JP5546993B2 - Manufacturing method of irregular porous hollow fiber membrane, irregular porous hollow fiber membrane, module using irregular porous hollow fiber membrane, filtration device using irregular porous hollow fiber membrane, and filtration using irregular porous hollow fiber membrane Method - Google Patents

Description

  The present invention relates to a method for producing an irregular porous hollow fiber membrane, an irregular porous hollow fiber membrane, a module using the irregular porous hollow fiber membrane, a filtration device using the irregular porous hollow fiber membrane, and an irregular porous hollow fiber membrane. The present invention relates to a filtration method using.

  In recent years, porous membranes such as ultrafiltration membranes and microfiltration membranes have been used for electrodeposition paint collection, removal of fine particles from ultrapure water, production of pyrogen-free water, enzyme concentration, sterilization / clarification of fermentation broth, etc. Used in a wide range of fields such as water, sewage and wastewater treatment. In particular, porous hollow fiber membranes are widely used because they have a high membrane packing density per unit volume and are effective in reducing the size of processing equipment. Recently, membrane separation is spreading to purification and recovery of valuable components from cells and tissue culture such as biopharmaceuticals and antibody drugs.

  For filtration using a porous hollow fiber membrane, an internal pressure filtration method for filtering the liquid to be treated from the inner surface side to the outer surface side of the porous hollow fiber membrane, and an external pressure filtration method for filtering from the outer surface side to the inner surface side There is. In particular, the internal pressure filtration method is suitable for use in the industrial field and bioprocess field because the filter can be designed with the inner diameter of the hollow fiber for various raw water viscosities.

  When various treatment liquids are filtered using a porous hollow fiber membrane, a part of solids contained in the treatment liquid is adsorbed, blocked or deposited in the membrane pores or on the membrane surface, so-called concentration polarization. Forming a layer or a cake layer. As a result, a phenomenon called fouling occurs, and the filtration performance of the porous hollow fiber membrane is reduced to a fraction to a hundredth of the filtration performance when pure water is filtered. In order to prevent a fouling phenomenon, in the case of internal pressure filtration, cross flow filtration is generally performed. Since cross-flow filtration performs filtration while scraping off the fouling substance on the membrane surface by a shearing force caused by a parallel flow, the progress of the fouling phenomenon can be suppressed.

  In order to improve the filtration performance in performing the cross flow filtration by the internal pressure filtration method, there is a method of increasing the liquid linear velocity (hereinafter, linear velocity) in the cross flow. When the linear velocity of the cross flow is increased, the effect of scraping by the parallel flow is increased, so that the filtration performance can be improved. However, particularly in the bioprocess field, when purifying and concentrating a liquid containing bacterial cells and cells, the target bacterial cells and cells may be crushed, and further, the crushed material may enter the membrane pores. There is a limit to the increase in the crossflow linear velocity because clogging causes a sudden drop in filtration performance.

  Therefore, in order to improve the filtration performance at a low linear velocity, a method of providing irregularities on the inner surface side of the hollow fiber membrane has been proposed. By providing this unevenness, the cross flow passing through the inside of the hollow fiber membrane becomes a turbulent flow, so that the effect of scraping is increased. Therefore, filtration performance can be improved without increasing the linear velocity. For example, in the one described in Patent Document 1, melt spinning is performed using a spinneret for shaping a deformed hollow fiber having 8 or more dents to obtain a deformed cross-section unstretched hollow fiber, and then stretching it. By making it porous, irregularities are formed on the inner surface. Further, in the method described in Patent Document 2, in a method of obtaining a porous membrane by mixing a thermoplastic resin and an additive, melt spinning, and extracting and removing the additive, the deformed hollow fiber is used during melt spinning. A modified hollow fiber membrane is obtained by using a spinneret.

Japanese Unexamined Patent Publication No. 63-21914 JP-A-61-120606

  However, in the case of the above-mentioned Patent Document 1, since the hollow fiber is stretched to generate a large number of cracks in the amorphous region between the crystals, the porous structure is obtained. There is a problem that (small fibers) are generated. In the method described in Patent Document 2, the pore diameter on the inner surface side is large and the pore diameter on the outer surface side is small, and the pores have an inclined structure with respect to the film cross-sectional direction. For this reason, since fouling substances accumulate in the pores of the membrane during internal pressure filtration, the effect of scraping by crossflow cannot be expected. Therefore, even when unevenness is imparted to the inner surface of the hollow fiber membrane, it is difficult to sufficiently obtain the effect.

  The present invention has been made to solve the above-described problems, and suppresses disruption of cells and cells contained in the liquid to be treated, and improves filtration performance in a low linear velocity cross flow. A method for producing an irregular porous hollow fiber membrane, an irregular porous hollow fiber membrane, a module using the irregular porous hollow fiber membrane, a filtration device using the irregular porous hollow fiber membrane, and an irregular porous hollow fiber membrane It aims at providing the used filtration method.

  As a result of intensive studies in order to solve the above problems, the present inventors have obtained thermoplasticity from a spinneret provided with irregularities along the circumferential direction on the outer peripheral surface of the interior part constituting the double annular discharge port. Discharge the molten kneaded product of resin, organic liquid, and inorganic fine powder, cool and solidify, and then crush the cells and cells by using a deformed porous hollow fiber membrane obtained by extracting and removing the organic liquid and inorganic fine powder. In addition, the present inventors have found that the filtration performance can be improved in a low linear velocity cross flow and have reached the present invention.

That is, the present invention is as follows.
(1) After a melt-kneaded material containing a thermoplastic resin, an organic liquid and inorganic fine powder is discharged from a double annular discharge port of a hollow fiber molding nozzle to form a hollow fiber material, and the hollow fiber material is cooled and solidified. A method for producing an irregular porous hollow fiber membrane by extracting and removing organic liquid and inorganic fine powder, wherein the discharge port is composed of an annular interior part and an exterior part disposed so as to surround the interior part An irregularly shaped porous hollow fiber membrane, wherein irregularities are formed in the outer peripheral portion of the interior portion along the circumferential direction of the interior portion, and the melt-kneaded material is molded and discharged at a discharge port. Manufacturing method,
(2) Producing a deformed porous hollow fiber membrane according to (1), wherein a filter is provided in at least one position until the melt-kneaded material is discharged from the discharge port, and the melt-kneaded material is passed through the filter. Method,
(3) The method for producing a deformed porous hollow fiber membrane according to (2), wherein the ratio between the slit width of the filter and the primary particle diameter of the inorganic fine powder is 1000 to 120,000,
(4) The filter is provided so as to be 2 or more and 5 or less at a position where the thermoplastic resin, the organic liquid and the inorganic fine powder are melt-kneaded and pass within 2000 seconds. (2) or (3) a method for producing a deformed porous hollow fiber membrane,
(5) A deformed porous hollow fiber membrane produced by the method for producing a deformed porous hollow fiber membrane according to any one of (1) to (4),
(6) A module using the irregular porous hollow fiber membrane produced by the method for producing an irregular porous hollow fiber membrane according to any one of (1) to (4),
(7) A filtration device using a deformed porous hollow fiber membrane manufactured by the method for manufacturing a deformed porous hollow fiber membrane according to any one of (1) to (4),
(8) A filtration method using an irregularly shaped porous hollow fiber membrane produced by the method for producing an irregularly shaped porous hollow fiber membrane according to any one of (1) to (4),
It is.

