｍまでの構造が、孔径が外表面から離れる方向に向けて漸増する三次元網目構造である（１）～（３）のいずれかに記載の多孔質中空糸膜。
（５） 外表面から深さ５μｍまでの多孔質層の平均孔径が、前記外表面から深さ５μｍよりも離れた部位に存在する多孔質層の平均孔径よりも小さい（１）～（４）のいずれかに記載の多孔質中空糸膜。
（６） 前記外表面から深さ５μｍよりも離れた部位に存在する多孔質層の平均孔径が、１０μｍ以下である（１）～（５）のいずれかに記載の多孔質中空糸膜。
（７） 外表面から深さ５μｍまでを構成する熱可塑性樹脂が同一の熱可塑性樹脂からなる（１）～（６）のいずれかに記載の多孔質中空糸膜。
（８） 外表面から深さ１０μｍよりも離れていない部位の多孔質層に、孔径１０μｍを超えるマクロボイド及びその一部を含有しない（１）～（７）いずれかに記載の多孔質中空糸膜。
（９） 非溶媒相分離法により形成されてなる（１）～（８）のいずれかに記載の多孔質中空糸膜。
（１０） 前記多孔質層が中空糸状の支持体の外表面側に形成されている（１）～（９）のいずれかに記載の多孔質中空糸膜。
（１１） 前記中空糸状の支持体が熱処理された支持体である（１０）記載の多孔質中空糸膜。
（１２） 前記中空糸状の支持体が中空編紐である（１０）又は（１１）に記載の多孔質中空糸膜。
（１３） 支持体が、マルチフィラメントからなる１本の糸を丸編した中空編紐である（１１）又は（１２）記載の多孔質中空糸膜。
（１４） 熱可塑性樹脂と親水性化合物とを含む膜形成性樹脂溶液を、紡糸ノズルから吐出させた後、前記吐出させた膜形成性樹脂溶液を膜形成性樹脂溶液の成分にとって非溶媒の飽和蒸気に接触させ、その後に凝固液に浸漬させることにより凝固させて多孔質中空糸膜とする、多孔質中空糸膜の製造方法であって、前記紡糸ノズルが１重又は２重以上の管状ノズルであって、前記多孔質中空糸膜は少なくとも外表面から深さ５μｍの部位を同一の膜形成性樹脂溶液により形成する多孔質中空糸膜の製造方法。
（１５） 前記非溶媒の飽和蒸気が、飽和水蒸気である、（１４）記載の多孔質中空糸膜の製造方法。
（１６） 紡糸ノズルを用いて、中空状の支持体の外周面に膜形成性樹脂溶液を塗布し膜形成性樹脂層とした後、前記膜形成性樹脂層を非溶媒の飽和蒸気に接触させる、（１４）又は（１５）に記載の多孔質中空糸膜の製造方法。
（１７） 前記支持体は熱処理された支持体を用いることを特徴とする、（１６）に記載の多孔質中空糸膜の製造方法。
（１８） 支持体が編紐であることを特徴とする、（１６）又は（１７）に記載の多孔質中空糸膜の製造方法。
（１９） 支持体が、マルチフィラメントからなる１本の糸を丸編した中空状編紐である（１７）又は（１８）に記載の多孔質中空糸膜の製造方法。 In order to solve the above-described problems, the present invention has the following embodiments.
(1) A porous hollow fiber membrane having a porous layer on at least an outer surface, wherein an average pore diameter (Ad) from the outer surface to a depth of 1 μm in a cross-sectional structure of the porous hollow fiber membrane is from a depth of 2 μm A porous hollow fiber membrane having a ratio (Ad / Bd) to an average pore diameter (Bd) of up to 3 μm of 0.6 or less.
(2) The porous hollow fiber membrane according to (1), wherein the outer surface has an average pore diameter P1 of 0.05 to 1.0 μm and an open area ratio A1 of 15 to 65%.
(3) The average pore diameter P2 of the layer from the outer surface to the depth of 10 μm in the cross-sectional structure is 0.1 to 5.0 μm, and the open area ratio A2 is 10 to 50%, as described in (1) or (2) Porous hollow fiber membrane (4) The structure from the outer surface to a depth of 5 μm is a three-dimensional network structure in which the pore diameter gradually increases in the direction away from the outer surface (1) to (3) Porous hollow fiber membrane.
(5) The average pore diameter of the porous layer from the outer surface to a depth of 5 μm is smaller than the average pore diameter of the porous layer existing at a position farther from the outer surface than the depth of 5 μm (1) to (4) The porous hollow fiber membrane according to any one of the above.
(6) The porous hollow fiber membrane according to any one of (1) to (5), wherein an average pore diameter of the porous layer existing at a part farther from the outer surface than a depth of 5 μm is 10 μm or less.
(7) The porous hollow fiber membrane according to any one of (1) to (6), wherein the thermoplastic resin constituting the depth of 5 μm from the outer surface is made of the same thermoplastic resin.
(8) The porous hollow fiber according to any one of (1) to (7), which does not contain a macrovoid exceeding 10 μm in pore diameter and a part thereof in the porous layer at a part not more than 10 μm deep from the outer surface. film.
(9) The porous hollow fiber membrane according to any one of (1) to (8), which is formed by a non-solvent phase separation method.
(10) The porous hollow fiber membrane according to any one of (1) to (9), wherein the porous layer is formed on the outer surface side of a hollow fiber-like support.
(11) The porous hollow fiber membrane according to (10), wherein the hollow fiber-shaped support is a heat-treated support.
(12) The porous hollow fiber membrane according to (10) or (11), wherein the hollow fiber-shaped support is a hollow knitted string.
(13) The porous hollow fiber membrane according to (11) or (12), wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
(14) A film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, and then the discharged film-forming resin solution is used as a component of the film-forming resin solution to saturate a non-solvent. A method for producing a porous hollow fiber membrane, which is brought into contact with steam and then solidified by being immersed in a coagulating liquid to form a porous hollow fiber membrane, wherein the spinning nozzle is a single or double tubular nozzle And the said porous hollow fiber membrane is a manufacturing method of the porous hollow fiber membrane which forms the site | part of 5 micrometers in depth from an outer surface with the same film forming resin solution.
(15) The method for producing a porous hollow fiber membrane according to (14), wherein the non-solvent saturated vapor is saturated water vapor.
(16) Using a spinning nozzle, a film-forming resin solution is applied to the outer peripheral surface of the hollow support to form a film-forming resin layer, and then the film-forming resin layer is brought into contact with a non-solvent saturated vapor. (14) The manufacturing method of the porous hollow fiber membrane as described in (15).
(17) The method for producing a porous hollow fiber membrane according to (16), wherein the support is a heat-treated support.
(18) The method for producing a porous hollow fiber membrane according to (16) or (17), wherein the support is a knitted string.
(19) The method for producing a porous hollow fiber membrane according to (17) or (18), wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
また、本発明の実施態様は、以下のような側面を有する。前述のようなかかる課題を解決する、本実施態様の第１の要旨は、外表面の開孔率が１５～６５％である多孔質中空糸膜である。
また、本実施態様の第２の要旨は、以下の工程を有する多孔質中空糸膜の評価方法にある。
工程（１）：多孔質中空糸膜の断面を走査型電子顕微鏡で観察し、断面表面にあらわれる各孔の面積を計測する工程
工程（２）：工程（１）において計測された各孔の面積の値を面積の小さいほうから積算し、全面積に対して５０％に相当するところの孔を平均孔径指数として算出する工程 The embodiment of the present invention has the following aspects. The first gist of the present embodiment that solves the above-mentioned problems is a porous hollow fiber membrane having an outer surface open area ratio of 15 to 65%.
The second gist of the present embodiment is a method for evaluating a porous hollow fiber membrane having the following steps.
Step (1): A step of observing a cross section of the porous hollow fiber membrane with a scanning electron microscope and measuring an area of each hole appearing on the surface of the cross section. Step (2): Area of each hole measured in step (1) Of calculating the average pore diameter index for the holes corresponding to 50% of the total area
また、本実施態様の第２の要旨は、以下の工程を有する多孔質中空糸膜の評価方法にある。
工程（１）：多孔質中空糸膜の断面を走査型電子顕微鏡で観察し、断面表面にあらわれる各孔の面積を計測する工程
工程（２）：工程（１）において計測された各孔の面積の値を面積の小さいほうから積算し、全面積に対して５０％に相当するところの孔を平均孔径指数として算出する工程 The embodiment of the present invention has the following aspects. The first gist of the present embodiment that solves the above-mentioned problems is a porous hollow fiber membrane having an outer surface open area ratio of 15 to 65%.
The second gist of the present embodiment is a method for evaluating a porous hollow fiber membrane having the following steps.
Step (1): A step of observing a cross section of the porous hollow fiber membrane with a scanning electron microscope and measuring an area of each hole appearing on the surface of the cross section. Step (2): Area of each hole measured in step (1) Of calculating the average pore diameter index for the holes corresponding to 50% of the total area
また、本実施態様は、少なくとも外表面及びその近傍に熱可塑性樹脂からなる多孔質層を有する多孔質中空糸膜であって、断面構造における表面から深さ１μｍまでの平均孔径Ａｄが、深さ２μｍから３μｍまでの平均孔径Ｂｄの１／２以下である多孔質中空糸膜にある。
さらに本実施態様は、熱可塑性樹脂と親水性化合物とを含む膜形成性樹脂溶液を、紡糸ノズルから吐出させ、直後に膜形成性樹脂の非溶媒の飽和蒸気に接触させ、その後に凝固液に浸漬させることにより凝固させる、多孔質中空糸膜の製造方法である。 Further, this embodiment is a porous hollow fiber membrane having a porous layer made of a thermoplastic resin at least on the outer surface and in the vicinity thereof, and the average pore diameter Ad from the surface in the cross-sectional structure to the depth of 1 μm is the depth. The porous hollow fiber membrane has a mean pore diameter Bd of 2 μm to 3 μm that is 1/2 or less.
Furthermore, in this embodiment, a film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, immediately after being brought into contact with a non-solvent saturated vapor of the film-forming resin, and then into a coagulating liquid. This is a method for producing a porous hollow fiber membrane that is solidified by dipping.
さらに本実施態様は、熱可塑性樹脂と親水性化合物とを含む膜形成性樹脂溶液を、紡糸ノズルから吐出させ、直後に膜形成性樹脂の非溶媒の飽和蒸気に接触させ、その後に凝固液に浸漬させることにより凝固させる、多孔質中空糸膜の製造方法である。 Further, this embodiment is a porous hollow fiber membrane having a porous layer made of a thermoplastic resin at least on the outer surface and in the vicinity thereof, and the average pore diameter Ad from the surface in the cross-sectional structure to the depth of 1 μm is the depth. The porous hollow fiber membrane has a mean pore diameter Bd of 2 μm to 3 μm that is 1/2 or less.
Furthermore, in this embodiment, a film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, immediately after being brought into contact with a non-solvent saturated vapor of the film-forming resin, and then into a coagulating liquid. This is a method for producing a porous hollow fiber membrane that is solidified by dipping.
また、本発明の実施態様は、以下のような側面を有する。
（１Ａ）少なくとも外表面側が多孔質層からなる多孔質中空糸膜であって、外表面の開孔率が１５～６５％である多孔質中空糸膜。
（２Ａ）外表面の平均孔径指数Ｐ１が０．０５～１．０（μｍ）である（１Ａ）に記載の多孔質中空糸膜。
（３Ａ）外表面近傍１０μｍまでに緻密層を持ち、その緻密層の平均孔径指数Ｐ２（μｍ）が０．１～５．０（μｍ）の範囲である（１Ａ）又は（２Ａ）に記載の多孔質中空糸膜。
（４Ａ） 緻密層の開孔率Ａ２（％）が１０～５０％である（３Ａ）に記載の多孔質中空糸膜。
（５Ａ） 前記多孔質層の総厚みが２００μｍ以下である（１Ａ）～（４Ａ）に記載の多孔質中空糸膜。
（６Ａ） 外表面から連続する多孔質層の孔径指数が、傾斜的に漸増する（１Ａ）～（５Ａ）に記載の多孔質膜。
（７Ａ） 下記の各工程からなる、外表面側が多孔質層からなる多孔質中空糸膜の評価方法。
工程１：多孔質中空糸膜の断面を走査型電子顕微鏡で観察し、断面表面にあらわれる各孔の面積を計測する工程
工程２：工程１において計測された各孔の面積の値を面積の小さいほうから積算し、全面積に対して５０％に相当するところの孔を用いて、平均孔径指数を算出する工程 The embodiment of the present invention has the following aspects.
(1A) A porous hollow fiber membrane in which at least the outer surface side is composed of a porous layer, and the porosity of the outer surface is 15 to 65%.
(2A) The porous hollow fiber membrane according to (1A), wherein the outer surface has an average pore diameter index P1 of 0.05 to 1.0 (μm).
(3A) As described in (1A) or (2A), the dense layer has a dense layer up to 10 μm near the outer surface, and the average pore diameter index P2 (μm) of the dense layer is in the range of 0.1 to 5.0 (μm). Porous hollow fiber membrane.
(4A) The porous hollow fiber membrane according to (3A), wherein the open area ratio A2 (%) of the dense layer is 10 to 50%.
(5A) The porous hollow fiber membrane according to (1A) to (4A), wherein the total thickness of the porous layer is 200 μm or less.
(6A) The porous membrane according to (1A) to (5A), wherein the pore diameter index of the porous layer continuous from the outer surface gradually increases.
(7A) A method for evaluating a porous hollow fiber membrane comprising the following steps, wherein the outer surface side is a porous layer.
Step 1: A step of observing the cross section of the porous hollow fiber membrane with a scanning electron microscope and measuring the area of each hole appearing on the surface of the cross section. Step 2: The area value of each hole measured in Step 1 is small. Step of calculating the average pore diameter index using the holes corresponding to 50% of the total area
（１Ａ）少なくとも外表面側が多孔質層からなる多孔質中空糸膜であって、外表面の開孔率が１５～６５％である多孔質中空糸膜。
（２Ａ）外表面の平均孔径指数Ｐ１が０．０５～１．０（μｍ）である（１Ａ）に記載の多孔質中空糸膜。
（３Ａ）外表面近傍１０μｍまでに緻密層を持ち、その緻密層の平均孔径指数Ｐ２（μｍ）が０．１～５．０（μｍ）の範囲である（１Ａ）又は（２Ａ）に記載の多孔質中空糸膜。
（４Ａ） 緻密層の開孔率Ａ２（％）が１０～５０％である（３Ａ）に記載の多孔質中空糸膜。
（５Ａ） 前記多孔質層の総厚みが２００μｍ以下である（１Ａ）～（４Ａ）に記載の多孔質中空糸膜。
（６Ａ） 外表面から連続する多孔質層の孔径指数が、傾斜的に漸増する（１Ａ）～（５Ａ）に記載の多孔質膜。
（７Ａ） 下記の各工程からなる、外表面側が多孔質層からなる多孔質中空糸膜の評価方法。
工程１：多孔質中空糸膜の断面を走査型電子顕微鏡で観察し、断面表面にあらわれる各孔の面積を計測する工程
工程２：工程１において計測された各孔の面積の値を面積の小さいほうから積算し、全面積に対して５０％に相当するところの孔を用いて、平均孔径指数を算出する工程 The embodiment of the present invention has the following aspects.
(1A) A porous hollow fiber membrane in which at least the outer surface side is composed of a porous layer, and the porosity of the outer surface is 15 to 65%.
(2A) The porous hollow fiber membrane according to (1A), wherein the outer surface has an average pore diameter index P1 of 0.05 to 1.0 (μm).
(3A) As described in (1A) or (2A), the dense layer has a dense layer up to 10 μm near the outer surface, and the average pore diameter index P2 (μm) of the dense layer is in the range of 0.1 to 5.0 (μm). Porous hollow fiber membrane.
(4A) The porous hollow fiber membrane according to (3A), wherein the open area ratio A2 (%) of the dense layer is 10 to 50%.
(5A) The porous hollow fiber membrane according to (1A) to (4A), wherein the total thickness of the porous layer is 200 μm or less.
(6A) The porous membrane according to (1A) to (5A), wherein the pore diameter index of the porous layer continuous from the outer surface gradually increases.
(7A) A method for evaluating a porous hollow fiber membrane comprising the following steps, wherein the outer surface side is a porous layer.
Step 1: A step of observing the cross section of the porous hollow fiber membrane with a scanning electron microscope and measuring the area of each hole appearing on the surface of the cross section. Step 2: The area value of each hole measured in Step 1 is small. Step of calculating the average pore diameter index using the holes corresponding to 50% of the total area
また、本発明の実施態様は、さらに以下のような側面を有する。
（１Ｂ） 少なくとも外表面及びその近傍に熱可塑性樹脂からなる多孔質層を有する多孔質中空糸膜であって、断面構造における表面から深さ１μｍまでの平均孔径Ａｄが、深さ２μｍから３μｍまでの平均孔径Ｂｄの１／２以下である多孔質中空糸膜。
（２Ｂ） 外表面から深さ５μｍまでの構造が、孔径が中心に向けて漸増する三次元網目構造である（１Ｂ）記載の多孔質中空糸膜。
（３Ｂ） 外表面から深さ５μｍまでの多孔質層の平均孔径が、深さ５μｍより内側に存在する多孔質層の平均孔径よりも小さい（１Ｂ）又は（２Ｂ）に記載の多孔質中空糸膜。
（４Ｂ） 深さ５μｍより内側に存在する多孔質層の平均孔径が、１０μｍ以下である（１Ｂ）～（３Ｂ）のいずれかに記載の多孔質中空糸膜。
（５Ｂ） 外表面から深さ５μｍまでを構成する熱可塑性樹脂が同一の熱可塑性樹脂からなる（１Ｂ）～（４Ｂ）のいずれかに記載の多孔質中空糸膜。
（６Ｂ） 外表面から深さ１０μｍまでの多孔質層に、孔径１０μｍを超えるマクロボイドを含有しない（１Ｂ）～（５Ｂ）いずれかに記載の多孔質中空糸膜。
（７Ｂ） 前記多孔質層が中空糸状の支持体の外表面側に形成されている（１Ｂ）～（６Ｂ）のいずれかに記載の多孔質中空糸膜。
（８Ｂ） 前記中空糸状の支持体が中空編紐である（７Ｂ）記載の多孔質中空糸膜。
（９Ｂ） 前記中空糸状の支持体が熱処理された中空編紐である（８Ｂ）記載の多孔質中空糸膜。
（１０Ｂ） 支持体が、マルチフィラメントからなる１本の糸を丸編した中空編紐である（８Ｂ）又は（９Ｂ）記載の多孔質中空糸膜。
（１１Ｂ） 熱可塑性樹脂と親水性化合物とを含む膜形成性樹脂溶液を、紡糸ノズルから吐出させた後、膜形成性樹脂の非溶媒の飽和蒸気に接触させ、その後に凝固液に浸漬させることにより凝固させる、多孔質中空糸膜の製造方法。
（１２Ｂ） 紡糸ノズルが１重又は２重以上の管状ノズルであって、少なくとも外表面から深さ４μｍを同一の膜形成性樹脂溶液により形成する（１１Ｂ）に記載の多孔質中空糸膜の製造方法。
（１３Ｂ） 前記非溶媒の飽和蒸気が、１００℃の飽和水蒸気である、（１２Ｂ）の多孔質中空糸膜の製造方法。
（１４Ｂ） 紡糸ノズルから吐出した膜形成性樹脂溶液を、膜形成性樹脂の非溶媒の飽和蒸気に接触させる前に、乾燥空気に接触させる、（１２Ｂ）又は（１３Ｂ）に記載の多孔質中空糸膜の製造方法。
（１５Ｂ） 前記乾燥空気が、ノズル吐出面から鉛直下方に向かって供給された後、前記非溶媒の飽和蒸気と相対して接触する、（１４Ｂ）記載の多孔質中空糸膜の製造方法。
（１６Ｂ） 前記乾燥空気により、紡糸ノズル近傍の雰囲気における非溶媒の相対湿度を１０％未満にする、（１４Ｂ）又は（１５Ｂ）記載の多孔質中空糸膜の製造方法。 The embodiment of the present invention further has the following aspects.
(1B) A porous hollow fiber membrane having a porous layer made of a thermoplastic resin at least on the outer surface and in the vicinity thereof, wherein the average pore diameter Ad from the surface to the depth of 1 μm in the cross-sectional structure is from the depth of 2 μm to 3 μm A porous hollow fiber membrane having a mean pore diameter Bd of ½ or less.
(2B) The porous hollow fiber membrane according to (1B), wherein the structure from the outer surface to a depth of 5 μm is a three-dimensional network structure in which the pore diameter gradually increases toward the center.
(3B) The porous hollow fiber according to (1B) or (2B), wherein the average pore diameter of the porous layer from the outer surface to a depth of 5 μm is smaller than the average pore diameter of the porous layer existing inside the depth of 5 μm. film.
(4B) The porous hollow fiber membrane according to any one of (1B) to (3B), wherein the average pore diameter of the porous layer existing inside the depth of 5 μm is 10 μm or less.
(5B) The porous hollow fiber membrane according to any one of (1B) to (4B), wherein the thermoplastic resin constituting the depth of 5 μm from the outer surface is made of the same thermoplastic resin.
(6B) The porous hollow fiber membrane according to any one of (1B) to (5B), wherein the porous layer from the outer surface to a depth of 10 μm does not contain macrovoids having a pore diameter exceeding 10 μm.
(7B) The porous hollow fiber membrane according to any one of (1B) to (6B), wherein the porous layer is formed on the outer surface side of a hollow fiber-like support.
(8B) The porous hollow fiber membrane according to (7B), wherein the hollow fiber-shaped support is a hollow knitted string.
(9B) The porous hollow fiber membrane according to (8B), wherein the hollow fiber-shaped support is a heat-treated hollow knitted string.
(10B) The porous hollow fiber membrane according to (8B) or (9B), wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
(11B) A film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, then contacted with a non-solvent saturated vapor of the film-forming resin, and then immersed in a coagulation liquid. A method for producing a porous hollow fiber membrane, which is solidified by the method.
(12B) The production of the porous hollow fiber membrane according to (11B), wherein the spinning nozzle is a single or double or more tubular nozzle, and at least 4 μm in depth is formed from the outer surface with the same membrane-forming resin solution. Method.
(13B) The method for producing a porous hollow fiber membrane according to (12B), wherein the non-solvent saturated vapor is saturated steam at 100 ° C.
(14B) The porous hollow film according to (12B) or (13B), wherein the film-forming resin solution discharged from the spinning nozzle is contacted with dry air before contacting with the non-solvent saturated vapor of the film-forming resin. Yarn membrane manufacturing method.
(15B) The method for producing a porous hollow fiber membrane according to (14B), wherein the dry air is supplied vertically downward from a nozzle discharge surface, and then comes into contact with the saturated vapor of the non-solvent.
(16B) The method for producing a porous hollow fiber membrane according to (14B) or (15B), wherein the relative humidity of the non-solvent in the atmosphere near the spinning nozzle is made less than 10% by the dry air.
（１Ｂ） 少なくとも外表面及びその近傍に熱可塑性樹脂からなる多孔質層を有する多孔質中空糸膜であって、断面構造における表面から深さ１μｍまでの平均孔径Ａｄが、深さ２μｍから３μｍまでの平均孔径Ｂｄの１／２以下である多孔質中空糸膜。
（２Ｂ） 外表面から深さ５μｍまでの構造が、孔径が中心に向けて漸増する三次元網目構造である（１Ｂ）記載の多孔質中空糸膜。
（３Ｂ） 外表面から深さ５μｍまでの多孔質層の平均孔径が、深さ５μｍより内側に存在する多孔質層の平均孔径よりも小さい（１Ｂ）又は（２Ｂ）に記載の多孔質中空糸膜。
（４Ｂ） 深さ５μｍより内側に存在する多孔質層の平均孔径が、１０μｍ以下である（１Ｂ）～（３Ｂ）のいずれかに記載の多孔質中空糸膜。
（５Ｂ） 外表面から深さ５μｍまでを構成する熱可塑性樹脂が同一の熱可塑性樹脂からなる（１Ｂ）～（４Ｂ）のいずれかに記載の多孔質中空糸膜。
（６Ｂ） 外表面から深さ１０μｍまでの多孔質層に、孔径１０μｍを超えるマクロボイドを含有しない（１Ｂ）～（５Ｂ）いずれかに記載の多孔質中空糸膜。
（７Ｂ） 前記多孔質層が中空糸状の支持体の外表面側に形成されている（１Ｂ）～（６Ｂ）のいずれかに記載の多孔質中空糸膜。
（８Ｂ） 前記中空糸状の支持体が中空編紐である（７Ｂ）記載の多孔質中空糸膜。
（９Ｂ） 前記中空糸状の支持体が熱処理された中空編紐である（８Ｂ）記載の多孔質中空糸膜。
（１０Ｂ） 支持体が、マルチフィラメントからなる１本の糸を丸編した中空編紐である（８Ｂ）又は（９Ｂ）記載の多孔質中空糸膜。
（１１Ｂ） 熱可塑性樹脂と親水性化合物とを含む膜形成性樹脂溶液を、紡糸ノズルから吐出させた後、膜形成性樹脂の非溶媒の飽和蒸気に接触させ、その後に凝固液に浸漬させることにより凝固させる、多孔質中空糸膜の製造方法。
（１２Ｂ） 紡糸ノズルが１重又は２重以上の管状ノズルであって、少なくとも外表面から深さ４μｍを同一の膜形成性樹脂溶液により形成する（１１Ｂ）に記載の多孔質中空糸膜の製造方法。
（１３Ｂ） 前記非溶媒の飽和蒸気が、１００℃の飽和水蒸気である、（１２Ｂ）の多孔質中空糸膜の製造方法。
（１４Ｂ） 紡糸ノズルから吐出した膜形成性樹脂溶液を、膜形成性樹脂の非溶媒の飽和蒸気に接触させる前に、乾燥空気に接触させる、（１２Ｂ）又は（１３Ｂ）に記載の多孔質中空糸膜の製造方法。
（１５Ｂ） 前記乾燥空気が、ノズル吐出面から鉛直下方に向かって供給された後、前記非溶媒の飽和蒸気と相対して接触する、（１４Ｂ）記載の多孔質中空糸膜の製造方法。
（１６Ｂ） 前記乾燥空気により、紡糸ノズル近傍の雰囲気における非溶媒の相対湿度を１０％未満にする、（１４Ｂ）又は（１５Ｂ）記載の多孔質中空糸膜の製造方法。 The embodiment of the present invention further has the following aspects.
(1B) A porous hollow fiber membrane having a porous layer made of a thermoplastic resin at least on the outer surface and in the vicinity thereof, wherein the average pore diameter Ad from the surface to the depth of 1 μm in the cross-sectional structure is from the depth of 2 μm to 3 μm A porous hollow fiber membrane having a mean pore diameter Bd of ½ or less.
(2B) The porous hollow fiber membrane according to (1B), wherein the structure from the outer surface to a depth of 5 μm is a three-dimensional network structure in which the pore diameter gradually increases toward the center.
(3B) The porous hollow fiber according to (1B) or (2B), wherein the average pore diameter of the porous layer from the outer surface to a depth of 5 μm is smaller than the average pore diameter of the porous layer existing inside the depth of 5 μm. film.
(4B) The porous hollow fiber membrane according to any one of (1B) to (3B), wherein the average pore diameter of the porous layer existing inside the depth of 5 μm is 10 μm or less.
(5B) The porous hollow fiber membrane according to any one of (1B) to (4B), wherein the thermoplastic resin constituting the depth of 5 μm from the outer surface is made of the same thermoplastic resin.
(6B) The porous hollow fiber membrane according to any one of (1B) to (5B), wherein the porous layer from the outer surface to a depth of 10 μm does not contain macrovoids having a pore diameter exceeding 10 μm.
(7B) The porous hollow fiber membrane according to any one of (1B) to (6B), wherein the porous layer is formed on the outer surface side of a hollow fiber-like support.
(8B) The porous hollow fiber membrane according to (7B), wherein the hollow fiber-shaped support is a hollow knitted string.
(9B) The porous hollow fiber membrane according to (8B), wherein the hollow fiber-shaped support is a heat-treated hollow knitted string.
(10B) The porous hollow fiber membrane according to (8B) or (9B), wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
(11B) A film-forming resin solution containing a thermoplastic resin and a hydrophilic compound is discharged from a spinning nozzle, then contacted with a non-solvent saturated vapor of the film-forming resin, and then immersed in a coagulation liquid. A method for producing a porous hollow fiber membrane, which is solidified by the method.
(12B) The production of the porous hollow fiber membrane according to (11B), wherein the spinning nozzle is a single or double or more tubular nozzle, and at least 4 μm in depth is formed from the outer surface with the same membrane-forming resin solution. Method.
(13B) The method for producing a porous hollow fiber membrane according to (12B), wherein the non-solvent saturated vapor is saturated steam at 100 ° C.
(14B) The porous hollow film according to (12B) or (13B), wherein the film-forming resin solution discharged from the spinning nozzle is contacted with dry air before contacting with the non-solvent saturated vapor of the film-forming resin. Yarn membrane manufacturing method.
(15B) The method for producing a porous hollow fiber membrane according to (14B), wherein the dry air is supplied vertically downward from a nozzle discharge surface, and then comes into contact with the saturated vapor of the non-solvent.
(16B) The method for producing a porous hollow fiber membrane according to (14B) or (15B), wherein the relative humidity of the non-solvent in the atmosphere near the spinning nozzle is made less than 10% by the dry air.
本発明の多孔質中空糸膜は、少なくとも外表面及び前記外表面の近傍に熱可塑性樹脂を含む多孔質層を有する多孔質中空糸膜であって、前記多孔質中空糸膜の厚さ方向の断面構造における表面から深さ１μｍまでの平均孔径（Ａｄ）の大きさが、深さ２μｍから３μｍまでの平均孔径（Ｂｄ）の大きさに対する比で０．６以下であることにより、いわゆる緻密層が薄く、その結果分離特性・濾過安定性・機械的強度に優れる多孔質中空糸膜となる。
The porous hollow fiber membrane of the present invention is a porous hollow fiber membrane having a porous layer containing a thermoplastic resin at least on the outer surface and in the vicinity of the outer surface, and is in the thickness direction of the porous hollow fiber membrane. The size of the average pore diameter (Ad) from the surface to the depth of 1 μm in the cross-sectional structure is not more than 0.6 in terms of the ratio of the average pore diameter (Bd) from the depth of 2 μm to 3 μm. As a result, a porous hollow fiber membrane excellent in separation characteristics, filtration stability and mechanical strength is obtained.
また、本発明によれば、少なくとも外表面側が多孔質層からなる多孔質中空糸膜であって、外表面の開孔率が１５～６５％である多孔質中空糸膜とすることで、内部構造が表面より粗大な傾斜構造を有する構造であるため、内部での目詰まりが無く洗浄回復性も高いと考えられる。また、膜分離特性の保持性と回復性に優れた多孔質中空糸膜を得ることができる。
Further, according to the present invention, by forming a porous hollow fiber membrane having a porous layer at least on the outer surface side and a porosity of 15 to 65% on the outer surface, Since the structure has an inclined structure coarser than the surface, it is considered that there is no clogging inside and the cleaning recovery is high. Moreover, a porous hollow fiber membrane excellent in retention and recovery of membrane separation characteristics can be obtained.
本発明の多孔質中空糸膜は、浄水膜、飲料処理膜、海水除濁膜等の種々の水性流体の処理において使用することができ、特に浄水処理に適する多孔質中空糸膜を提供することができる。また、本願の多孔質中空糸膜は、優れた分画特性、透過性を有しながら、モジュール成型時や実際の使用時の破断やリークを招くことのない十分な膜強度を有し、これらの特性の経時的な低下の抑制が実現され、洗浄による膜分離特性の回復性に優れている。
The porous hollow fiber membrane of the present invention can be used in the treatment of various aqueous fluids such as water purification membranes, beverage treatment membranes and seawater turbidity membranes, and provides a porous hollow fiber membrane particularly suitable for water purification treatments. Can do. Moreover, the porous hollow fiber membrane of the present application has sufficient membrane strength that does not cause breakage or leakage during module molding or actual use, while having excellent fractionation characteristics and permeability. In this way, it is possible to suppress the deterioration of the characteristics of the film over time, and it is excellent in recovering the membrane separation characteristics by washing.
また、本発明の多孔質中空糸膜は、断面構造における表面から深さ１μｍまでの平均孔径Ａｄが、深さ２μｍから３μｍまでの平均孔径Ｂｄの１／２以下であることにより、いわゆる緻密層が薄く、その結果分離特性・濾過安定性・機械的強度に優れる多孔質中空糸膜となる。
The porous hollow fiber membrane of the present invention has a so-called dense layer because the average pore diameter Ad from the surface to the depth of 1 μm in the cross-sectional structure is ½ or less of the average pore diameter Bd from the depth of 2 μm to 3 μm. As a result, a porous hollow fiber membrane excellent in separation characteristics, filtration stability and mechanical strength is obtained.
