JP2008190081A - Method for producing hollow fiber membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a hollow fiber membrane, which is capable of preventing channeling in a hollow fiber membrane module and enabling expression of stable high permeability, while suppressing the formation of inferior quality product such as flattening or clogging of the hollow fiber membrane. <P>SOLUTION: The method for producing the hollow fiber membrane imparts crimps by passing the hollow fiber membrane through a crimp-imparting device consisting of at least a pair of rolls each equipped with many rods on the outer circumferential surface, wherein while the hollow fiber membrane travels along the rods on the outer circumferential surfaces of the rolls and changes its progressing direction, the hollow fiber membrane is caught a biting part between the rolls, meandered and imparted with the crimps. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a hollow fiber membrane. More specifically, while preventing the occurrence of poor quality of the hollow fiber membrane, by reducing the adhesion failure in the production of the hollow fiber membrane module, the drift of the external reflux liquid can be prevented and stable high dialysis efficiency can be expressed. The present invention relates to a method for producing a hollow fiber membrane.

  Compared to flat membranes, hollow fiber membranes that can accommodate a large membrane area in a small module are superior in volumetric efficiency and are used in various fields related to liquid processing, especially in the field of blood purification treatment Occupy its mainstream.

  The hollow fiber membranes are housed in a housing called a module in a state where 1000 to 20000 wires are bundled, and assembled as a hollow fiber membrane module. The performance of the hollow fiber membrane module depends on the permeation performance of the hollow fiber membrane itself, but the influence of the structure cannot be ignored.

  When the hollow fiber membrane module is used, for example, for blood purification, in its use, blood flows inside the hollow fiber membrane, and dialysate flows outside the hollow fiber membrane, that is, through the gap between the hollow fiber membranes. A mechanism is used to remove unnecessary substances in the blood to the dialysate side through a membrane between the blood and the dialysate. At this time, if the dialysate does not flow uniformly between all the hollow fiber membranes, but flows only to a certain part, the hollow fiber membranes where the dialysate does not flow cannot be used effectively, so the dialysis efficiency is significantly reduced, and the module As a result, the permeation performance is not sufficiently exhibited. This phenomenon is called drift or channeling, and it is known to have a great adverse effect on the ability to remove low-molecular substances such as urea.

  On the other hand, the hollow fiber membrane bundle in which the gap between the hollow fiber membranes is not sufficient as described above is liable to cause poor adhesion at the time of module assembly. That is, in the module assembling process, when the hollow fiber membrane end and the module end are bonded with resin, if the gap between the hollow fiber membranes is insufficient, the resin does not enter between them and a space is created, causing a minute leak or Adhesion failure called slip-out occurs. Therefore, many attempts have been made so far to avoid the drift phenomenon and adhesion failure as described above.

For example, a technique is disclosed in which a plurality of fins are formed in the longitudinal direction on the outer side of the hollow fiber membrane to prevent the hollow fiber membranes from sticking to each other, thereby maintaining the gap between the hollow fiber membranes. (See Patent Document 1). In addition, a technique for securing a gap between hollow fiber membranes by winding a spacer yarn around a hollow fiber membrane and utilizing the spreading force of the spacer yarn is shown. (For example, see Patent Document 2). However, the former technique requires a special die, restricts the operation surface and spinning conditions, and makes it difficult to express the permeation performance as a perfect circular hollow fiber membrane, which is not realistic. In addition, the latter technique has a problem in that a process for winding the spacer yarn is required, and thus the cost is high, and the bulkiness increases, so that a compact module cannot be obtained.
JP-A-61-119274 Japanese Patent Laid-Open No. 5-41979