  According to the present invention, it is possible to suppress crushing of bacterial cells and cells contained in the liquid to be treated, and to improve filtration performance in a low linear velocity cross flow.

It is the schematic explaining an example of the irregular porous hollow fiber membrane manufactured by the manufacturing method of the irregular porous hollow fiber membrane which concerns on one Embodiment of this invention. It is a figure which shows the structure of the manufacturing apparatus which manufactures a deformed porous hollow fiber membrane. It is sectional drawing which shows the structure of a discharge outlet. It is a figure which shows the structure of a filter. It is a figure which shows the structure of a hollow fiber membrane module. It is a block diagram which shows an example of a filtration apparatus. It is the schematic of the evaluation apparatus used in order to evaluate the filtration performance of a deformed porous hollow fiber membrane. It is a table | surface which shows a measurement result. It is a table | surface which shows a measurement result.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  Examples of the method for producing a deformed porous hollow fiber membrane include a phase separation method, a stretched hole opening method, and a track etching method. A phase separation method capable of creating a wide variation in pore diameter is preferable. Examples of the phase separation method include a non-solvent induced phase separation method and a thermally induced phase separation method. In the non-solvent induced phase separation method, the polymer is dissolved in a solvent capable of dissolving the polymer, and then the dissolved polymer solution is discharged together with water and a solvent, which are hollow forming materials, from a bicyclic spinneret. To induce phase separation. In addition, in the thermally induced phase separation method, the polymer is dissolved in a latent solvent that does not dissolve at room temperature but dissolves at high temperature, and is dissolved together with air and solvent as a hollow forming material from a double ring spinneret. Is discharged and brought into contact with air or water to cool and induce phase separation. In this embodiment, an irregularly shaped porous hollow fiber membrane manufactured by a thermally induced phase separation method using a thermoplastic resin, an organic liquid, and inorganic fine powder will be described. In this method for producing a deformed porous hollow fiber membrane, a deformed porous hollow fiber membrane having a uniform pore diameter in the cross-sectional direction of the membrane can be obtained. Easy to get scraping effect.

[Configuration of irregularly shaped porous hollow fiber membrane]
FIG. 1 is a schematic view showing an example of a hollow fiber membrane produced by a method for producing a deformed porous hollow fiber membrane according to an embodiment of the present invention. Fig.1 (a) is a perspective view of a deformed porous hollow fiber membrane, and FIG.1 (b) is sectional drawing of a deformed porous hollow fiber membrane. As shown in each figure, the deformed porous hollow fiber membrane 1 has a substantially cylindrical shape with an opening 2 provided in the central portion, and has unevenness 3 continuous in the longitudinal direction on the inner peripheral portion thereof. It is a porous hollow fiber membrane having. The inner peripheral portion means the inner surface portion of the deformed porous hollow fiber membrane 1, and the longitudinal direction means a direction orthogonal to the inner peripheral circle (outer peripheral circle) of the deformed porous hollow fiber membrane 1 (that is, open). It means the extending direction of the hole 2 and the direction indicated by the arrow “x” in FIG. Having continuous unevenness means that the cross section of the inner circumferential circular direction orthogonal to the longitudinal direction of the irregular porous hollow fiber membrane 1 has substantially the same uneven structure at an arbitrary location. Each unevenness 3 extends along the longitudinal direction of the irregular porous hollow fiber membrane 1. Therefore, the irregular porous hollow fiber membrane 1 has substantially the same uneven structure on the cut surface regardless of the cutting position.

  Further, the concave and convex portions included in the concave and convex portions are the convex portion 3A and the concave portion on the outer side of the inner peripheral portion of the membrane in the cross section of the deformed porous hollow fiber membrane 1. The part which is is called the recessed part 3B (refer an Example about a convex part and a recessed part). The shape of the unevenness is not particularly limited, and examples thereof include various shapes such as a convex shape and a concave shape.

[Method for producing irregularly shaped porous hollow fiber membrane]
Then, the manufacturing method of the above-mentioned deformed porous hollow fiber membrane by the thermally induced phase separation method will be specifically described. First, the structure of the melt-kneaded material that forms the irregular porous hollow fiber membrane 1 will be described. The melt-kneaded product is composed of a thermoplastic resin, an organic solution, and inorganic fine powder.

(Thermoplastic resin)
Thermoplastic resins are not easily deformed at room temperature (20 ° C. ± 15 ° C. (5-35 ° C.)) and have elasticity and do not show plasticity. However, plasticity is manifested by appropriate heating to allow molding and cooling. When the temperature drops, the resin reversibly changes back to its original elastic body, and does not cause chemical changes such as the molecular structure during that time (edited by the Chemistry Dictionary Editorial Committee, Chemistry Dictionary 6 Miniature Edition, Kyoritsu Shuppan, 860 and 867, 1963). As examples of thermoplastic resins, examples of thermoplastic resins include resins described in the pages of thermoplastics (pages 829 to 882) of 12695 chemical products (Chemical Industry Daily, 1995), and chemical handbook applications. Resins etc. described in pages 809 to 810 of the edition 3 edition (The Chemical Society of Japan, Maruzen, 1980) can be mentioned.

  Specifically, as the thermoplastic resin, polyethylene, polyolefin such as polypropylene, polyvinylidene fluoride, ethylene-vinyl alcohol copolymer, polyamide, polyetherimide, polystyrene, polysulfone, polyvinyl alcohol, polyphenylene ether, polyphenylene sulfide, Cellulose acetate, polyacrylonitrile and the like can be used. In particular, a thermoplastic resin having crystallinity such as polyethylene, polypropylene, polyvinylidene fluoride, ethylene / vinyl alcohol copolymer, and polyvinyl alcohol is preferable from the viewpoint of the mechanical strength of the deformed porous hollow fiber membrane 1.