以下、本発明の好適な実施の形態について説明する。
Hereinafter, preferred embodiments of the present invention will be described.
（第一の実施形態）
本実施形態の多孔質中空糸膜は、本実施形態の少なくとも外表面側が多孔質層からなる多孔質中空糸膜であって、外表面の開孔率が外表面の全体面積に対して１５～６０％である多孔質中空糸膜である。ここで外表面とは、膜の両表面のうち、膜を中空糸状（円筒状）に形成して多孔質中空糸膜とした際に、円筒の外周に面する側の表面を指す。円筒の内周に面する側の表面を内表面とする。ここで多孔質層とは、層のほぼ全体に分散する形で後述する性質の孔を有している層をいう。また、ここで開孔率とは、多孔質中空糸膜の外表面を顕微鏡等で観察し、画像解析等によって孔の面積を測定、全孔についてこれを合計し、開孔率（％）＝全孔の面積の和／観察した外表面全体の面積（視野内の膜面積）として求めた値である。少なくとも外表面側が多孔質層からなる多孔質中空糸膜であって、外表面の開孔率が外表面の全体面積に対して１５～６０％であることにより、表面が緻密でありかつ透水性能にすぐれた多孔質中空糸膜となる。外表面の開孔率は、外表面の全体面積に対して、好ましくは２０％以上６０％以下であり、より好ましくは、２５％以上５５％以下である。 (First embodiment)
The porous hollow fiber membrane of the present embodiment is a porous hollow fiber membrane in which at least the outer surface side of the present embodiment is composed of a porous layer, and the porosity of the outer surface is from 15 to the total area of the outer surface. It is a porous hollow fiber membrane that is 60%. Here, the outer surface refers to the surface on the side facing the outer periphery of the cylinder when the membrane is formed into a hollow fiber shape (cylindrical shape) to form a porous hollow fiber membrane. The surface on the side facing the inner periphery of the cylinder is defined as the inner surface. Here, the porous layer refers to a layer having pores having the properties described later in a form dispersed in almost the entire layer. Further, here, the open area ratio means that the outer surface of the porous hollow fiber membrane is observed with a microscope or the like, the area of the holes is measured by image analysis or the like, and the total area of all the holes is totaled. It is a value obtained as the sum of the areas of all the holes / the area of the entire observed outer surface (film area in the field of view). A porous hollow fiber membrane having a porous layer at least on the outer surface side, and the porosity of the outer surface is 15 to 60% with respect to the entire area of the outer surface. It becomes an excellent porous hollow fiber membrane. The porosity of the outer surface is preferably 20% or more and 60% or less, and more preferably 25% or more and 55% or less with respect to the entire area of the outer surface.
本実施形態の多孔質中空糸膜は、本実施形態の少なくとも外表面側が多孔質層からなる多孔質中空糸膜であって、外表面の開孔率が外表面の全体面積に対して１５～６０％である多孔質中空糸膜である。ここで外表面とは、膜の両表面のうち、膜を中空糸状（円筒状）に形成して多孔質中空糸膜とした際に、円筒の外周に面する側の表面を指す。円筒の内周に面する側の表面を内表面とする。ここで多孔質層とは、層のほぼ全体に分散する形で後述する性質の孔を有している層をいう。また、ここで開孔率とは、多孔質中空糸膜の外表面を顕微鏡等で観察し、画像解析等によって孔の面積を測定、全孔についてこれを合計し、開孔率（％）＝全孔の面積の和／観察した外表面全体の面積（視野内の膜面積）として求めた値である。少なくとも外表面側が多孔質層からなる多孔質中空糸膜であって、外表面の開孔率が外表面の全体面積に対して１５～６０％であることにより、表面が緻密でありかつ透水性能にすぐれた多孔質中空糸膜となる。外表面の開孔率は、外表面の全体面積に対して、好ましくは２０％以上６０％以下であり、より好ましくは、２５％以上５５％以下である。 (First embodiment)
The porous hollow fiber membrane of the present embodiment is a porous hollow fiber membrane in which at least the outer surface side of the present embodiment is composed of a porous layer, and the porosity of the outer surface is from 15 to the total area of the outer surface. It is a porous hollow fiber membrane that is 60%. Here, the outer surface refers to the surface on the side facing the outer periphery of the cylinder when the membrane is formed into a hollow fiber shape (cylindrical shape) to form a porous hollow fiber membrane. The surface on the side facing the inner periphery of the cylinder is defined as the inner surface. Here, the porous layer refers to a layer having pores having the properties described later in a form dispersed in almost the entire layer. Further, here, the open area ratio means that the outer surface of the porous hollow fiber membrane is observed with a microscope or the like, the area of the holes is measured by image analysis or the like, and the total area of all the holes is totaled. It is a value obtained as the sum of the areas of all the holes / the area of the entire observed outer surface (film area in the field of view). A porous hollow fiber membrane having a porous layer at least on the outer surface side, and the porosity of the outer surface is 15 to 60% with respect to the entire area of the outer surface. It becomes an excellent porous hollow fiber membrane. The porosity of the outer surface is preferably 20% or more and 60% or less, and more preferably 25% or more and 55% or less with respect to the entire area of the outer surface.
また、本実施形態の多孔質中空糸膜の多孔質層が有する各孔の平均孔径指数（又は、平均孔径Ｐ１）が０．０５～１．０（μｍ）であってもよい。これにより回復性に優れた多孔質中空糸膜となる。多孔質中空糸膜の平均孔径指数は好ましくは０．０６～０．９（μｍ）であり、より好ましくは、０．７５～０．８（μｍ）である。
なお、平均孔径指数とは、画像解析ソフトを用いて顕微鏡写真から読み取った孔径に算術的な処理を行い算出した孔径を指す。これにより、画素の濃淡による微小ノイズを除外する効果がある。本実施形態では、多孔質中空糸膜の外表面を顕微鏡により撮影し、写真内の孔の孔径の平均値を計測して求めている。 Further, the average pore diameter index (or average pore diameter P1) of each pore of the porous layer of the porous hollow fiber membrane of the present embodiment may be 0.05 to 1.0 (μm). Thereby, it becomes a porous hollow fiber membrane excellent in recoverability. The average pore diameter index of the porous hollow fiber membrane is preferably 0.06 to 0.9 (μm), more preferably 0.75 to 0.8 (μm).
The average pore size index refers to the pore size calculated by performing arithmetic processing on the pore size read from the micrograph using image analysis software. As a result, there is an effect of excluding minute noise due to the density of pixels. In the present embodiment, the outer surface of the porous hollow fiber membrane is photographed with a microscope, and the average value of the pore diameters in the photograph is measured.
なお、平均孔径指数とは、画像解析ソフトを用いて顕微鏡写真から読み取った孔径に算術的な処理を行い算出した孔径を指す。これにより、画素の濃淡による微小ノイズを除外する効果がある。本実施形態では、多孔質中空糸膜の外表面を顕微鏡により撮影し、写真内の孔の孔径の平均値を計測して求めている。 Further, the average pore diameter index (or average pore diameter P1) of each pore of the porous layer of the porous hollow fiber membrane of the present embodiment may be 0.05 to 1.0 (μm). Thereby, it becomes a porous hollow fiber membrane excellent in recoverability. The average pore diameter index of the porous hollow fiber membrane is preferably 0.06 to 0.9 (μm), more preferably 0.75 to 0.8 (μm).
The average pore size index refers to the pore size calculated by performing arithmetic processing on the pore size read from the micrograph using image analysis software. As a result, there is an effect of excluding minute noise due to the density of pixels. In the present embodiment, the outer surface of the porous hollow fiber membrane is photographed with a microscope, and the average value of the pore diameters in the photograph is measured.
また、本実施形態の多孔質中空糸膜は、厚さ方向の断面を観測した際、その断面構造における表面から深さ１０μｍまでの層の平均孔径Ｐ２が、０．１～５．０（μｍ）であり、この層における開孔率Ａ２が１０～５０％であることが好ましい。この範囲であれば、耐目詰まり性と強度を両立できる効果がある。
In the porous hollow fiber membrane of this embodiment, when the cross section in the thickness direction is observed, the average pore diameter P2 of the layer from the surface to the depth of 10 μm in the cross-sectional structure is 0.1 to 5.0 (μm It is preferable that the porosity A2 in this layer is 10 to 50%. If it is this range, there exists an effect which can make clogging-proof property and intensity | strength compatible.
本実施形態の多孔質中空糸膜を構成する多孔質膜層においては、その厚さが２００μｍ以下であるのが好ましい。これは、多孔質膜層の厚さが２００μｍ以下であることによって、膜分離時における透過抵抗が低減され、優れた透水性能が得られるとともに、高分子樹脂溶液である製膜原液を用いて多孔質膜層を形成させる際の凝固時間を短くでき、マクロボイド（欠損部位）抑制に効果的であると共に、優れた生産性を得ることができる傾向にあるためである。より好ましくは、多孔質膜層の厚さが１５０μｍ以下である。
また、本実施形態の多孔質中空糸膜を構成する多孔質膜層においては、その厚さが１００μｍ以上であるのが好ましい。これは、多孔質膜層の厚さが１００μｍ以上であることによって、実用上問題のない機械的強度を得ることができる傾向にあるためである。ただし、膜外径が細い場合は厚さが１００μｍ未満でも機械的強度が維持できる場合があるためこの限りではない。 The porous membrane layer constituting the porous hollow fiber membrane of the present embodiment preferably has a thickness of 200 μm or less. This is because when the thickness of the porous membrane layer is 200 μm or less, the permeation resistance at the time of membrane separation is reduced, and excellent water permeability is obtained. This is because the coagulation time when forming the membrane layer can be shortened, and it is effective in suppressing macrovoids (defects), and excellent productivity tends to be obtained. More preferably, the thickness of the porous membrane layer is 150 μm or less.
Moreover, in the porous membrane layer which comprises the porous hollow fiber membrane of this embodiment, it is preferable that the thickness is 100 micrometers or more. This is because when the thickness of the porous membrane layer is 100 μm or more, there is a tendency that mechanical strength having no practical problem can be obtained. However, when the outer diameter of the membrane is small, the mechanical strength may be maintained even if the thickness is less than 100 μm, so this is not the case.
また、本実施形態の多孔質中空糸膜を構成する多孔質膜層においては、その厚さが１００μｍ以上であるのが好ましい。これは、多孔質膜層の厚さが１００μｍ以上であることによって、実用上問題のない機械的強度を得ることができる傾向にあるためである。ただし、膜外径が細い場合は厚さが１００μｍ未満でも機械的強度が維持できる場合があるためこの限りではない。 The porous membrane layer constituting the porous hollow fiber membrane of the present embodiment preferably has a thickness of 200 μm or less. This is because when the thickness of the porous membrane layer is 200 μm or less, the permeation resistance at the time of membrane separation is reduced, and excellent water permeability is obtained. This is because the coagulation time when forming the membrane layer can be shortened, and it is effective in suppressing macrovoids (defects), and excellent productivity tends to be obtained. More preferably, the thickness of the porous membrane layer is 150 μm or less.
Moreover, in the porous membrane layer which comprises the porous hollow fiber membrane of this embodiment, it is preferable that the thickness is 100 micrometers or more. This is because when the thickness of the porous membrane layer is 100 μm or more, there is a tendency that mechanical strength having no practical problem can be obtained. However, when the outer diameter of the membrane is small, the mechanical strength may be maintained even if the thickness is less than 100 μm, so this is not the case.
この多孔質膜層は、その少なくとも外表面近傍に緻密層を有するものである。ここで外表面近傍とは、多孔質膜層の内部の部位で多孔質膜層の外表面に隣接した（多孔質膜層の内側の）部位をいう。また、ここで緻密層とは、多孔質膜層中において、より小孔径の微細孔が集合している領域のことをいうが、本実施形態においては、多孔質中空糸膜の透水性能と分離性能を両立できることから、表面近傍の緻密層においては、その平均孔径指数を０．０１～１μｍの範囲とするのが好ましい。
The porous membrane layer has a dense layer at least near the outer surface. Here, the vicinity of the outer surface refers to a portion adjacent to the outer surface of the porous membrane layer (inside the porous membrane layer) at a portion inside the porous membrane layer. Here, the dense layer refers to a region in which fine pores having smaller pore diameters are gathered in the porous membrane layer. In this embodiment, the water permeability and separation of the porous hollow fiber membrane are used. In order to achieve both performances, in the dense layer near the surface, the average pore diameter index is preferably in the range of 0.01 to 1 μm.
本実施形態における緻密層の厚さは、分離特性の安定性向上と透水性能向上の両方の点から、１０～１２５μｍの範囲であるのが好ましい。
外表面近傍の緻密層においては、分離特性の安定性向上の点から、その厚さを２５～１００μｍの範囲であるのがより好ましい。さらに好ましくは、緻密層の厚さは４０～７５μｍの範囲である。 The thickness of the dense layer in this embodiment is preferably in the range of 10 to 125 μm from the viewpoints of both improving the stability of separation characteristics and improving water permeability.
In the dense layer near the outer surface, the thickness is more preferably in the range of 25 to 100 μm from the viewpoint of improving the stability of the separation characteristics. More preferably, the dense layer has a thickness in the range of 40 to 75 μm.
外表面近傍の緻密層においては、分離特性の安定性向上の点から、その厚さを２５～１００μｍの範囲であるのがより好ましい。さらに好ましくは、緻密層の厚さは４０～７５μｍの範囲である。 The thickness of the dense layer in this embodiment is preferably in the range of 10 to 125 μm from the viewpoints of both improving the stability of separation characteristics and improving water permeability.
In the dense layer near the outer surface, the thickness is more preferably in the range of 25 to 100 μm from the viewpoint of improving the stability of the separation characteristics. More preferably, the dense layer has a thickness in the range of 40 to 75 μm.
外表面近傍の緻密層の位置は、膜内部での透水抵抗の上昇を避ける観点からこの多孔質膜層の外表面から２０μｍ以内の位置に存在するのが好ましい。さらに、この緻密層が多孔質膜層の外表面を構成するのが特に好ましい。
The position of the dense layer in the vicinity of the outer surface is preferably present at a position within 20 μm from the outer surface of the porous membrane layer from the viewpoint of avoiding an increase in water permeability resistance inside the membrane. Furthermore, it is particularly preferred that this dense layer constitutes the outer surface of the porous membrane layer.
この多孔質膜層は、上述の外表面近傍の緻密層の内側（より外表面から離れた部位、外表面から見て深い部位）に、平均孔径指数が２μｍ以上のスポンジ層を有するのが好ましい。この中間多孔質層は、特に本実施形態の多孔質中空糸膜における透水性能に寄与するものであるので、その孔径は大きいほど良いが、大きすぎるとマクロボイドとなり、その機械的強度を低下させる。従って、その平均孔径指数は８μｍ以下とするのが好ましく、実質的に１０μｍ以上の細孔は存在しないのがより好ましい。さらに好ましくは、３～５μｍの範囲である。
また、透水性能向上の点から、この中間多孔質層、特に外表面から深さ５μｍより離れた部位においては、外表面近傍の緻密層から外表面から離れる方向に向かって、すなわち内表面近傍に向かって孔径が漸増する傾斜構造を有するのが好ましい。特に、この中間多孔質層は、細孔が互いに立体的に交差する三次元網目構造をとっていることが好ましい。
また、外表面から深さ５μｍまでの多孔質層の平均孔径が、前記外表面から深さ５μｍよりも深い部位に存在する多孔質層の平均孔径よりも小さいことが好ましい。さらに、外表面から深さ５μｍよりも深い部位に存在する多孔質層の平均孔径が、１０μｍ以下であることが特に好ましい。この構成により、外表面近傍の緻密層を抜けた物質が内部で詰まることを抑止できると共に、品質も両立できる効果がある。
なお、これまで記載してきた多孔質層は、素材や平均孔径の違いによって非連続的に複数の層（例えば、緻密層と、緻密層以外の層）に分かれていることもあるが、これが連続的に（例えば、表面からの距離に従って次第に口径の平均値が変化するなど）変化している場合もある。この場合、層は部位（例えば、緻密部位とそれ以外の部位等）と呼ぶこともある。 The porous membrane layer preferably has a sponge layer having an average pore diameter index of 2 μm or more inside the dense layer near the outer surface (a portion further away from the outer surface and a portion deeper when viewed from the outer surface). . Since this intermediate porous layer contributes to the water permeability in the porous hollow fiber membrane of this embodiment in particular, the larger the pore diameter, the better. However, if it is too large, it becomes a macrovoid and reduces its mechanical strength. . Therefore, the average pore diameter index is preferably 8 μm or less, and more preferably substantially no pores of 10 μm or more are present. More preferably, it is in the range of 3 to 5 μm.
In addition, from the viewpoint of improving water permeability, this intermediate porous layer, particularly at a part away from the outer surface by a depth of 5 μm, is directed away from the dense layer near the outer surface toward the outer surface, that is, near the inner surface. It is preferable to have an inclined structure in which the hole diameter gradually increases. In particular, the intermediate porous layer preferably has a three-dimensional network structure in which the pores sterically intersect with each other.
Moreover, it is preferable that the average pore diameter of the porous layer from the outer surface to a depth of 5 μm is smaller than the average pore diameter of the porous layer existing at a site deeper than the depth of 5 μm from the outer surface. Furthermore, it is particularly preferable that the average pore diameter of the porous layer existing at a site deeper than 5 μm from the outer surface is 10 μm or less. With this configuration, it is possible to prevent substances that have passed through the dense layer in the vicinity of the outer surface from being clogged inside, and to achieve both effects of quality.
The porous layer described so far may be discontinuously divided into a plurality of layers (for example, a dense layer and a layer other than the dense layer) depending on the material and the average pore diameter. (For example, the average value of the diameter gradually changes according to the distance from the surface). In this case, the layer may be referred to as a part (for example, a dense part and other parts).
また、透水性能向上の点から、この中間多孔質層、特に外表面から深さ５μｍより離れた部位においては、外表面近傍の緻密層から外表面から離れる方向に向かって、すなわち内表面近傍に向かって孔径が漸増する傾斜構造を有するのが好ましい。特に、この中間多孔質層は、細孔が互いに立体的に交差する三次元網目構造をとっていることが好ましい。
また、外表面から深さ５μｍまでの多孔質層の平均孔径が、前記外表面から深さ５μｍよりも深い部位に存在する多孔質層の平均孔径よりも小さいことが好ましい。さらに、外表面から深さ５μｍよりも深い部位に存在する多孔質層の平均孔径が、１０μｍ以下であることが特に好ましい。この構成により、外表面近傍の緻密層を抜けた物質が内部で詰まることを抑止できると共に、品質も両立できる効果がある。
なお、これまで記載してきた多孔質層は、素材や平均孔径の違いによって非連続的に複数の層（例えば、緻密層と、緻密層以外の層）に分かれていることもあるが、これが連続的に（例えば、表面からの距離に従って次第に口径の平均値が変化するなど）変化している場合もある。この場合、層は部位（例えば、緻密部位とそれ以外の部位等）と呼ぶこともある。 The porous membrane layer preferably has a sponge layer having an average pore diameter index of 2 μm or more inside the dense layer near the outer surface (a portion further away from the outer surface and a portion deeper when viewed from the outer surface). . Since this intermediate porous layer contributes to the water permeability in the porous hollow fiber membrane of this embodiment in particular, the larger the pore diameter, the better. However, if it is too large, it becomes a macrovoid and reduces its mechanical strength. . Therefore, the average pore diameter index is preferably 8 μm or less, and more preferably substantially no pores of 10 μm or more are present. More preferably, it is in the range of 3 to 5 μm.
In addition, from the viewpoint of improving water permeability, this intermediate porous layer, particularly at a part away from the outer surface by a depth of 5 μm, is directed away from the dense layer near the outer surface toward the outer surface, that is, near the inner surface. It is preferable to have an inclined structure in which the hole diameter gradually increases. In particular, the intermediate porous layer preferably has a three-dimensional network structure in which the pores sterically intersect with each other.
Moreover, it is preferable that the average pore diameter of the porous layer from the outer surface to a depth of 5 μm is smaller than the average pore diameter of the porous layer existing at a site deeper than the depth of 5 μm from the outer surface. Furthermore, it is particularly preferable that the average pore diameter of the porous layer existing at a site deeper than 5 μm from the outer surface is 10 μm or less. With this configuration, it is possible to prevent substances that have passed through the dense layer in the vicinity of the outer surface from being clogged inside, and to achieve both effects of quality.
The porous layer described so far may be discontinuously divided into a plurality of layers (for example, a dense layer and a layer other than the dense layer) depending on the material and the average pore diameter. (For example, the average value of the diameter gradually changes according to the distance from the surface). In this case, the layer may be referred to as a part (for example, a dense part and other parts).
次に、本実施形態の多孔質中空糸膜の製造方法について説明する。
本実施形態の多孔質中空糸膜は、環状ノズルを用いて、中空状の支持体の外周面に、多孔質膜層の材料及び溶剤を含む、第一製膜原液と第二製膜原液の製膜原液を連続的に塗布して積層し、これらの製膜原液を同時に凝固させることによって製造することができる。
この場合、凝固は片面からのみの凝固でよく、この方法によって二種類の製膜原液から一体の多孔質膜構造を得ることができる。 Next, the manufacturing method of the porous hollow fiber membrane of this embodiment is demonstrated.
The porous hollow fiber membrane of the present embodiment includes an annular nozzle and a first membrane undiluted solution and a second membrane undiluted solution containing the material and solvent for the porous membrane layer on the outer peripheral surface of the hollow support. The film-forming stock solution can be continuously applied and laminated, and these film-forming stock solutions can be coagulated at the same time.
In this case, the solidification may be from only one side, and an integral porous membrane structure can be obtained from two types of film-forming stock solutions by this method.
本実施形態の多孔質中空糸膜は、環状ノズルを用いて、中空状の支持体の外周面に、多孔質膜層の材料及び溶剤を含む、第一製膜原液と第二製膜原液の製膜原液を連続的に塗布して積層し、これらの製膜原液を同時に凝固させることによって製造することができる。
この場合、凝固は片面からのみの凝固でよく、この方法によって二種類の製膜原液から一体の多孔質膜構造を得ることができる。 Next, the manufacturing method of the porous hollow fiber membrane of this embodiment is demonstrated.
The porous hollow fiber membrane of the present embodiment includes an annular nozzle and a first membrane undiluted solution and a second membrane undiluted solution containing the material and solvent for the porous membrane layer on the outer peripheral surface of the hollow support. The film-forming stock solution can be continuously applied and laminated, and these film-forming stock solutions can be coagulated at the same time.
In this case, the solidification may be from only one side, and an integral porous membrane structure can be obtained from two types of film-forming stock solutions by this method.
例えば、特許文献７の図１に記載されているような二重環状ノズルを使用し、その支持体通路に中空状支持体（編紐）を通過させ、第一供給口からの第一製膜原液（内層側製膜原液）と第二供給口からの第二製膜原液（外層側製膜原液）とを同時に吐出させ、第一製膜原液を中空状編紐の外周面に塗布した後に、第二製膜原液を該前記第一製膜原液の塗布層上に塗布する。この後、製膜原液を塗布した中空状編紐を所定時間空走させた後、凝固液に浸漬して製膜原液凝固させ、水洗及び乾燥させることによって、本実施形態で特定する多孔質中空糸膜の構造を得ることができる。
For example, a double annular nozzle as shown in FIG. 1 of Patent Document 7 is used, a hollow support (knitted string) is passed through the support passage, and the first film is formed from the first supply port. After discharging the stock solution (inner layer side film forming stock solution) and the second film forming stock solution (outer layer side film forming stock solution) from the second supply port at the same time, and applying the first film forming stock solution to the outer peripheral surface of the hollow knitted string The second film-forming stock solution is applied onto the coating layer of the first film-forming stock solution. After this, the hollow knitted string coated with the film-forming stock solution is idled for a predetermined time, and then immersed in a coagulation liquid to solidify the film-forming stock solution, washed with water, and dried, so that the porous hollow specified in this embodiment is used. A thread membrane structure can be obtained.
また、二重環状ノズルを用いる場合は、ノズル内で第一製膜原液と第二製膜原液とを予め合流させ、ノズル面からこれらを同時に吐出させ、中空状支持体に塗布することもできる。
さらに、中央部、内側部及び外側部を有する三重環状ノズルを用い、中央部に中空状支持体を通過させながら、内側部からの第一製膜原液と外側部からの第二製膜原液とを同時に吐出させ、製膜原液を中空状の支持体に塗布することもできる。
上述のような環状ノズルを用いることによって、第一製膜原液及び第二製膜原液のそれぞれを均一に塗布することができ、さらに、第一製膜原液と第二製膜原液を積層させた際に層間に気泡が生じないようにすることができる。なお、第一製膜原液と第二製膜原液を順次塗布してもよい。この場合、第一の成膜原液と第二の成膜原液を塗布する際は、連続的になるよう塗布しても、それぞれ間をおいてもよいが、第一製膜原液と第二製膜原液を積層させた際に層間に気泡が生じないようにするため、連続的に行うのが好ましい。 When a double annular nozzle is used, the first film-forming stock solution and the second film-forming stock solution can be combined in the nozzle in advance, and these can be simultaneously discharged from the nozzle surface and applied to the hollow support. .
Furthermore, using a triple annular nozzle having a central part, an inner part and an outer part, while passing a hollow support through the central part, the first film-forming stock solution from the inner part and the second film-forming stock solution from the outer part Can be simultaneously discharged to apply the film-forming stock solution to a hollow support.
By using the annular nozzle as described above, each of the first film-forming stock solution and the second film-forming stock solution can be uniformly applied, and the first film-forming stock solution and the second film-forming stock solution are laminated. In this case, bubbles can be prevented from being generated between the layers. The first film-forming stock solution and the second film-forming stock solution may be applied in sequence. In this case, when the first film-forming stock solution and the second film-forming stock solution are applied, the first film-forming stock solution and the second film-forming solution may be applied either continuously or at intervals. In order to prevent bubbles from being generated between the layers when laminating the membrane stock solution, it is preferably performed continuously.
さらに、中央部、内側部及び外側部を有する三重環状ノズルを用い、中央部に中空状支持体を通過させながら、内側部からの第一製膜原液と外側部からの第二製膜原液とを同時に吐出させ、製膜原液を中空状の支持体に塗布することもできる。
上述のような環状ノズルを用いることによって、第一製膜原液及び第二製膜原液のそれぞれを均一に塗布することができ、さらに、第一製膜原液と第二製膜原液を積層させた際に層間に気泡が生じないようにすることができる。なお、第一製膜原液と第二製膜原液を順次塗布してもよい。この場合、第一の成膜原液と第二の成膜原液を塗布する際は、連続的になるよう塗布しても、それぞれ間をおいてもよいが、第一製膜原液と第二製膜原液を積層させた際に層間に気泡が生じないようにするため、連続的に行うのが好ましい。 When a double annular nozzle is used, the first film-forming stock solution and the second film-forming stock solution can be combined in the nozzle in advance, and these can be simultaneously discharged from the nozzle surface and applied to the hollow support. .
Furthermore, using a triple annular nozzle having a central part, an inner part and an outer part, while passing a hollow support through the central part, the first film-forming stock solution from the inner part and the second film-forming stock solution from the outer part Can be simultaneously discharged to apply the film-forming stock solution to a hollow support.
By using the annular nozzle as described above, each of the first film-forming stock solution and the second film-forming stock solution can be uniformly applied, and the first film-forming stock solution and the second film-forming stock solution are laminated. In this case, bubbles can be prevented from being generated between the layers. The first film-forming stock solution and the second film-forming stock solution may be applied in sequence. In this case, when the first film-forming stock solution and the second film-forming stock solution are applied, the first film-forming stock solution and the second film-forming solution may be applied either continuously or at intervals. In order to prevent bubbles from being generated between the layers when laminating the membrane stock solution, it is preferably performed continuously.
上記の場合では二種類の製膜原液が使用されるが、いずれも高分子樹脂、添加剤、及び有機溶媒を含有するものである。
これら製膜原液に用いられる高分子樹脂としては、例えば、ポリスルホン樹脂、ポリエーテルスルホン樹脂、スルホン化ポリスルホン樹脂、ポリフッ化ビニリデン樹脂、ポリアクリロニトリル樹脂、ポリイミド樹脂、ポリアミドイミド樹脂又はポリエステルイミド樹脂等を挙げることができる。これらは必要に応じて適宜選択して使用することができるが、中でも耐薬品性に優れることから、ポリフッ化ビニリデン樹脂が好ましい。 In the above case, two types of film-forming stock solutions are used, both of which contain a polymer resin, an additive, and an organic solvent.
Examples of the polymer resin used in these film-forming stock solutions include polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyvinylidene fluoride resin, polyacrylonitrile resin, polyimide resin, polyamideimide resin, or polyesterimide resin. be able to. These can be appropriately selected and used as necessary, but among these, polyvinylidene fluoride resin is preferred because of its excellent chemical resistance.
これら製膜原液に用いられる高分子樹脂としては、例えば、ポリスルホン樹脂、ポリエーテルスルホン樹脂、スルホン化ポリスルホン樹脂、ポリフッ化ビニリデン樹脂、ポリアクリロニトリル樹脂、ポリイミド樹脂、ポリアミドイミド樹脂又はポリエステルイミド樹脂等を挙げることができる。これらは必要に応じて適宜選択して使用することができるが、中でも耐薬品性に優れることから、ポリフッ化ビニリデン樹脂が好ましい。 In the above case, two types of film-forming stock solutions are used, both of which contain a polymer resin, an additive, and an organic solvent.
Examples of the polymer resin used in these film-forming stock solutions include polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyvinylidene fluoride resin, polyacrylonitrile resin, polyimide resin, polyamideimide resin, or polyesterimide resin. be able to. These can be appropriately selected and used as necessary, but among these, polyvinylidene fluoride resin is preferred because of its excellent chemical resistance.
添加剤としては、相分離の制御等を目的として使用することができ、例えば、ポリエチレングリコールによって代表されるモノオール系、ジオール系、トリオール系、又はポリビニルピロリドンなどの親水性高分子樹脂を使用することができる。これらは必要に応じて適宜選択して使用することができるが、中でも増粘効果に優れることから、ポリビニルピロリドンが好ましい。
As an additive, it can be used for the purpose of controlling phase separation and the like, for example, a hydrophilic polymer resin such as monool, diol, triol, or polyvinylpyrrolidone represented by polyethylene glycol is used. be able to. These can be appropriately selected and used as necessary, and among them, polyvinylpyrrolidone is preferred because of its excellent thickening effect.
有機溶媒としては、上述の高分子樹脂及び添加剤を溶解できるものであれば特に限定されるものではなく、例えば、ジメチルスルホキシド、ジメチルアセトアミド又はジメチルホルムアミドを用いることができる。
The organic solvent is not particularly limited as long as it can dissolve the above-described polymer resin and additives, and for example, dimethyl sulfoxide, dimethylacetamide, or dimethylformamide can be used.
上述の二種類の製膜原液の組成は、特に限定されるものではなく、同じ成膜原液を用いてもよいし、異なる成膜原液を用いてもよい。しかし、層間剥離を防ぎ機械的強度を向上させる観点から、凝固に際して二種類の製膜原液から一体構造を形成させるために、使用する溶媒ならびに高分子樹脂は同種類のものであることが好ましい。
The composition of the two types of film-forming stock solutions described above is not particularly limited, and the same film-forming stock solution or different film-forming stock solutions may be used. However, from the viewpoint of preventing delamination and improving mechanical strength, it is preferable that the solvent and polymer resin used are the same type in order to form an integral structure from two types of film-forming stock solutions during solidification.
本実施形態の多孔質中空糸膜を上述の方法で製造する場合においては、内層側製膜原液である第一製膜原液の粘度を外層側製膜原液である第二製膜原液のそれよりも高くすることが好ましい。
これは、粘度のより高い第一製膜原液を前記中空状の支持体の外周面に塗布することによって、製膜原液が中空状支持体の内部に過度に侵入することを抑え、多孔質中空糸膜の中空部の閉塞を防ぐことができるためである。
これを達成するためには、この第一製膜原液は、充分な粘度を有する必要があり、４０℃での粘度が５万ｍＰａ・ｓｅｃ以上であることが好ましい。より好ましくは１０万ｍＰａ・ｓｅｃ以上であり、さらに好ましくは１５万ｍＰａ・ｓｅｃ以上である。具体的には、例えば、第一成膜原液の４０℃での粘度は５～２５万ｍＰａ・ｓｅｃの範囲、第二成膜原液の４０℃での粘度は１０～３０万ｍＰａ・ｓｅｃの範囲である。 In the case of producing the porous hollow fiber membrane of the present embodiment by the above method, the viscosity of the first membrane forming stock solution that is the inner layer side membrane forming stock solution is higher than that of the second membrane forming stock solution that is the outer layer side membrane forming stock solution. It is preferable to increase the height.