Therefore, there are few restrictions on the operation surface and spinning conditions, and as a method of preventing drift phenomenon and adhesion failure simply at low cost, the hollow fiber membranes are crimped to provide close contact between adjacent hollow fiber membranes. Techniques for preventing this are disclosed. (For example, refer to Patent Document 3). In the technique disclosed in this document, a hollow fiber membrane that is spun is wound around a bobbin at a specific twill angle so that the hollow fiber membranes that overlap each other are in point contact. By corrugating the wound cheese, the corrugated shape (crimp) with the point-contacted portion as a fulcrum can be fixed to the hollow fiber membrane. This method is certainly an effective technique, but in order to heat-set the crimp, a process for heat treatment under special conditions is necessary after spinning, and the time required for the process cannot be ignored. Moreover, it is limited to the treatment in a bobbin winding state, and there is a problem that it cannot be applied to a hollow fiber membrane in which bobbin winding cannot be performed. Furthermore, since the number of crimps per unit length differs between the inner layer and the outer layer of the bobbin, the module manufactured using the hollow fiber membrane on the outer layer side is different from the module manufactured using the hollow fiber membrane on the inner layer side. There is a problem that a difference in performance occurs.
JP 58-182722 A

  In recent years, the effect of the above crimp has been reconfirmed, and attempts have been made to impart crimp to hollow fiber membranes manufactured in forms other than bobbin winding. In recent years, a hollow fiber membrane having an asymmetric structure having a dense skin layer inside the hollow fiber membrane has attracted attention. The asymmetric structure membrane is manufactured using a liquid having a coagulation property with respect to a polymer, particularly an aqueous solution, as a core liquid in order to form a skin layer inside the hollow fiber membrane. When such a hollow fiber membrane is wound around a bobbin, a core liquid containing water is contained, so that when the heat treatment is performed for crimp fixation, the membrane is crushed due to the influence of surface tension accompanying water evaporation.

  As a method of applying a crimp to a hollow fiber membrane having an asymmetric structure, trials are made to mechanically form a wave in the hollow fiber membrane by passing the hollow fiber membrane while meandering between opposing gears. Has been. However, in such a mechanical treatment, an effective crimp has not been provided so far, especially for delicate hollow fiber membranes used for blood purification. This is because in order to give an effective strong crimp, it is necessary to apply a stronger mechanical external force to the hollow fiber membrane, so that the hollow fiber membrane may be deformed or blocked, or the membrane may be damaged. This is because there is a very high possibility of falling.

  Therefore, in the prior art, only a wave having a large wave waving structure with a long pitch between crimps can be used as a product so as not to damage the hollow fiber membrane as much as possible. However, in such a wave waving structure, the effect of ensuring the gap between the adjacent hollow fiber membranes is not sufficient, so this alone cannot completely avoid the drift, such as improvement of the module housing structure, etc. The reality is that it is supported by using it together with other technologies.

For example, in Patent Document 4, the above problem is solved by applying a crimp with a wavelength of 10 mm or more and an amplitude of 0.2 mm or more. However, there is a problem in the stability of the drift suppression effect, and many modules were manufactured. In some cases, modules that cannot express the original transmission performance may be mixed.
JP-A-2005-348784

  Therefore, in view of these conventional techniques, the present invention suppresses the quality defect of the hollow fiber membrane, prevents the drift phenomenon of dialysate when assembled as a module, and exhibits stable high permeation performance and reduction of adhesion failure. Provided is a method for producing a hollow fiber membrane that makes it possible.