(Organic liquid)
The organic liquid is a potential solvent for the thermoplastic resin. The latent solvent is a solvent that does not dissolve the thermoplastic resin at room temperature (25 ° C.) and can dissolve the thermoplastic resin at a temperature higher than room temperature. The organic liquid may be liquid at the melt kneading temperature with the thermoplastic resin, and does not necessarily need to be liquid at room temperature.

  As the organic liquid, when the thermoplastic resin is polyethylene, phthalates such as dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, bis (2-ethylhexyl) phthalate, diisodecyl phthalate, and ditridecyl phthalate; sebacic acid Sebacic acid esters such as dibutyl; adipic acid esters such as dioctyl adipate; trimellitic acid esters such as trioctyl trimellitic acid; phosphoric acid esters such as tributyl phosphate and trioctyl phosphate; propylene glycol dicaprate, propylene Glycerin esters such as glycol dioleate; paraffins such as liquid paraffin; and mixtures thereof can be used.

  As the organic liquid, when the thermoplastic resin is polyvinylidene fluoride, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dicyclohexyl phthalate, diheptyl phthalate, dioctyl phthalate, bis (2-ethylhexyl) phthalate, etc. Phthalic acid esters; benzoic acid esters such as methyl benzoate and ethyl benzoate; phosphoric acid esters such as triphenyl phosphate, tributyl phosphate and tricresyl phosphate; Y-butyrolactone, ethylene carbonate, propylene carbonate, cyclohexanone , Ketones such as acetophenone and isophorone; and mixtures thereof.

(Inorganic fine powder)
As the inorganic fine powder, silica, alumina, titanium oxide, zirconia, calcium carbonate, and the like can be used. Particularly, fine powder silica having an average primary particle size of 3 nm to 500 nm is preferable, and more preferably, 5 nm to 100 nm. It is finely divided silica. In addition, hydrophobic silica fine powder that hardly aggregates and has good dispersibility is more preferable, and more preferable is hydrophobic silica whose NW value measured by the methanol wettability (NW) method for measuring the volume% of methanol is 30% by volume or more. is there. The MW value here is a value of the volume% of methanol at which the powder is completely wetted. Specifically, when silica is added to pure water and methanol is added below the liquid level with stirring, the volume percentage of methanol in the aqueous solution when 50% by mass of silica settles is obtained. Determined. As for the addition amount of the inorganic fine powder, the mass ratio of the inorganic fine powder in the melt-kneaded product is preferably 5% by mass or more and 40% by mass or less. If the proportion of the inorganic fine powder is 5% by mass or more, the effect of the inorganic fine powder kneading can be sufficiently exhibited, and if it is 40% by mass or less, stable spinning can be achieved.

(Configuration of hollow fiber membrane production equipment)
Next, the structure of the hollow fiber membrane manufacturing apparatus for manufacturing the irregular porous hollow fiber membrane will be described. FIG. 2 is a diagram showing a configuration of a hollow fiber membrane production apparatus for producing a deformed porous hollow fiber membrane. As shown in FIG. 2, the hollow fiber membrane manufacturing apparatus 10 includes a melt kneader 11 that melts and kneads a thermoplastic resin, an organic liquid, and inorganic fine powder to extrude a melt kneaded product, and a tip (extrusion) side of the melt kneader 11. A hollow fiber molding nozzle 12 provided in the vacuum, a suction device 13 for generating cooling air to the melt-kneaded material discharged from the hollow fiber molding nozzle 12, and a cooling tank for cooling and solidifying the melt-kneaded part 14 and a take-up roller 15 for winding the solidified hollow fiber-like material. The melt kneader 11 is a normal melt kneader, for example, a twin screw extruder.

  In the hollow fiber membrane manufacturing apparatus 10, the melt-kneaded product P supplied from the melt-kneader 11 is discharged from the hollow fiber molding nozzle 12 and is idled while receiving cooling air from the suction machine 13. The melt-kneaded product is solidified through the cooling bath, and the solidified hollow fiber-like product is taken up by the take-up roller 15.

  In the hollow fiber molding nozzle 12, the melt-kneaded product supplied from the melt-kneader 11 flows through the space provided in the melt-kneader 11 and the hollow fiber molding nozzle 12, so that the hollow fiber molding nozzle 12 is discharged from a discharge port 21 of a spinneret 20 provided at 12. At the same time, a hollow portion forming fluid such as air or a high boiling point liquid passes through a cylindrical through-hole provided in the central portion of the hollow fiber molding nozzle 12 and is a discharge portion for a hollow portion forming fluid different from the discharge port 21. (Discharge port 23b in FIG. 3) is discharged downward.

  Here, the spinneret 20 is a part that molds and discharges the melt-kneaded material that has been melt-kneaded and extruded by the melt-kneader 11 and is a spinneret for hollow fiber molding. The spinneret 20 has an inlet 22 for receiving the melt-kneaded product extruded from the extrusion port 11a of the melt-kneader 11, and a discharge port 21 for molding and discharging the melt-kneaded product. FIG. 3 is a cross-sectional view of the discharge port in the spinneret. As shown in the figure, the discharge port 21 of the spinneret 20 is a double annular discharge port. Specifically, the discharge port 21 includes an annular interior part 23 and an exterior part 24. As for the interior part 23, the outer peripheral part 23a is deformed. Specifically, the outer peripheral portion 23a of the interior portion 23 is provided with irregularities 25 over the entire circumference along the circumferential direction. The irregularities 25 are formed by providing convex portions 25A and concave portions 25B alternately and continuously. A discharge port 23 b is formed in the central portion of the interior portion 23. In addition, the discharge port 21 should just be an outer peripheral part 23a of the interior part 23, and should just be an annular shape more than double.

(Definition of the concave and convex portions of the interior part of the spinneret, the width of the convex portions, and the height of the convex portions)
Here, the definition of the convex part 25A and the concave part 25B of the spinneret 20 will be described below. As shown in FIG. 3, from the average outer diameter of the interior portion 23 of the spinneret 20, the portion on the exterior portion 24 side is defined as a convex portion 25A, and the portion on the center point side is defined as a concave portion 25B. The average outer diameter d _ave is the minimum outer diameter d _min where the distance from the center point of the spinneret 20 to the outer peripheral portion of the inner portion 23 of the spinneret 20 is the minimum outer diameter d _{min. When} it is set to _max , it represents the average value of the two diameters. That is, the average outer diameter can be expressed by the following formula (1).