This is because the first membrane-forming solution having a higher viscosity is applied to the outer peripheral surface of the hollow support, thereby preventing the membrane-forming stock solution from excessively penetrating into the hollow support, This is because blockage of the hollow portion of the yarn membrane can be prevented.
In order to achieve this, the first film-forming stock solution needs to have a sufficient viscosity, and the viscosity at 40 ° C. is preferably 50,000 mPa · sec or more. More preferably, it is 100,000 mPa * sec or more, More preferably, it is 150,000 mPa * sec or more. Specifically, for example, the viscosity of the first film forming stock solution at 40 ° C. is in the range of 5 to 250,000 mPa · sec, and the viscosity of the second film forming stock solution at 40 ° C. is in the range of 100,000 to 300,000 mPa · sec. It is.
これは、粘度のより高い第一製膜原液を前記中空状の支持体の外周面に塗布することによって、製膜原液が中空状支持体の内部に過度に侵入することを抑え、多孔質中空糸膜の中空部の閉塞を防ぐことができるためである。
これを達成するためには、この第一製膜原液は、充分な粘度を有する必要があり、４０℃での粘度が５万ｍＰａ・ｓｅｃ以上であることが好ましい。より好ましくは１０万ｍＰａ・ｓｅｃ以上であり、さらに好ましくは１５万ｍＰａ・ｓｅｃ以上である。具体的には、例えば、第一成膜原液の４０℃での粘度は５～２５万ｍＰａ・ｓｅｃの範囲、第二成膜原液の４０℃での粘度は１０～３０万ｍＰａ・ｓｅｃの範囲である。 In the case of producing the porous hollow fiber membrane of the present embodiment by the above method, the viscosity of the first membrane forming stock solution that is the inner layer side membrane forming stock solution is higher than that of the second membrane forming stock solution that is the outer layer side membrane forming stock solution. It is preferable to increase the height.
This is because the first membrane-forming solution having a higher viscosity is applied to the outer peripheral surface of the hollow support, thereby preventing the membrane-forming stock solution from excessively penetrating into the hollow support, This is because blockage of the hollow portion of the yarn membrane can be prevented.
In order to achieve this, the first film-forming stock solution needs to have a sufficient viscosity, and the viscosity at 40 ° C. is preferably 50,000 mPa · sec or more. More preferably, it is 100,000 mPa * sec or more, More preferably, it is 150,000 mPa * sec or more. Specifically, for example, the viscosity of the first film forming stock solution at 40 ° C. is in the range of 5 to 250,000 mPa · sec, and the viscosity of the second film forming stock solution at 40 ° C. is in the range of 100,000 to 300,000 mPa · sec. It is.
また、上述の製膜原液の粘度調整方法は特に限定されるものではなく、例えば、高分子樹脂の分子量を変えたり、高分子樹脂の濃度を変えたりすることによっても可能である。高分子樹脂の分子量を変える方法として、異なる分子量の二種類の高分子樹脂をブレンドする方法を用いることもできる。
The method for adjusting the viscosity of the film-forming stock solution described above is not particularly limited. For example, the viscosity can be changed by changing the molecular weight of the polymer resin or changing the concentration of the polymer resin. As a method of changing the molecular weight of the polymer resin, a method of blending two kinds of polymer resins having different molecular weights can also be used.
製膜原液の粘度調整は、上述のように適宜選択することができるが、第一製膜原液においては、高分子樹脂の濃度で調整し、かつ濃度をより高くするのが、凝固速度の遅い内層においても、マクロボイドの発生を抑制できる傾向にあり好ましい。また、第一製膜原液の濃度をより高くすることにより多孔質層全体の構造安定性を向上できる傾向にあり好ましい。
一方、第二製膜原液においては、高分子樹脂の分子量で調整するのが、多孔質膜層の外表面の開孔率を高く維持できる傾向にあり好ましい。 The viscosity adjustment of the film-forming stock solution can be appropriately selected as described above. However, in the first film-forming stock solution, adjusting the concentration of the polymer resin and increasing the concentration is a slow coagulation rate. The inner layer is also preferred because it tends to suppress the generation of macrovoids. Further, it is preferable because the structural stability of the entire porous layer can be improved by increasing the concentration of the first film-forming stock solution.
On the other hand, in the second membrane forming undiluted solution, it is preferable to adjust the molecular weight of the polymer resin because the porosity of the outer surface of the porous membrane layer tends to be maintained high.
一方、第二製膜原液においては、高分子樹脂の分子量で調整するのが、多孔質膜層の外表面の開孔率を高く維持できる傾向にあり好ましい。 The viscosity adjustment of the film-forming stock solution can be appropriately selected as described above. However, in the first film-forming stock solution, adjusting the concentration of the polymer resin and increasing the concentration is a slow coagulation rate. The inner layer is also preferred because it tends to suppress the generation of macrovoids. Further, it is preferable because the structural stability of the entire porous layer can be improved by increasing the concentration of the first film-forming stock solution.
On the other hand, in the second membrane forming undiluted solution, it is preferable to adjust the molecular weight of the polymer resin because the porosity of the outer surface of the porous membrane layer tends to be maintained high.
上述のように、製膜原液を凝固させて製膜する場合は、相分離により多孔質構造が形成される。多孔質構造としては、製膜条件によって種々の構造が得られるが、代表的な多孔質構造としては、高分子樹脂が海側となる海島構造より導かれるスポンジ構造、高分子樹脂が島側となる海島構造より導かれる粒子凝集構造、及びスピノーダル分解により高分子樹脂と溶媒がネットワーク状にからみ合った共連続構造より導かれる三次元網目構造の三つを挙げることができる。
多孔質構造としては、これらの構造のうちから適宜選択することができるが、粒子凝集構造は、高分子樹脂層が凝集した構造となりやすく、機械的強度に劣る傾向にあるため、本実施形態においては、スポンジ構造や三次元網目構造を採用するのが好ましい。
スポンジ構造は、孔径が膜厚方向に対して大きく変化しない均質構造となる傾向にあり、分離特性の安定性向上に適した構造である。
一方、三次元網目構造は、スポンジ構造と比較して、空孔同士の連通度が高い構造となる傾向にあり、透過性能の向上に適した構造である。 As described above, when the film-forming stock solution is solidified to form a film, a porous structure is formed by phase separation. As the porous structure, various structures can be obtained depending on the film forming conditions, but as a typical porous structure, a sponge structure derived from a sea-island structure in which the polymer resin is on the sea side, and the polymer resin is on the island side. The particle aggregation structure derived from the sea-island structure, and the three-dimensional network structure derived from the co-continuous structure in which the polymer resin and the solvent are entangled in a network form by spinodal decomposition.
The porous structure can be appropriately selected from these structures, but the particle aggregate structure tends to be a structure in which the polymer resin layer is aggregated and tends to be inferior in mechanical strength. It is preferable to adopt a sponge structure or a three-dimensional network structure.
The sponge structure tends to be a homogeneous structure in which the pore diameter does not change greatly in the film thickness direction, and is a structure suitable for improving the stability of the separation characteristics.
On the other hand, the three-dimensional network structure tends to be a structure having a higher degree of communication between pores than the sponge structure, and is a structure suitable for improving the permeation performance.
多孔質構造としては、これらの構造のうちから適宜選択することができるが、粒子凝集構造は、高分子樹脂層が凝集した構造となりやすく、機械的強度に劣る傾向にあるため、本実施形態においては、スポンジ構造や三次元網目構造を採用するのが好ましい。
スポンジ構造は、孔径が膜厚方向に対して大きく変化しない均質構造となる傾向にあり、分離特性の安定性向上に適した構造である。
一方、三次元網目構造は、スポンジ構造と比較して、空孔同士の連通度が高い構造となる傾向にあり、透過性能の向上に適した構造である。 As described above, when the film-forming stock solution is solidified to form a film, a porous structure is formed by phase separation. As the porous structure, various structures can be obtained depending on the film forming conditions, but as a typical porous structure, a sponge structure derived from a sea-island structure in which the polymer resin is on the sea side, and the polymer resin is on the island side. The particle aggregation structure derived from the sea-island structure, and the three-dimensional network structure derived from the co-continuous structure in which the polymer resin and the solvent are entangled in a network form by spinodal decomposition.
The porous structure can be appropriately selected from these structures, but the particle aggregate structure tends to be a structure in which the polymer resin layer is aggregated and tends to be inferior in mechanical strength. It is preferable to adopt a sponge structure or a three-dimensional network structure.
The sponge structure tends to be a homogeneous structure in which the pore diameter does not change greatly in the film thickness direction, and is a structure suitable for improving the stability of the separation characteristics.
On the other hand, the three-dimensional network structure tends to be a structure having a higher degree of communication between pores than the sponge structure, and is a structure suitable for improving the permeation performance.
内層側製膜原液である第一製膜原液の組成は、形成させる膜構造に応じて適宜選択することができる。
第一製膜原液から、スポンジ構造を得る条件についても同様であり、組成について特に限定されるものではないが、製膜原液中の添加剤と高分子樹脂の質量比（添加剤／高分子樹脂）を０．４５以下、より好ましくは０．４０以下とするのが好ましい。
この質量比を０．４５以下とすることによって、均質構造が緻密化する傾向にあり、またマクロボイドも発生しにくくなる傾向にある。
一方、この質量比が低すぎると、孔径が小さくなりすぎ、透過性能が低下しやすくなる傾向にあるため、この質量比は０．３以上とするのが好ましい。
製膜原液の組成の例としては、製膜原液の全体質量に対してポリフッ化ビニリデン樹脂２０～３０質量％、ポリビニルピロリドン５～１２質量％、ジメチルアセトアミド６０～８５質量％であり、かつ、ポリビニルピロリドンとポリフッ化ビニリデン樹脂の質量比（ポリビニルピロリドン／ポリフッ化ビニリデン樹脂）が０．３～０．４５の範囲にあるものを挙げることができる。 The composition of the first film-forming stock solution that is the inner-layer side film-forming stock solution can be appropriately selected according to the film structure to be formed.
The conditions for obtaining the sponge structure from the first film-forming stock solution are the same, and the composition is not particularly limited, but the mass ratio of the additive to the polymer resin in the film-forming stock solution (additive / polymer resin) ) Is 0.45 or less, more preferably 0.40 or less.
By setting the mass ratio to 0.45 or less, the homogeneous structure tends to be densified, and macrovoids tend not to occur easily.
On the other hand, if this mass ratio is too low, the pore size tends to be too small and the permeation performance tends to be lowered, so this mass ratio is preferably 0.3 or more.
Examples of the composition of the film-forming stock solution include 20-30% by weight of polyvinylidene fluoride resin, 5-12% by weight of polyvinylpyrrolidone, 60-85% by weight of dimethylacetamide, and polyvinyl There may be mentioned those having a mass ratio of pyrrolidone to polyvinylidene fluoride resin (polyvinylpyrrolidone / polyvinylidene fluoride resin) in the range of 0.3 to 0.45.
第一製膜原液から、スポンジ構造を得る条件についても同様であり、組成について特に限定されるものではないが、製膜原液中の添加剤と高分子樹脂の質量比（添加剤／高分子樹脂）を０．４５以下、より好ましくは０．４０以下とするのが好ましい。
この質量比を０．４５以下とすることによって、均質構造が緻密化する傾向にあり、またマクロボイドも発生しにくくなる傾向にある。
一方、この質量比が低すぎると、孔径が小さくなりすぎ、透過性能が低下しやすくなる傾向にあるため、この質量比は０．３以上とするのが好ましい。
製膜原液の組成の例としては、製膜原液の全体質量に対してポリフッ化ビニリデン樹脂２０～３０質量％、ポリビニルピロリドン５～１２質量％、ジメチルアセトアミド６０～８５質量％であり、かつ、ポリビニルピロリドンとポリフッ化ビニリデン樹脂の質量比（ポリビニルピロリドン／ポリフッ化ビニリデン樹脂）が０．３～０．４５の範囲にあるものを挙げることができる。 The composition of the first film-forming stock solution that is the inner-layer side film-forming stock solution can be appropriately selected according to the film structure to be formed.
The conditions for obtaining the sponge structure from the first film-forming stock solution are the same, and the composition is not particularly limited, but the mass ratio of the additive to the polymer resin in the film-forming stock solution (additive / polymer resin) ) Is 0.45 or less, more preferably 0.40 or less.
By setting the mass ratio to 0.45 or less, the homogeneous structure tends to be densified, and macrovoids tend not to occur easily.
On the other hand, if this mass ratio is too low, the pore size tends to be too small and the permeation performance tends to be lowered, so this mass ratio is preferably 0.3 or more.
Examples of the composition of the film-forming stock solution include 20-30% by weight of polyvinylidene fluoride resin, 5-12% by weight of polyvinylpyrrolidone, 60-85% by weight of dimethylacetamide, and polyvinyl There may be mentioned those having a mass ratio of pyrrolidone to polyvinylidene fluoride resin (polyvinylpyrrolidone / polyvinylidene fluoride resin) in the range of 0.3 to 0.45.
第一製膜原液から多孔質層の三次元網目構造を得る条件についても、特に限定されるものではないが、製膜原液中の添加剤と高分子樹脂の質量比（添加剤／高分子樹脂）を０．４５以上、より好ましくは０．５１以上とするのが好ましい。
また、有機溶媒の比率を製膜原液の全体質量に対して６８質量％以下とするのが好ましい。これによって、マクロボイドの発生が抑制される傾向にあると共に、多孔質層全体の構造安定性を向上できる傾向にあるためである。より好ましくは製膜原液の全体質量に対して６０重量％以下である。
製膜原液の組成の例としては、製膜原液の全体質量に対してポリフッ化ビニリデン樹脂２０～３０質量％、ポリビニルピロリドン１０～２０質量％、ジメチルアセトアミド５５～６８質量％であり、かつ、ポリビニルピロリドンとポリフッ化ビニリデン樹脂の質量比（ポリビニルピロリドン／ポリフッ化ビニリデン樹脂）が０．４５以上であるものを挙げることができる。 The conditions for obtaining the three-dimensional network structure of the porous layer from the first film-forming stock solution are not particularly limited, but the mass ratio of the additive to the polymer resin in the film-forming stock solution (additive / polymer resin) ) Is 0.45 or more, more preferably 0.51 or more.
Moreover, it is preferable that the ratio of an organic solvent shall be 68 mass% or less with respect to the whole mass of a film-forming stock solution. This is because the generation of macrovoids tends to be suppressed, and the structural stability of the entire porous layer tends to be improved. More preferably, it is 60% by weight or less based on the total mass of the film-forming stock solution.
Examples of the composition of the film-forming stock solution include 20-30% by weight of polyvinylidene fluoride resin, 10-20% by weight of polyvinylpyrrolidone, 55-68% by weight of dimethylacetamide, and polyvinyl The thing whose mass ratio (polyvinyl pyrrolidone / polyvinylidene fluoride resin) of a pyrrolidone and a polyvinylidene fluoride resin is 0.45 or more can be mentioned.
また、有機溶媒の比率を製膜原液の全体質量に対して６８質量％以下とするのが好ましい。これによって、マクロボイドの発生が抑制される傾向にあると共に、多孔質層全体の構造安定性を向上できる傾向にあるためである。より好ましくは製膜原液の全体質量に対して６０重量％以下である。
製膜原液の組成の例としては、製膜原液の全体質量に対してポリフッ化ビニリデン樹脂２０～３０質量％、ポリビニルピロリドン１０～２０質量％、ジメチルアセトアミド５５～６８質量％であり、かつ、ポリビニルピロリドンとポリフッ化ビニリデン樹脂の質量比（ポリビニルピロリドン／ポリフッ化ビニリデン樹脂）が０．４５以上であるものを挙げることができる。 The conditions for obtaining the three-dimensional network structure of the porous layer from the first film-forming stock solution are not particularly limited, but the mass ratio of the additive to the polymer resin in the film-forming stock solution (additive / polymer resin) ) Is 0.45 or more, more preferably 0.51 or more.
Moreover, it is preferable that the ratio of an organic solvent shall be 68 mass% or less with respect to the whole mass of a film-forming stock solution. This is because the generation of macrovoids tends to be suppressed, and the structural stability of the entire porous layer tends to be improved. More preferably, it is 60% by weight or less based on the total mass of the film-forming stock solution.
Examples of the composition of the film-forming stock solution include 20-30% by weight of polyvinylidene fluoride resin, 10-20% by weight of polyvinylpyrrolidone, 55-68% by weight of dimethylacetamide, and polyvinyl The thing whose mass ratio (polyvinyl pyrrolidone / polyvinylidene fluoride resin) of a pyrrolidone and a polyvinylidene fluoride resin is 0.45 or more can be mentioned.
外層側製膜原液である第二製膜原液の組成についても、多孔質膜層の外表面近傍に緻密層を持ち、多孔質膜層の内表面に向けて孔径が漸増する傾斜構造が相分離により形成できるものであれば、特に限定されない。
第二製膜原液の組成は、目的とする膜構造に応じて適宜選択することができるが、多孔質膜層の表面開孔率を高くできる点から、有機溶媒の比率を７０質量％以上とすることが好ましい。
また、大きなマクロボイドの無い傾斜構造を形成できる傾向があることから、添加剤／高分子樹脂の質量比は０．４５以上であることが好ましい。製膜原液の組成の例としては、ポリフッ化ビニリデン樹脂１５～２５質量％、ポリビニルピロリドン５～１５質量％、ジメチルアセトアミド７０～８０質量％であり、かつ、（ポリビニルピロリドン／ポリフッ化ビニリデン樹脂）が０．４５以上であるものを挙げることができる。 Regarding the composition of the second membrane forming stock solution, which is the outer layer side membrane forming stock solution, the gradient structure has a dense layer near the outer surface of the porous membrane layer and the pore diameter gradually increases toward the inner surface of the porous membrane layer. If it can form by this, it will not specifically limit.
The composition of the second membrane forming stock solution can be appropriately selected according to the target membrane structure, but from the viewpoint that the surface porosity of the porous membrane layer can be increased, the ratio of the organic solvent is 70% by mass or more. It is preferable to do.
Moreover, since there exists a tendency which can form the inclination structure without a big macrovoid, it is preferable that mass ratio of an additive / polymer resin is 0.45 or more. Examples of the composition of the film forming stock solution include 15 to 25% by weight of polyvinylidene fluoride resin, 5 to 15% by weight of polyvinylpyrrolidone, 70 to 80% by weight of dimethylacetamide, and (polyvinylpyrrolidone / polyvinylidene fluoride resin) The thing which is 0.45 or more can be mentioned.
第二製膜原液の組成は、目的とする膜構造に応じて適宜選択することができるが、多孔質膜層の表面開孔率を高くできる点から、有機溶媒の比率を７０質量％以上とすることが好ましい。
また、大きなマクロボイドの無い傾斜構造を形成できる傾向があることから、添加剤／高分子樹脂の質量比は０．４５以上であることが好ましい。製膜原液の組成の例としては、ポリフッ化ビニリデン樹脂１５～２５質量％、ポリビニルピロリドン５～１５質量％、ジメチルアセトアミド７０～８０質量％であり、かつ、（ポリビニルピロリドン／ポリフッ化ビニリデン樹脂）が０．４５以上であるものを挙げることができる。 Regarding the composition of the second membrane forming stock solution, which is the outer layer side membrane forming stock solution, the gradient structure has a dense layer near the outer surface of the porous membrane layer and the pore diameter gradually increases toward the inner surface of the porous membrane layer. If it can form by this, it will not specifically limit.
The composition of the second membrane forming stock solution can be appropriately selected according to the target membrane structure, but from the viewpoint that the surface porosity of the porous membrane layer can be increased, the ratio of the organic solvent is 70% by mass or more. It is preferable to do.
Moreover, since there exists a tendency which can form the inclination structure without a big macrovoid, it is preferable that mass ratio of an additive / polymer resin is 0.45 or more. Examples of the composition of the film forming stock solution include 15 to 25% by weight of polyvinylidene fluoride resin, 5 to 15% by weight of polyvinylpyrrolidone, 70 to 80% by weight of dimethylacetamide, and (polyvinylpyrrolidone / polyvinylidene fluoride resin) The thing which is 0.45 or more can be mentioned.
外層と内層それぞれの塗布時の厚さは、適宜設定することができるが、有機溶媒の比率がより高い傾向にある外層を厚くすると、製膜時にマクロボイドが発生しやすい傾向にあることから、外層の膜厚は１５０μｍ以下とするのが好ましい。より好ましくは１００μｍ以下であり、さらに好ましくは８０μｍ以下である。一方、外層の膜厚の下限は５μｍである。
The thickness at the time of application of each of the outer layer and the inner layer can be set as appropriate, but if the outer layer tends to have a higher ratio of organic solvent, macro voids tend to occur during film formation, The thickness of the outer layer is preferably 150 μm or less. More preferably, it is 100 micrometers or less, More preferably, it is 80 micrometers or less. On the other hand, the lower limit of the thickness of the outer layer is 5 μm.
支持体として中空状編紐を使用する場合は、支持体内部への過度の製膜原液の浸入を防ぐため、予め製膜原液に対する非溶媒を支持体に含浸させておいても良い。上述の組成の製膜原液を使用する場合の非溶媒としては、グリセリンを例示することができる。ただし、使用する製膜原液に対する凝固能力の高すぎる非溶媒や、粘度の高すぎる非溶媒は、多孔質膜層の支持体内部への侵入を阻害し耐剥離性が大きく低下するため、好適ではない。
When a hollow knitted string is used as the support, the support may be previously impregnated with a non-solvent for the film-forming stock solution in order to prevent excessive infiltration of the film-forming stock solution into the support. An example of the non-solvent in the case of using the film-forming stock solution having the above composition is glycerin. However, non-solvents with too high coagulation ability for the film-forming stock solution to be used and non-solvents with too high viscosity hinder the penetration of the porous membrane layer into the support and greatly reduce the peel resistance. Absent.
また、添加剤としてポリビニルピロリドンを用いた場合は、凝固から膜構造形成後の洗浄において、次亜塩素酸ナトリウム等を用いて、多孔質中空糸膜の薬液洗浄を施すことが好ましい。
Further, when polyvinylpyrrolidone is used as an additive, it is preferable to perform chemical cleaning of the porous hollow fiber membrane using sodium hypochlorite or the like in the cleaning after the formation of the membrane structure from coagulation.
（多孔質膜）
多孔質膜層の材料としては、ポリフッ化ビニリデン、ポリスルホン、ポリアクリロニトリル、ポリビニルピロリドン、又はポリエチレングリコール等が挙げられ、耐薬品性、耐熱性等の点から、ポリフッ化ビニリデン、又はポリフッ化ビニリデンとポリビニルピロリドンとの組み合わせが好ましい。
多孔質膜層は、これらの構成素材のいずれか１種からなる層の単層であってもよく、それらの単層を２層以上積層してなる複合多孔質膜層であってもよい。 (Porous membrane)
Examples of the material for the porous membrane layer include polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyvinyl pyrrolidone, and polyethylene glycol. From the viewpoint of chemical resistance and heat resistance, polyvinylidene fluoride, or polyvinylidene fluoride and polyvinyl A combination with pyrrolidone is preferred.
The porous membrane layer may be a single layer composed of any one of these constituent materials, or may be a composite porous membrane layer formed by laminating two or more of these single layers.
多孔質膜層の材料としては、ポリフッ化ビニリデン、ポリスルホン、ポリアクリロニトリル、ポリビニルピロリドン、又はポリエチレングリコール等が挙げられ、耐薬品性、耐熱性等の点から、ポリフッ化ビニリデン、又はポリフッ化ビニリデンとポリビニルピロリドンとの組み合わせが好ましい。
多孔質膜層は、これらの構成素材のいずれか１種からなる層の単層であってもよく、それらの単層を２層以上積層してなる複合多孔質膜層であってもよい。 (Porous membrane)
Examples of the material for the porous membrane layer include polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyvinyl pyrrolidone, and polyethylene glycol. From the viewpoint of chemical resistance and heat resistance, polyvinylidene fluoride, or polyvinylidene fluoride and polyvinyl A combination with pyrrolidone is preferred.
The porous membrane layer may be a single layer composed of any one of these constituent materials, or may be a composite porous membrane layer formed by laminating two or more of these single layers.
（第二の実施形態）
以下、本実施形態の別の好適な実施の形態について説明する。
本実施形態の中空状多孔質中空糸膜は、その厚さ方向に切断し観察した際の断面構造において、表面から深さ１μｍまでの層（以下、多孔質層Ａという。）の平均孔径Ａｄの大きさが、深さ２μｍから３μｍの層（以下、多孔質層Ｂという。）Ｂｄの大きさに対する比で０．６以下、好ましくは１／２以下（０．５以下）である多孔質中空糸膜にある。 (Second embodiment)
Hereinafter, another preferred embodiment of the present embodiment will be described.
The hollow porous hollow fiber membrane of this embodiment has an average pore diameter Ad of a layer from the surface to a depth of 1 μm (hereinafter referred to as porous layer A) in the cross-sectional structure when cut and observed in the thickness direction. Is a porous layer whose ratio to the size of a layer having a depth of 2 to 3 μm (hereinafter referred to as porous layer B) Bd is 0.6 or less, preferably ½ or less (0.5 or less) It is in a hollow fiber membrane.
以下、本実施形態の別の好適な実施の形態について説明する。
本実施形態の中空状多孔質中空糸膜は、その厚さ方向に切断し観察した際の断面構造において、表面から深さ１μｍまでの層（以下、多孔質層Ａという。）の平均孔径Ａｄの大きさが、深さ２μｍから３μｍの層（以下、多孔質層Ｂという。）Ｂｄの大きさに対する比で０．６以下、好ましくは１／２以下（０．５以下）である多孔質中空糸膜にある。 (Second embodiment)
Hereinafter, another preferred embodiment of the present embodiment will be described.
The hollow porous hollow fiber membrane of this embodiment has an average pore diameter Ad of a layer from the surface to a depth of 1 μm (hereinafter referred to as porous layer A) in the cross-sectional structure when cut and observed in the thickness direction. Is a porous layer whose ratio to the size of a layer having a depth of 2 to 3 μm (hereinafter referred to as porous layer B) Bd is 0.6 or less, preferably ½ or less (0.5 or less) It is in a hollow fiber membrane.
これは、本実施形態の多孔質中空糸膜が、外表面を形成する多孔質層Ａに最も孔径の小さい層を有する膜が実質的に１μｍ未満ということになり、外表面を抜けた極微小物や溶解性有機高分子が、膜内部で詰まりにくい特徴を有するものである。
This is because the porous hollow fiber membrane of the present embodiment has a membrane having the smallest pore diameter in the porous layer A forming the outer surface, which is substantially less than 1 μm. Or a soluble organic polymer has a characteristic that it is difficult to be clogged inside the film.
また、本実施形態の多孔質中空糸膜多孔質層Ａと、深さ４μｍから５μｍまでの層（以下、多孔質層Ｃという。）まで孔径が漸増する構造を示すことがより好ましい。孔径が均一な場合、外表面を抜けた極微小物や溶解性有機高分子が外表面近傍の層で詰まり易く、濾過安定性を低下させる要因となる。熱誘起相分離法、可塑剤抽出法や延伸法による膜がこのような構造を形成し易い。一方で、孔径が非連続的に大きくなる場合、外表面を含む層の厚さが薄くなり、機械的強度が低下し、外表面剥がれ等の問題が生じる原因となる。
Further, it is more preferable that the porous hollow fiber membrane porous layer A of the present embodiment and a structure in which the pore diameter gradually increases to a layer having a depth of 4 μm to 5 μm (hereinafter referred to as porous layer C) are more preferable. When the pore diameter is uniform, the very small objects or the soluble organic polymer that have passed through the outer surface are likely to be clogged with the layer near the outer surface, which causes a decrease in filtration stability. A film formed by a heat-induced phase separation method, a plasticizer extraction method, or a stretching method easily forms such a structure. On the other hand, when the pore diameter increases discontinuously, the thickness of the layer including the outer surface becomes thin, the mechanical strength decreases, and problems such as peeling of the outer surface occur.
孔径の漸増の割合は大きければ大きいほど、多孔質層Ａを通過した極微小物や溶解性有機高分子が多孔質層Ａより内表面側の層で詰まりにくくなるため、濾過安定性は向上するが、大きすぎると濾過に寄与する層が外表面を含む層のみとなってしまい、外的要因等により分離特性が低下し易くなる。そのため、断面構造において、外表面を形成する多孔質層Ａの孔径Ａｄに対し、多孔質層Ｂの孔径Ｂｄが５／３以上（すなわち、Ａｄ／Ｂｄが０．６以下）であってもよい。さらに、Ａｄに対してＢｄが２倍以上（Ａｄ／Ｂｄが０．５以下）になることが好ましく、３倍以上（Ａｄ／Ｂｄが０．３３以下）がより好ましく、４倍以上（Ａｄ／Ｂｄが０．２５以下）がさらに好ましい。分離特性が維持できる場合、５倍以上（Ａｄ／Ｂｄが０．２以下）になることがさらに好ましい。
なお、多孔質層Ｂは、外表面を構成する多孔質層Ａと、間に一つの層を挟んで隣り合う層を意味するのが好ましい。多孔質層の孔径が内部（外表面から離れる方向）に向かって漸増する構造を形成しやすい非溶媒誘起相分離法においても、外表面直下のこの領域は凝固液の拡散浸入速度が速く、十分な相分離が進行しないまま凝固されるため、多孔質層Ａに対し十分大きい構造を有する多孔質層Ｂを形成することは困難であった。 As the rate of the gradual increase in the pore diameter increases, the filtration stability improves because the microscopic matter and the soluble organic polymer that have passed through the porous layer A are less likely to be clogged by the layer on the inner surface side of the porous layer A. If it is too large, the layer that contributes to filtration becomes only the layer including the outer surface, and the separation characteristics are likely to deteriorate due to external factors and the like. Therefore, in the cross-sectional structure, the pore diameter Bd of the porous layer B may be 5/3 or more (that is, Ad / Bd is 0.6 or less) with respect to the pore diameter Ad of the porous layer A forming the outer surface. . Further, Bd is preferably 2 times or more (Ad / Bd is 0.5 or less) with respect to Ad, more preferably 3 times or more (Ad / Bd is 0.33 or less), and 4 times or more (Ad / B). More preferably, Bd is 0.25 or less. When the separation characteristics can be maintained, it is more preferable that the separation characteristic is 5 times or more (Ad / Bd is 0.2 or less).
The porous layer B preferably means a layer adjacent to the porous layer A constituting the outer surface with one layer interposed therebetween. Even in the non-solvent-induced phase separation method, where the pore diameter of the porous layer gradually increases toward the inside (in the direction away from the outer surface), this region directly under the outer surface has a high diffusion diffusion rate of the coagulating liquid, which is sufficient. Since solid phase separation does not proceed, it is difficult to form a porous layer B having a sufficiently large structure with respect to the porous layer A.
なお、多孔質層Ｂは、外表面を構成する多孔質層Ａと、間に一つの層を挟んで隣り合う層を意味するのが好ましい。多孔質層の孔径が内部（外表面から離れる方向）に向かって漸増する構造を形成しやすい非溶媒誘起相分離法においても、外表面直下のこの領域は凝固液の拡散浸入速度が速く、十分な相分離が進行しないまま凝固されるため、多孔質層Ａに対し十分大きい構造を有する多孔質層Ｂを形成することは困難であった。 As the rate of the gradual increase in the pore diameter increases, the filtration stability improves because the microscopic matter and the soluble organic polymer that have passed through the porous layer A are less likely to be clogged by the layer on the inner surface side of the porous layer A. If it is too large, the layer that contributes to filtration becomes only the layer including the outer surface, and the separation characteristics are likely to deteriorate due to external factors and the like. Therefore, in the cross-sectional structure, the pore diameter Bd of the porous layer B may be 5/3 or more (that is, Ad / Bd is 0.6 or less) with respect to the pore diameter Ad of the porous layer A forming the outer surface. . Further, Bd is preferably 2 times or more (Ad / Bd is 0.5 or less) with respect to Ad, more preferably 3 times or more (Ad / Bd is 0.33 or less), and 4 times or more (Ad / B). More preferably, Bd is 0.25 or less. When the separation characteristics can be maintained, it is more preferable that the separation characteristic is 5 times or more (Ad / Bd is 0.2 or less).
The porous layer B preferably means a layer adjacent to the porous layer A constituting the outer surface with one layer interposed therebetween. Even in the non-solvent-induced phase separation method, where the pore diameter of the porous layer gradually increases toward the inside (in the direction away from the outer surface), this region directly under the outer surface has a high diffusion diffusion rate of the coagulating liquid, which is sufficient. Since solid phase separation does not proceed, it is difficult to form a porous layer B having a sufficiently large structure with respect to the porous layer A.
孔径Ａｄは実質的に濾過特性を決定しており、被濾過物により適宜選択されるが、本実施形態においては、多孔質中空糸膜の透水性能と分離特性を両立できることから、０．０１～１μｍの範囲とするのが好ましく、０．０２～０．５μｍの範囲がより好ましく、０．０４～０．２μｍの範囲がさらに好ましい。
The pore size Ad substantially determines the filtration characteristics and is appropriately selected depending on the material to be filtered. In this embodiment, since the water permeability and separation characteristics of the porous hollow fiber membrane can be compatible, 0.01 to The range is preferably 1 μm, more preferably 0.02 to 0.5 μm, and still more preferably 0.04 to 0.2 μm.