The manufacturing method of the hollow fiber membrane of this invention which can solve said subject consists of the following structures.
(1) A method for producing a hollow fiber membrane in which a hollow fiber membrane is applied by passing the hollow fiber membrane through a crimp applying device comprising at least a pair of rolls having a large number of rods on the outer peripheral surface, the hollow fiber membrane being a roll A method for producing a hollow fiber membrane, characterized in that the hollow fiber membrane is sandwiched between meandering portions between rolls, meandering, and crimped while changing the traveling direction while traveling along a rod on the outer peripheral surface .
(2) The method for producing a hollow fiber membrane according to (1), wherein the meshing portions of the roll do not contact each other.
(3) The method for producing a hollow fiber membrane according to (1) or (2), wherein a pitch between the rods is 15 mm or less.
(4) The method for producing a hollow fiber membrane according to any one of (1) to (3), wherein an outer diameter of the rod is 1 to 5 mmφ.
(5) The method for producing a hollow fiber membrane according to any one of (1) to (4), wherein the rod rotates freely.
(6) The method for producing a hollow fiber membrane according to any one of (1) to (5), wherein the surface of the rod is mirror-finished.
(7) The hollow fiber membrane according to any one of (1) to (6), wherein a biting depth in which the hollow fiber membrane is sandwiched between the meshing portions between the rolls is 0.3 to 5.0 mm Manufacturing method.

  According to the method for producing a hollow fiber membrane of the present invention, it is possible to provide an effective crimp for reducing adhesion failure when assembling a hollow fiber membrane module and preventing drift when the module is used, so that stable and high permeation performance can be expressed. It becomes possible to obtain a hollow fiber membrane with a high yield. In addition, when crimping is mechanically applied, the risk of flattening, blocking, and breakage of the hollow fiber membrane has been a big problem in the past, but the production method of the present invention can suppress the occurrence of such defective products. It becomes possible. Furthermore, the energy required for heat fixing is not required, which is effective for cost saving and simplification of equipment. Therefore, it can be suitably used as a method for producing a hollow fiber membrane that is particularly required to maintain quality.

  Embodiments of a method for producing a hollow fiber membrane to which the present invention is applied will be described below.

  The present inventors have investigated and examined in detail the cause of not being able to impart sufficient crimps by conventional crimping techniques other than the heat setting method.

  First, in the hollow fiber membrane module, a critical crimp element for securing a gap between the hollow fiber membranes and preventing a drift of the fluid flowing through the gap was examined. The shape of the corrugated shape similar to or similar to that of the hollow fiber membrane that retains the corrugated shape to the extent that the hollow fiber membrane is suspended vertically is called a crimp. It is evaluated by the number of crimps (the number existing per unit length of the hollow fiber membrane) and the amplitude (size of the hollow fiber membrane swinging perpendicular to the length direction). When both of these were examined, it was found that the number of crimps was more important than the amplitude of the crimps. In other words, between hollow fiber membranes having a large amplitude with a small number of crimps, the section of the same traveling while the hollow fiber membranes are in contact with each other cannot be ignored, whereas hollow fiber membranes having a large number of crimps Then, since the probability of traveling the same physically decreased, it was found that it is effective for preventing drift. Furthermore, a crimp that is not heat-fixed may lose its shape and function due to tension or other external force applied to the hollow fiber membrane after crimping, but the greater the number of crimps, the greater the effect of external force on one crimp. Therefore, there is an advantage that the crimp shape and the function can be easily maintained.

  Therefore, when the crimping device was examined, the conventional device as shown in FIG. 7 has a pitch effective for increasing the number of crimps due to technical problems such as machining accuracy, assembly accuracy, and play of operation. It turned out to be difficult to narrow. Further investigation and examination were carried out, and the equipment as shown in FIG. 6 succeeded in securing an effective pitch in terms of equipment, but especially for hollow fiber membranes having a thin film thickness and relatively low strength. An effective crimp could not be given. In addition, if the crimping is forcibly applied, the hollow fiber membrane is flattened or clogged, and the quality and function of the hollow fiber membrane are lost.