  Next, the width w of the convex portion 25A will be described. As shown in FIG. 3, the width w of the convex portion 25A is defined as a circle having the above average inner diameter (dotted circle in FIG. 3) and an intersection of the convex portion 25A (points a and b in FIG. 3 are examples). The connected straight line is defined as the width of one convex portion 25A, and the average value of the widths w of all the convex portions 25A of the irregular porous hollow fiber membrane 1 is the width of the convex portion 25A of the irregular porous hollow fiber membrane 1. And Next, the height h of the convex portion 25A will be described. The height h of the convex portion is the distance from the point closest to the outer sheath 24 of the spinneret 20 to the straight line drawn when measuring the width of the convex portion 25A. It was height.

  In FIG. 3, “h” is, for example, 10 μm to 4500 μm. “W” is, for example, 10 μm to 4500 μm. “T” is, for example, 50 μm to 2000 μm. The shapes of the convex portions 25A and the concave portions 25B are not limited to the smooth mountain shape as shown in FIG. 3, and may be various shapes such as a triangular shape and a rectangular shape.

  The exterior part 24 is disposed so as to surround the interior part 23. The diameter of the exterior part 24 is about 0.2 mm to 10 mm, for example. A discharge path for the melt-kneaded material is formed between the outer peripheral surface of the interior portion 23 and the inner peripheral surface of the exterior portion 24, and the deformed porous hollow fiber membrane is formed by the melt-kneaded material passing through this discharge path. Concavities and convexities 3 that are continuous in the longitudinal direction are formed on the inner peripheral portion of 1. Air or the like is discharged from the discharge port 23 b of the interior portion 23.

(filter)
The hollow fiber molding nozzle 12 is provided with a plurality (two in this case) of filters 26. The filter 26 is provided between the extrusion port of the melt kneader 11 and the discharge port 21 of the spinneret 20 in the hollow fiber molding nozzle 12, and the attachment position is melted from the extrusion port 11 a of the melt kneader 11. It is a position where the kneaded material passes within 2000 seconds after being extruded. That is, the melt-kneaded product extruded from the extrusion port 11a of the melt-kneader 11 passes through the filter 26 within 2000 seconds. It is preferable that the filter 26 is provided in the hollow fiber molding nozzle 12 so as to be 2 or more and 5 or less.

  FIG. 4 is a diagram illustrating the configuration of the filter 26. As shown in the figure, the filter 26 has a predetermined slit width d. The ratio between the slit width d of the filter 26 and the primary particle diameter of the inorganic fine powder is preferably 1000 to 120,000. When this ratio is 1000 or more, clogging in the filter 26 can be prevented. Moreover, the effect which an inorganic fine powder distributes can be exhibited as it is less than 120,000, As a result, the fall of the aperture property of the uneven | corrugated 3 between parts can be prevented.

  By passing the melt-kneaded material through the filter 26, it is possible to obtain the irregular porous hollow fiber membrane 1 having a small number of independent pores and high communication properties, that is, high actual liquid performance. In general, it is known to use a filter having a relatively large opening (slit width) in order to remove foreign matters such as insoluble matters and scorching. However, the filter 26 of the present embodiment is clear from this purpose. Different.

  In the melt-kneaded product, it is difficult to uniformly disperse the added inorganic fine powder, and it has a portion where the inorganic fine powder is aggregated. This is not a non-uniformity at a macro size (several hundreds of μm) disclosed in conventional literature, but a kneading unevenness at a more microscopic size (several tens to 100 μm). It is difficult to disperse the inorganic fine powder uniformly in this micro size. As a result of intensive studies, the present inventors have many communication holes that allow the melt-kneaded product to pass through the filter 26 provided between the melt-kneading step and the hollow fiber-like discharge step and then discharge the hollow kneaded product into the hollow fiber shape. It was found to be important for obtaining a porous hollow fiber membrane. This is presumably due to the following two reasons.

(1) Dispersibility improvement of inorganic fine powder Aggregates are dispersed below the slit size by passing the melt-kneaded material through the opening of the filter, that is, the narrow slit. As a result, it is possible to reach the uniformity even higher than that of the dispersion in the melt-kneading step. As a result, the polymer concentration is low (relatively high organic liquid concentration), phase separation proceeds quickly in the cooling process after ejection, and it becomes difficult to form a non-uniform region where independent holes are likely to be formed.

(2) Orientation of aggregate of inorganic fine powder By passing the melt-kneaded material through a narrow slit, the aggregate state of the inorganic fine powder changes. Specifically, a linear aggregated state is created. Thus, the aggregate of the inorganic fine powder is oriented in the hollow fiber film thickness direction due to the ballast effect when the aggregate of the inorganic fine powder oriented in the flow direction of the melt-kneaded product is discharged from the discharge port 21. When phase separation occurs in the cooling process after discharge, the start of phase separation occurs from the inorganic fine powder as the base point, and the phase separation proceeds. ) Is oriented. As a result, a porous hollow fiber membrane having high communication is obtained.

  Here, as one index representing the effect of the production method of the present embodiment, variation in physical properties of the obtained porous hollow fiber membrane (standard deviation in terms of statistics) can be mentioned. For example, the physical properties of the obtained porous hollow fiber membrane have a certain standard deviation (variation). According to the manufacturing method of the present embodiment, a film having a small standard deviation, that is, a more uniform distribution can be obtained. A smaller standard deviation is a great advantage in production and in designing the membrane. Normally, when considering a standard (physical property value) in a certain product, the upper limit and the lower limit of the standard are determined in consideration of the distribution of the porous hollow fiber membrane.

  As the filter 26, a commercially available sintered filter, a woven stainless steel wire, a ceramic filter, or the like can be suitably used. What woven the stainless wire which is easy to make the filter which has high durability at high temperature and has a fine slit is preferable. Furthermore, when the slit width is small, stainless steel wire with a thin wire diameter is used, so it is also possible to apply a filter with a large wire diameter and a large slit width from the back to make a double, in order to avoid risks such as filter breakage. It can be used suitably.

(Extraction method of organic liquid and inorganic fine powder)
Next, extraction and removal of organic liquid and extraction and removal of inorganic fine powder will be described. The extraction and removal of the organic liquid and the inorganic fine powder can be performed simultaneously as long as they can be extracted and removed with the same solvent, but usually the extraction and removal are performed separately.

  The extraction and removal of the organic liquid can be performed by using an extraction liquid that is miscible with the organic liquid without dissolving or modifying the kneaded thermoplastic resin and contacting the extraction liquid by a technique such as immersion. it can. The extraction liquid is conveniently volatile so that it can be easily removed from the hollow fiber membrane after extraction. Examples of the extraction liquid include alcohols and methylene chloride. If the organic liquid is water-soluble, water can be used as the extraction liquid.