本実施形態における多孔質中空糸膜は、多孔質層Ａから多孔質層Ｃまでの孔径よりも、多孔質層Ｃから内表面を形成する層までの孔径が大きくなることが好ましい。多孔質層Ｃから内表面を形成する層までの孔径の方が小さくなると、多孔質層Ｃを抜けた極微小物や溶解性有機高分子が膜内部で詰まりやすくなる。
In the porous hollow fiber membrane in the present embodiment, it is preferable that the pore diameter from the porous layer C to the layer forming the inner surface is larger than the pore diameter from the porous layer A to the porous layer C. When the pore diameter from the porous layer C to the layer forming the inner surface becomes smaller, the microscopic matter and the soluble organic polymer that have passed through the porous layer C tend to be clogged inside the membrane.
多孔質層Ｃから内表面を形成する層までの孔径は目的により適宜選択される。透水性能が優先される系であれば大きい方が好ましく、分離特性が優先される系であれば、Ｃｄに近い孔径を維持することが好ましい。分離膜においては分離特性が優先される系が多く、その場合は、多孔質層Ｃから内表面を形成する層までの孔径は８μｍ以下が好ましく、実質的に１０μｍ以上の細孔は存在しないのがより好ましい。５μｍ以下がさらに好ましい。なお、多孔質層Ｃから内表面を形成する層までの構造形成においては、異なるドープを積層し２層以上の複層構造を形成する方法や、凝固液の組成と温度により制御する方法が取り得る。
The pore diameter from the porous layer C to the layer forming the inner surface is appropriately selected according to the purpose. If the system is prioritized for water permeability, the larger one is preferable, and if the system is prioritized for separation characteristics, it is preferable to maintain a pore diameter close to Cd. In many separation membranes, separation characteristics are given priority. In that case, the pore diameter from the porous layer C to the layer forming the inner surface is preferably 8 μm or less, and there are substantially no pores of 10 μm or more. Is more preferable. More preferably, it is 5 μm or less. In forming the structure from the porous layer C to the layer forming the inner surface, there are a method of stacking different dopes to form a multilayer structure of two or more layers, and a method of controlling by the composition and temperature of the coagulation liquid. obtain.
一方で、多孔質層Ａから多孔質層Ｃまでの層は、一つのドープから形成されることが好ましい。すなわち、同一の構成素材、より具体的には層を実質的に構成する同一の化合物の熱可塑性樹脂及びその他膜構成添加剤等を含む。複層構造にすると、層間に界面構造が発生し、外表面を抜けた極微小物や溶解性有機高分子が詰まり易くなる可能性があると共に、一つ一つの層の強度が低下し、剥がれ問題が発生する可能性があるためである。
On the other hand, the layers from the porous layer A to the porous layer C are preferably formed from one dope. That is, it includes the same constituent material, more specifically, a thermoplastic resin of the same compound that substantially constitutes the layer, and other film constituent additives. If a multi-layer structure is used, an interfacial structure will be generated between the layers, which may cause clogging of microscopic objects and soluble organic polymers that have passed through the outer surface, and the strength of each layer will decrease, causing a peeling problem. This is because there is a possibility of occurrence.
本実施形態における多孔質中空糸膜は、マクロボイドと呼ばれる孔径が１０μｍ以上ある欠損部位を有しないことが好ましい。外表面近傍の構造を内部に向かって漸増させる方法として、ドープ粘度を大きく低下させることが考えらえるが、このような手法では外表面近傍に同時にマクロボイドが発生しやすく、外的要因等により分離特性が大きく低下してしまう。そのため本実施形態では、多孔質層Ａから多孔質層Ｃの間にマクロボイドあるいはマクロボイドの一部を有しないことが好ましい。特に、外表面から深さ１０μｍの層までの多孔質層には孔径が１０μｍを超えるマクロボイド及びその一部を含有しないことがより好ましく、断面構造を観察した際に断面の全域で前記マクロボイドを含有しないことがさらに好ましい。
なお、本実施形態における「外表面から深さ１０μｍの層までに、マクロボイド及びその一部を含む」とは、マクロボイドの一部が外表面から深さ１０μｍのより外側（外表面近く）に掛かっている場合も含まれる。 It is preferable that the porous hollow fiber membrane in the present embodiment does not have a defect site called a macrovoid having a pore diameter of 10 μm or more. As a method of gradually increasing the structure in the vicinity of the outer surface toward the inside, it can be considered that the dope viscosity is greatly reduced. However, in this method, macro voids are likely to occur near the outer surface at the same time. Separation characteristics are greatly reduced. Therefore, in this embodiment, it is preferable that the macro void or part of the macro void is not provided between the porous layer A and the porous layer C. In particular, it is more preferable that the porous layer from the outer surface to the layer having a depth of 10 μm does not contain a macro void having a pore diameter exceeding 10 μm and a part thereof, and the macro void is observed over the entire cross section when the cross-sectional structure is observed. It is further preferable not to contain.
In the present embodiment, “including a macro void and a part thereof from the outer surface to a layer having a depth of 10 μm” means that a part of the macro void is outside the outer surface by a depth of 10 μm (near the outer surface). It is also included when it is hung.
なお、本実施形態における「外表面から深さ１０μｍの層までに、マクロボイド及びその一部を含む」とは、マクロボイドの一部が外表面から深さ１０μｍのより外側（外表面近く）に掛かっている場合も含まれる。 It is preferable that the porous hollow fiber membrane in the present embodiment does not have a defect site called a macrovoid having a pore diameter of 10 μm or more. As a method of gradually increasing the structure in the vicinity of the outer surface toward the inside, it can be considered that the dope viscosity is greatly reduced. However, in this method, macro voids are likely to occur near the outer surface at the same time. Separation characteristics are greatly reduced. Therefore, in this embodiment, it is preferable that the macro void or part of the macro void is not provided between the porous layer A and the porous layer C. In particular, it is more preferable that the porous layer from the outer surface to the layer having a depth of 10 μm does not contain a macro void having a pore diameter exceeding 10 μm and a part thereof, and the macro void is observed over the entire cross section when the cross-sectional structure is observed. It is further preferable not to contain.
In the present embodiment, “including a macro void and a part thereof from the outer surface to a layer having a depth of 10 μm” means that a part of the macro void is outside the outer surface by a depth of 10 μm (near the outer surface). It is also included when it is hung.
本実施形態の中空状多孔質中空糸膜は、上述の多孔質層のみからなるものであっても良いが、優れた機械的強度が得られることから、中空状の支持体上にこの多孔質層を有するものが特に好ましい。なお、ここでは多孔質層と支持体との位置関係を明確にするために支持体上と表現しているが、多孔質層が支持体の空隙を通じて支持体内部に含浸している場合もある。本実施形態では、多孔質層が中空糸状の支持体の外表面側に形成されている。
The hollow porous hollow fiber membrane of the present embodiment may be composed only of the above-mentioned porous layer, but since excellent mechanical strength is obtained, the porous porous fiber membrane is formed on the hollow support. Those having a layer are particularly preferred. Here, in order to clarify the positional relationship between the porous layer and the support, it is expressed as on the support, but the porous layer may be impregnated inside the support through the gap of the support. . In the present embodiment, the porous layer is formed on the outer surface side of the hollow fiber support.
支持体としては、高い機械的強度を有し、かつ多孔質層と一体化できるものであれば、適宜選択して使用することができ、特に限定するものではないが、製造コストが低く、柔軟性と断面の形状安定性（真円性）を両立でき、多孔質層との接着性にも優れることから、編紐が好ましい。中でも、マルチフィラメントからなる１本の糸を丸編した中空状編紐であることが好ましい。支持体の構成素材としては、耐薬品性に優れる点から、ポリエステル系繊維、アクリル系繊維、ポリビニルアルコール系繊維、ポリアミド系繊維、またはポリオレフィン系繊維、ポリ塩化ビニル系繊維が好ましく、ポリエステル系繊維、アクリル系繊維、またはポリ塩化ビニル系繊維が特に好ましい。また、支持体は、外径を規制しつつ、繊維の熱変形温度より高く、かつ繊維の溶融温度よりも低い温度で熱処理されたものであることが好ましい。この構成により、支持体外径の安定化や伸縮性の抑制、支持体の空隙部の緻密化という効果がある。
The support is not particularly limited as long as it has high mechanical strength and can be integrated with the porous layer, and is not particularly limited. Knitted cords are preferable because they can achieve both the stability and shape stability (roundness) of the cross section and are excellent in adhesion to the porous layer. Among these, a hollow knitted string obtained by circularly knitting a single yarn made of multifilament is preferable. The constituent material of the support is preferably a polyester fiber, an acrylic fiber, a polyvinyl alcohol fiber, a polyamide fiber, a polyolefin fiber, or a polyvinyl chloride fiber from the viewpoint of excellent chemical resistance, a polyester fiber, Acrylic fibers or polyvinyl chloride fibers are particularly preferred. The support is preferably heat-treated at a temperature higher than the thermal deformation temperature of the fiber and lower than the melting temperature of the fiber while regulating the outer diameter. With this configuration, there are effects of stabilizing the outer diameter of the support, suppressing stretchability, and densifying the voids of the support.
この場合、多孔質層と支持体（中空状編紐）とは、必ずしも密着している必要はないが、これらの接着性が低いと、中空糸膜を引っ張った時にこれらが分離し、多孔質層が巣抜けてしまう可能性がある。従って、本実施形態の中空状多孔質中空糸膜においては、この多孔質層の一部を中空状編紐の編目を通じて、編紐内に浸入させ、多孔質層と中空状編紐とを一体化させるのが好ましい。
多孔質層と支持体に充分な接着性を付与するためには、多孔質層が、中空状編紐の厚さの５０％以上浸入しているのがより好ましい。さらには、異なる編目を通じて５０％以上侵入した多孔質層同士が連結し、支持体の一部を包み込んだ状態になっているものが耐剥離性の観点からさらに好ましい。加えて、支持体の一部を包み込んだ部分が繊維軸方向につながって存在すると、耐剥離性がさらに増すため好ましい。さらには、繊維軸方向へのつながり方がらせん状であれば、耐剥離性が著しく向上することからさらに好ましい。なお、このような場合においても、本実施形態における上述の膜厚は、支持体上に露出している部分の厚さを意味するものとする。 In this case, the porous layer and the support (hollow knitted string) do not necessarily need to be in close contact with each other. However, if their adhesiveness is low, they are separated when the hollow fiber membrane is pulled, Layers can escape. Therefore, in the hollow porous hollow fiber membrane of the present embodiment, a part of the porous layer is infiltrated into the knitted string through the stitch of the hollow knitted string, and the porous layer and the hollow knitted string are integrated. It is preferable to make it.
In order to provide sufficient adhesion between the porous layer and the support, it is more preferable that the porous layer penetrates 50% or more of the thickness of the hollow knitted string. Furthermore, it is more preferable from the viewpoint of peeling resistance that the porous layers that have penetrated 50% or more through different stitches are connected to each other and wrap around a part of the support. In addition, it is preferable that a portion that wraps a part of the support is connected in the fiber axis direction because the peel resistance is further increased. Furthermore, if the connection in the fiber axis direction is spiral, it is more preferable because the peel resistance is remarkably improved. Even in such a case, the above-described film thickness in the present embodiment means the thickness of the portion exposed on the support.
多孔質層と支持体に充分な接着性を付与するためには、多孔質層が、中空状編紐の厚さの５０％以上浸入しているのがより好ましい。さらには、異なる編目を通じて５０％以上侵入した多孔質層同士が連結し、支持体の一部を包み込んだ状態になっているものが耐剥離性の観点からさらに好ましい。加えて、支持体の一部を包み込んだ部分が繊維軸方向につながって存在すると、耐剥離性がさらに増すため好ましい。さらには、繊維軸方向へのつながり方がらせん状であれば、耐剥離性が著しく向上することからさらに好ましい。なお、このような場合においても、本実施形態における上述の膜厚は、支持体上に露出している部分の厚さを意味するものとする。 In this case, the porous layer and the support (hollow knitted string) do not necessarily need to be in close contact with each other. However, if their adhesiveness is low, they are separated when the hollow fiber membrane is pulled, Layers can escape. Therefore, in the hollow porous hollow fiber membrane of the present embodiment, a part of the porous layer is infiltrated into the knitted string through the stitch of the hollow knitted string, and the porous layer and the hollow knitted string are integrated. It is preferable to make it.
In order to provide sufficient adhesion between the porous layer and the support, it is more preferable that the porous layer penetrates 50% or more of the thickness of the hollow knitted string. Furthermore, it is more preferable from the viewpoint of peeling resistance that the porous layers that have penetrated 50% or more through different stitches are connected to each other and wrap around a part of the support. In addition, it is preferable that a portion that wraps a part of the support is connected in the fiber axis direction because the peel resistance is further increased. Furthermore, if the connection in the fiber axis direction is spiral, it is more preferable because the peel resistance is remarkably improved. Even in such a case, the above-described film thickness in the present embodiment means the thickness of the portion exposed on the support.
多孔質層は、膜形成性樹脂によって形成される。膜形成性樹脂としては、上述したように熱可塑性樹脂を用いることができ、例えば、ポリスルホン樹脂、ポリエーテルスルホン樹脂、スルホン化ポリスルホン樹脂、ポリフソ化ビニリデン樹脂、ポリアクリロニトリル樹脂、ポリイミド樹脂、ポリアミドイミド樹脂、又はポリエステルイミド樹脂などが挙げられる。これらの中でも、耐薬品性に優れることから、ポリフッ化ビニリデン樹脂が好ましい。
The porous layer is formed of a film-forming resin. As the film-forming resin, a thermoplastic resin can be used as described above, for example, polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyfluorinated vinylidene resin, polyacrylonitrile resin, polyimide resin, polyamideimide resin. Or polyesterimide resin. Among these, polyvinylidene fluoride resin is preferable because of excellent chemical resistance.
次に、本実施形態の中空状多孔質中空糸膜の製造方法について説明する。
本実施形態の多孔質中空糸膜は、非溶媒相分離法により形成されてなることが好ましい。非溶媒相分離法とは、非溶媒（水等）の取り込みにより相分離を誘起する多孔化の方法である。
熱で相分離を誘起する熱誘起相分離法では、熱の伝播速度が早いため、多孔質層の孔径が内部に向かって漸増する構造を形成しにくい。電子線照射、微粒子充填や延伸によって多孔化する方法においてはその製法上均質構造が形成される。これらの手法に対し、非溶媒相分離法では非溶媒の内部への拡散速度が遅いため、内部に向かって漸増する構造を形成しやすいという効果がある。
具体的には、本実施形態の多孔質中空糸膜は、環状ノズルを用いて中空状の支持体の外表面に多孔質層の材料及び溶媒を含む膜形成性樹脂を塗布し、膜形成性樹脂層とした後、膜形成性樹脂層の表面に飽和水蒸気（温度等の条件については後述する）を接触させた後、凝固液によって凝固させることにより製造することができる。 Next, the manufacturing method of the hollow porous hollow fiber membrane of this embodiment is demonstrated.
The porous hollow fiber membrane of this embodiment is preferably formed by a non-solvent phase separation method. The non-solvent phase separation method is a method for making a porous layer that induces phase separation by incorporating a non-solvent (water or the like).
In the thermally induced phase separation method in which phase separation is induced by heat, since the heat propagation speed is high, it is difficult to form a structure in which the pore diameter of the porous layer gradually increases toward the inside. In the method of making porous by electron beam irradiation, fine particle filling or stretching, a homogeneous structure is formed in terms of the production method. In contrast to these methods, the non-solvent phase separation method has an effect of easily forming a structure that gradually increases toward the inside because the diffusion rate of the non-solvent into the inside is slow.
Specifically, the porous hollow fiber membrane of this embodiment is formed by applying a film-forming resin containing a porous layer material and a solvent to the outer surface of a hollow support using an annular nozzle. After forming the resin layer, it can be produced by bringing saturated water vapor (conditions such as temperature will be described later) into contact with the surface of the film-forming resin layer and then coagulating with a coagulating liquid.
本実施形態の多孔質中空糸膜は、非溶媒相分離法により形成されてなることが好ましい。非溶媒相分離法とは、非溶媒（水等）の取り込みにより相分離を誘起する多孔化の方法である。
熱で相分離を誘起する熱誘起相分離法では、熱の伝播速度が早いため、多孔質層の孔径が内部に向かって漸増する構造を形成しにくい。電子線照射、微粒子充填や延伸によって多孔化する方法においてはその製法上均質構造が形成される。これらの手法に対し、非溶媒相分離法では非溶媒の内部への拡散速度が遅いため、内部に向かって漸増する構造を形成しやすいという効果がある。
具体的には、本実施形態の多孔質中空糸膜は、環状ノズルを用いて中空状の支持体の外表面に多孔質層の材料及び溶媒を含む膜形成性樹脂を塗布し、膜形成性樹脂層とした後、膜形成性樹脂層の表面に飽和水蒸気（温度等の条件については後述する）を接触させた後、凝固液によって凝固させることにより製造することができる。 Next, the manufacturing method of the hollow porous hollow fiber membrane of this embodiment is demonstrated.
The porous hollow fiber membrane of this embodiment is preferably formed by a non-solvent phase separation method. The non-solvent phase separation method is a method for making a porous layer that induces phase separation by incorporating a non-solvent (water or the like).
In the thermally induced phase separation method in which phase separation is induced by heat, since the heat propagation speed is high, it is difficult to form a structure in which the pore diameter of the porous layer gradually increases toward the inside. In the method of making porous by electron beam irradiation, fine particle filling or stretching, a homogeneous structure is formed in terms of the production method. In contrast to these methods, the non-solvent phase separation method has an effect of easily forming a structure that gradually increases toward the inside because the diffusion rate of the non-solvent into the inside is slow.
Specifically, the porous hollow fiber membrane of this embodiment is formed by applying a film-forming resin containing a porous layer material and a solvent to the outer surface of a hollow support using an annular nozzle. After forming the resin layer, it can be produced by bringing saturated water vapor (conditions such as temperature will be described later) into contact with the surface of the film-forming resin layer and then coagulating with a coagulating liquid.
本実施形態の製造装置について説明する。図１２に、本実施形態の製造装置を示す。本実施形態の製造装置１ｇは、紡糸ノズル１０と、紡糸ノズル１０の下流側に配置された処理用容器２０Ａと、凝固液Ｂを収納する凝固槽３０と、紡糸ノズルの吐出面１０ａに掃気用気体を掃気する掃気手段４０Ａとを備える。
The manufacturing apparatus of this embodiment will be described. FIG. 12 shows the manufacturing apparatus of this embodiment. The manufacturing apparatus 1g of the present embodiment is for scavenging a spinning nozzle 10, a processing container 20A disposed on the downstream side of the spinning nozzle 10, a coagulating tank 30 for storing the coagulating liquid B, and a discharge surface 10a of the spinning nozzle. Scavenging means 40A for scavenging gas.
（処理用容器）
処理用容器２０Ａは、前記膜形成性樹脂の非溶媒を含む気体（以下、「処理用気体」と言う。）を収容し、紡糸ノズル１０から吐出した糸状体Ａ‘を処理用気体に接触させるよう構成されてなる容器である。
ここで非溶媒とは、この工程の反応条件において膜形成樹脂を溶解する能力が無い（例えば、常温において溶解度が１質量％未満の）溶媒を指す。非溶媒としては、水、エタノール等のアルコール類、アセトン、トルエン、エチレングリコール、又は、水と膜形成性樹脂溶液に用いる良溶媒の混合体等を用いることができる。その中で特に好ましいのは水である。 (Processing container)
Theprocessing container 20A contains a gas containing a non-solvent of the film-forming resin (hereinafter referred to as “processing gas”), and brings the filament A ′ discharged from the spinning nozzle 10 into contact with the processing gas. The container is configured as described above.
Here, the non-solvent refers to a solvent that does not have the ability to dissolve the film-forming resin under the reaction conditions in this step (for example, the solubility is less than 1% by mass at room temperature). As the non-solvent, water, alcohols such as ethanol, acetone, toluene, ethylene glycol, or a mixture of water and a good solvent used for the film-forming resin solution can be used. Of these, water is particularly preferred.
処理用容器２０Ａは、前記膜形成性樹脂の非溶媒を含む気体（以下、「処理用気体」と言う。）を収容し、紡糸ノズル１０から吐出した糸状体Ａ‘を処理用気体に接触させるよう構成されてなる容器である。
ここで非溶媒とは、この工程の反応条件において膜形成樹脂を溶解する能力が無い（例えば、常温において溶解度が１質量％未満の）溶媒を指す。非溶媒としては、水、エタノール等のアルコール類、アセトン、トルエン、エチレングリコール、又は、水と膜形成性樹脂溶液に用いる良溶媒の混合体等を用いることができる。その中で特に好ましいのは水である。 (Processing container)
The
Here, the non-solvent refers to a solvent that does not have the ability to dissolve the film-forming resin under the reaction conditions in this step (for example, the solubility is less than 1% by mass at room temperature). As the non-solvent, water, alcohols such as ethanol, acetone, toluene, ethylene glycol, or a mixture of water and a good solvent used for the film-forming resin solution can be used. Of these, water is particularly preferred.
本実施形態で使用される処理用容器２０Ａは、平板状の天井部２１、平板状の底部２２及び円筒状の側部２３を有する円筒体であり、天井部２１に、糸状体Ａ‘が導入される第１の開口部２１ａが形成され、底部２２に、糸状体Ａ’が導入される第２の開口部２２ａが形成されている。第１の開口部２１ａ及び第２の開口部２２ａの開口部は同等、あるいは処理用容器２０Ａ内の処理用気体が熱浮力によって第２の開口部２２ａよりも第１の開口部２１ａから多く流出することを抑制するために、第１の開口部２１ａの開口径より第２の開口部２２ａの開口径を大きくすることもある。また、第２の開口部２２ａは、凝固槽３０内の凝固液Ｂの液面よりも上方に配置されている。すなわち、本実施形態では、処理用容器２０Ａと凝固槽内の凝固液Ｂとが離れており、第２の開口部２２ａが凝固液Ｂで塞がれていない。
The processing container 20A used in the present embodiment is a cylindrical body having a flat ceiling portion 21, a flat bottom portion 22 and a cylindrical side portion 23, and the filament A ′ is introduced into the ceiling portion 21. The first opening 21a is formed, and the bottom 22 is formed with a second opening 22a into which the filament A ′ is introduced. The openings of the first opening 21a and the second opening 22a are the same, or more processing gas in the processing container 20A flows out of the first opening 21a than the second opening 22a due to thermal buoyancy. In order to suppress this, the opening diameter of the second opening 22a may be made larger than the opening diameter of the first opening 21a. Further, the second opening 22 a is disposed above the liquid level of the coagulating liquid B in the coagulating tank 30. That is, in the present embodiment, the processing container 20A and the coagulation liquid B in the coagulation tank are separated from each other, and the second opening 22a is not closed with the coagulation liquid B.
この処理用容器２０Ａにおいては、第１の開口部２１ａから糸状体Ａ‘が導入され、処理用容器２０Ａ内の処理用気体に接触させた糸状体Ａ’が第２の開口部２２ａから外部に導出されるようになっている。
また、気体供給管２４から供給された処理用気体は、処理用容器２０Ａの内部を通った後、第１の開孔部２１ａ及び第２の開口部２２ａから排出されるようになっている。 In theprocessing container 20A, the filament A ′ is introduced from the first opening 21a, and the filament A ′ brought into contact with the processing gas in the processing container 20A is exposed to the outside from the second opening 22a. Has been derived.
Further, the processing gas supplied from thegas supply pipe 24 passes through the inside of the processing container 20A, and is then discharged from the first opening portion 21a and the second opening portion 22a.
また、気体供給管２４から供給された処理用気体は、処理用容器２０Ａの内部を通った後、第１の開孔部２１ａ及び第２の開口部２２ａから排出されるようになっている。 In the
Further, the processing gas supplied from the
（掃気手段）
掃気手段４０Ａは、紡糸ノズル１０近傍に流出した処理用気体を掃気用気体で置換して除去するよう構成されてなる気体除去手段であり、紡糸ノズル１０の吐出面１０ａに設けられた掃気ノズル４１と、掃気ノズル４１に掃気用気体を供給する気体供給手段４２とを備えるものである。
掃気ノズル４１は、環状の部材からなり、中央の円形開口部４１ａと、気体供給手段４２に接続されて掃気用気体が導入される環状の空間からなる気体導入室４１ｂと、円形開口部４１ａにて露出した紡糸ノズル１０の吐出面１０ａに向けて、気体導入室４１ｂから供給された掃気用気体を吐出する環状の気体吐出口４１ｃとを備える。
円形開口部４１ａは、その中心が、紡糸ノズル１０の支持体吐出口及び樹脂溶液吐出口の中心と一致するように配置される。したがって、円形開口部４１ａには、糸状体Ａ‘が通過するようになっている。気体導入室４１ｂは、円形開口部４１ａよりも外周側に、掃気ノズル４１と同心円状に形成されている。気体吐出口４１ｃは、気体導入室４１ｂと連通し、図１２３に示すように、円形開口部４１ａの中心に向かって開口しているため、掃気用気体を、円形開口部４１ａの外周側から中心に向かって吐出するようになっている。 (Scavenging means)
The scavenging means 40A is a gas removing means configured to replace the processing gas flowing out in the vicinity of the spinningnozzle 10 with the scavenging gas and remove it, and the scavenging nozzle 41 provided on the discharge surface 10a of the spinning nozzle 10. And a gas supply means 42 for supplying a scavenging gas to the scavenging nozzle 41.
The scavengingnozzle 41 is formed of an annular member, and has a central circular opening 41a, a gas introduction chamber 41b that is connected to the gas supply means 42 and is formed of an annular space into which scavenging gas is introduced, and a circular opening 41a. And an annular gas discharge port 41c for discharging the scavenging gas supplied from the gas introduction chamber 41b toward the discharge surface 10a of the spinning nozzle 10 exposed.
Thecircular opening 41a is arranged so that the center thereof coincides with the center of the support discharge port and the resin solution discharge port of the spinning nozzle 10. Accordingly, the filament A ′ passes through the circular opening 41a. The gas introduction chamber 41b is formed concentrically with the scavenging nozzle 41 on the outer peripheral side of the circular opening 41a. Since the gas discharge port 41c communicates with the gas introduction chamber 41b and opens toward the center of the circular opening 41a as shown in FIG. 123, the scavenging gas is centered from the outer peripheral side of the circular opening 41a. It discharges toward
掃気手段４０Ａは、紡糸ノズル１０近傍に流出した処理用気体を掃気用気体で置換して除去するよう構成されてなる気体除去手段であり、紡糸ノズル１０の吐出面１０ａに設けられた掃気ノズル４１と、掃気ノズル４１に掃気用気体を供給する気体供給手段４２とを備えるものである。
掃気ノズル４１は、環状の部材からなり、中央の円形開口部４１ａと、気体供給手段４２に接続されて掃気用気体が導入される環状の空間からなる気体導入室４１ｂと、円形開口部４１ａにて露出した紡糸ノズル１０の吐出面１０ａに向けて、気体導入室４１ｂから供給された掃気用気体を吐出する環状の気体吐出口４１ｃとを備える。
円形開口部４１ａは、その中心が、紡糸ノズル１０の支持体吐出口及び樹脂溶液吐出口の中心と一致するように配置される。したがって、円形開口部４１ａには、糸状体Ａ‘が通過するようになっている。気体導入室４１ｂは、円形開口部４１ａよりも外周側に、掃気ノズル４１と同心円状に形成されている。気体吐出口４１ｃは、気体導入室４１ｂと連通し、図１２３に示すように、円形開口部４１ａの中心に向かって開口しているため、掃気用気体を、円形開口部４１ａの外周側から中心に向かって吐出するようになっている。 (Scavenging means)
The scavenging means 40A is a gas removing means configured to replace the processing gas flowing out in the vicinity of the spinning
The scavenging
The
本実施形態では、掃気手段４０Ａにおける掃気ノズル４１の下面に、糸状体Ａ‘を覆って保護するための保護筒５０が設けられている。
In the present embodiment, a protective cylinder 50 is provided on the lower surface of the scavenging nozzle 41 in the scavenging means 40A to cover and protect the filament A ′.
保護筒５０は、円筒状部材であり、貫通孔５０ａが形成されている。また、保護筒５０の上端部５１は、掃気ノズル４１の下面に、貫通孔５０ａが掃気ノズル４１の円形開口部４１ａと連通するように密着固定されている。保護筒５０の下端部５２は、処理用容器２０Ａから離間し設置されており、保護筒５０と処置用容器２０Ａとの間には隙間Ｑが形成されている。
The protective cylinder 50 is a cylindrical member and has a through hole 50a. Further, the upper end portion 51 of the protective cylinder 50 is closely fixed to the lower surface of the scavenging nozzle 41 so that the through hole 50 a communicates with the circular opening 41 a of the scavenging nozzle 41. The lower end portion 52 of the protective cylinder 50 is spaced apart from the processing container 20A, and a gap Q is formed between the protective cylinder 50 and the treatment container 20A.
貫通孔５０ａの開孔面積、及び、下端部５２側の開口部５２ａの開口面積は、糸状体Ａ‘が接触せずに通過できる範囲で小さいことが好ましい。貫通孔５０ａの断面積が小さいほど、掃気用気体の供給量が少なくても、流速を速くでき、掃気能力を向上させることができる。また、下端部５２側の開口部５２ａの開口面積が小さいほど、第１の開口部２１ａから流出した処理用気体が貫通孔５０ａ内に流入することを防ぐことができる。
ただし、下端部５２側から第１の開口部２１ａに向かう掃気用気体の流速は必要以上に速くしないことが好ましく、下端部５２側の開口部５２ａの開口面積は必要以上に小さくしないことが好ましい。第１の開口部２１ａに向かう掃気用気体の流速が過度に速い、もしくは、下端部５２の開口部５２ａの開口面積が過度に小さいと、掃気用気体が第１の開口部２１ａを通過して処理用容器２０Ａ内に侵入し、処理用容器２０Ａ内の気体の温湿度を変動させるおそれがある。 It is preferable that the opening area of the through-hole 50a and the opening area of the opening 52a on the lower end 52 side are small as long as the filament A ′ can pass without contacting. The smaller the cross-sectional area of the through-hole 50a, the higher the flow rate can be achieved and the scavenging ability can be improved even if the supply amount of the scavenging gas is small. Further, as the opening area of the opening 52a on the lower end 52 side is smaller, the processing gas flowing out from the first opening 21a can be prevented from flowing into the through hole 50a.
However, it is preferable that the flow rate of the scavenging gas from thelower end 52 side toward the first opening 21a is not made faster than necessary, and the opening area of the opening 52a on the lower end 52 side is not made smaller than necessary. . When the flow rate of the scavenging gas toward the first opening 21a is excessively high, or the opening area of the opening 52a of the lower end 52 is excessively small, the scavenging gas passes through the first opening 21a. There is a risk of entering the processing container 20A and changing the temperature and humidity of the gas in the processing container 20A.
ただし、下端部５２側から第１の開口部２１ａに向かう掃気用気体の流速は必要以上に速くしないことが好ましく、下端部５２側の開口部５２ａの開口面積は必要以上に小さくしないことが好ましい。第１の開口部２１ａに向かう掃気用気体の流速が過度に速い、もしくは、下端部５２の開口部５２ａの開口面積が過度に小さいと、掃気用気体が第１の開口部２１ａを通過して処理用容器２０Ａ内に侵入し、処理用容器２０Ａ内の気体の温湿度を変動させるおそれがある。 It is preferable that the opening area of the through-
However, it is preferable that the flow rate of the scavenging gas from the
保護筒５０の材質は、処理用容器２０Ａから流出した気体で腐食や侵されたりしない材質が好ましい。これらを満たすものとして、ポリエチレン、ポリプロピレン、フッ素系樹脂、ステンレス、アルミニウム、セラミック、又はガラスなどが挙げられる。また、保護筒５０の材質は、貫通孔５０ａを流れる掃気用気体の放熱や、外部雰囲気からの受熱によって掃気用気体の温度変化することを抑制するために、熱伝導率が低いことが好ましい。熱伝導率が低い素材としては、ポリエチレン、ポリプロピレン、フッ素系樹脂、セラミック、又はガラスなどが挙げられる。さらに、保護筒５０の材質としては、貫通孔５０ａを走行する糸状体Ａ‘の状態を外部から観察できることから、透明性の高いものが好ましく、透明性の高いポリエチレン、透明性の高いポリプロピレン、透明性の高いフッ素系樹脂のテトラフルオロエチレン－パーフルオロアルキルビニルエーテル共重合樹脂（ＰＦＡ）、又はガラスが特に好ましい。
The material of the protective cylinder 50 is preferably a material that is not corroded or attacked by the gas flowing out of the processing container 20A. Examples of materials that satisfy these requirements include polyethylene, polypropylene, fluororesin, stainless steel, aluminum, ceramic, and glass. In addition, the material of the protective cylinder 50 preferably has a low thermal conductivity in order to suppress heat dissipation of the scavenging gas flowing through the through hole 50a and temperature change of the scavenging gas due to heat received from the external atmosphere. Examples of the material having low thermal conductivity include polyethylene, polypropylene, fluorine-based resin, ceramic, or glass. Further, the material of the protective cylinder 50 is preferably highly transparent because the state of the filament A ′ running through the through hole 50a can be observed from the outside. Highly transparent polyethylene, highly transparent polypropylene, transparent Particularly preferred is a highly fluoropolymer tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA) or glass.