As a result of detailed investigations on the disappearance and relaxation of the crimp, it was found that the hollow fiber membrane was slipped at the portion sandwiched by the crimping device by pulling the hollow fiber membrane in the rear step. It was. That is, the stress applied to the hollow fiber membrane is not concentrated in one point, but is dispersed in the length direction of the hollow fiber membrane, so that the crimps that appear to be applied are taken up, bundled, washed, dried, bundled During the storage period, the crimps are stretched, resulting in a decrease in the yield of producing hollow fiber membrane modules such as blood purifiers, or inability to fully develop the performance of the hollow fiber membrane modules.
Another reason is that slippage of the hollow fiber membrane cannot be avoided even when the hollow fiber membrane is sandwiched between the gears and rolls of the crimping device. In particular, when the hollow fiber membrane has traveled more freely than in the previous process, the slip at the biting portion becomes larger, the stress is not concentrated on one point, and the crimp is not fixed to the hollow fiber membrane. it was thought.
Therefore, as a result of intensive studies on the prevention of slippage of the hollow fiber membrane in the crimp applying device, the present inventors have determined that the hollow fiber membrane is formed on the outer circumferential surface of the roll before and after the hollow fiber membrane is sandwiched between at least a pair of rolls. By moving the rod along a certain distance or more, slipping between the rod and the hollow fiber membrane is suppressed, and by concentrating the pressure of the rod on one point of the hollow fiber membrane, it is extremely possible without adding energy such as heat. It was discovered that a good crimp could be fixed to the hollow fiber membrane, and the present invention was finally completed.

  The crimping in the present invention is preferably performed by sandwiching a hollow fiber membrane in an engagement portion between at least a pair of rolls provided with a large number of rods on the outer peripheral surface. At least a pair of rolls rotate at a constant speed, and the outer peripheral surface of the roll is composed of a large number of rods arranged in parallel so that they can be engaged with each other in a gear shape so that they do not completely contact each other. Has been. A crimp can be applied by sandwiching a hollow fiber membrane between the rolls. The rods are preferably arranged in parallel, but even if they are not geometrically completely parallel, if the gap can be provided so that the hollow fiber membrane is not crushed when the roll is bitten, Deviation may be acceptable. In the present invention, crimping may be performed only once between a pair of rolls, but a hollow fiber membrane may be run in an eight-letter shape using a pair of rolls, or three or more rolls are combined. It is also within the scope of the present invention to use a method of sequentially passing the respective meshing portions using a material.

  In the present invention, the diameter of the roll is not particularly limited, but if it is too large, not only the equipment cost increases, but also the workability when passing the hollow fiber membrane between the rolls and the slackness of the hollow fiber membrane during running There is concern about thread breakage. Moreover, when too small, it will become difficult to equip a roll with a sufficient number of rods, and the condition setting of a crimp provision part may become too sensitive. For example, assuming that crimping is applied to a hollow fiber membrane having an outer diameter of 100 to 2000 μm, a roll outer diameter of about 10 to 50 cmφ is appropriate. Two or more such rolls are used in combination for crimping.

  The number of rods or protrusions varies depending on the size of the roll and what kind of wavelength and amplitude crimp is obtained, and is not particularly limited. However, when the number is extremely small, it is difficult to physically sandwich the hollow fiber membrane. Therefore, there is a possibility that an effective crimp cannot be given. On the other hand, when the number is extremely large, not only the equipment becomes huge, but also slack and thread breakage may occur during traveling. Accordingly, the number is preferably 20 or more and 1000 or less, more preferably 50 or more and 300 or less.

  In the present invention, the rod provided on the outer peripheral surface of the roll is not particularly limited as long as the rod portion of the other roll can be engaged with the groove portion between the rods of the one roll in a gear shape. A large number of rods may be arranged on the outer peripheral surface in parallel, or a plurality of grooves and protrusions may be formed in parallel by cutting out the outer peripheral surface of the roll instead of the rod. However, since the outer peripheral part of the protrusion formed by the rod or shaving is in direct contact with the hollow fiber membrane, the rod arranged on the outer peripheral surface is preferably cylindrical so that the hollow fiber membrane is not damaged, or the protrusion is It is preferable that it is formed in an arc shape along the traveling direction of the hollow fiber membrane. The surface of the rod and projection that contacts the hollow fiber membrane is preferably mirror-finished so that the hollow fiber membrane is not damaged by contact with the hollow fiber membrane and the hollow fiber membrane does not slip. Further, in the case of a rod, it is more preferable that the rod is designed to rotate along the travel of the hollow fiber membrane because damage to the hollow fiber membrane is further reduced. The material of the rod and the protrusion is not particularly limited, but is preferably made of stainless steel or aluminum from the viewpoint of workability and availability, and stainless steel is more preferred from the viewpoint of durability. Further, it is also within the scope of the present invention to use a material whose surface has been subjected to a coating treatment for improving corrosion resistance, anti-slip and abrasion resistance.