  For example, when the inorganic fine powder is silica, the inorganic fine powder can be extracted and removed by first contacting with an alkaline solution to convert the silica to silicate, and then contacting with water to extract and remove the silicate. it can.

  Either the extraction removal of the organic liquid or the extraction removal of the inorganic fine powder may be performed first. However, since both of them (organic liquid and inorganic fine powder) usually coexist in the organic liquid concentrated partial phase, if the organic liquid is immiscible with water, the organic liquid is first extracted and removed. The extraction and removal of the inorganic fine powder is advantageous because the inorganic fine powder can be smoothly extracted and removed using the aqueous extraction liquid. In this way, the deformed porous hollow fiber membrane 1 can be obtained by extracting and removing the organic liquid and the inorganic fine powder from the cooled and solidified hollow fiber.

  In addition, for the hollow fiber-like material after cooling and solidification, (1) before extraction and removal of organic liquid and inorganic fine powder, (2) after extraction removal of organic liquid and before extraction removal of inorganic fine powder, (3) extraction and removal of inorganic fine powder Before the extraction and removal of the organic liquid, and (4) after the extraction and removal of the organic liquid and inorganic fine powder, the hollow fiber-like material may be stretched in the longitudinal direction within a range of 3 times or less. it can. In general, when the deformed porous hollow fiber membrane 1 is stretched in the longitudinal direction, the water permeability is improved, but the pressure resistance (rupture strength and compressive strength) is lowered. . However, since the melt-kneaded material in which the inorganic fine powder is kneaded in addition to the thermoplastic resin and the organic liquid is discharged and molded from at least one annular discharge port 21, the deformed porous hollow fiber membrane 1 is High mechanical strength. Therefore, it can be carried out as long as the stretching is performed at a low magnification within 3 times. By this stretching, the water permeability of the irregular porous hollow fiber membrane 1 can be improved.

  In addition, the draw ratio said here shows the value which divided the hollow fiber length after extending | stretching by the hollow fiber length before extending | stretching. For example, when a hollow fiber having a hollow fiber length of 10 cm is drawn to a hollow fiber length of 20 cm, the draw ratio is 20 cm ÷ 10 cm = 2 (times). Further, if necessary, the stretched film may be subjected to heat treatment to increase the pressure resistance. The heat treatment temperature is usually suitably carried out below the melting point of the thermoplastic resin.

(Plastomill temperature)
In producing the irregular porous hollow fiber membrane 1, it is preferable that both the resin temperature Tm at the time of melt-kneading and the resin temperature Ts at the time of discharging from the discharge port 21 (spinning port) be equal to or higher than the torque inflection temperature Tp. . Here, the torque inflection temperature means that the organic liquid bleeds in the melt-kneaded material containing silica (for example, the organic liquid starts to exist independently from the thermoplastic resin and the aggregate of inorganic fine powder during cooling. ) Temperature. This torque inflection temperature can be measured, for example, by the following method. That is, the melt-kneaded product (one melt-kneaded and solidified) is kneaded with a plastmill at a temperature equal to or higher than the melting point (in the case of polyvinylidene fluoride resin, about 190 ° C.) until it melts uniformly, and then heated to increase the organic liquid Is mixed with the thermoplastic resin and the torque is increased. When a certain temperature is exceeded, the organic liquid and the thermoplastic resin become uniform, and thereafter, the decrease in the viscosity of the thermoplastic resin becomes dominant, and the torque decreases conversely. At this time, the temperature at which the torque becomes maximum is defined as a torque inflection temperature.

  As described above, by setting the resin temperature Tm and the resin temperature Ts to be equal to or higher than the torque inflection temperature Tp, a film having high communication can be obtained. This is because by making the resin temperature Tm at the time of melt-kneading higher than the torque inflection temperature Tp at which the organic liquid begins to bleed, a more uniform melt-kneaded product can be obtained, resulting in higher communication Become a film. Also, the resin temperature Ts at the time of discharge is made higher than the torque inflection temperature Tp, so that bleeding before discharge, that is, phase separation is not started. Thereby, a film having higher communication can be obtained more efficiently by forming a porous structure by phase-separating only the state in which inorganic fine powders are arranged in the film thickness direction after ejection. The resin temperature Tm and the resin temperature Ts are more preferably 5 ° C. or higher, more preferably 10 ° C. or higher than the torque inflection temperature Tp, from the viewpoint of suitably exhibiting the above effects.

(Hollow fiber membrane module, filtration device and filtration method)
The deformed porous hollow fiber membrane 1 obtained as described above is used for a hollow fiber membrane module, a filtration device to which the hollow fiber membrane module is attached, a water treatment (water treatment method) using the filtration device, and the like.

  Hereinafter, a hollow fiber membrane module in which a large number of irregular porous hollow fiber membranes 1 are integrated, and a filtration method and a filtration apparatus using the hollow fiber membrane module will be described. In addition, although various aspects are assumed as a hollow fiber membrane module, in the following description, a casing type filtration type membrane module will be described as an example.

  FIG. 5 is a diagram showing a configuration of the hollow fiber membrane module. As shown in FIG. 5A, the hollow fiber membrane module 30 includes a bundle (hereinafter referred to as a hollow fiber membrane bundle) 31 of the above-described irregularly shaped porous hollow fiber membrane 1. The hollow fiber membrane bundle 31 has its upper end portion and lower end portion fixed by fixing portions 32a and 32b. Further, the hollow fiber membrane bundle 31 and the fixing portions 32 a and 32 b are accommodated in a pipe-shaped case 33. In the hollow fiber membrane module 30 having such a configuration, the liquid to be filtered L is supplied between the case 33 and the hollow fiber membrane bundle 31 from the lower part (the downward direction in the figure), and a deformed porous hollow is formed by applying a pressure difference. The liquid L to be filtered is filtered by the thread membrane 1, and the filtrate is transported through a header pipe or the like disposed above the hollow fiber membrane module 30. As a means for applying the pressure difference, a pressure pump, a vacuum (decompression) pump or the like is used. As shown in FIG. 5 (b), during filtration, the liquid L to be filtered in the hollow fiber membrane module 30 is deformed from the inner surface toward the outer surface of the deformed porous hollow fiber membrane 1. And filtered through.