保護筒５０は、掃気ノズルに対して着脱可能であることが好ましい。保護筒５０が着脱可能であると、掃気ノズル４１から取り外すことができるため、吐出面１０ａ近傍に手が容易に届き、製膜開始時の操作性を向上させることができる。着脱手段としては、ネジやクランプなどの機械的着脱手段、又は、磁石と磁石に吸着する金属を利用した磁石吸着的着脱手段が簡便で好適である。
The protective cylinder 50 is preferably detachable from the scavenging nozzle. If the protective cylinder 50 is detachable, it can be removed from the scavenging nozzle 41, so that the hand can easily reach the vicinity of the discharge surface 10a, and the operability at the start of film formation can be improved. As the attachment / detachment means, a mechanical attachment / detachment means such as a screw or a clamp, or a magnet adsorption attachment / detachment means using a magnet and a metal adsorbed to the magnet is simple and suitable.
本実施形態では、紡糸ノズル１０から吐出した糸状体Ａ‘は、気体吐出口４１ｃを通過した後に保護筒５０の貫通孔５０ａ内を通過するようになっている。
また、掃気ノズル４１の気体吐出口４１ｃから吐出した掃気用気体は、貫通孔５０ａを通過する糸状体Ａ‘の周囲を糸状体Ａ’と並行に、上端部５１から下端部５２に向かって流動する。そして、貫通孔５０ａから、第１の開口部２１ａから流出する処理用気体に向かって吐出する。その後、掃気用気体は、隙間Ｑにて、第１の開孔部２１ａから流出した処理用気体と共に第１の開口部２１ａから離間するように外側に向かって流動する。 In the present embodiment, the filament A ′ discharged from the spinningnozzle 10 passes through the through hole 50a of the protective cylinder 50 after passing through the gas discharge port 41c.
Further, the scavenging gas discharged from thegas discharge port 41c of the scavenging nozzle 41 flows from the upper end 51 toward the lower end 52 in parallel with the filament A 'passing through the through hole 50a. To do. And it discharges toward the process gas which flows out out of the 1st opening part 21a from the through-hole 50a. Thereafter, the scavenging gas flows outward in the gap Q so as to be separated from the first opening 21a together with the processing gas flowing out from the first opening 21a.
また、掃気ノズル４１の気体吐出口４１ｃから吐出した掃気用気体は、貫通孔５０ａを通過する糸状体Ａ‘の周囲を糸状体Ａ’と並行に、上端部５１から下端部５２に向かって流動する。そして、貫通孔５０ａから、第１の開口部２１ａから流出する処理用気体に向かって吐出する。その後、掃気用気体は、隙間Ｑにて、第１の開孔部２１ａから流出した処理用気体と共に第１の開口部２１ａから離間するように外側に向かって流動する。 In the present embodiment, the filament A ′ discharged from the spinning
Further, the scavenging gas discharged from the
掃気手段４０Ａによって、第１の開口部２１ａから流出した処理用気体を掃気用気体で置換して、吐出面１０ａ近傍から除去できるため、非溶媒による吐出面１０ａの結露を防止することができる。これにより、得られる多孔質中空糸膜Ａの膜表面構造の精密な制御、膜表面構造の均一化、多孔質中空糸膜Ａの品質を向上させることができる。
The treatment gas flowing out from the first opening 21a can be replaced with the scavenging gas by the scavenging means 40A and removed from the vicinity of the ejection surface 10a, so that condensation on the ejection surface 10a due to a non-solvent can be prevented. Thereby, precise control of the membrane surface structure of the obtained porous hollow fiber membrane A, uniformity of the membrane surface structure, and quality of the porous hollow fiber membrane A can be improved.
掃気用気体としては、乾燥空気が好ましい。本実施形態で乾燥空気とは、相対湿度（飽和蒸気圧に対する蒸気圧）が０～９％の気体を指す。工場などで室温下での相対湿度が１％程度の乾燥空気が供給されている場合には、乾燥空気を気体温度調整手段によって所定温度に調整して加熱乾燥空気とし、これを掃気ノズル４１に供給することが好ましい。
As the scavenging gas, dry air is preferable. In this embodiment, dry air refers to a gas having a relative humidity (vapor pressure with respect to saturated vapor pressure) of 0 to 9%. When dry air having a relative humidity of about 1% at room temperature is supplied in a factory or the like, the dry air is adjusted to a predetermined temperature by a gas temperature adjusting means to be heated dry air, which is supplied to the scavenging nozzle 41. It is preferable to supply.
（多孔質中空糸膜の製造方法）
上記製造装置１ａを用いた多孔質中空糸膜Ａの製造方法について説明する。本製造方法は、紡糸工程と掃気工程と凝固工程とを有する。 (Method for producing porous hollow fiber membrane)
The manufacturing method of the porous hollow fiber membrane A using the said manufacturing apparatus 1a is demonstrated. This manufacturing method has a spinning process, a scavenging process, and a coagulation process.
上記製造装置１ａを用いた多孔質中空糸膜Ａの製造方法について説明する。本製造方法は、紡糸工程と掃気工程と凝固工程とを有する。 (Method for producing porous hollow fiber membrane)
The manufacturing method of the porous hollow fiber membrane A using the said manufacturing apparatus 1a is demonstrated. This manufacturing method has a spinning process, a scavenging process, and a coagulation process.
［紡糸工程］
本実施形態における紡糸工程では、紡糸ノズル１０の支持体吐出口から中空紐状支持体Ａ１を下方に吐出させながら、樹脂溶液吐出口から膜形成性樹脂溶液を下方に吐出することによって、中空紐状支持体Ａ１の外周面に膜形成性樹脂溶液の塗膜Ａ２を形成して中空の糸状体Ａ‘を作製する。 [Spinning process]
In the spinning step in the present embodiment, the hollow string-like support A1 is discharged downward from the support discharge port of the spinningnozzle 10 while the film-forming resin solution is discharged downward from the resin solution discharge port, thereby forming the hollow string. A film A2 of a film-forming resin solution is formed on the outer peripheral surface of the support A1 to produce a hollow filamentous body A ′.
本実施形態における紡糸工程では、紡糸ノズル１０の支持体吐出口から中空紐状支持体Ａ１を下方に吐出させながら、樹脂溶液吐出口から膜形成性樹脂溶液を下方に吐出することによって、中空紐状支持体Ａ１の外周面に膜形成性樹脂溶液の塗膜Ａ２を形成して中空の糸状体Ａ‘を作製する。 [Spinning process]
In the spinning step in the present embodiment, the hollow string-like support A1 is discharged downward from the support discharge port of the spinning
膜形成性樹脂溶液は、通常、膜形成性樹脂と親水性樹脂とこれらを溶解する溶媒とを含む。膜形成性樹脂溶液は、必要に応じてその他の添加成分を含んでもよい。親水性樹脂は、膜形成性樹脂溶液の粘度を中空状多孔質中空糸膜Ａの形成に好適な範囲に調整し、製膜状態の安定化を図るために添加されるものであって、ポリエチレングリコール又はポリビニルピロリドンなどが好ましく使用される。これらの中でも、得られる中空状多孔質中空糸膜の孔径の制御や中空状多孔質中空糸膜の強度の点から、ポリビニルピロリドン又はポリビニルピロリドンに他の単量体が共重合した共重合体が好ましい。
また、親水性樹脂は、２種以上の樹脂を混合して使用することもできる。例えば親水性樹脂として、より高分子量のものを用いると、膜構造の良好な中空状多孔質中空糸膜を形成しやすい傾向がある。一方、低分子量の親水性樹脂は、中空状多孔質中空糸膜Ａからより除去されやすい点で好適である。よって、目的に応じて、分子量が異なる同種の親水性樹脂を適宜ブレンドして用いてもよい。 The film-forming resin solution usually contains a film-forming resin, a hydrophilic resin, and a solvent for dissolving them. The film-forming resin solution may contain other additive components as necessary. The hydrophilic resin is added to adjust the viscosity of the film-forming resin solution to a range suitable for the formation of the hollow porous hollow fiber membrane A, and to stabilize the film-forming state. Glycol or polyvinyl pyrrolidone is preferably used. Among these, polyvinyl pyrrolidone or a copolymer obtained by copolymerizing other monomers with polyvinyl pyrrolidone from the viewpoint of controlling the pore diameter of the obtained hollow porous hollow fiber membrane and the strength of the hollow porous hollow fiber membrane. preferable.
Moreover, 2 or more types of hydrophilic resin can also be mixed and used. For example, when a higher molecular weight hydrophilic resin is used, a hollow porous hollow fiber membrane having a good membrane structure tends to be formed. On the other hand, a low molecular weight hydrophilic resin is preferable in that it is more easily removed from the hollow porous hollow fiber membrane A. Therefore, the same kind of hydrophilic resins having different molecular weights may be appropriately blended depending on the purpose.
また、親水性樹脂は、２種以上の樹脂を混合して使用することもできる。例えば親水性樹脂として、より高分子量のものを用いると、膜構造の良好な中空状多孔質中空糸膜を形成しやすい傾向がある。一方、低分子量の親水性樹脂は、中空状多孔質中空糸膜Ａからより除去されやすい点で好適である。よって、目的に応じて、分子量が異なる同種の親水性樹脂を適宜ブレンドして用いてもよい。 The film-forming resin solution usually contains a film-forming resin, a hydrophilic resin, and a solvent for dissolving them. The film-forming resin solution may contain other additive components as necessary. The hydrophilic resin is added to adjust the viscosity of the film-forming resin solution to a range suitable for the formation of the hollow porous hollow fiber membrane A, and to stabilize the film-forming state. Glycol or polyvinyl pyrrolidone is preferably used. Among these, polyvinyl pyrrolidone or a copolymer obtained by copolymerizing other monomers with polyvinyl pyrrolidone from the viewpoint of controlling the pore diameter of the obtained hollow porous hollow fiber membrane and the strength of the hollow porous hollow fiber membrane. preferable.
Moreover, 2 or more types of hydrophilic resin can also be mixed and used. For example, when a higher molecular weight hydrophilic resin is used, a hollow porous hollow fiber membrane having a good membrane structure tends to be formed. On the other hand, a low molecular weight hydrophilic resin is preferable in that it is more easily removed from the hollow porous hollow fiber membrane A. Therefore, the same kind of hydrophilic resins having different molecular weights may be appropriately blended depending on the purpose.
溶媒としては、Ｎ，Ｎ―ジメチルホルムアミド、Ｎ，Ｎ―ジメチルアセトアミド、ジメチルスルホキシド、Ｎ―メチル―２―ピロリドン、又はＮ―メチルモルホリン―Ｎ一オキンドなどが挙げられ、これらを１種以上使用できる。また、溶媒への膜形成性樹脂や親水性樹脂の溶解性を損なわない範囲で、膜形成性樹脂や親水性樹脂の貧溶媒や非溶媒を混合して使用してもよい。
Examples of the solvent include N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, or N-methylmorpholine-N monooxide, and one or more of these can be used. . In addition, a poor solvent or a non-solvent of the film-forming resin or the hydrophilic resin may be mixed and used as long as the solubility of the film-forming resin or the hydrophilic resin in the solvent is not impaired.
膜形成性樹脂溶液の温度は、特に制限はないが通常は２０～４０℃とされる。膜形成性樹脂溶液の４０℃における粘度は、２万～５０万ｍＰａ・秒であることが好ましく、５万～３０万ｍＰａ・秒であることがより好ましく、７万～２５万ｍＰａ・秒であることがさらに好ましい。粘度が低すぎると相分離速度が増大し、Ａｄ及びＢｄが大きくなりすぎ分離特性が低下する。一方、粘度が高すぎると相分離の速度が低下し、ＢｄをＡｄよりも十分に大きくすることが困難となる。
The temperature of the film-forming resin solution is not particularly limited, but is usually 20 to 40 ° C. The viscosity of the film-forming resin solution at 40 ° C. is preferably 20,000 to 500,000 mPa · second, more preferably 50,000 to 300,000 mPa · second, and 70,000 to 250,000 mPa · second. More preferably it is. If the viscosity is too low, the phase separation rate increases, and Ad and Bd become too large, and the separation characteristics deteriorate. On the other hand, if the viscosity is too high, the speed of phase separation decreases, and it becomes difficult to make Bd sufficiently larger than Ad.
膜形成性樹脂溶液中における膜形成性樹脂の濃度は、薄すぎても濃すぎても製膜時の安定性が低下し、目的の中空状多孔質中空糸膜が得られにくくなる傾向にあるため、膜形成性樹脂溶液の全体質量に対して、下限は１０質量％が好ましく、１５質量％がより好ましい。また、上限は膜形成性樹脂溶液の全体質量に対して３０質量％が好ましく、２５質量％がより好ましい。具体的には、膜形成樹脂は膜形成性樹脂溶液の全体質量に対して１０～３０質量％、好ましくは１５～２５質量％といった範囲でもよい。
一方、親水性樹脂の濃度の下限は、中空状多孔質中空糸膜をより形成しやすいものとするために、膜形成性樹脂溶液の全体質量に対して１質量％が好ましく、５質量％がより好ましい。親水性樹脂の濃度の上限は、膜形成性樹脂溶液の取扱性の点から膜形成性樹脂溶液の全体質量に対して２０質量％が好ましく、１２質量％がより好ましい。具体的には、膜形成性樹脂溶液の全体質量に対して１～２０質量％、好ましくは５～２０質量％といった範囲でもよい。 If the concentration of the film-forming resin in the film-forming resin solution is too thin or too thick, the stability during film formation tends to decrease, and the desired hollow porous hollow fiber membrane tends to be difficult to obtain. Therefore, the lower limit is preferably 10% by mass and more preferably 15% by mass with respect to the total mass of the film-forming resin solution. Further, the upper limit is preferably 30% by mass, and more preferably 25% by mass with respect to the total mass of the film-forming resin solution. Specifically, the film-forming resin may be in the range of 10 to 30% by mass, preferably 15 to 25% by mass, based on the total mass of the film-forming resin solution.
On the other hand, the lower limit of the concentration of the hydrophilic resin is preferably 1% by mass, preferably 5% by mass with respect to the total mass of the film-forming resin solution in order to make it easier to form a hollow porous hollow fiber membrane. More preferred. The upper limit of the concentration of the hydrophilic resin is preferably 20% by mass and more preferably 12% by mass with respect to the total mass of the film-forming resin solution from the viewpoint of the handleability of the film-forming resin solution. Specifically, it may be in the range of 1 to 20% by mass, preferably 5 to 20% by mass with respect to the total mass of the film-forming resin solution.
一方、親水性樹脂の濃度の下限は、中空状多孔質中空糸膜をより形成しやすいものとするために、膜形成性樹脂溶液の全体質量に対して１質量％が好ましく、５質量％がより好ましい。親水性樹脂の濃度の上限は、膜形成性樹脂溶液の取扱性の点から膜形成性樹脂溶液の全体質量に対して２０質量％が好ましく、１２質量％がより好ましい。具体的には、膜形成性樹脂溶液の全体質量に対して１～２０質量％、好ましくは５～２０質量％といった範囲でもよい。 If the concentration of the film-forming resin in the film-forming resin solution is too thin or too thick, the stability during film formation tends to decrease, and the desired hollow porous hollow fiber membrane tends to be difficult to obtain. Therefore, the lower limit is preferably 10% by mass and more preferably 15% by mass with respect to the total mass of the film-forming resin solution. Further, the upper limit is preferably 30% by mass, and more preferably 25% by mass with respect to the total mass of the film-forming resin solution. Specifically, the film-forming resin may be in the range of 10 to 30% by mass, preferably 15 to 25% by mass, based on the total mass of the film-forming resin solution.
On the other hand, the lower limit of the concentration of the hydrophilic resin is preferably 1% by mass, preferably 5% by mass with respect to the total mass of the film-forming resin solution in order to make it easier to form a hollow porous hollow fiber membrane. More preferred. The upper limit of the concentration of the hydrophilic resin is preferably 20% by mass and more preferably 12% by mass with respect to the total mass of the film-forming resin solution from the viewpoint of the handleability of the film-forming resin solution. Specifically, it may be in the range of 1 to 20% by mass, preferably 5 to 20% by mass with respect to the total mass of the film-forming resin solution.
膜形成性樹脂溶液の組成については、多孔質層Ａから多孔質層Ｃへ漸増する構造を相分離により形成できるものであれば特に限定されないが、多孔質層の表面開孔率を高くできる点から、溶媒の比率を膜形成性樹脂溶液の全体質量に対して６８質量％以上、より好ましくは７０％以上とすることが好ましい。
また、大きなマクロボイドの無い漸増構造を形成できる傾向があることから、親水性樹脂／膜形成性樹脂の質量比は０．４５以上であることが好ましい。この値を下回ると、マクロボイドを形成しやすくなる傾向があると共に、共連続構造ではなく海島構造を形成しやすくなる傾向にあり、結果として表面開孔率の低下や均質構造の形成を招き、好ましくない。 The composition of the film-forming resin solution is not particularly limited as long as the structure that gradually increases from the porous layer A to the porous layer C can be formed by phase separation, but the surface porosity of the porous layer can be increased. Therefore, the ratio of the solvent is preferably 68% by mass or more, more preferably 70% or more with respect to the total mass of the film-forming resin solution.
Moreover, since there exists a tendency which can form the gradual increase structure without a big macrovoid, it is preferable that the mass ratio of hydrophilic resin / film-forming resin is 0.45 or more. Below this value, it tends to form macrovoids and tends to form a sea-island structure rather than a co-continuous structure, resulting in a decrease in surface porosity and formation of a homogeneous structure, It is not preferable.
また、大きなマクロボイドの無い漸増構造を形成できる傾向があることから、親水性樹脂／膜形成性樹脂の質量比は０．４５以上であることが好ましい。この値を下回ると、マクロボイドを形成しやすくなる傾向があると共に、共連続構造ではなく海島構造を形成しやすくなる傾向にあり、結果として表面開孔率の低下や均質構造の形成を招き、好ましくない。 The composition of the film-forming resin solution is not particularly limited as long as the structure that gradually increases from the porous layer A to the porous layer C can be formed by phase separation, but the surface porosity of the porous layer can be increased. Therefore, the ratio of the solvent is preferably 68% by mass or more, more preferably 70% or more with respect to the total mass of the film-forming resin solution.
Moreover, since there exists a tendency which can form the gradual increase structure without a big macrovoid, it is preferable that the mass ratio of hydrophilic resin / film-forming resin is 0.45 or more. Below this value, it tends to form macrovoids and tends to form a sea-island structure rather than a co-continuous structure, resulting in a decrease in surface porosity and formation of a homogeneous structure, It is not preferable.
［掃気工程］
本実施形態における掃気工程は、紡糸ノズル１０の吐出面１０ａに掃気用気体を送気する工程である。
具体的に、掃気工程では、まず、気体供給手段４３２から供給した掃気用気体を気体濾過手段４３により濾過し、気体調整手段４４によって温度及び湿度を調整した後、気体導入室４１ｂに供給する。その際、吐出面１０ａの結露をより紡糸できることから、気体調整手段４４によって、掃気用気体は、露点が紡糸ノズル１０の吐出面の表面温度よりも低くなるように調整されることが好ましい。また、紡糸ノズル１０や糸状体Ａ‘の温度を設定状態から変化しないようにしたい場合は、掃気用気体の温度お紡糸ノズル１０の設定温度と同じ温度として供給することが好ましい。
次いで、気体導入室４１ｂにて、気体吐出口４１ｃに設けられた抵抗付与体４１ｄによって掃気用気体の圧力分布を均一化する。次いで、気体導入室４１ｂ内の掃気用気体を、気体吐出口４１ｃの抵抗付与体４１ｄを通して、円形開口部４１ａの中心に向けて吐出して、吐出面１０ａに掃気用気体を送気する。気体吐出口４１ｃから吐出した掃気用気体は、貫通孔５０ａを通過する糸状体Ａ‘の周囲を糸状体Ａ’と並行に、上端部５１から下端部５２に向かって流動する。そして、貫通孔５０ａから、第１の開口部２１ａから流出する処理用気体に向かって吐出する。その後、掃気用気体は、隙間Ｑにて、第１の開孔部２１ａから流出した処理用気体と共に第１の開口部２１ａから離間するように外側に向かって排出される。 [Scavenging process]
The scavenging step in the present embodiment is a step of feeding a scavenging gas to thedischarge surface 10a of the spinning nozzle 10.
Specifically, in the scavenging step, first, the scavenging gas supplied from the gas supply unit 432 is filtered by thegas filtering unit 43, the temperature and humidity are adjusted by the gas adjusting unit 44, and then supplied to the gas introduction chamber 41 b. At this time, since the condensation on the discharge surface 10a can be further spun, the scavenging gas is preferably adjusted by the gas adjusting means 44 so that the dew point is lower than the surface temperature of the discharge surface of the spinning nozzle 10. In order to keep the temperature of the spinning nozzle 10 and the filament A ′ from changing from the set state, it is preferable to supply the scavenging gas at the same temperature as the set temperature of the spinning nozzle 10.
Next, in thegas introduction chamber 41b, the pressure distribution of the scavenging gas is made uniform by the resistance applying body 41d provided in the gas discharge port 41c. Next, the scavenging gas in the gas introduction chamber 41b is discharged toward the center of the circular opening 41a through the resistance applying body 41d of the gas discharge port 41c, and the scavenging gas is sent to the discharge surface 10a. The scavenging gas discharged from the gas discharge port 41c flows from the upper end 51 toward the lower end 52 around the filament A ′ passing through the through hole 50a in parallel with the filament A ′. And it discharges toward the process gas which flows out out of the 1st opening part 21a from the through-hole 50a. Thereafter, the scavenging gas is discharged toward the outside in the gap Q together with the processing gas flowing out from the first opening 21a so as to be separated from the first opening 21a.
本実施形態における掃気工程は、紡糸ノズル１０の吐出面１０ａに掃気用気体を送気する工程である。
具体的に、掃気工程では、まず、気体供給手段４３２から供給した掃気用気体を気体濾過手段４３により濾過し、気体調整手段４４によって温度及び湿度を調整した後、気体導入室４１ｂに供給する。その際、吐出面１０ａの結露をより紡糸できることから、気体調整手段４４によって、掃気用気体は、露点が紡糸ノズル１０の吐出面の表面温度よりも低くなるように調整されることが好ましい。また、紡糸ノズル１０や糸状体Ａ‘の温度を設定状態から変化しないようにしたい場合は、掃気用気体の温度お紡糸ノズル１０の設定温度と同じ温度として供給することが好ましい。
次いで、気体導入室４１ｂにて、気体吐出口４１ｃに設けられた抵抗付与体４１ｄによって掃気用気体の圧力分布を均一化する。次いで、気体導入室４１ｂ内の掃気用気体を、気体吐出口４１ｃの抵抗付与体４１ｄを通して、円形開口部４１ａの中心に向けて吐出して、吐出面１０ａに掃気用気体を送気する。気体吐出口４１ｃから吐出した掃気用気体は、貫通孔５０ａを通過する糸状体Ａ‘の周囲を糸状体Ａ’と並行に、上端部５１から下端部５２に向かって流動する。そして、貫通孔５０ａから、第１の開口部２１ａから流出する処理用気体に向かって吐出する。その後、掃気用気体は、隙間Ｑにて、第１の開孔部２１ａから流出した処理用気体と共に第１の開口部２１ａから離間するように外側に向かって排出される。 [Scavenging process]
The scavenging step in the present embodiment is a step of feeding a scavenging gas to the
Specifically, in the scavenging step, first, the scavenging gas supplied from the gas supply unit 432 is filtered by the
Next, in the
上記掃気工程では、紡糸ノズル１０近傍の雰囲気における非溶媒の露点を紡糸ノズル１０の表面温度未満にする。紡糸ノズル１０近傍の雰囲気における非溶媒の露点が紡糸ノズル１０以上になると、結露の紡糸が困難になる。ここで、「雰囲気における非溶媒の露点」とは、雰囲気が含むことができる非溶媒の量と、その雰囲気に含まれる非溶媒の量とが一致し、雰囲気温度が下がった際には、含みきれなくなった非溶媒が凝結し始める温度のことである。
また、上記掃気工程によって、結露をより防止できることから、紡糸ノズル近傍の雰囲気における非溶媒の相対湿度を１０％未満にすることが好ましい、ここで、「雰囲気における非溶媒の相対湿度」とは、ある温度の雰囲気に含まれる非溶媒の量／その温度の飽和非溶媒量×１００で求められる値（単位：％）のことである。 In the scavenging step, the dew point of the non-solvent in the atmosphere in the vicinity of the spinningnozzle 10 is made lower than the surface temperature of the spinning nozzle 10. When the dew point of the non-solvent in the atmosphere in the vicinity of the spinning nozzle 10 is equal to or higher than the spinning nozzle 10, spinning of condensation becomes difficult. Here, “the dew point of the non-solvent in the atmosphere” means that when the amount of the non-solvent that the atmosphere can contain matches the amount of the non-solvent contained in the atmosphere and the ambient temperature decreases, This is the temperature at which the non-solvent that cannot be used begins to condense.
In addition, since the above-described scavenging step can prevent condensation more, it is preferable that the relative humidity of the non-solvent in the atmosphere near the spinning nozzle is less than 10%. Here, “the relative humidity of the non-solvent in the atmosphere” It is a value (unit:%) determined by the amount of non-solvent contained in an atmosphere at a certain temperature / the amount of saturated non-solvent at that temperature × 100.
また、上記掃気工程によって、結露をより防止できることから、紡糸ノズル近傍の雰囲気における非溶媒の相対湿度を１０％未満にすることが好ましい、ここで、「雰囲気における非溶媒の相対湿度」とは、ある温度の雰囲気に含まれる非溶媒の量／その温度の飽和非溶媒量×１００で求められる値（単位：％）のことである。 In the scavenging step, the dew point of the non-solvent in the atmosphere in the vicinity of the spinning
In addition, since the above-described scavenging step can prevent condensation more, it is preferable that the relative humidity of the non-solvent in the atmosphere near the spinning nozzle is less than 10%. Here, “the relative humidity of the non-solvent in the atmosphere” It is a value (unit:%) determined by the amount of non-solvent contained in an atmosphere at a certain temperature / the amount of saturated non-solvent at that temperature × 100.
［凝固工程］
凝固工程は、紡糸ノズル１０から吐出した膜形成性樹脂溶液を処理用容器２０Ａ内の処理用気体に接触させた後に凝固槽３０内の凝固液Ｂに浸漬させる工程である。
本実施形態における凝固工程では、糸状体Ａ‘を処理用容器２０Ａ内の処理用気体及び凝固槽３０内の凝固液Ｂに接触させることによって、糸状体Ａ’の膜形成性樹脂溶液の塗膜Ａ２を凝固させて、多孔質中空糸膜Ａを得る。
具体的には、紡糸工程にて膜形成性樹脂溶液の塗膜Ａ２が形成された糸状体Ａ‘を、処理用容器２０Ａの第１開口部２１ａから処理用容器２０Ａの内部に導入して、処理用気体に接触させる。処理用気体と接触した塗膜Ａ２には、処理用気体に含まれる非溶媒成分が拡散浸入し、相分離が始まる。 [Coagulation process]
The coagulation step is a step in which the film-forming resin solution discharged from the spinningnozzle 10 is immersed in the coagulation liquid B in the coagulation tank 30 after being brought into contact with the processing gas in the processing vessel 20A.
In the solidification step in the present embodiment, the filament A ′ is brought into contact with the processing gas in theprocessing vessel 20A and the coagulation liquid B in the coagulation tank 30 to thereby form a coating film of the film-forming resin solution of the filament A ′. A2 is solidified to obtain a porous hollow fiber membrane A.
Specifically, the filament A ′ formed with the coating film A2 of the film-forming resin solution in the spinning process is introduced into theprocessing container 20A from the first opening 21a of the processing container 20A. Contact with processing gas. The non-solvent component contained in the processing gas diffuses and enters the coating film A2 that has come into contact with the processing gas, and phase separation starts.
凝固工程は、紡糸ノズル１０から吐出した膜形成性樹脂溶液を処理用容器２０Ａ内の処理用気体に接触させた後に凝固槽３０内の凝固液Ｂに浸漬させる工程である。
本実施形態における凝固工程では、糸状体Ａ‘を処理用容器２０Ａ内の処理用気体及び凝固槽３０内の凝固液Ｂに接触させることによって、糸状体Ａ’の膜形成性樹脂溶液の塗膜Ａ２を凝固させて、多孔質中空糸膜Ａを得る。
具体的には、紡糸工程にて膜形成性樹脂溶液の塗膜Ａ２が形成された糸状体Ａ‘を、処理用容器２０Ａの第１開口部２１ａから処理用容器２０Ａの内部に導入して、処理用気体に接触させる。処理用気体と接触した塗膜Ａ２には、処理用気体に含まれる非溶媒成分が拡散浸入し、相分離が始まる。 [Coagulation process]
The coagulation step is a step in which the film-forming resin solution discharged from the spinning
In the solidification step in the present embodiment, the filament A ′ is brought into contact with the processing gas in the
Specifically, the filament A ′ formed with the coating film A2 of the film-forming resin solution in the spinning process is introduced into the
ここで、処理用気体としては、非溶媒が飽和状態にある空気、非溶媒が非飽和状態にある空気、非溶媒の飽和蒸気が挙げられるが、本実施形態の多孔質中空糸膜を得るためには、非溶媒の飽和蒸気が好ましい。
また、膜形成性樹脂が疎水性ポリマーである場合は、非溶媒としては、水、エタノール等のアルコール類、アセトン、トルエン、又はエチレングリコールなどを使用することができるが、水が特に好ましい。 Here, examples of the processing gas include air in which the non-solvent is saturated, air in which the non-solvent is non-saturated, and saturated vapor of the non-solvent. In order to obtain the porous hollow fiber membrane of this embodiment For this, a non-solvent saturated vapor is preferred.
When the film-forming resin is a hydrophobic polymer, water, alcohols such as ethanol, acetone, toluene, ethylene glycol, or the like can be used as the non-solvent, but water is particularly preferable.
また、膜形成性樹脂が疎水性ポリマーである場合は、非溶媒としては、水、エタノール等のアルコール類、アセトン、トルエン、又はエチレングリコールなどを使用することができるが、水が特に好ましい。 Here, examples of the processing gas include air in which the non-solvent is saturated, air in which the non-solvent is non-saturated, and saturated vapor of the non-solvent. In order to obtain the porous hollow fiber membrane of this embodiment For this, a non-solvent saturated vapor is preferred.
When the film-forming resin is a hydrophobic polymer, water, alcohols such as ethanol, acetone, toluene, ethylene glycol, or the like can be used as the non-solvent, but water is particularly preferable.
処理用気体が、非溶媒の飽和蒸気である場合は、処理用容器２０Ａ内を通過する糸状体Ａ‘の周囲は、全て非溶媒で満たされている。以下に、処理用気体が、大気圧化での飽和水蒸気である場合の特徴について説明する。
大気圧下での飽和水蒸気の温度は約１００℃で、飽和水蒸気が満たされた処理用容器２０Ａ内の空間は１００％水分子で満たされている。したがって、処理用気体として飽和水蒸気を用いた場合には、糸状体Ａ‘の周囲の雰囲気温度及び湿度を均一化しやすい。
また、飽和水蒸気は、他の水分を含んだ気体と比較して、処理用容器２０Ａ内を通過する糸状体Ａ‘に単位時間当たりに供給する水分量及び熱量を多くすることができる。また、水蒸気が凝縮する際の凝縮熱量は極めて多く、凝縮伝熱は加熱効率が高いため、糸状体Ａ’の表層付近の温度を瞬時に１００℃近くまで上昇させることができる。
そのため、糸状体Ａ‘との温度差による飽和水蒸気凝縮での水分供給、熱供給によって、非飽和状態で水を含んだ気体中に糸状体Ａ’を通過させた場合とは全く異なる相分離挙動を生じさせることができる。
すなわち、多量の水分供給により、膜外表面は相分離を経て即座に凝固まで進むため、膜形成性樹脂溶液の粘度を比較的高く調整しておけば、濾過に適した緻密な構造を膜外表面に形成させることができる。そして多量の水分は膜内部まで即座に拡散浸入し、糸状体Ａ‘が処理用容器２０Ａ内にいる間に、糸状体Ａ’の表層部の相分離まで引き起こすことができる。
ここで、糸状体Ａ’の表層付近の温度は１００℃近くまで上昇していることから、その相分離速度は非常に速く、これにより多孔質層Ａの構造に対して十分に大きい構造を、多孔質層Ａより内部の表層に形成することが可能となる。 In the case where the processing gas is a non-solvent saturated vapor, the entire periphery of the filament A ′ passing through theprocessing container 20A is filled with the non-solvent. Hereinafter, characteristics when the processing gas is saturated water vapor at atmospheric pressure will be described.