  The pitch between the rods or protrusions provided in the crimping device of the present invention may be set as appropriate depending on the desired number of crimps, but it is preferable that the pitch is as narrow as possible in order to ensure an effective number of crimps. However, if it is too narrow, it becomes difficult to secure a gap for sandwiching the hollow fiber membranes because of a decrease in workability and durability, and is preferably 1 mm or more and 15 mm or less, more preferably 3 mm or more and 10 mm or less, and further preferably 4 mm or more and 8 mm or less. is there. It is more convenient for manufacturing and maintenance that the pitch between the rods or the projections is equal, but the spacing may be changed intentionally as long as they can be engaged with each other in a gear shape. In addition, it is convenient for manufacturing and maintenance to arrange the rod or the projection in parallel with the rotation axis of the cylindrical portion, but this may be changed intentionally as long as it can be meshed with each other in a gear shape. .

  If the diameter of the protrusion formed by cutting out the rod or groove is too large, it will be difficult to ensure the above pitch, and if it is too small, the risk that the hollow fiber membrane will break increases. Although it depends on the strength and elongation of the hollow fiber membrane, it is preferably 1.0 to 5.0 mmφ, and more preferably 2.0 to 4.0 mmφ.

  In the present invention, when crimping the hollow fiber membrane, it is important to run the hollow fiber membrane along the outer peripheral surface of the roll before and after the biting portion of the roll. As a result, the hollow fiber membrane is gripped without slipping at the biting portion of the roll, and the stress of the rod or protrusion is concentrated at one point of the hollow fiber membrane, so that an effective crimp can be imparted. As a result of further studies on this point, a certain interval is required from when the hollow fiber membrane contacts the crimp applying device until it passes through the meshing portion between the rolls and leaves the crimp applying device. When the preferred section is expressed by an angle around the rotation axis of the crimping device that travels while the hollow fiber membrane is in contact, it can be said that a total of 90 ° or more is sufficient. It is more preferable to take 45 ° or more before and after biting. When there are few sections that run while in contact, the hollow fiber membrane that passes through the meshing portion between the rolls may slip due to the tension received from winding or the subsequent process, and an effective crimp cannot be obtained. Sometimes. In addition, the yarn path where the section running in contact exceeds 720 ° is not only complicated, but also the workability when passing the hollow fiber membrane through the crimping device, the slackness of the thread, the thread breakage, etc. Operational risks may increase. Therefore, the section in which the hollow fiber membrane travels along the outer peripheral surface of the crimp of the crimping device of the present invention is preferably 90 ° or more and 720 ° or less, and more preferably 180 ° or more and 540 ° or less.

Conventionally, hollow fiber membranes that have only been mechanically crimped without being heat-set may be loosened or lost during subsequent washing and drying processes, module production, and storage. The generation of problems could not be suppressed. Although the details of this reason are not known, when the hollow fiber membrane that has been traveling freely enters the meshing portion of the gear or belt of the crimping device, the slip of the hollow fiber membrane at the meshing portion increases. When slip occurs in this way, stress is not concentrated on one point of the hollow fiber membrane, so that it is considered that a phenomenon occurs in which the crimp is relaxed in the external force that the hollow fiber membrane receives later or in post-processing.
In the present invention, by applying consideration to prevent slipping when the hollow fiber membrane enters the meshing portion of the crimping device, it is possible to provide a crimp that is strong and has good crimp retention for a long time without heat fixing. I guess it was possible.