  The module in which the above-described irregularly shaped porous hollow fiber membrane 1 is integrated is assumed to have other modes. For example, the module is not limited to the above-described casing type, and may be a non-casing type. Further, the cross-sectional shape of the module is not limited to the above-described circular shape (so-called cylindrical module) but may be a square shape (so-called casket type module). The filtration method (method) may be a full-volume filtration method or a cross flow filtration method, but in this embodiment, a cross flow filtration method is preferred. Moreover, a pressure filtration system or a suction filtration system may be used. As the operation method, the above-described fouling substance (the material to be filtered deposited on the membrane surface) may be performed simultaneously or individually, such as reverse pressure cleaning or hot water cleaning used for the purpose of removing. Moreover, as a liquid used for back pressure washing | cleaning, oxidizing agents, such as sodium hypochlorite, hydrogen peroxide, ozone, etc. can be used suitably.

  Next, a pressure filtration type filtration device will be described. FIG. 6 is a configuration diagram illustrating an example of a filtration device. As shown in the figure, the filtration device 40 includes a pump 41 for supplying pressure to the hollow fiber membrane module 30, a tank 42 for storing the filtrate, a tank 43 for storing the filtrate, and, if necessary, back pressure washing. The apparatus provided with the chemical | medical solution tank 44 and the liquid feeding pump 45 used for can be used suitably.

  Said filtration apparatus 40 can be used for the upstream process represented by isolation | separation of a microbial cell in the bioprocess field | area, downstream processes, such as isolation | separation refinement | purification and concentration of a bioproduct, and the process related to bioproduction itself.

  In the filtration method according to the present embodiment, high filtration performance and long-term stable filtration are achieved by using the hollow fiber membrane module 30, the filtration device 40, and the filtration method provided with the above-described many shaped porous hollow fiber membranes 1. Driving is possible.

  As described above, in the method for producing the deformed porous hollow fiber membrane 1, after melt-kneaded melt-kneaded thermoplastic resin, organic liquid and inorganic fine powder are ejected from the spinneret 20 and molded and cooled and solidified, In the method of extracting and removing the organic liquid and the inorganic fine powder, irregularities 25 are formed along the circumferential direction on the outer peripheral portion 23 a of the interior portion 23 constituting the discharge port 21 of the spinneret 20. With such a configuration, it is possible to suppress crushing of bacterial cells and cells contained in the liquid to be treated, and to improve filtration performance in a low linear velocity cross flow.

  In the present embodiment, a filter 26 is provided in at least one place until the melt-kneaded material is discharged from the discharge port 21 of the spinneret 20, and the melt-kneaded material is passed through the filter 26. When the irregular porous hollow fiber membrane 1 is produced by the above-described method, pores may be lowered in the concave portions 3B of the irregularities 3 of the irregular porous hollow fiber membrane 1 obtained due to uneven distribution of the inorganic fine powder. . The uneven distribution means that the inorganic fine powder is unevenly present at the tip portion of the convex portion 3A due to the force acting on the inside of the hollow fiber-like melt-kneaded product when the melt-kneaded product is discharged from the spinneret 20. The uneven distribution of the inorganic fine powder does not increase the openability of the tip portion of the convex portion 3A. Therefore, the openability of the inner surface of the hollow fiber membrane may be lowered and the filterability may not be sufficiently exhibited. Therefore, by providing the filter 26 at least at one point until the melt-kneaded material is discharged from the discharge port, uneven distribution of the inorganic fine powder can be suppressed, and deterioration of the openability in the recess 3B can be prevented. it can.

  The ratio between the pore diameter d of the filter 26 and the primary particle diameter of the inorganic fine powder is 1000 to 120,000. According to such a configuration, clogging in the filter 26 can be prevented, and the effect of distributing the inorganic fine powder can be exhibited, so that it is possible to prevent a decrease in the openability between the convex portions 3A (the concave portions 3B).

  Furthermore, it is preferable to provide the filter 26 at a position where it passes within 2000 seconds after the thermoplastic resin, the organic liquid and the inorganic fine powder are melt-kneaded so that there are 2 or more and 5 or less. According to such a structure, the effect of distributing inorganic fine powder uniformly can be acquired. Further, the time from when the melt-kneaded material passes through the last (lowermost) filter 26 to the time it is discharged is preferably within 0.1 to 100 seconds. If the time is 0.1 seconds or more, the ejection can be stably performed without being affected by the flow disturbance occurring in the filter 26. Moreover, if time is less than 100 second, the state (aggregation state, orientation of an aggregate) of the inorganic fine powder produced by letting it pass through the filter 17 can fully be maintained. The time from when the melt-kneaded material passes through the filter 26 until it is discharged is more preferably 75 seconds or less, still more preferably 60 seconds or less, and most preferably 30 seconds or less.

  Hereinafter, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to only these examples. In addition, the measuring method used for this Embodiment is as follows. The following measurements were all performed at 25 ° C. unless otherwise specified. Below, after explaining an evaluation method, the manufacturing method and evaluation result of an Example and a comparative example are explained.

  Moreover, in an Example, the filter should just have a slit which a melt-kneaded material passes, and the shape, thickness, etc. are selected suitably and are not specifically limited. That is, it may be in the form of a mesh as shown in FIG. 4, may be in the form of a honeycomb as found in a ceramic filter, or may be in the form of a narrow channel such as an orifice. May be. In particular, a mesh shape or a honeycomb shape having a plurality of slits is preferable from the viewpoint of dispersibility, and a thin mesh filter with little pressure loss is most preferable.

[Measurement of outer diameter and inner diameter (mm)]
The hollow fiber membrane is thinly cut with a razor or the like in a direction perpendicular to the longitudinal direction of the membrane, and the major axis and minor axis of the cross section and the major axis and minor axis of the outer diameter are measured using a microscope, and the following formulas (2) and ( According to 3), the inner diameter and the outer diameter were determined.

[Measurement of width and height (μm) of protrusions]
A photograph taken at an arbitrary magnification capable of clearly confirming the shape of the convex portion of the inner peripheral portion of the cross section of the irregular porous hollow fiber membrane by a scanning electron microscope was used. On the photograph, the length from the inner periphery without the convex portion to the tip of the convex portion was measured to determine the height of the convex portion. Moreover, the length of the recessed part and the recessed part was measured, and it was set as the width | variety of a convex part.