The temperature of the saturated water vapor under atmospheric pressure is about 100 ° C., and the space in theprocessing vessel 20A filled with the saturated water vapor is filled with 100% water molecules. Therefore, when saturated steam is used as the processing gas, the ambient temperature and humidity around the filament A ′ can be easily made uniform.
Further, the saturated water vapor can increase the amount of water and the amount of heat supplied per unit time to the filament A ′ passing through theprocessing container 20A, as compared with gases containing other moisture. Further, the amount of heat of condensation when water vapor condenses is extremely large, and the heat of condensation heat transfer is high, so that the temperature near the surface layer of the filament A ′ can be instantaneously raised to near 100 ° C.
Therefore, the phase separation behavior is completely different from the case where the filament A ′ is passed through a gas containing water in an unsaturated state by water supply and heat supply in saturated steam condensation due to a temperature difference from the filament A ′. Can be generated.
In other words, since a large amount of water is supplied, the outer surface of the membrane proceeds to solidification immediately after phase separation. Therefore, if the viscosity of the film-forming resin solution is adjusted to a relatively high value, a dense structure suitable for filtration can be obtained. It can be formed on the surface. A large amount of moisture immediately diffuses and penetrates to the inside of the membrane, and can cause up to phase separation of the surface layer portion of the filament A ′ while the filament A ′ is in theprocessing container 20A.
Here, since the temperature in the vicinity of the surface layer of the filament A ′ has risen to nearly 100 ° C., the phase separation rate is very high, and thereby a structure sufficiently large with respect to the structure of the porous layer A is obtained. The porous layer A can be formed on the inner surface layer.
大気圧下での飽和水蒸気の温度は約１００℃で、飽和水蒸気が満たされた処理用容器２０Ａ内の空間は１００％水分子で満たされている。したがって、処理用気体として飽和水蒸気を用いた場合には、糸状体Ａ‘の周囲の雰囲気温度及び湿度を均一化しやすい。
また、飽和水蒸気は、他の水分を含んだ気体と比較して、処理用容器２０Ａ内を通過する糸状体Ａ‘に単位時間当たりに供給する水分量及び熱量を多くすることができる。また、水蒸気が凝縮する際の凝縮熱量は極めて多く、凝縮伝熱は加熱効率が高いため、糸状体Ａ’の表層付近の温度を瞬時に１００℃近くまで上昇させることができる。
そのため、糸状体Ａ‘との温度差による飽和水蒸気凝縮での水分供給、熱供給によって、非飽和状態で水を含んだ気体中に糸状体Ａ’を通過させた場合とは全く異なる相分離挙動を生じさせることができる。
すなわち、多量の水分供給により、膜外表面は相分離を経て即座に凝固まで進むため、膜形成性樹脂溶液の粘度を比較的高く調整しておけば、濾過に適した緻密な構造を膜外表面に形成させることができる。そして多量の水分は膜内部まで即座に拡散浸入し、糸状体Ａ‘が処理用容器２０Ａ内にいる間に、糸状体Ａ’の表層部の相分離まで引き起こすことができる。
ここで、糸状体Ａ’の表層付近の温度は１００℃近くまで上昇していることから、その相分離速度は非常に速く、これにより多孔質層Ａの構造に対して十分に大きい構造を、多孔質層Ａより内部の表層に形成することが可能となる。 In the case where the processing gas is a non-solvent saturated vapor, the entire periphery of the filament A ′ passing through the
The temperature of the saturated water vapor under atmospheric pressure is about 100 ° C., and the space in the
Further, the saturated water vapor can increase the amount of water and the amount of heat supplied per unit time to the filament A ′ passing through the
Therefore, the phase separation behavior is completely different from the case where the filament A ′ is passed through a gas containing water in an unsaturated state by water supply and heat supply in saturated steam condensation due to a temperature difference from the filament A ′. Can be generated.
In other words, since a large amount of water is supplied, the outer surface of the membrane proceeds to solidification immediately after phase separation. Therefore, if the viscosity of the film-forming resin solution is adjusted to a relatively high value, a dense structure suitable for filtration can be obtained. It can be formed on the surface. A large amount of moisture immediately diffuses and penetrates to the inside of the membrane, and can cause up to phase separation of the surface layer portion of the filament A ′ while the filament A ′ is in the
Here, since the temperature in the vicinity of the surface layer of the filament A ′ has risen to nearly 100 ° C., the phase separation rate is very high, and thereby a structure sufficiently large with respect to the structure of the porous layer A is obtained. The porous layer A can be formed on the inner surface layer.
このように、処理用容器２０Ａ内で、外表面構造が固定し、その内部の表層まで相分離が進行した糸状体Ａ‘を、次に凝固槽３０内に導入し、凝固液Ｂに接触させる。これにより、凝固液Ｂの非溶媒成分が膜形成性樹脂溶液の塗膜Ａ２の内部に拡散浸入する。凝固液Ｂは液体であるため、飽和水蒸気に比べても多量の非溶媒が急速に浸入することで、内部まで相分離を経て凝固することで、多孔質中空糸膜Ａとなる。
In this way, the filament A ′ whose outer surface structure is fixed and the phase separation has proceeded to the inner surface layer in the processing vessel 20A is then introduced into the coagulation tank 30 and brought into contact with the coagulation liquid B. . Thereby, the non-solvent component of the coagulation liquid B diffuses and penetrates into the coating film A2 of the film-forming resin solution. Since the coagulating liquid B is a liquid, a large amount of non-solvent rapidly enters even when compared with saturated water vapor, and solidifies through phase separation to the inside, so that the porous hollow fiber membrane A is obtained.
凝固液Ｂは、膜形成性樹脂の非溶媒で、親水性樹脂の良溶媒であり、水、工タノール、又はメタノール等やこれらの混合物が挙げられるが、なかでも、膜形成性樹脂溶液に用いた溶媒と水との混合液が安全性、運転管理の面から好ましい。
膜形成性樹脂溶液に用いた溶媒と水との混合液を用いる場合は、溶媒の濃度が溶媒と水と混合液の全体質量に対して溶媒が５～５０質量％の範囲であることが好ましく、１０～４０質量％の範囲であることがより好ましい。この範囲を下回ると非溶媒の増加速度が速まり、内部の構造が緻密になりすぎることがある。また、この範囲を上回ると、十分な量の非溶媒が浸入できず、凝固槽内で凝固が完了しないことがある。 The coagulation liquid B is a non-solvent for the film-forming resin and a good solvent for the hydrophilic resin, and examples thereof include water, techanol, methanol, and mixtures thereof. Among them, the coagulating liquid B is used for the film-forming resin solution. A mixed solution of a solvent and water is preferable from the viewpoints of safety and operation management.
When a mixed solution of the solvent and water used for the film-forming resin solution is used, the concentration of the solvent is preferably in the range of 5 to 50% by mass with respect to the total mass of the solvent, water and the mixed solution. The range of 10 to 40% by mass is more preferable. Below this range, the rate of increase of the non-solvent increases and the internal structure may become too dense. Moreover, if it exceeds this range, a sufficient amount of non-solvent cannot enter and solidification may not be completed in the coagulation tank.
膜形成性樹脂溶液に用いた溶媒と水との混合液を用いる場合は、溶媒の濃度が溶媒と水と混合液の全体質量に対して溶媒が５～５０質量％の範囲であることが好ましく、１０～４０質量％の範囲であることがより好ましい。この範囲を下回ると非溶媒の増加速度が速まり、内部の構造が緻密になりすぎることがある。また、この範囲を上回ると、十分な量の非溶媒が浸入できず、凝固槽内で凝固が完了しないことがある。 The coagulation liquid B is a non-solvent for the film-forming resin and a good solvent for the hydrophilic resin, and examples thereof include water, techanol, methanol, and mixtures thereof. Among them, the coagulating liquid B is used for the film-forming resin solution. A mixed solution of a solvent and water is preferable from the viewpoints of safety and operation management.
When a mixed solution of the solvent and water used for the film-forming resin solution is used, the concentration of the solvent is preferably in the range of 5 to 50% by mass with respect to the total mass of the solvent, water and the mixed solution. The range of 10 to 40% by mass is more preferable. Below this range, the rate of increase of the non-solvent increases and the internal structure may become too dense. Moreover, if it exceeds this range, a sufficient amount of non-solvent cannot enter and solidification may not be completed in the coagulation tank.
凝固液Ｂの温度は３０～９５℃の範囲にし、４０～８５℃にすることが好ましい。凝固液Ｂの温度を前記下限値以上とすることにより、得られる中空状多孔質中空糸膜の透水性能が高くなり、前記上限値以下とすることにより、得られる中空状多孔質中空糸膜の膜品質が向上する。
The temperature of the coagulation liquid B is in the range of 30 to 95 ° C, preferably 40 to 85 ° C. By setting the temperature of the coagulation liquid B to the lower limit value or more, the water permeability of the obtained hollow porous hollow fiber membrane is increased, and by setting the temperature to the upper limit value or less, the resulting hollow porous hollow fiber membrane The film quality is improved.
親水性樹脂として、ポリビニルピロリドン等の高分子を用いた場合は、多孔質中空糸膜Ａを熱水で洗浄した後、酸化剤含有液で処理して親水性樹脂を分解し、除去することが好ましい。
When a polymer such as polyvinylpyrrolidone is used as the hydrophilic resin, the porous hollow fiber membrane A can be washed with hot water and then treated with an oxidant-containing liquid to decompose and remove the hydrophilic resin. preferable.
本実施形態の多孔質中空糸膜の製造方法及びそれにより製造した中空糸膜は、水処理の分野を中心に応用できる。例えば、本実施形態の多孔質中空糸膜の製造方法及びそれにより製造した中空糸膜を用いた浄水処理の方法、及びその他の水処理の方法に用いることができる。また、本実施形態の多孔質中空糸膜の製造方法及びそれにより製造した中空糸膜は、それを構成に備える浄水装置等に用いることができ、またその浄水装置等の製造方法に使用することができる。
なお、これらの用途において、上述した実施形態の構成のそれぞれは、適宜組み合わせて用いることができる。 The method for producing a porous hollow fiber membrane of the present embodiment and the hollow fiber membrane produced thereby can be applied mainly in the field of water treatment. For example, it can be used in a method for producing a porous hollow fiber membrane of the present embodiment, a water purification treatment method using the hollow fiber membrane produced thereby, and other water treatment methods. Moreover, the manufacturing method of the porous hollow fiber membrane of this embodiment and the hollow fiber membrane manufactured thereby can be used in a water purification device or the like provided with the structure, and used in the manufacturing method of the water purification device or the like. Can do.
In these applications, each of the configurations of the above-described embodiments can be used in appropriate combination.
なお、これらの用途において、上述した実施形態の構成のそれぞれは、適宜組み合わせて用いることができる。 The method for producing a porous hollow fiber membrane of the present embodiment and the hollow fiber membrane produced thereby can be applied mainly in the field of water treatment. For example, it can be used in a method for producing a porous hollow fiber membrane of the present embodiment, a water purification treatment method using the hollow fiber membrane produced thereby, and other water treatment methods. Moreover, the manufacturing method of the porous hollow fiber membrane of this embodiment and the hollow fiber membrane manufactured thereby can be used in a water purification device or the like provided with the structure, and used in the manufacturing method of the water purification device or the like. Can do.
In these applications, each of the configurations of the above-described embodiments can be used in appropriate combination.
さらに、本実施形態を以下の実施例等により具体的に説明する。
（画像解析）
多孔質膜の諸物性は、次のようにして画像解析により測定した。 Further, the present embodiment will be specifically described with reference to the following examples.
(Image analysis)
Various physical properties of the porous membrane were measured by image analysis as follows.
（画像解析）
多孔質膜の諸物性は、次のようにして画像解析により測定した。 Further, the present embodiment will be specifically described with reference to the following examples.
(Image analysis)
Various physical properties of the porous membrane were measured by image analysis as follows.
（１）多孔質膜の平均孔径指数
多孔質膜について、走査型電子顕微鏡（ＳＥＭ）を用いて、断面及び表面の写真撮影を行い、その写真のコンピュターによる画像解析から内部構造及び表面の平均孔径指数を求めた。画像解析によって得られる平均孔径指数は、画像解析のための画質調整や、画像解析ソフトによっても若干変動があるが、その差は通常の実験誤差の範囲内である。 (1) Average pore size index of porous membrane Using a scanning electron microscope (SEM), the cross-section and surface of the porous membrane are photographed, and the internal structure and the average pore size of the surface are analyzed by image analysis using a computer. The index was determined. The average pore size index obtained by image analysis varies slightly depending on image quality adjustment for image analysis and image analysis software, but the difference is within the range of normal experimental error.
多孔質膜について、走査型電子顕微鏡（ＳＥＭ）を用いて、断面及び表面の写真撮影を行い、その写真のコンピュターによる画像解析から内部構造及び表面の平均孔径指数を求めた。画像解析によって得られる平均孔径指数は、画像解析のための画質調整や、画像解析ソフトによっても若干変動があるが、その差は通常の実験誤差の範囲内である。 (1) Average pore size index of porous membrane Using a scanning electron microscope (SEM), the cross-section and surface of the porous membrane are photographed, and the internal structure and the average pore size of the surface are analyzed by image analysis using a computer. The index was determined. The average pore size index obtained by image analysis varies slightly depending on image quality adjustment for image analysis and image analysis software, but the difference is within the range of normal experimental error.
得られた多孔質膜の外表面を、走査型電子顕微鏡（ＳＥＭ）観察を行う。多孔質膜が多孔質中空糸膜の場合には、多孔質中空糸膜外表面の基準点を定め、これを０°位置とし、９０°、１８０°及び２７０°の４方向からＳＥＭ写真を撮影する。観察倍率は所望とする分画孔径によるので一概には言えないが、精密ろ過膜の場合、１０，０００～１００，０００倍である。このような範囲を外れた場合、５０００倍以下では外表面の孔径が十分に観察することができず、１００，００００倍以上になると視野中の孔の数が少なくなり、平均的な孔径とは言い難くなるおそれがある。画像解析ソフトが認識した孔の直径を孔径とし、ＳＥＭ写真内の全孔の孔径を計算し、その平均値から孔径指数を算出し、それを以って多孔質膜の表面若しくは断面の構造を定量的に評価する。ここで、算出された全孔を面積で降順となるようにデータを並べ、上位の孔から面積を積算し、全面積に対して任意の割合５０％に相当するところまでの孔を用いて、孔径指数を算出する。例えば、限られないがこの任意の割合Ａをとする。
The outer surface of the obtained porous film is observed with a scanning electron microscope (SEM). When the porous membrane is a porous hollow fiber membrane, a reference point on the outer surface of the porous hollow fiber membrane is determined, and this is set to 0 °, and SEM photographs are taken from four directions of 90 °, 180 °, and 270 °. To do. Although the observation magnification depends on the desired fractional pore diameter, it cannot be generally stated, but in the case of a microfiltration membrane, it is 10,000 to 100,000 times. When outside this range, the pore diameter on the outer surface cannot be sufficiently observed at 5000 times or less, and when it is 100,000 or more times, the number of holes in the field of view decreases, and the average pore diameter is May be difficult to say. The diameter of the hole recognized by the image analysis software is taken as the hole diameter, the hole diameter of all the holes in the SEM photograph is calculated, the hole diameter index is calculated from the average value, and the surface or cross-sectional structure of the porous membrane is calculated accordingly. Assess quantitatively. Here, the data is arranged so that the calculated total holes are in descending order by area, the area is integrated from the upper holes, and the holes up to a place corresponding to an arbitrary ratio of 50% with respect to the total area are used. Calculate the pore size index. For example, although not limited, this arbitrary ratio A is assumed.
（２）多孔質膜の開孔率
多孔質膜のＳＥＭ写真を上記画像解析を用いて孔の面積を測定し、多孔質膜の開孔率を求めた。
開孔率（％）＝画像解析で認識される全孔の面積の和／ＳＥＭ写真内の視野内の膜面積 (2) Porosity of Porous Membrane The area of the pores was measured from the SEM photograph of the porous membrane using the above image analysis, and the porosity of the porous membrane was determined.
Open area ratio (%) = sum of all hole areas recognized by image analysis / film area in field of view in SEM photograph
多孔質膜のＳＥＭ写真を上記画像解析を用いて孔の面積を測定し、多孔質膜の開孔率を求めた。
開孔率（％）＝画像解析で認識される全孔の面積の和／ＳＥＭ写真内の視野内の膜面積 (2) Porosity of Porous Membrane The area of the pores was measured from the SEM photograph of the porous membrane using the above image analysis, and the porosity of the porous membrane was determined.
Open area ratio (%) = sum of all hole areas recognized by image analysis / film area in field of view in SEM photograph
（支持体の外径）
支持体の外径は、以下の方法で測定した。
測定するサンプルを約１０ｃｍに切断し、数本を束ねて、全体をポリウレタン樹脂で覆った。ポリウレタン樹脂は支持体の中空部にも入るようにした。
ポリウレタン樹脂硬化後、カミソリ刃を用いて厚さ（膜の長手方向）約０．５ｍｍの薄片をサンプリングした。
次にサンプリングした支持体の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している支持体断面のＸ方向、Ｙ方向の外表面の位置にマーク（ライン）をあわせて外径を読み取った。これを３回測定して外径の平均値を求めた。 (Outer diameter of support)
The outer diameter of the support was measured by the following method.
A sample to be measured was cut into approximately 10 cm, several bundles were bundled, and the whole was covered with a polyurethane resin. The polyurethane resin also entered the hollow part of the support.
After the polyurethane resin was cured, a thin piece having a thickness (longitudinal direction of the film) of about 0.5 mm was sampled using a razor blade.
Next, the sampled cross section of the support was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens magnification of 100 times.
A mark (line) was aligned with the position of the outer surface in the X direction and Y direction of the cross section of the support being observed, and the outer diameter was read. This was measured three times to determine the average value of the outer diameter.
支持体の外径は、以下の方法で測定した。
測定するサンプルを約１０ｃｍに切断し、数本を束ねて、全体をポリウレタン樹脂で覆った。ポリウレタン樹脂は支持体の中空部にも入るようにした。
ポリウレタン樹脂硬化後、カミソリ刃を用いて厚さ（膜の長手方向）約０．５ｍｍの薄片をサンプリングした。
次にサンプリングした支持体の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している支持体断面のＸ方向、Ｙ方向の外表面の位置にマーク（ライン）をあわせて外径を読み取った。これを３回測定して外径の平均値を求めた。 (Outer diameter of support)
The outer diameter of the support was measured by the following method.
A sample to be measured was cut into approximately 10 cm, several bundles were bundled, and the whole was covered with a polyurethane resin. The polyurethane resin also entered the hollow part of the support.
After the polyurethane resin was cured, a thin piece having a thickness (longitudinal direction of the film) of about 0.5 mm was sampled using a razor blade.
Next, the sampled cross section of the support was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens magnification of 100 times.
A mark (line) was aligned with the position of the outer surface in the X direction and Y direction of the cross section of the support being observed, and the outer diameter was read. This was measured three times to determine the average value of the outer diameter.
（支持体の内径）
支持体の内径は、以下の方法で測定した。
測定するサンプルは外径を測定したサンプルと同様の方法でサンプリングした。
次にサンプリングした支持体の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している支持体断面のＸ方向、Ｙ方向の内表面の位置にマーク（ライン）をあわせて内径を読み取った。これを３回測定して内径の平均値を求めた。 (Inner diameter of support)
The inner diameter of the support was measured by the following method.
The sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
Next, the sampled cross section of the support was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens magnification of 100 times.
A mark (line) was aligned with the position of the inner surface in the X direction and Y direction of the cross section of the support being observed, and the inner diameter was read. This was measured three times to determine the average inner diameter.
支持体の内径は、以下の方法で測定した。
測定するサンプルは外径を測定したサンプルと同様の方法でサンプリングした。
次にサンプリングした支持体の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している支持体断面のＸ方向、Ｙ方向の内表面の位置にマーク（ライン）をあわせて内径を読み取った。これを３回測定して内径の平均値を求めた。 (Inner diameter of support)
The inner diameter of the support was measured by the following method.
The sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
Next, the sampled cross section of the support was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens magnification of 100 times.
A mark (line) was aligned with the position of the inner surface in the X direction and Y direction of the cross section of the support being observed, and the inner diameter was read. This was measured three times to determine the average inner diameter.
（多孔質中空糸膜の外径）
多孔質中空糸膜の外径は、以下の方法で測定した。
測定するサンプルを約１０ｃｍに切断し、数本を束ねて、全体をポリウレタン樹脂で覆った。ポリウレタン樹脂は支持体の中空部にも入るようにした。
ポリウレタン樹脂硬化後、カミソリ刃を用いて厚さ（膜の長手方向）約０．５ｍｍの薄片をサンプリングした。
次に、サンプリングした多孔質中空糸膜の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している多孔質中空糸膜断面のＸ方向、Ｙ方向の外表面の位置にマーク（ライン）をあわせて外径を読み取った。これを３回測定して外径の平均値を求めた。 (Outer diameter of porous hollow fiber membrane)
The outer diameter of the porous hollow fiber membrane was measured by the following method.
A sample to be measured was cut into approximately 10 cm, several bundles were bundled, and the whole was covered with a polyurethane resin. The polyurethane resin also entered the hollow part of the support.
After the polyurethane resin was cured, a thin piece having a thickness (longitudinal direction of the film) of about 0.5 mm was sampled using a razor blade.
Next, a cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
A mark (line) was placed at the position of the outer surface in the X direction and Y direction of the cross section of the porous hollow fiber membrane being observed, and the outer diameter was read. This was measured three times to determine the average value of the outer diameter.
多孔質中空糸膜の外径は、以下の方法で測定した。
測定するサンプルを約１０ｃｍに切断し、数本を束ねて、全体をポリウレタン樹脂で覆った。ポリウレタン樹脂は支持体の中空部にも入るようにした。
ポリウレタン樹脂硬化後、カミソリ刃を用いて厚さ（膜の長手方向）約０．５ｍｍの薄片をサンプリングした。
次に、サンプリングした多孔質中空糸膜の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している多孔質中空糸膜断面のＸ方向、Ｙ方向の外表面の位置にマーク（ライン）をあわせて外径を読み取った。これを３回測定して外径の平均値を求めた。 (Outer diameter of porous hollow fiber membrane)
The outer diameter of the porous hollow fiber membrane was measured by the following method.
A sample to be measured was cut into approximately 10 cm, several bundles were bundled, and the whole was covered with a polyurethane resin. The polyurethane resin also entered the hollow part of the support.
After the polyurethane resin was cured, a thin piece having a thickness (longitudinal direction of the film) of about 0.5 mm was sampled using a razor blade.
Next, a cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
A mark (line) was placed at the position of the outer surface in the X direction and Y direction of the cross section of the porous hollow fiber membrane being observed, and the outer diameter was read. This was measured three times to determine the average value of the outer diameter.
（多孔質中空糸膜の内径）
多孔質中空糸膜の内径は、以下の方法で測定した。
測定するサンプルは外径を測定したサンプルと同様の方法でサンプリングした。
次に、サンプリングした多孔質中空糸膜の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している多孔質中空糸膜断面のＸ方向、Ｙ方向の支持体内面の位置にマーク（ライン）をあわせて内径を読み取った。これを３回測定して内径の平均値を求めた。 (Inner diameter of porous hollow fiber membrane)
The inner diameter of the porous hollow fiber membrane was measured by the following method.
The sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
Next, a cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
A mark (line) was aligned with the position of the inner surface of the support in the X and Y directions of the cross section of the porous hollow fiber membrane being observed, and the inner diameter was read. This was measured three times to determine the average inner diameter.
多孔質中空糸膜の内径は、以下の方法で測定した。
測定するサンプルは外径を測定したサンプルと同様の方法でサンプリングした。
次に、サンプリングした多孔質中空糸膜の断面を、投影機（ニコン社製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している多孔質中空糸膜断面のＸ方向、Ｙ方向の支持体内面の位置にマーク（ライン）をあわせて内径を読み取った。これを３回測定して内径の平均値を求めた。 (Inner diameter of porous hollow fiber membrane)
The inner diameter of the porous hollow fiber membrane was measured by the following method.
The sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
Next, a cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
A mark (line) was aligned with the position of the inner surface of the support in the X and Y directions of the cross section of the porous hollow fiber membrane being observed, and the inner diameter was read. This was measured three times to determine the average inner diameter.
（多孔質膜層の膜厚）
実施例等における多孔質膜層の膜厚は、支持体の表面から多孔質中空糸膜の表面までの厚さであり、以下の方法で測定した。
測定するサンプルは外径を測定したサンプルと同様の方法でサンプリングした。
次に、サンプリングした多孔質中空糸膜の断面を、投影機（株式会社ニコン製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している多孔質中空糸膜断面の３時方向位置の膜厚の外表面と内表面の位置にマーク（ライン）をあわせて膜厚を読み取った。同様に、９時方向、１２時方向、６時方向の順で膜厚を読み取った。これを３回測定して内径の平均値を求めた。 (Thickness of porous membrane layer)
The film thickness of the porous membrane layer in Examples and the like is the thickness from the surface of the support to the surface of the porous hollow fiber membrane, and was measured by the following method.
The sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
Next, the cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
The film thickness was read by aligning marks (lines) at the positions of the outer surface and inner surface of the film at the 3 o'clock position on the cross section of the porous hollow fiber membrane being observed. Similarly, the film thickness was read in the order of 9 o'clock, 12 o'clock, and 6 o'clock. This was measured three times to determine the average inner diameter.
実施例等における多孔質膜層の膜厚は、支持体の表面から多孔質中空糸膜の表面までの厚さであり、以下の方法で測定した。
測定するサンプルは外径を測定したサンプルと同様の方法でサンプリングした。
次に、サンプリングした多孔質中空糸膜の断面を、投影機（株式会社ニコン製、ＰＲＯＦＩＬＥ ＰＲＯＪＥＣＴＯＲ Ｖ－１２）を用い、対物レンズ１００倍にて観察した。
観察している多孔質中空糸膜断面の３時方向位置の膜厚の外表面と内表面の位置にマーク（ライン）をあわせて膜厚を読み取った。同様に、９時方向、１２時方向、６時方向の順で膜厚を読み取った。これを３回測定して内径の平均値を求めた。 (Thickness of porous membrane layer)
The film thickness of the porous membrane layer in Examples and the like is the thickness from the surface of the support to the surface of the porous hollow fiber membrane, and was measured by the following method.
The sample to be measured was sampled in the same manner as the sample whose outer diameter was measured.
Next, the cross section of the sampled porous hollow fiber membrane was observed with a projector (Nikon Corporation, PROFILE PROJECTOR V-12) at an objective lens of 100 times.
The film thickness was read by aligning marks (lines) at the positions of the outer surface and inner surface of the film at the 3 o'clock position on the cross section of the porous hollow fiber membrane being observed. Similarly, the film thickness was read in the order of 9 o'clock, 12 o'clock, and 6 o'clock. This was measured three times to determine the average inner diameter.
（多孔質膜層の孔径）
多孔質層の孔径は、以下の方法で測定した。
測定したい断面構造を、走査型電子顕微鏡を用いて倍率１０，０００倍で撮影し、得られた写真の画像解析処理によりその構造の平均孔径指数を求めた。画像解析処理ソフトとしては、Ｍｅｄｉａ Ｃｙｂｅｒｎｅｔｉｃｓ社のＩＭＡＧＥ－ＰＲＯ ＰＬＵＳ ｖｅｒｓｉｏｎ５．０を使用した。 (Pore diameter of porous membrane layer)
The pore diameter of the porous layer was measured by the following method.
The cross-sectional structure to be measured was photographed at a magnification of 10,000 using a scanning electron microscope, and the average pore diameter index of the structure was obtained by image analysis processing of the obtained photograph. As image analysis processing software, IMAGE-PRO PLUS version 5.0 of Media Cybernetics was used.
多孔質層の孔径は、以下の方法で測定した。
測定したい断面構造を、走査型電子顕微鏡を用いて倍率１０，０００倍で撮影し、得られた写真の画像解析処理によりその構造の平均孔径指数を求めた。画像解析処理ソフトとしては、Ｍｅｄｉａ Ｃｙｂｅｒｎｅｔｉｃｓ社のＩＭＡＧＥ－ＰＲＯ ＰＬＵＳ ｖｅｒｓｉｏｎ５．０を使用した。 (Pore diameter of porous membrane layer)
The pore diameter of the porous layer was measured by the following method.
The cross-sectional structure to be measured was photographed at a magnification of 10,000 using a scanning electron microscope, and the average pore diameter index of the structure was obtained by image analysis processing of the obtained photograph. As image analysis processing software, IMAGE-PRO PLUS version 5.0 of Media Cybernetics was used.
（多孔質中空糸膜の透水性能）
多孔質中空糸膜の透水性能は、以下の方法で測定した。
測定するサンプルを４ｃｍに切断し、片端面をポリウレタン樹脂で中空部の封をした。
次に、サンプルをエタノール中で５分間以上減圧した後、純水中に浸して置換した。
容器に純水（２５℃）を入れ、サンプルの他端面とチューブで繋ぎ、容器に２００ｋＰａの空気圧をかけてサンプルから出る純水の量を１分間測定した。これを３回測定して平均値を求めた。この数値をサンプルの表面積で割り、透水性能とした。 (Permeability of porous hollow fiber membrane)
The water permeability of the porous hollow fiber membrane was measured by the following method.
The sample to be measured was cut into 4 cm, and one end face was sealed with a polyurethane resin at the hollow portion.
Next, the sample was decompressed in ethanol for 5 minutes or more and then immersed in pure water for replacement.
Pure water (25 ° C.) was placed in the container, connected to the other end of the sample with a tube, and an air pressure of 200 kPa was applied to the container to measure the amount of pure water coming out of the sample for 1 minute. This was measured three times to obtain an average value. This value was divided by the surface area of the sample to determine the water permeability.
多孔質中空糸膜の透水性能は、以下の方法で測定した。
測定するサンプルを４ｃｍに切断し、片端面をポリウレタン樹脂で中空部の封をした。
次に、サンプルをエタノール中で５分間以上減圧した後、純水中に浸して置換した。
容器に純水（２５℃）を入れ、サンプルの他端面とチューブで繋ぎ、容器に２００ｋＰａの空気圧をかけてサンプルから出る純水の量を１分間測定した。これを３回測定して平均値を求めた。この数値をサンプルの表面積で割り、透水性能とした。 (Permeability of porous hollow fiber membrane)
The water permeability of the porous hollow fiber membrane was measured by the following method.
The sample to be measured was cut into 4 cm, and one end face was sealed with a polyurethane resin at the hollow portion.
Next, the sample was decompressed in ethanol for 5 minutes or more and then immersed in pure water for replacement.
Pure water (25 ° C.) was placed in the container, connected to the other end of the sample with a tube, and an air pressure of 200 kPa was applied to the container to measure the amount of pure water coming out of the sample for 1 minute. This was measured three times to obtain an average value. This value was divided by the surface area of the sample to determine the water permeability.
（多孔質中空糸膜の分離特性）
多孔質中空糸膜の分離特性は、バブルポイント法によりＪＩＳ Ｋ ３８３２に準拠して求められる最大孔径より評価した。エタノールを測定媒体として測定した。 (Separation characteristics of porous hollow fiber membrane)
The separation characteristics of the porous hollow fiber membrane were evaluated from the maximum pore diameter determined in accordance with JIS K3832 by the bubble point method. Ethanol was used as a measurement medium.
多孔質中空糸膜の分離特性は、バブルポイント法によりＪＩＳ Ｋ ３８３２に準拠して求められる最大孔径より評価した。エタノールを測定媒体として測定した。 (Separation characteristics of porous hollow fiber membrane)
The separation characteristics of the porous hollow fiber membrane were evaluated from the maximum pore diameter determined in accordance with JIS K3832 by the bubble point method. Ethanol was used as a measurement medium.
（平均孔径指数、開口率）
平均孔径指数は、ＳＥＭ写真（３０，０００倍）と（株）プラネトロン製Ｉｍａｇｅ－Ｐｒｏ Ｐｌｕｓを用いて画像解析を行い、各方向から観察した外表面写真の平均孔径指数を求めた。平均孔径指数及び開口率は、以下の一連の各工程により算出した。
工程（１）
多孔質中空糸膜の断面表面をＳＥＭで観察し、電子顕微鏡写真で捉えられる全孔の孔径の面積を測定する。
工程（２）
工程（１）において、算出された孔径を面積で降順となるようにデータを並べ、上位の孔から面積を積算し、全面積に対して特定の割合Ｂ（５０％）に相当するところまでの孔を用いて、その面積を孔が真円であるとみなしてその直径（孔径）を平均孔径指数として算出する。 (Average pore diameter index, opening ratio)
The average pore size index was subjected to image analysis using an SEM photograph (30,000 times) and Image-Pro Plus manufactured by Planetron Co., Ltd., and the average pore size index of the outer surface photograph observed from each direction was obtained. The average pore diameter index and the opening ratio were calculated by the following series of steps.
Process (1)
The cross-sectional surface of the porous hollow fiber membrane is observed with an SEM, and the area of the hole diameter of all the holes captured by an electron micrograph is measured.
Step (2)
In step (1), data are arranged so that the calculated hole diameters are in descending order by area, the areas are integrated from the upper holes, and up to a place corresponding to a specific ratio B (50%) with respect to the total area. Using the holes, the area is regarded as a perfect circle, and the diameter (hole diameter) is calculated as an average hole diameter index.
平均孔径指数は、ＳＥＭ写真（３０，０００倍）と（株）プラネトロン製Ｉｍａｇｅ－Ｐｒｏ Ｐｌｕｓを用いて画像解析を行い、各方向から観察した外表面写真の平均孔径指数を求めた。平均孔径指数及び開口率は、以下の一連の各工程により算出した。
工程（１）
多孔質中空糸膜の断面表面をＳＥＭで観察し、電子顕微鏡写真で捉えられる全孔の孔径の面積を測定する。
工程（２）
工程（１）において、算出された孔径を面積で降順となるようにデータを並べ、上位の孔から面積を積算し、全面積に対して特定の割合Ｂ（５０％）に相当するところまでの孔を用いて、その面積を孔が真円であるとみなしてその直径（孔径）を平均孔径指数として算出する。 (Average pore diameter index, opening ratio)
The average pore size index was subjected to image analysis using an SEM photograph (30,000 times) and Image-Pro Plus manufactured by Planetron Co., Ltd., and the average pore size index of the outer surface photograph observed from each direction was obtained. The average pore diameter index and the opening ratio were calculated by the following series of steps.
Process (1)
The cross-sectional surface of the porous hollow fiber membrane is observed with an SEM, and the area of the hole diameter of all the holes captured by an electron micrograph is measured.
Step (2)
In step (1), data are arranged so that the calculated hole diameters are in descending order by area, the areas are integrated from the upper holes, and up to a place corresponding to a specific ratio B (50%) with respect to the total area. Using the holes, the area is regarded as a perfect circle, and the diameter (hole diameter) is calculated as an average hole diameter index.
（実施例１）
中空補強支持体用糸として、ポリエステル繊維（ポリエチレンテレフタレート（ＰＥＴ）、繊度：８４ｄｔｅｘ、フィラメント数：３６、仮撚り糸）を用いた。中空補強支持体を作製する際に使用するボビンとしては、ポリエステル繊維の５ｋｇを巻いたものを５つ用意し、丸編機として、卓上型紐編機（園井繊維機械社製、メリヤス針数：１２本、針サイズ：１６ゲージ、スピンドルの円周直径：８ｍｍ）を用いた。紐供給装置及び引取り装置としては、ネルソンロールを用いた。加熱ダイスとしては、加熱手段を有するステンレス製のダイス（外径Ｄ：５ｍｍ、内径ｄ：２．５ｍｍ、長さＬ：３００ｍｍ）を用いた。
ボビンから引き出されたポリエステル繊維５本を１つに合糸（合計繊度；４２０ｄｔｅｘ）した後、丸編機によって丸編して中空状編紐を編成した。該中空状編紐を２１０℃ の加熱ダイスに通し、熱処理された中空状編紐を中空補強支持体として、巻取り装置を用いて巻き取り速度２００ｍ／時間で巻き取った。
得られた中空補強支持体の外径は約２．５ｍｍであり、内径は約１．７ｍｍであった。中空補強支持体を構成する中空状編組のループの数は、１周あたり１２個、編目の最大開口幅は約０．１ｍｍであった。中空補強支持体の長さは１２０００ｍであった。 Example 1
Polyester fibers (polyethylene terephthalate (PET), fineness: 84 dtex, number of filaments: 36, false twisted yarn) were used as hollow reinforcing support yarns. As bobbins used for producing the hollow reinforcing support, five pieces of polyester fiber wound around 5 kg are prepared. As a circular knitting machine, a table type string knitting machine (manufactured by Sonai Textile Machinery Co., Ltd., number of knitted needles: 12 needles, needle size: 16 gauge, spindle diameter: 8 mm) were used. A Nelson roll was used as the string supply device and the take-up device. As the heating die, a stainless steel die (outer diameter D: 5 mm, inner diameter d: 2.5 mm, length L: 300 mm) having heating means was used.
Five polyester fibers drawn from the bobbin were combined into a single yarn (total fineness: 420 dtex), and then circular knitted by a circular knitting machine to form a hollow knitted string. The hollow knitted string was passed through a heating die at 210 ° C., and the heat-treated hollow knitted string was wound as a hollow reinforcing support using a winding device at a winding speed of 200 m / hour.
The obtained hollow reinforcing support had an outer diameter of about 2.5 mm and an inner diameter of about 1.7 mm. The number of loops of the hollow braid constituting the hollow reinforcing support was 12 per round, and the maximum opening width of the stitch was about 0.1 mm. The length of the hollow reinforcing support was 12000 m.
中空補強支持体用糸として、ポリエステル繊維（ポリエチレンテレフタレート（ＰＥＴ）、繊度：８４ｄｔｅｘ、フィラメント数：３６、仮撚り糸）を用いた。中空補強支持体を作製する際に使用するボビンとしては、ポリエステル繊維の５ｋｇを巻いたものを５つ用意し、丸編機として、卓上型紐編機（園井繊維機械社製、メリヤス針数：１２本、針サイズ：１６ゲージ、スピンドルの円周直径：８ｍｍ）を用いた。紐供給装置及び引取り装置としては、ネルソンロールを用いた。加熱ダイスとしては、加熱手段を有するステンレス製のダイス（外径Ｄ：５ｍｍ、内径ｄ：２．５ｍｍ、長さＬ：３００ｍｍ）を用いた。
ボビンから引き出されたポリエステル繊維５本を１つに合糸（合計繊度；４２０ｄｔｅｘ）した後、丸編機によって丸編して中空状編紐を編成した。該中空状編紐を２１０℃ の加熱ダイスに通し、熱処理された中空状編紐を中空補強支持体として、巻取り装置を用いて巻き取り速度２００ｍ／時間で巻き取った。
得られた中空補強支持体の外径は約２．５ｍｍであり、内径は約１．７ｍｍであった。中空補強支持体を構成する中空状編組のループの数は、１周あたり１２個、編目の最大開口幅は約０．１ｍｍであった。中空補強支持体の長さは１２０００ｍであった。 Example 1
Polyester fibers (polyethylene terephthalate (PET), fineness: 84 dtex, number of filaments: 36, false twisted yarn) were used as hollow reinforcing support yarns. As bobbins used for producing the hollow reinforcing support, five pieces of polyester fiber wound around 5 kg are prepared. As a circular knitting machine, a table type string knitting machine (manufactured by Sonai Textile Machinery Co., Ltd., number of knitted needles: 12 needles, needle size: 16 gauge, spindle diameter: 8 mm) were used. A Nelson roll was used as the string supply device and the take-up device. As the heating die, a stainless steel die (outer diameter D: 5 mm, inner diameter d: 2.5 mm, length L: 300 mm) having heating means was used.
Five polyester fibers drawn from the bobbin were combined into a single yarn (total fineness: 420 dtex), and then circular knitted by a circular knitting machine to form a hollow knitted string. The hollow knitted string was passed through a heating die at 210 ° C., and the heat-treated hollow knitted string was wound as a hollow reinforcing support using a winding device at a winding speed of 200 m / hour.
The obtained hollow reinforcing support had an outer diameter of about 2.5 mm and an inner diameter of about 1.7 mm. The number of loops of the hollow braid constituting the hollow reinforcing support was 12 per round, and the maximum opening width of the stitch was about 0.1 mm. The length of the hollow reinforcing support was 12000 m.
ポリフッ化ビニリデン（アルケマ社製、商品名；カイナー３０１Ｆ）１１．５質量％、ポリフッ化ビニリデン（アルケマ社製、商品名；カイナー９０００ＬＤ）１１．５質量％及びポリビニルピロリドン（日本触媒社製、商品名；Ｋ－８０）１２質量％を、Ｎ，Ｎ－ジメチルアセトアミド６５質量％に撹拌しながら溶解させて第１膜形成性樹脂溶液を調製した。この第１膜形成性樹脂溶液の４０℃での粘度は２１万ｍＰ・秒であった。
ポリフッ化ビニリデン（アルケマ社製、商品名；カイナー３０１Ｆ）１９質量％及びポリビニルピロリドン（日本触媒社製、商品名；Ｋ－８０）１０質量％を、Ｎ，Ｎ－ジメチルアセトアミド７１質量％に撹拌しながら溶解させて第２膜形成性樹脂溶液を調製した。この第２膜形成性樹脂溶液の４０℃での粘度は１３万ｍＰ・秒であった。
次いで、図１２に示す製造装置を用いて多孔質中空糸膜を製造した。なお、本例では、紡糸ノズルとして、中空補強支持体を通過させる支持体用貫通孔と、２種の膜成性樹脂溶液の樹脂溶液用流路（第１樹脂溶液用流路、第２樹脂溶液用流路）とが形成された多重環状ノズルを用いた。この紡糸ノズルにおいては、下面に、支持体吐出口、第１樹脂溶液吐出口及び第２樹脂溶液吐出口が形成されている。 Polyvinylidene fluoride (Arkema, trade name: Kyner 301F) 11.5% by mass, Polyvinylidene fluoride (Arkema, trade name: Kyner 9000LD) 11.5% by mass and polyvinylpyrrolidone (Nippon Shokubai, trade name) K-80) was dissolved in 65% by mass of N, N-dimethylacetamide with stirring to prepare a first film-forming resin solution. The viscosity of this first film-forming resin solution at 40 ° C. was 210,000 mP · sec.
Polyvinylidene fluoride (Arkema, trade name; Kyner 301F) 19% by mass and polyvinylpyrrolidone (Nippon Shokubai, trade name; K-80) 10% by mass were stirred into N, N-dimethylacetamide 71% by mass. This was dissolved while preparing a second film-forming resin solution. The viscosity of this second film-forming resin solution at 40 ° C. was 130,000 mP · sec.
Subsequently, the porous hollow fiber membrane was manufactured using the manufacturing apparatus shown in FIG. In this example, as a spinning nozzle, a through hole for a support that allows a hollow reinforcing support to pass through, and a flow path for resin solutions of two types of film-forming resin solutions (first flow path for resin solution, second resin) A multi-annular nozzle formed with a solution flow path) was used. In this spinning nozzle, a support discharge port, a first resin solution discharge port, and a second resin solution discharge port are formed on the lower surface.
ポリフッ化ビニリデン（アルケマ社製、商品名；カイナー３０１Ｆ）１９質量％及びポリビニルピロリドン（日本触媒社製、商品名；Ｋ－８０）１０質量％を、Ｎ，Ｎ－ジメチルアセトアミド７１質量％に撹拌しながら溶解させて第２膜形成性樹脂溶液を調製した。この第２膜形成性樹脂溶液の４０℃での粘度は１３万ｍＰ・秒であった。
次いで、図１２に示す製造装置を用いて多孔質中空糸膜を製造した。なお、本例では、紡糸ノズルとして、中空補強支持体を通過させる支持体用貫通孔と、２種の膜成性樹脂溶液の樹脂溶液用流路（第１樹脂溶液用流路、第２樹脂溶液用流路）とが形成された多重環状ノズルを用いた。この紡糸ノズルにおいては、下面に、支持体吐出口、第１樹脂溶液吐出口及び第２樹脂溶液吐出口が形成されている。 Polyvinylidene fluoride (Arkema, trade name: Kyner 301F) 11.5% by mass, Polyvinylidene fluoride (Arkema, trade name: Kyner 9000LD) 11.5% by mass and polyvinylpyrrolidone (Nippon Shokubai, trade name) K-80) was dissolved in 65% by mass of N, N-dimethylacetamide with stirring to prepare a first film-forming resin solution. The viscosity of this first film-forming resin solution at 40 ° C. was 210,000 mP · sec.
Polyvinylidene fluoride (Arkema, trade name; Kyner 301F) 19% by mass and polyvinylpyrrolidone (Nippon Shokubai, trade name; K-80) 10% by mass were stirred into N, N-dimethylacetamide 71% by mass. This was dissolved while preparing a second film-forming resin solution. The viscosity of this second film-forming resin solution at 40 ° C. was 130,000 mP · sec.
Subsequently, the porous hollow fiber membrane was manufactured using the manufacturing apparatus shown in FIG. In this example, as a spinning nozzle, a through hole for a support that allows a hollow reinforcing support to pass through, and a flow path for resin solutions of two types of film-forming resin solutions (first flow path for resin solution, second resin) A multi-annular nozzle formed with a solution flow path) was used. In this spinning nozzle, a support discharge port, a first resin solution discharge port, and a second resin solution discharge port are formed on the lower surface.
（多孔質中空糸膜の製造）
凝固槽の上方に、凝固液面と１０ｍｍの隙間が形成されるように処理用容器を配置した。処理用容器及び保護筒は、保護筒の下端開口部と処理用容器の第１の開口部との間に５ｍｍの隙間が形成されるように配置した。掃気ノズルは、その上面と紡糸ノズルの下面とが接着するように配置した。
掃気ノズルには、温度３２℃で相対湿度１％未満の乾燥空気を６Ｌ／分で供給した。処理用容器には、処理用気体として１００℃の飽和水蒸気を供給した。水蒸気の供給量は、掃気ノズルに乾燥空気を６Ｌ／分で供給している状態で、第１の開口部から内部に５ｍｍ挿入した直径０．５ｍｍの熱電対の温度を監視しながら流量調整バルブを少しずつ開き、熱電対温度が１００℃で１０分以上安定する下限流量に設定した。その調整された状態で、流量調整バルブから吐出する水蒸気を冷却液化し、単位時間に得られたドレン水の質量を測定し、１００℃の水蒸気体積に換算したところ、約５ＮＬ／分相当であった。
凝固槽には、溶媒成分としてＮ，Ｎ－ジメチルアセトアミドが１０質量％、非溶媒成分としての純水が９０質量％の組成の凝固液を満たした。凝固槽は７５℃で保温した。
紡糸ノズルに、３２℃の膜形成性樹脂溶液１を２３．２ｃｍ３／分、３２℃の膜形成性樹脂溶液２を２５．０ｃｍ３／分の供給量で供給した。次いで、樹脂溶液吐出口から膜形成性樹脂溶液１と膜形成性樹脂溶液２とを同心円状に吐出させ、支持体吐出口から２０ｍ／分で引き出される中空状編紐支持体外周面に膜形成性樹脂溶液１，２を塗布した。これにより、中空状編紐支持体に膜形成性樹脂溶液が塗布された糸状体Ａ‘を得た。その糸状体Ａ’を、掃気ノズル、処理用容器、凝固液の順に通過させ、多孔質中空糸膜を得た。
得られた多孔質中空糸膜を、９８℃の熱水に１分間通して脱溶剤させた。次いで、３０，０００ｍｇ／Ｌの次亜塩素酸ナトリウム水溶液に浸漬させた後、９８℃のスチーム槽中で２分間加熱処理した。次いで、９８℃の熱水中で１５分間洗浄し、１１０℃で１０分間乾燥した後、巻き取って、多孔質中空糸膜を得た。
得られた多孔質中空糸膜について、液体窒素を用いて凍結滑断した断面をＳＥＭで拡大観察し、写真を撮影した。得られた写真について、Ｉｍａｇｅ－Ｐｒｏ Ｐｌｕｓ（プラネトロン株式会社製）を用いて画像解析を行い、各層の平均孔径を算出した。結果を表１に示す。 (Manufacture of porous hollow fiber membrane)
The processing container was arranged above the coagulation tank so that a gap of 10 mm from the coagulation liquid surface was formed. The processing container and the protective cylinder were arranged such that a gap of 5 mm was formed between the lower end opening of the protective cylinder and the first opening of the processing container. The scavenging nozzle was arranged so that its upper surface and the lower surface of the spinning nozzle were bonded.
The scavenging nozzle was supplied with dry air at a temperature of 32 ° C. and a relative humidity of less than 1% at 6 L / min. 100 degreeC saturated water vapor | steam was supplied to the processing container as processing gas. The supply amount of water vapor is a flow rate adjusting valve while monitoring the temperature of a thermocouple having a diameter of 0.5 mm inserted 5 mm from the first opening while supplying dry air to the scavenging nozzle at 6 L / min. Was opened little by little and the lower limit flow rate at which the thermocouple temperature was stable at 100 ° C. for 10 minutes or more was set. In the adjusted state, the water vapor discharged from the flow rate adjusting valve is cooled and liquefied, and the mass of drain water obtained per unit time is measured and converted to a water vapor volume of 100 ° C., which is equivalent to about 5 NL / min. It was.
The coagulation tank was filled with a coagulation liquid having a composition of 10% by mass of N, N-dimethylacetamide as a solvent component and 90% by mass of pure water as a non-solvent component. The coagulation tank was kept at 75 ° C.
The film-forming resin solution 1 at 32 ° C. was supplied to the spinning nozzle at a supply rate of 23.2 cm 3 / min, and the film-forming resin solution 2 at 32 ° C. was supplied at 25.0 cm 3 / min. Next, the film-forming resin solution 1 and the film-forming resin solution 2 are discharged concentrically from the resin solution discharge port, and a film is formed on the outer peripheral surface of the hollow knitted string support drawn from the support discharge port at 20 m / min. Resin solutions 1 and 2 were applied. As a result, a filament A ′ in which the film-forming resin solution was applied to the hollow knitted string support was obtained. The filament A ′ was passed through a scavenging nozzle, a processing container, and a coagulating liquid in this order to obtain a porous hollow fiber membrane.
The obtained porous hollow fiber membrane was passed through hot water at 98 ° C. for 1 minute to remove the solvent. Next, after immersing in a 30,000 mg / L sodium hypochlorite aqueous solution, it was heat-treated in a steam bath at 98 ° C. for 2 minutes. Subsequently, it was washed in hot water at 98 ° C. for 15 minutes, dried at 110 ° C. for 10 minutes, and then wound up to obtain a porous hollow fiber membrane.
About the obtained porous hollow fiber membrane, the cross-section frozen and slipped using liquid nitrogen was enlarged and observed with SEM, and a photograph was taken. The obtained photograph was subjected to image analysis using Image-Pro Plus (manufactured by Planetron Co., Ltd.), and the average pore size of each layer was calculated. The results are shown in Table 1.
凝固槽の上方に、凝固液面と１０ｍｍの隙間が形成されるように処理用容器を配置した。処理用容器及び保護筒は、保護筒の下端開口部と処理用容器の第１の開口部との間に５ｍｍの隙間が形成されるように配置した。掃気ノズルは、その上面と紡糸ノズルの下面とが接着するように配置した。
掃気ノズルには、温度３２℃で相対湿度１％未満の乾燥空気を６Ｌ／分で供給した。処理用容器には、処理用気体として１００℃の飽和水蒸気を供給した。水蒸気の供給量は、掃気ノズルに乾燥空気を６Ｌ／分で供給している状態で、第１の開口部から内部に５ｍｍ挿入した直径０．５ｍｍの熱電対の温度を監視しながら流量調整バルブを少しずつ開き、熱電対温度が１００℃で１０分以上安定する下限流量に設定した。その調整された状態で、流量調整バルブから吐出する水蒸気を冷却液化し、単位時間に得られたドレン水の質量を測定し、１００℃の水蒸気体積に換算したところ、約５ＮＬ／分相当であった。
凝固槽には、溶媒成分としてＮ，Ｎ－ジメチルアセトアミドが１０質量％、非溶媒成分としての純水が９０質量％の組成の凝固液を満たした。凝固槽は７５℃で保温した。
紡糸ノズルに、３２℃の膜形成性樹脂溶液１を２３．２ｃｍ３／分、３２℃の膜形成性樹脂溶液２を２５．０ｃｍ３／分の供給量で供給した。次いで、樹脂溶液吐出口から膜形成性樹脂溶液１と膜形成性樹脂溶液２とを同心円状に吐出させ、支持体吐出口から２０ｍ／分で引き出される中空状編紐支持体外周面に膜形成性樹脂溶液１，２を塗布した。これにより、中空状編紐支持体に膜形成性樹脂溶液が塗布された糸状体Ａ‘を得た。その糸状体Ａ’を、掃気ノズル、処理用容器、凝固液の順に通過させ、多孔質中空糸膜を得た。
得られた多孔質中空糸膜を、９８℃の熱水に１分間通して脱溶剤させた。次いで、３０，０００ｍｇ／Ｌの次亜塩素酸ナトリウム水溶液に浸漬させた後、９８℃のスチーム槽中で２分間加熱処理した。次いで、９８℃の熱水中で１５分間洗浄し、１１０℃で１０分間乾燥した後、巻き取って、多孔質中空糸膜を得た。
得られた多孔質中空糸膜について、液体窒素を用いて凍結滑断した断面をＳＥＭで拡大観察し、写真を撮影した。得られた写真について、Ｉｍａｇｅ－Ｐｒｏ Ｐｌｕｓ（プラネトロン株式会社製）を用いて画像解析を行い、各層の平均孔径を算出した。結果を表１に示す。 (Manufacture of porous hollow fiber membrane)
The processing container was arranged above the coagulation tank so that a gap of 10 mm from the coagulation liquid surface was formed. The processing container and the protective cylinder were arranged such that a gap of 5 mm was formed between the lower end opening of the protective cylinder and the first opening of the processing container. The scavenging nozzle was arranged so that its upper surface and the lower surface of the spinning nozzle were bonded.
The scavenging nozzle was supplied with dry air at a temperature of 32 ° C. and a relative humidity of less than 1% at 6 L / min. 100 degreeC saturated water vapor | steam was supplied to the processing container as processing gas. The supply amount of water vapor is a flow rate adjusting valve while monitoring the temperature of a thermocouple having a diameter of 0.5 mm inserted 5 mm from the first opening while supplying dry air to the scavenging nozzle at 6 L / min. Was opened little by little and the lower limit flow rate at which the thermocouple temperature was stable at 100 ° C. for 10 minutes or more was set. In the adjusted state, the water vapor discharged from the flow rate adjusting valve is cooled and liquefied, and the mass of drain water obtained per unit time is measured and converted to a water vapor volume of 100 ° C., which is equivalent to about 5 NL / min. It was.
The coagulation tank was filled with a coagulation liquid having a composition of 10% by mass of N, N-dimethylacetamide as a solvent component and 90% by mass of pure water as a non-solvent component. The coagulation tank was kept at 75 ° C.
The film-forming resin solution 1 at 32 ° C. was supplied to the spinning nozzle at a supply rate of 23.2 cm 3 / min, and the film-forming resin solution 2 at 32 ° C. was supplied at 25.0 cm 3 / min. Next, the film-forming resin solution 1 and the film-forming resin solution 2 are discharged concentrically from the resin solution discharge port, and a film is formed on the outer peripheral surface of the hollow knitted string support drawn from the support discharge port at 20 m / min. Resin solutions 1 and 2 were applied. As a result, a filament A ′ in which the film-forming resin solution was applied to the hollow knitted string support was obtained. The filament A ′ was passed through a scavenging nozzle, a processing container, and a coagulating liquid in this order to obtain a porous hollow fiber membrane.
The obtained porous hollow fiber membrane was passed through hot water at 98 ° C. for 1 minute to remove the solvent. Next, after immersing in a 30,000 mg / L sodium hypochlorite aqueous solution, it was heat-treated in a steam bath at 98 ° C. for 2 minutes. Subsequently, it was washed in hot water at 98 ° C. for 15 minutes, dried at 110 ° C. for 10 minutes, and then wound up to obtain a porous hollow fiber membrane.
About the obtained porous hollow fiber membrane, the cross-section frozen and slipped using liquid nitrogen was enlarged and observed with SEM, and a photograph was taken. The obtained photograph was subjected to image analysis using Image-Pro Plus (manufactured by Planetron Co., Ltd.), and the average pore size of each layer was calculated. The results are shown in Table 1.
（実施例２）
第１及び第２膜形成性樹脂溶液として、ポリフッ化ビニリデン（アルケマ社製、商品名カイナー７６１Ａ）１９質量％及びポリビニルピロリドン（日本触媒社製、商品名Ｋ－８０）１２質量％を、Ｎ，Ｎ－ジメチルアセトアミド６９質量％に撹拌しながら溶解させた膜形成性樹脂溶液を用い、凝固液として、Ｎ，Ｎ－ジメチルアセトアミドが２０質量％、非溶媒成分としての純水が８０質量％の組成の凝固液を用いた以外は、実施例１と同様にして多孔質中空糸膜を得た。
この膜形成性樹脂溶液の４０℃での粘度は２５万ｍＰ・秒であった。
また、得られた多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Example 2)
As the first and second film-forming resin solutions, 19% by mass of polyvinylidene fluoride (trade name Kyner 761A, manufactured by Arkema Co., Ltd.) and 12% by mass of polyvinyl pyrrolidone (trade name, K-80, manufactured by Nippon Shokubai Co., Ltd.) Using a film-forming resin solution dissolved in 69% by mass of N-dimethylacetamide with stirring, a composition containing 20% by mass of N, N-dimethylacetamide as a coagulating liquid and 80% by mass of pure water as a non-solvent component A porous hollow fiber membrane was obtained in the same manner as in Example 1 except that the coagulating liquid was used.
The viscosity of this film-forming resin solution at 40 ° C. was 250,000 mP · sec.
For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
第１及び第２膜形成性樹脂溶液として、ポリフッ化ビニリデン（アルケマ社製、商品名カイナー７６１Ａ）１９質量％及びポリビニルピロリドン（日本触媒社製、商品名Ｋ－８０）１２質量％を、Ｎ，Ｎ－ジメチルアセトアミド６９質量％に撹拌しながら溶解させた膜形成性樹脂溶液を用い、凝固液として、Ｎ，Ｎ－ジメチルアセトアミドが２０質量％、非溶媒成分としての純水が８０質量％の組成の凝固液を用いた以外は、実施例１と同様にして多孔質中空糸膜を得た。
この膜形成性樹脂溶液の４０℃での粘度は２５万ｍＰ・秒であった。
また、得られた多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Example 2)
As the first and second film-forming resin solutions, 19% by mass of polyvinylidene fluoride (trade name Kyner 761A, manufactured by Arkema Co., Ltd.) and 12% by mass of polyvinyl pyrrolidone (trade name, K-80, manufactured by Nippon Shokubai Co., Ltd.) Using a film-forming resin solution dissolved in 69% by mass of N-dimethylacetamide with stirring, a composition containing 20% by mass of N, N-dimethylacetamide as a coagulating liquid and 80% by mass of pure water as a non-solvent component A porous hollow fiber membrane was obtained in the same manner as in Example 1 except that the coagulating liquid was used.
The viscosity of this film-forming resin solution at 40 ° C. was 250,000 mP · sec.
For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
（実施例３）
第１及び第２膜形成性樹脂溶液として、ポリフッ化ビニリデン（アルケマ社製、商品名カイナー７６１Ａ）１５質量％及びポリビニルピロリドン（日本触媒社製、商品名Ｋ－８０）１１質量％を、Ｎ，Ｎ－ジメチルアセトアミド７４質量％に撹拌しながら溶解させた膜形成性樹脂溶液を用いた以外は、実施例６と同様にして多孔質中空糸膜を得た。
この膜形成性樹脂溶液の４０℃での粘度は８万ｍＰ・秒であった。
また、得られた多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。
Example 3
As the first and second film-forming resin solutions, 15% by mass of polyvinylidene fluoride (trade name Kyner 761A, manufactured by Arkema Co., Ltd.) and 11% by mass of polyvinyl pyrrolidone (trade name, K-80, manufactured by Nippon Shokubai Co., Ltd.) A porous hollow fiber membrane was obtained in the same manner as in Example 6 except that the membrane-forming resin solution dissolved in 74% by mass of N-dimethylacetamide with stirring was used.
The viscosity of this film-forming resin solution at 40 ° C. was 80,000 mP · sec.
For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
第１及び第２膜形成性樹脂溶液として、ポリフッ化ビニリデン（アルケマ社製、商品名カイナー７６１Ａ）１５質量％及びポリビニルピロリドン（日本触媒社製、商品名Ｋ－８０）１１質量％を、Ｎ，Ｎ－ジメチルアセトアミド７４質量％に撹拌しながら溶解させた膜形成性樹脂溶液を用いた以外は、実施例６と同様にして多孔質中空糸膜を得た。
この膜形成性樹脂溶液の４０℃での粘度は８万ｍＰ・秒であった。
また、得られた多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。
Example 3
As the first and second film-forming resin solutions, 15% by mass of polyvinylidene fluoride (trade name Kyner 761A, manufactured by Arkema Co., Ltd.) and 11% by mass of polyvinyl pyrrolidone (trade name, K-80, manufactured by Nippon Shokubai Co., Ltd.) A porous hollow fiber membrane was obtained in the same manner as in Example 6 except that the membrane-forming resin solution dissolved in 74% by mass of N-dimethylacetamide with stirring was used.
The viscosity of this film-forming resin solution at 40 ° C. was 80,000 mP · sec.
For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
（比較例１）
実施例１と同じ、第１，第２膜形成性樹脂溶液を用いた。
凝固槽には、溶媒成分としてＮ，Ｎ－ジメチルアセトアミドが８質量％、非溶媒成分としての純水が９２質量％の組成の凝固液を満たした。凝固槽は７０℃で保温した。
紡糸ノズルに、３２℃の膜形成性樹脂溶液１を１７．４ｃｍ３／分、３２℃の膜形成性樹脂溶液２を１８．７ｃｍ３／分の供給量で供給した。次いで、樹脂溶液吐出口から膜形成性樹脂溶液１と膜形成性樹脂溶液２とを同心円状に吐出させ、支持体吐出口から１５ｍ／分で引き出される中空状編紐支持体外周面に膜形成性樹脂溶液１，２を塗布した。これにより、中空状編紐支持体に膜形成性樹脂溶液が塗布された糸状体Ａ‘を得た。
得られた糸状体Ａ‘を、内部を凝固液（温度７０℃）の蒸気で満たした高温高湿雰囲気形成用カバー内に導入して高温高湿処理した。その際、糸状体Ａ‘が、高温高湿雰囲気形成用カバー内の高温高湿雰囲気を走行する距離は６７ｍｍとした。
次いで、高温高湿処理した糸状体Ａ‘を凝固槽内の凝固液（温度７０℃）に通した。これにより、糸状体Ａ‘の外周面に凝固液を付着させて、膜形成性樹脂溶液の塗膜を凝固させ、多孔質中空糸膜を得た。
得られた多孔質中空糸膜を、実施例１と同様に洗浄・乾燥した。
また、得られた多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Comparative Example 1)
The same first and second film-forming resin solutions as in Example 1 were used.
The coagulation tank was filled with a coagulation liquid having a composition of 8% by mass of N, N-dimethylacetamide as a solvent component and 92% by mass of pure water as a non-solvent component. The coagulation tank was kept at 70 ° C.
The film forming resin solution 1 at 32 ° C. was supplied to the spinning nozzle at a supply rate of 17.4 cm 3 / min, and the film forming resin solution 2 at 32 ° C. was supplied at 18.7 cm 3 / min. Next, the film-forming resin solution 1 and the film-forming resin solution 2 are discharged concentrically from the resin solution discharge port, and a film is formed on the outer peripheral surface of the hollow knitted string support drawn from the support discharge port at 15 m / min. Resin solutions 1 and 2 were applied. As a result, a filament A ′ in which the film-forming resin solution was applied to the hollow knitted string support was obtained.
The obtained filament A ′ was introduced into a cover for forming a high-temperature and high-humidity atmosphere whose interior was filled with steam of a coagulating liquid (temperature of 70 ° C.) and subjected to a high-temperature and high-humidity treatment. At that time, the distance that the filament A ′ travels in the high temperature and high humidity atmosphere in the high temperature and high humidity atmosphere forming cover was set to 67 mm.
Subsequently, the filament A ′ subjected to the high-temperature and high-humidity treatment was passed through a coagulation liquid (temperature: 70 ° C.) in the coagulation tank. As a result, a coagulating liquid was adhered to the outer peripheral surface of the filament A ′, and the coating film of the film-forming resin solution was coagulated to obtain a porous hollow fiber membrane.
The obtained porous hollow fiber membrane was washed and dried in the same manner as in Example 1.