[Definition of concave and convex portions of hollow fiber membrane, width of convex portion, height of convex portion]
Here, the definition of the recessed part and convex part of a deformed porous hollow fiber membrane is demonstrated below. As shown in FIG. 1B, a portion on the center point side of the membrane from the average inner diameter is defined as a convex portion, and a portion on the outer diameter side of the membrane is defined as a concave portion. Here, the center point of the membrane is the intersection when the outer major axis and the outer minor axis are connected, and the average inner diameter D _ave is the value of the inner diameter when the inner diameter value is maximum from the center point of the membrane (hereinafter referred to as the maximum). The average value of the inner diameter D _max ) and the minimum inner diameter value (hereinafter, the minimum inner diameter D _min ) is shown. That is, the average inner diameter can be expressed by the following formula (4).

  Next, the width W of the convex portion will be described. The width W of the convex portion is a straight line connecting the circle having the above average inner diameter (dotted circle in FIG. 1B) and the intersection of the convex portions (points A and B in FIG. 1B are examples). The width of two convex portions is taken as the average value of the widths of all the convex portions of the convex portion of the hollow fiber membrane. Subsequently, the height H of the convex portion will be described. The height H of the convex portion was defined as the distance from the point closest to the center point of the film to the straight line drawn when measuring the width of the convex portion.

[Measurement of hole ratio]
In order to evaluate the decrease in the hole opening property of the recess, the hole opening ratio represented by the following formula (5) was used.
Aperture ratio = (opening ratio of concave part) / (opening ratio of convex part) (5)
Here, for example, as described in the pamphlet of International Publication No. WO2001 / 53213, the hole area ratio is obtained by overlaying a transparent sheet on a copy of an electron microscope image and painting the hole portion black using a black magic pen or the like. Then, by copying the transparent sheet onto white paper, the hole portion is clearly distinguished from black and the non-hole portion is clearly distinguished from white, and thereafter, it can be obtained using commercially available image analysis software. In addition, the opening ratio of the concave portion is an average value of the opening ratios of arbitrary five points of the concave portion, and the opening ratio of the convex portion is an average value of the opening ratios of arbitrary five points of the convex portion. .

[Measurement of pure water permeation flux (L / m ² / hr)]
FIG. 7 is a schematic diagram of an evaluation apparatus used for evaluating the filtration performance of the deformed porous hollow fiber membrane. As shown in FIG. 7, in the evaluation apparatus 50, the deformed porous hollow fiber membrane 51 wetted with pure water having a length of about 10 cm is set in a tube 52 having an inner diameter of 3 mm, and injection needles 54 and 55 having open ends are provided. The stab was set in the hollow portion of the irregularly shaped porous hollow fiber membrane 51. The both ends were sealed with silicon caps 53. Thereafter, the pure water filled in the stock solution tank 56 is sent from the pipe 58 and the pipe 59 to the tube 52 in which the deformed porous hollow fiber membrane 51 is set using the pump 57, and is returned to the stock solution tank 56 from the outlet 60. It was. Further, a part of the water sent to the tube 52 was filtered by the deformed porous hollow fiber membrane 51. The filtration operation was carried out for 60 minutes, the amount of filtered pure water permeated from the outlet 62 was measured, and the pure water permeation flux was determined by the following equation (6). At this time, the linear velocity of the water flowing in the deformed porous hollow fiber membrane was 0.1 m / sec, and the average value of pressures of the pressure gauge 63 and the pressure gauge 64 was 0.1 Mpa.
Pure water permeation flux J ₀ = (60 [min / h] × permeate amount [l]) / (π × membrane outer diameter [m] × membrane effective length [m] × measurement time [min]) (6)
In the above formula (4), the effective membrane length indicates the net membrane length of the irregular porous hollow fiber membrane excluding the portion where the injection needle is inserted, and π indicates the circumference.

[Measurement of permeation flux retention J / _{J 0]}
In the evaluation apparatus shown in FIG. 7, the pure water permeation flux (L / m ² / hr) except that the stock solution tank was filled with the cell culture solution (CHO-S cells 2 × 10 ⁶ cells / ml). The same operation as the measurement pure water permeation flux was performed. Using pure water permeation flux J ₀ obtained in the resulting membrane filtration water J and the (6), to calculate the flux retention J / J ₀ by the following equation (7).
Permeation flux retention ratio J / J ₀ = (permeation flux of cell culture medium) / (pure water permeation flux) (7)

[Torque inflection temperature of melt-kneaded product (℃)]
110 g of the solidified melt-kneaded product was put in a lab plast mill (manufactured by Toyo Seiki, model 30C150) and heated to 190 ° C. After the temperature increase, the mixture was kneaded at 50 rpm for about 10 minutes, and then heated to 270 ° C. at a temperature increase rate of 14 ° C./min, and the resin temperature at which the torque reached a maximum was defined as the torque inflection temperature.

[Extruder discharge resin temperature Tm (° C.), Spinner discharge resin temperature Ts (° C.)]
The extruder discharge resin temperature and the spinneret discharge resin temperature were measured by inserting a K-type thermocouple thermometer.
[raw materials]
The raw materials used in the examples are shown below.
<Plastic resin>
Vinylidene fluoride homopolymer (manufactured by Kureha Co., Ltd., trade name: KF # 1000)
<Organic liquid>
Bis (2-ethylhexyl) phthalate (manufactured by CG Esther)
Dibutyl phthalate (manufactured by CGester Co., Ltd.)
<Inorganic fine powder>
Fine silica (made by Nippon Aerosil Co., Ltd., trade name: AEROSIL-R972, average primary particle size of about 16 nm)
The formulation and production conditions in each example are shown in FIGS.

Example 1
A spinneret having a discharge port as shown in FIG. 3 using a vinylidene fluoride homopolymer as a thermoplastic resin, a mixture of bis (2-ethylhexyl) phthalate and dibutyl phthalate as an organic liquid, and finely divided silica as an inorganic fine powder. The hollow fiber membrane was melt extruded using a melt kneader. The composition of the melt-kneaded product is vinylidene fluoride homopolymer: phthalic acid (2-ethylhexyl): dibutyl phthalate: fine silica = 40: 30.8: 6.2: 23 (mass ratio), and as a fluid for forming a hollow part A hollow fiber melt-kneaded material was obtained at a resin temperature of 240 ° C. using air. Here, the filter was provided in the flow path between the outlet of the melt-kneader and before the spinneret. Specifically, it is a flow path between the extrusion port 11a and the discharge port 21 of the melt kneader 11 in FIG. The filter used was a laminate of 150 mesh (plain weave, slit width 109 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) and 40 mesh (plain weave, slit width 390 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) as a backup.

  The obtained hollow fiber melt-kneaded product was extracted with methylene chloride to remove phthalic acid (2-ethylhexyl) and dibutyl phthalate, and then dried. Then, it was immersed in 40 mass% ethanol aqueous solution for 30 minutes, and was immersed in water for 30 minutes. Next, it was immersed in a 5% by mass aqueous sodium hydroxide solution for 100 minutes, and further washed with water to extract and remove finely divided silica. The physical properties of the obtained film are shown in FIGS.

(Comparative example)
In the spinneret from which the hollow fiber melt-kneaded product is discharged, a deformed porosity is produced in the same manner as in Example 1 except that a double-ring spinneret having no notch in the annular ring inside the annular discharge outlet is used. A hollow fiber membrane was obtained. The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS. In the comparative example, the permeation flux retention is small because the scraping effect by the cross flow inside the hollow fiber is smaller than that of the irregular porous hollow fiber membrane.

(Example 2)
In Example 2, an irregularly shaped porous hollow fiber membrane was obtained in the same manner as in Example 1 except that no filter was installed after the melt-kneading step until the hollow fiber-like melt-kneaded product was discharged. . The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

(Example 3)
In Example 3, the method was the same as in Example 1 except that the ratio between the slit width of the filter and the primary particle size of the inorganic fine powder after the melt-kneading step until the hollow fiber-like melt-kneaded product was discharged was increased. A deformed porous hollow fiber membrane was obtained. Specifically, the ratio between the slit width of the filter and the primary particle diameter of the inorganic fine powder was 6813 in Example 1 and 24375 in this Example. The filter used was 40 mesh (plain weave, slit width 390 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) and 40 mesh (plain weave, slit width 390 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) as a backup. The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

Example 4
In Example 4, the same method as in Example 1 except that the ratio between the slit width of the filter and the primary particle size of the inorganic fine powder after the melt-kneading step until the hollow fiber-like melt-kneaded product is discharged is increased. A deformed porous hollow fiber membrane was obtained. Specifically, the ratio between the pore size of the filter and the primary particle size of the inorganic fine powder was 125,000. The filter used was 9 mesh (plain weave, slit width 2020 μm: manufactured by Taiyo Wire Mesh Co., Ltd.). The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

(Example 5)
In Example 5, the method was the same as in Example 1 except that the ratio between the slit width of the filter and the primary particle size of the inorganic fine powder after the melt-kneading process until the hollow fiber-like melt-kneaded product was discharged was reduced. A deformed porous hollow fiber membrane was obtained. Specifically, the ratio between the slit width of the filter and the primary particle size of the inorganic fine powder was 1625. The filter used was a stack of 500 mesh (twill, slit width 26 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) and 40 mesh (plain weave, slit width 390 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) as a backup. The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

(Example 6)
In Example 6, the same method as in Example 1 was used except that the ratio between the slit width of the filter and the primary particle size of the inorganic fine powder after the melt-kneading step until the hollow fiber-like melt-kneaded product was discharged was reduced. Carried out. Specifically, the ratio between the slit width of the filter and the primary particle diameter of the inorganic fine powder was 1250. The filter used was a laminate of 635 mesh (twill weave, slit width 20 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) and 40 mesh (plain weave, slit width 390 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) as a backup. The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

  Hereinafter, in Examples 7 to 9, the filter is a laminate of 150 mesh (plain weave, slit width 109 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) and 40 mesh (plain weave, slit width 390 μm: manufactured by Taiyo Wire Mesh Co., Ltd.) as a backup. Was used.

(Example 7)
In Example 7, an irregularly shaped porous hollow fiber membrane was obtained in the same manner as in Example 1 except that the number of filters between the melt kneading step and the discharge of the hollow fiber melt-kneaded product was changed from two to one. It was. The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

(Example 8)
In Example 8, an irregularly shaped porous hollow fiber membrane was obtained in the same manner as in Example 1 except that the number of filters after the melt-kneading step until discharging the hollow fiber-like melt-kneaded product was changed from 2 to 5. It was. The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

Example 9
In Example 9, a deformed porous hollow fiber membrane was obtained in the same manner as in Example 1 except that the number of filters after the melt-kneading step until discharging the hollow fiber-like melt-kneaded product was changed from 2 to 6. It was. The measurement results of the obtained film physical properties, pore ratio, and permeation flux retention are shown in FIGS.

  DESCRIPTION OF SYMBOLS 1 ... irregular-shaped porous hollow fiber membrane, 20 ... spinneret, 21 ... discharge outlet, 23 ... interior part, 23a ... outer peripheral part, 24 ... exterior part, 25 ... unevenness, 26 ... filter, 30 ... hollow fiber module, 40 ... Filtration device, d: slit width, P: melt-kneaded material.

Claims (7)

A molten kneaded material containing a thermoplastic resin, an organic liquid and inorganic fine powder is discharged from a double annular discharge port of a hollow fiber molding nozzle to form a hollow fiber-like material, and the hollow fiber-like material is cooled and solidified before the organic liquid And extracting and removing the inorganic fine powder to produce a deformed porous hollow fiber membrane,
The discharge port is composed of an annular interior part and an exterior part disposed so as to surround the interior part, and irregularities are formed in the outer peripheral part of the interior part along the circumferential direction of the interior part. Has been
Provide a filter in at least one place until the melt-kneaded product is discharged from the discharge port, and pass the melt-kneaded product through the filter.
The ratio between the slit width of the filter and the primary particle size of the inorganic fine powder is 1000 to 120,000,
A method for producing a deformed porous hollow fiber membrane, wherein the melt-kneaded product is molded and ejected at the ejection port. The filter is provided so as to be 2 or more and 5 or less at a position where the thermoplastic resin, the organic liquid, and the inorganic fine powder are melt-kneaded and pass within 2000 seconds. The method for producing a deformed porous hollow fiber membrane according to claim 1 . Two filters are stacked,
The slit width of one filter is 1000 to 120,000 times the primary particle diameter of the inorganic fine powder,
3. The slit width of another filter as a backup of the one filter is equal to or larger than the slit width of the one filter. A method for producing a deformed porous hollow fiber membrane. A deformed porous hollow fiber membrane produced by the method for producing a deformed porous hollow fiber membrane according to any one of claims 1 to 3 . The module using the irregular porous hollow fiber membrane manufactured by the manufacturing method of the irregular porous hollow fiber membrane as described in any one of Claims 1-3 . The filtration apparatus using the irregular porous hollow fiber membrane manufactured by the manufacturing method of the irregular porous hollow fiber membrane as described in any one of Claims 1-3 . The filtration method using the irregular porous hollow fiber membrane manufactured by the manufacturing method of the irregular porous hollow fiber membrane as described in any one of Claims 1-3 .

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