For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
実施例１と同じ、第１，第２膜形成性樹脂溶液を用いた。
凝固槽には、溶媒成分としてＮ，Ｎ－ジメチルアセトアミドが８質量％、非溶媒成分としての純水が９２質量％の組成の凝固液を満たした。凝固槽は７０℃で保温した。
紡糸ノズルに、３２℃の膜形成性樹脂溶液１を１７．４ｃｍ３／分、３２℃の膜形成性樹脂溶液２を１８．７ｃｍ３／分の供給量で供給した。次いで、樹脂溶液吐出口から膜形成性樹脂溶液１と膜形成性樹脂溶液２とを同心円状に吐出させ、支持体吐出口から１５ｍ／分で引き出される中空状編紐支持体外周面に膜形成性樹脂溶液１，２を塗布した。これにより、中空状編紐支持体に膜形成性樹脂溶液が塗布された糸状体Ａ‘を得た。
得られた糸状体Ａ‘を、内部を凝固液（温度７０℃）の蒸気で満たした高温高湿雰囲気形成用カバー内に導入して高温高湿処理した。その際、糸状体Ａ‘が、高温高湿雰囲気形成用カバー内の高温高湿雰囲気を走行する距離は６７ｍｍとした。
次いで、高温高湿処理した糸状体Ａ‘を凝固槽内の凝固液（温度７０℃）に通した。これにより、糸状体Ａ‘の外周面に凝固液を付着させて、膜形成性樹脂溶液の塗膜を凝固させ、多孔質中空糸膜を得た。
得られた多孔質中空糸膜を、実施例１と同様に洗浄・乾燥した。
また、得られた多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Comparative Example 1)
The same first and second film-forming resin solutions as in Example 1 were used.
The coagulation tank was filled with a coagulation liquid having a composition of 8% by mass of N, N-dimethylacetamide as a solvent component and 92% by mass of pure water as a non-solvent component. The coagulation tank was kept at 70 ° C.
The film forming resin solution 1 at 32 ° C. was supplied to the spinning nozzle at a supply rate of 17.4 cm 3 / min, and the film forming resin solution 2 at 32 ° C. was supplied at 18.7 cm 3 / min. Next, the film-forming resin solution 1 and the film-forming resin solution 2 are discharged concentrically from the resin solution discharge port, and a film is formed on the outer peripheral surface of the hollow knitted string support drawn from the support discharge port at 15 m / min. Resin solutions 1 and 2 were applied. As a result, a filament A ′ in which the film-forming resin solution was applied to the hollow knitted string support was obtained.
The obtained filament A ′ was introduced into a cover for forming a high-temperature and high-humidity atmosphere whose interior was filled with steam of a coagulating liquid (temperature of 70 ° C.) and subjected to a high-temperature and high-humidity treatment. At that time, the distance that the filament A ′ travels in the high temperature and high humidity atmosphere in the high temperature and high humidity atmosphere forming cover was set to 67 mm.
Subsequently, the filament A ′ subjected to the high-temperature and high-humidity treatment was passed through a coagulation liquid (temperature: 70 ° C.) in the coagulation tank. As a result, a coagulating liquid was adhered to the outer peripheral surface of the filament A ′, and the coating film of the film-forming resin solution was coagulated to obtain a porous hollow fiber membrane.
The obtained porous hollow fiber membrane was washed and dried in the same manner as in Example 1.
For the obtained porous hollow fiber membrane, the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
（比較例２）
ＧＥ社製多孔質中空糸膜（ＺｅｅＷｅｅｄ５００）について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Comparative Example 2)
For the porous hollow fiber membrane (ZeeWeed 500) manufactured by GE, the average pore size of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
ＧＥ社製多孔質中空糸膜（ＺｅｅＷｅｅｄ５００）について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Comparative Example 2)
For the porous hollow fiber membrane (ZeeWeed 500) manufactured by GE, the average pore size of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
（比較例３）
株式会社クボタ製（５１０型）の多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Comparative Example 3)
For the porous hollow fiber membrane made by Kubota Corporation (type 510), the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
株式会社クボタ製（５１０型）の多孔質中空糸膜について、実施例１と同様に、各層の平均孔径を算出した。結果を表１に示す。 (Comparative Example 3)
For the porous hollow fiber membrane made by Kubota Corporation (type 510), the average pore diameter of each layer was calculated in the same manner as in Example 1. The results are shown in Table 1.
＜ろ過評価＞
実施例１～３及び比較例１で得た多孔質中空糸膜を用いてモジュールをそれぞれ作り、ＭＬＳＳ（浮遊物質濃度）＝９０００ｍｇ／Ｌの活性汚泥水を用いて、水温１０℃、ろ過流速１．０ｍ／日でろ過を行った。
その結果、比較例１の多孔質中空糸膜を用いた作製したモジュールでは、運転２日後からろ過差圧が顕著に上昇したのに対し、実施例１～３の多孔質中空糸膜を用いた作製したモジュールでは、ろ過差圧に大きな変化は見られず、安定して運転することができた。 <Evaluation of filtration>
Modules were made using the porous hollow fiber membranes obtained in Examples 1 to 3 and Comparative Example 1, respectively, and MLSS (suspended substance concentration) = 9000 mg / L using activated sludge water,water temperature 10 ° C., filtration flow rate 1 Filtration was performed at 0.0 m / day.
As a result, in the module produced using the porous hollow fiber membrane of Comparative Example 1, the filtration differential pressure increased significantly after 2 days of operation, whereas the porous hollow fiber membranes of Examples 1 to 3 were used. The produced module did not show a significant change in the filtration differential pressure, and was able to operate stably.
実施例１～３及び比較例１で得た多孔質中空糸膜を用いてモジュールをそれぞれ作り、ＭＬＳＳ（浮遊物質濃度）＝９０００ｍｇ／Ｌの活性汚泥水を用いて、水温１０℃、ろ過流速１．０ｍ／日でろ過を行った。
その結果、比較例１の多孔質中空糸膜を用いた作製したモジュールでは、運転２日後からろ過差圧が顕著に上昇したのに対し、実施例１～３の多孔質中空糸膜を用いた作製したモジュールでは、ろ過差圧に大きな変化は見られず、安定して運転することができた。 <Evaluation of filtration>
Modules were made using the porous hollow fiber membranes obtained in Examples 1 to 3 and Comparative Example 1, respectively, and MLSS (suspended substance concentration) = 9000 mg / L using activated sludge water,
As a result, in the module produced using the porous hollow fiber membrane of Comparative Example 1, the filtration differential pressure increased significantly after 2 days of operation, whereas the porous hollow fiber membranes of Examples 1 to 3 were used. The produced module did not show a significant change in the filtration differential pressure, and was able to operate stably.
＜参考実施例１＞
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて多孔質中空糸膜１を製造した。
ポリフッ化ビニリデンＡ（アルケマ社製、商品名：カイナー７６１Ａ）、ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（１）と（５）を調製した。
製膜速度を２０ｍ／ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（１）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 1>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 1 was produced using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at a mass ratio shown in Table 2 to prepare membrane-forming stock solutions (1) and (5).
The film-forming rate is 20 m / min, the length of the 100% water vapor emphasis region is 5 mm, and the film-forming stock solution (1) is combined with the outer layer and the film-forming stock solution (5) is combined with the inner layer at a coagulation bath temperature of 75 ° C. Application and film formation were performed.
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて多孔質中空糸膜１を製造した。
ポリフッ化ビニリデンＡ（アルケマ社製、商品名：カイナー７６１Ａ）、ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（１）と（５）を調製した。
製膜速度を２０ｍ／ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（１）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 1>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 1 was produced using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at a mass ratio shown in Table 2 to prepare membrane-forming stock solutions (1) and (5).
The film-forming rate is 20 m / min, the length of the 100% water vapor emphasis region is 5 mm, and the film-forming stock solution (1) is combined with the outer layer and the film-forming stock solution (5) is combined with the inner layer at a coagulation bath temperature of 75 ° C. Application and film formation were performed.
得られた多孔質中空糸膜１の外径は、約２．８０ｍｍであり、内径は約１．２ｍｍであり、多孔質膜層１１の膜厚は平均約１５０μｍであり、バブルポイント（Ｐｉ）２１０ｋＰａ、透水性能は４９ｍ３／ｍ２／ｈ／ＭＰａであった。表面開孔率Ａ１は４０％、孔径指数Ｐ１は０．２１μｍであった。内部最緻密層での開孔率Ａ２は２７％、孔径指数Ｐ２は０．４６μｍとなった。
The outer diameter of the obtained porous hollow fiber membrane 1 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 μm on average, and the bubble point (Pi) The water permeability was 210 m 3 / m 2 / h / MPa. The surface opening ratio A1 was 40%, and the pore diameter index P1 was 0.21 μm. The aperture ratio A2 in the inner dense layer was 27%, and the pore diameter index P2 was 0.46 μm.
ＭＢＲ濾過運転条件は表４に示す条件にて濾過試験を実施した。
MBR filtration operation conditions were subjected to a filtration test under the conditions shown in Table 4.
＜参考実施例２＞
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて、参考実施例１と同様に多孔質中空糸膜２を製造した。
ポリフッ化ビニリデンＡ（アルケマ社製、商品名：カイナー７６１Ａ）、ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（２）と（５）を調製した。
製膜速度を２０ｍ／Ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（２）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 2>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 2 was produced in the same manner as in Reference Example 1 using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at the mass ratio shown in Table 2 to prepare membrane-forming stock solutions (2) and (5).
The film-forming speed is 20 m / Min, the length of the 100% water vapor emphasis region is 5 mm, the temperature of the coagulation bath is 75 ° C., the film-forming stock solution (2) is the outer layer, and the film-forming stock solution (5) is the inner layer. Application and film formation were performed.
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて、参考実施例１と同様に多孔質中空糸膜２を製造した。
ポリフッ化ビニリデンＡ（アルケマ社製、商品名：カイナー７６１Ａ）、ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（２）と（５）を調製した。
製膜速度を２０ｍ／Ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（２）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 2>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 2 was produced in the same manner as in Reference Example 1 using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at the mass ratio shown in Table 2 to prepare membrane-forming stock solutions (2) and (5).
The film-forming speed is 20 m / Min, the length of the 100% water vapor emphasis region is 5 mm, the temperature of the coagulation bath is 75 ° C., the film-forming stock solution (2) is the outer layer, and the film-forming stock solution (5) is the inner layer. Application and film formation were performed.
得られた多孔質中空糸膜２の外径は、約２．８０ｍｍであり、内径は約１．２ｍｍであり、多孔質膜層１１の膜厚は平均約１５０μｍであり、バブルポイント（Ｐｉ）は１９７ｋＰａ、透水性能は４９ｍ３／ｍ２／ｈ／ＭＰａであった。表面開孔率Ａ１は４１％、孔径指数Ｐ１は０．２３μｍであった。内部最緻密層での開孔率Ａ２は２３％、孔径指数Ｐ２は０．４５μｍとなった。
The outer diameter of the obtained porous hollow fiber membrane 2 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 μm on average, and the bubble point (Pi) Was 197 kPa, and the water permeability was 49 m 3 / m 2 / h / MPa. The surface opening ratio A1 was 41%, and the pore diameter index P1 was 0.23 μm. The aperture ratio A2 in the inner dense layer was 23%, and the pore diameter index P2 was 0.45 μm.
＜参考実施例３＞
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて、参考実施例１と同様に多孔質中空糸膜３を製造した。
ポリフッ化ビニリデンＡ（アルケマ社製、商品名：カイナー７６１Ａ）、ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（３）と（５）を調製した。製膜速度を２０ｍ／Ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（３）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 3>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 3 was produced in the same manner as in Reference Example 1 using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at the mass ratio shown in Table 2 to prepare membrane-forming stock solutions (3) and (5). The film-forming speed is 20 m / Min, the length of the 100% water vapor emphasis region is 5 mm, and the temperature of the coagulation bath is 75 ° C. Application and film formation were performed.
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて、参考実施例１と同様に多孔質中空糸膜３を製造した。
ポリフッ化ビニリデンＡ（アルケマ社製、商品名：カイナー７６１Ａ）、ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（３）と（５）を調製した。製膜速度を２０ｍ／Ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（３）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 3>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 3 was produced in the same manner as in Reference Example 1 using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride A (Arkema, trade name: Kyner 761A), Polyvinylidene fluoride B (Arkema, trade name: Kyner 301F), Polyvinylidene fluoride C (Arkema, trade name: Kyner 9000LD), polyvinylpyrrolidone (Nippon Shokubai Co., Ltd., trade name: K-80) and N, N-dimethylacetamide were mixed at the mass ratio shown in Table 2 to prepare membrane-forming stock solutions (3) and (5). The film-forming speed is 20 m / Min, the length of the 100% water vapor emphasis region is 5 mm, and the temperature of the coagulation bath is 75 ° C. Application and film formation were performed.
得られた多孔質中空糸膜３の外径は、約２．８０ｍｍであり、内径は約１．２ｍｍであり、多孔質膜層１１の膜厚は平均約１５０μｍであり、バブルポイント（Ｐｉ）１６４ｋＰａ、透水性能は９８ｍ３／ｍ２／ｈ／ＭＰａであった。表面開孔率Ａ１は４５％、孔径指数Ｐ１は０．３１μｍであった。内部最緻密層での開孔率Ａ２は２５％、孔径指数Ｐ２は０．６７μｍとなった。
The outer diameter of the obtained porous hollow fiber membrane 3 is about 2.80 mm, the inner diameter is about 1.2 mm, the average thickness of the porous membrane layer 11 is about 150 μm, and the bubble point (Pi) The water permeability was 164 kPa and 98 m 3 / m 2 / h / MPa. The surface opening ratio A1 was 45%, and the pore diameter index P1 was 0.31 μm. The aperture ratio A2 in the inner dense layer was 25%, and the pore diameter index P2 was 0.67 μm.
＜参考実施例４＞
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて、参考実施例１と同様に多孔質中空糸膜４を製造した。
ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（４）と（５）を調製した。
製膜速度を２０ｍ／ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（４）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 4>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 4 was produced in the same manner as in Reference Example 1 using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride B (manufactured by Arkema, product name: Kyner 301F), polyvinylidene fluoride C (manufactured by Arkema, product name: Kyner 9000LD), polyvinylpyrrolidone (manufactured by Nippon Shokubai Co., Ltd., product name: K-80), and N , N-dimethylacetamide was mixed so as to have a mass ratio shown in Table 2 to prepare membrane-forming stock solutions (4) and (5).
The film-forming speed is 20 m / min, the length of the 100% water vapor emphasis region is 5 mm, and the film-forming stock solution (4) is the outer layer and the film-forming stock solution (5) is the inner layer at a coagulation bath temperature of 75 ° C. Application and film formation were performed.
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて、参考実施例１と同様に多孔質中空糸膜４を製造した。
ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（４）と（５）を調製した。
製膜速度を２０ｍ／ｍｉｎ、１００％水蒸気重点領域の長さは５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（４）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Example 4>
(Manufacture of porous hollow fiber membrane)
A porous hollow fiber membrane 4 was produced in the same manner as in Reference Example 1 using a porous hollow fiber membrane production apparatus.
Polyvinylidene fluoride B (manufactured by Arkema, product name: Kyner 301F), polyvinylidene fluoride C (manufactured by Arkema, product name: Kyner 9000LD), polyvinylpyrrolidone (manufactured by Nippon Shokubai Co., Ltd., product name: K-80), and N , N-dimethylacetamide was mixed so as to have a mass ratio shown in Table 2 to prepare membrane-forming stock solutions (4) and (5).
The film-forming speed is 20 m / min, the length of the 100% water vapor emphasis region is 5 mm, and the film-forming stock solution (4) is the outer layer and the film-forming stock solution (5) is the inner layer at a coagulation bath temperature of 75 ° C. Application and film formation were performed.
得られた多孔質中空糸膜４の外径は、約２．８０ｍｍであり、内径は約１．２ｍｍであり、多孔質膜層１１の膜厚は平均約１５０μｍであり、バブルポイント（Ｐｉ）９１ｋＰａ、透水性能は１６８ｍ３／ｍ２／ｈ／ＭＰａであった。表面開孔率Ａ１は５０％、孔径指数Ｐ１は０．３６μｍであった。内部最緻密層での開孔率Ａ２は２６％、孔径指数Ｐ２は１．１μｍとなった。
The outer diameter of the obtained porous hollow fiber membrane 4 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 μm on average, and the bubble point (Pi) The water permeation performance was 91 kPa and 168 m 3 / m 2 / h / MPa. The surface opening ratio A1 was 50%, and the pore diameter index P1 was 0.36 μm. The aperture ratio A2 in the internal dense layer was 26%, and the pore diameter index P2 was 1.1 μm.
＜参考比較例１＞
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて多孔質中空糸膜５を製造した。
ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（４）と（５）を調製した。製膜速度を１２．５ｍ／ｍｉｎ、高湿高温度領域長を６３．５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（４）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Comparative Example 1>
(Manufacture of porous hollow fiber membrane)
The poroushollow fiber membrane 5 was manufactured using the porous hollow fiber membrane manufacturing apparatus.
Polyvinylidene fluoride B (manufactured by Arkema, product name: Kyner 301F), polyvinylidene fluoride C (manufactured by Arkema, product name: Kyner 9000LD), polyvinylpyrrolidone (manufactured by Nippon Shokubai Co., Ltd., product name: K-80), and N , N-dimethylacetamide was mixed so as to have a mass ratio shown in Table 2 to prepare membrane-forming stock solutions (4) and (5). The film forming speed is 12.5 m / min, the high humidity and high temperature region length is 63.5 mm, and the coagulation bath temperature is 75 ° C. The film forming stock solution (4) is combined with the outer layer and the film forming stock solution (5) is combined with the inner layer. The film was applied to form a film.
（多孔質中空糸膜の製造）
多孔質中空糸膜製造装置を用いて多孔質中空糸膜５を製造した。
ポリフッ化ビニリデンＢ（アルケマ社製、商品名：カイナー３０１Ｆ）、ポリフッ化ビニリデンＣ（アルケマ社製、商品名：カイナー９０００ＬＤ）、ポリビニルピロリドン（日本触媒社製、商品名：Ｋ－８０）、及びＮ，Ｎ－ジメチルアセトアミドを、表２に示す質量比となるように混合し、製膜原液（４）と（５）を調製した。製膜速度を１２．５ｍ／ｍｉｎ、高湿高温度領域長を６３．５ｍｍ、凝固浴温度を７５℃条件にて製膜原液（４）を外層に、製膜原液（５）を内層に複合的に塗布し製膜を行った。 <Reference Comparative Example 1>
(Manufacture of porous hollow fiber membrane)
The porous
Polyvinylidene fluoride B (manufactured by Arkema, product name: Kyner 301F), polyvinylidene fluoride C (manufactured by Arkema, product name: Kyner 9000LD), polyvinylpyrrolidone (manufactured by Nippon Shokubai Co., Ltd., product name: K-80), and N , N-dimethylacetamide was mixed so as to have a mass ratio shown in Table 2 to prepare membrane-forming stock solutions (4) and (5). The film forming speed is 12.5 m / min, the high humidity and high temperature region length is 63.5 mm, and the coagulation bath temperature is 75 ° C. The film forming stock solution (4) is combined with the outer layer and the film forming stock solution (5) is combined with the inner layer. The film was applied to form a film.
得られた多孔質中空糸膜４の外径は、約２．８０ｍｍであり、内径は約１．２ｍｍであり、多孔質膜層１１の膜厚は平均約１５０μｍであり、バブルポイント（Ｐｉ）１７０ｋＰａ、透水性能は４６ｍ３／ｍ２／ｈ／ＭＰａであった。表面開孔率Ａ１は２６％、孔径指数Ｐ１は０．１７μｍであった。内部最緻密層での開孔率Ａ２は５％、孔径指数Ｐ２は０．１３μｍとなった。
The outer diameter of the obtained porous hollow fiber membrane 4 is about 2.80 mm, the inner diameter is about 1.2 mm, the thickness of the porous membrane layer 11 is about 150 μm on average, and the bubble point (Pi) The water permeation performance was 170 m 3 / m 2 / h / MPa. The surface opening ratio A1 was 26%, and the pore diameter index P1 was 0.17 μm. The aperture ratio A2 in the inner dense layer was 5%, and the pore diameter index P2 was 0.13 μm.
本実施形態によれば、浄水処理、飲料処理、海水除濁等の種々の水性流体の処理において使用することができ、優れた分画特性、透過性を有しながら、経時的な性能の低下が抑制され、洗浄による膜分離特性の回復性に優れた多孔質中空糸膜、並びにその評価方法を提供できる。
According to the present embodiment, it can be used in the treatment of various aqueous fluids such as water purification treatment, beverage treatment, seawater turbidity, etc., and it has excellent fractionation characteristics and permeability, while the performance deterioration with time. Can be provided, and a porous hollow fiber membrane excellent in recovery of membrane separation characteristics by washing, and an evaluation method thereof can be provided.
本実施形態の多孔質中空糸膜は、外表面を形成する層の孔径に対して、その内部の層の孔径が十分に大きく、目詰まりしにくい構造になっている。よって、本実施形態の中空状多孔質中空糸膜はろ過安定性が高く、精密濾過、限外濾過等による浄水処理等の水処理に用いる濾過膜として好適である。
The porous hollow fiber membrane of the present embodiment has a structure in which the pore diameter of the inner layer is sufficiently large relative to the pore diameter of the layer forming the outer surface and is not easily clogged. Therefore, the hollow porous hollow fiber membrane of this embodiment has high filtration stability, and is suitable as a filtration membrane used for water treatment such as water purification such as microfiltration and ultrafiltration.
１ 製造装置
１０ 紡糸ノズル
１１ 支持体用貫通孔
１２ 樹脂溶液用流路
２０Ａ 処理用容器
２１ 天井部
２１ａ 第１の開口部
２２ａ 第２の開口部
２２ｃ 貫通孔
２３ 側部
２４ 気体供給管
２５ 管部
３０ 凝固槽
３１ 第１のガイドロール
３２ 第２のガイドロール
３３ 天板
３３ａ，３３ｂ 開口部
４０Ａ，４０Ｂ，４０Ｃ 換気手段
４１，換気ノズル
４１ａ 円形開口部
４１ｂ 気体導入室
４１ｃ 気体吐出口
４１ｄ 抵抗付与体
４２ 気体供給手段
４３ 気体濾過手段
４４ 気体調整手段
５０ 保護筒
５０ａ 貫通孔
５１ 上端部
５２ 下端部
５２ａ 開口部
Ａ 多孔質中空状膜
Ａ１ 中空紐状支持体
Ａ２ 膜形成性樹脂溶液の塗膜
Ｂ 凝固液 DESCRIPTION OF SYMBOLS 1Manufacturing apparatus 10 Spinning nozzle 11 Supporting through-hole 12 Resin solution flow path 20A Processing container 21 Ceiling part 21a 1st opening part 22a 2nd opening part 22c Through-hole 23 Side part 24 Gas supply pipe 25 Pipe part DESCRIPTION OF SYMBOLS 30 Coagulation tank 31 1st guide roll 32 2nd guide roll 33 Top plate 33a, 33b Opening part 40A, 40B, 40C Ventilation means 41, Ventilation nozzle 41a Circular opening part 41b Gas introduction chamber 41c Gas discharge port 41d Resistance imparting body 42 Gas supply means 43 Gas filtration means 44 Gas adjustment means 50 Protection tube 50a Through hole 51 Upper end 52 Lower end 52a Opening A A porous hollow membrane A1 A hollow string-like support A2 A coating film of a film-forming resin solution B Coagulation liquid
１０ 紡糸ノズル
１１ 支持体用貫通孔
１２ 樹脂溶液用流路
２０Ａ 処理用容器
２１ 天井部
２１ａ 第１の開口部
２２ａ 第２の開口部
２２ｃ 貫通孔
２３ 側部
２４ 気体供給管
２５ 管部
３０ 凝固槽
３１ 第１のガイドロール
３２ 第２のガイドロール
３３ 天板
３３ａ，３３ｂ 開口部
４０Ａ，４０Ｂ，４０Ｃ 換気手段
４１，換気ノズル
４１ａ 円形開口部
４１ｂ 気体導入室
４１ｃ 気体吐出口
４１ｄ 抵抗付与体
４２ 気体供給手段
４３ 気体濾過手段
４４ 気体調整手段
５０ 保護筒
５０ａ 貫通孔
５１ 上端部
５２ 下端部
５２ａ 開口部
Ａ 多孔質中空状膜
Ａ１ 中空紐状支持体
Ａ２ 膜形成性樹脂溶液の塗膜
Ｂ 凝固液 DESCRIPTION OF SYMBOLS 1
Claims (19)
- 少なくとも外表面に多孔質層を有する多孔質中空糸膜であって、
前記多孔質中空糸膜の厚さ方向の断面構造における外表面から深さ１μｍまでの平均孔径（Ａｄ）が、深さ２μｍから３μｍまでの平均孔径（Ｂｄ）に対する比（Ａｄ／Ｂｄ）で０．６以下である多孔質中空糸膜。 A porous hollow fiber membrane having a porous layer on at least an outer surface,
The average pore diameter (Ad) from the outer surface to a depth of 1 μm in the cross-sectional structure in the thickness direction of the porous hollow fiber membrane is 0 as a ratio (Ad / Bd) to the average pore diameter (Bd) from a depth of 2 μm to 3 μm. A porous hollow fiber membrane of 6 or less. - 前記外表面は、平均孔径Ｐ１が０．０５～１．０μｍであり、開孔率Ａ１が１５～６５％である請求項１記載の多孔質中空糸膜。 2. The porous hollow fiber membrane according to claim 1, wherein the outer surface has an average pore diameter P1 of 0.05 to 1.0 μm and an open area ratio A1 of 15 to 65%.
- 前記断面構造における外表面から深さ１０μｍまでの層の平均孔径Ｐ２が０．１～５．０μｍであり、開孔率Ａ２が１０～５０％である請求項１又は２に記載の多孔質中空糸膜。 3. The porous hollow according to claim 1, wherein an average pore diameter P2 of a layer from the outer surface to a depth of 10 μm in the cross-sectional structure is 0.1 to 5.0 μm, and an open area ratio A2 is 10 to 50%. Yarn membrane.
- 前記外表面から深さ５μｍまでの構造が、孔径が外表面から離れる方向に向けて漸増する三次元網目構造である請求項１～３のいずれかに記載の多孔質中空糸膜。 The porous hollow fiber membrane according to any one of claims 1 to 3, wherein the structure from the outer surface to a depth of 5 µm is a three-dimensional network structure in which the pore diameter gradually increases in a direction away from the outer surface.
- 前記外表面から深さ５μｍまでの多孔質層の平均孔径が、前記外表面から深さ５μｍよりも離れた部位に存在する多孔質層の平均孔径よりも小さい請求項１～４のいずれかに記載の多孔質中空糸膜。 5. The average pore diameter of the porous layer having a depth of 5 μm from the outer surface is smaller than the average pore diameter of the porous layer existing at a position farther than the depth of 5 μm from the outer surface. The porous hollow fiber membrane according to the description.
- 前記外表面から深さ５μｍよりも離れた部位に存在する多孔質層の平均孔径が、１０μｍ以下である請求項１～５のいずれかに記載の多孔質中空糸膜。 6. The porous hollow fiber membrane according to any one of claims 1 to 5, wherein an average pore diameter of the porous layer existing at a part farther than 5 μm deep from the outer surface is 10 μm or less.
- 前記外表面から深さ５μｍまでを実質的に構成する熱可塑性樹脂が同一の化合物の熱可塑性樹脂からなる請求項１～６のいずれかに記載の多孔質中空糸膜。 The porous hollow fiber membrane according to any one of claims 1 to 6, wherein the thermoplastic resin substantially constituting the depth from the outer surface to 5 μm is made of a thermoplastic resin of the same compound.
- 前記外表面から深さ１０μｍよりも離れていない部位の多孔質層に、孔径１０μｍを超えるマクロボイド及びその一部を含有しない請求項１～７いずれかに記載の多孔質中空糸膜。 The porous hollow fiber membrane according to any one of claims 1 to 7, which does not contain a macrovoid having a pore diameter of more than 10 µm and a part thereof in the porous layer at a portion not more than 10 µm deep from the outer surface.
- 非溶媒相分離法により形成されてなる請求項１～８のいずれかに記載の多孔質中空糸膜。 The porous hollow fiber membrane according to any one of claims 1 to 8, which is formed by a non-solvent phase separation method.
- 前記多孔質層が中空糸状の支持体の外表面側に形成されている請求項１～９のいずれかに記載の多孔質中空糸膜。 The porous hollow fiber membrane according to any one of claims 1 to 9, wherein the porous layer is formed on the outer surface side of a hollow fiber-like support.
- 前記中空糸状の支持体が熱処理された支持体である請求項１０記載の多孔質中空糸膜。 The porous hollow fiber membrane according to claim 10, wherein the hollow fiber-shaped support is a heat-treated support.
- 前記中空糸状の支持体が中空編紐である請求項１０又は１１に記載の多孔質中空糸膜。 The porous hollow fiber membrane according to claim 10 or 11, wherein the hollow fiber support is a hollow knitted string.
- 支持体が、マルチフィラメントからなる１本の糸を丸編した中空編紐である請求項１１又は１２記載の多孔質中空糸膜。 The porous hollow fiber membrane according to claim 11 or 12, wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
- 熱可塑性樹脂と親水性化合物とを含む膜形成性樹脂溶液を紡糸ノズルから吐出させた後、前記吐出させた膜形成性樹脂溶液を膜形成性樹脂溶液の成分にとって非溶媒の飽和蒸気に接触させ、その後に凝固液に浸漬させることにより凝固させて多孔質中空糸膜とする、多孔質中空糸膜の製造方法であって、
前記紡糸ノズルが１重又は２重以上の管状ノズルであって、前記多孔質中空糸膜は少なくとも外表面から深さ５μｍの部位を同一の膜形成性樹脂溶液により形成する多孔質中空糸膜の製造方法。 After the film-forming resin solution containing the thermoplastic resin and the hydrophilic compound is discharged from the spinning nozzle, the discharged film-forming resin solution is brought into contact with a non-solvent saturated vapor for the components of the film-forming resin solution. A method for producing a porous hollow fiber membrane, which is then solidified by being immersed in a coagulation liquid to form a porous hollow fiber membrane,
The spinning nozzle is a single or double or more tubular nozzle, and the porous hollow fiber membrane is a porous hollow fiber membrane in which at least a part having a depth of 5 μm from the outer surface is formed by the same membrane-forming resin solution. Production method. - 前記非溶媒の飽和蒸気が、飽和水蒸気である、請求項１４記載の多孔質中空糸膜の製造方法。 The method for producing a porous hollow fiber membrane according to claim 14, wherein the non-solvent saturated steam is saturated steam.
- 紡糸ノズルを用いて、中空状の支持体の外周面に膜形成性樹脂溶液を塗布し膜形成性樹脂層とした後、前記膜形成性樹脂層を非溶媒の飽和蒸気に接触させる、請求項１４又は１５に記載の多孔質中空糸膜の製造方法。 The film-forming resin solution is applied to the outer peripheral surface of a hollow support by using a spinning nozzle to form a film-forming resin layer, and then the film-forming resin layer is brought into contact with a non-solvent saturated vapor. The method for producing a porous hollow fiber membrane according to 14 or 15.
- 前記支持体は熱処理された支持体を用いることを特徴とする、請求項１６に記載の多孔質中空糸膜の製造方法。 The method for producing a porous hollow fiber membrane according to claim 16, wherein the support is a heat-treated support.
- 前記支持体が編紐であることを特徴とする、請求項１６又は１７に記載の多孔質中空糸膜の製造方法。 The method for producing a porous hollow fiber membrane according to claim 16 or 17, wherein the support is a knitted string.
- 前記支持体が、マルチフィラメントからなる１本の糸を丸編した中空状編紐である請求項１７又は１８に記載の多孔質中空糸膜の製造方法。 The method for producing a porous hollow fiber membrane according to claim 17 or 18, wherein the support is a hollow knitted string obtained by circularly knitting a single yarn made of multifilament.
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| EP3056261A4 (en) * | 2013-10-11 | 2016-09-28 | Mitsubishi Rayon Co | Hollow porous membrane |
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| WO2020059344A1 (en) * | 2018-09-20 | 2020-03-26 | 住友電気工業株式会社 | Hollow-fiber membrane |
| KR20220057247A (en) * | 2020-10-29 | 2022-05-09 | 서울대학교산학협력단 | Manufacturing method of growth body and the growth body manufactured thereby |
| KR102412426B1 (en) | 2020-10-29 | 2022-06-23 | 서울대학교산학협력단 | Manufacturing method of growth body and the growth body manufactured thereby |
| WO2023276614A1 (en) * | 2021-06-28 | 2023-01-05 | 旭化成株式会社 | Forward osmosis membrane and forward osmosis membrane module including same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP6020592B2 (en) | 2016-11-02 |
| CN105722585A (en) | 2016-06-29 |
| JP2016196004A (en) | 2016-11-24 |
| KR20160044582A (en) | 2016-04-25 |
| JPWO2015041286A1 (en) | 2017-03-02 |
| KR101826451B1 (en) | 2018-02-06 |
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