In the present invention, the number of crimps per 1 cm of the hollow fiber membrane is preferably 0.50 piece / cm or more. In the prior art of the present inventors, the drift prevention effect of a module manufactured using a hollow fiber membrane to which crimping is applied by bobbin winding and heat fixing has a track record in clinical practice. The number of crimps of this bobbin wound product was targeted, and the lower limit of the number of crimps was within the above range. 0.60 piece / cm or more is more preferable, and 0.65 piece / cm or more is more preferable. Although there are no particular problems due to the excessive number of crimps, the upper limit is considered to be about 10 pieces / cm or less in consideration of the manufacturing cost and technical difficulty of the crimping device.
In addition, it is preferable that the number of crimps after module fabrication is maintained at 80% or more of the number of crimps immediately after passing the crimping device. The fact that the above range is maintained means that the degree of disappearance of the crimp is small even after various steps after passing the crimping equipment, and that the crimp is firmly fixed to the hollow fiber membrane. is there. Therefore, the possibility of occurrence of drift during actual use can be kept low, which is preferable. The crimp retention is more preferably 85% or more, and still more preferably 90% or more.

  The hollow fiber membrane of the present invention is preferably provided with a crimp having an amplitude of 0.2 mm or more. When the amplitude of the hollow fiber membrane is too small, the module assembly process deteriorates due to the displacement of the hollow fiber membrane in the film in the module assembly process, or due to the close contact between the hollow fiber membranes and the drift of the dialysate, A decrease in transmission performance may occur. On the other hand, if the amplitude of the crimp becomes too large, the resistance when inserting the bundle of hollow fiber membranes into the module case is increased in the module assembling process, and the surface of the hollow fiber membranes may be damaged and leakage may occur. . Therefore, the amplitude of the crimp is 5 mm or less, more preferably 4 mm or less.

  In the crimping device, the depth of the meshing portion that sandwiches the hollow fiber membrane is the diameter of the rod or protrusion, or their pitch, and further the strength and elongation of the hollow fiber membrane, the outer diameter, the desired crimp amplitude, etc. May be set as appropriate. If the depth of the meshing portion is too shallow, an effective crimp cannot be imparted, and conversely if too deep, problems such as flatness of the hollow fiber membrane, loosening during running, and thread breakage may occur. The depth of the mating portion is not less than 0.5 mm and not more than 5.0 mm.

  In addition, since an effective crimp cannot be imparted when the hollow fiber membrane is completely relaxed, it is necessary to apply an appropriate tension to the crimp imparting portion, but the strength of this is also the strength of the crimp imparting device. An appropriate strength is appropriately selected according to the diameter of the rod or the protrusion, or their pitch, the strength and elongation of the hollow fiber membrane, the outer diameter, and the like. It can be adjusted according to the rotation speed and the biting depth of the crimping device, and in order to impart the crimp effectively, it is preferable to set so that the most deformed portion is higher than the yield strength of the film and less than the breaking strength. . Specifically, it is preferable to give a tension of 0.5 to 50 gf per hollow fiber membrane.

  In the present invention, the speed of the hollow fiber membrane that runs through the crimping device is not particularly limited as long as it is a speed that does not cause a problem in winding of the hollow fiber membrane, but in the case of a hollow fiber membrane for blood purification, the performance of the hollow fiber membrane Considering the impact on the environment, 5 ~ 200m / min is appropriate.

  The diameter and film thickness of the hollow fiber membrane in the present invention are appropriately selected depending on the application and membrane material, and are not particularly defined as long as they are useful as a hollow fiber membrane. It is difficult to ensure the gap of the film, and if the diameter is too small, there is a problem that the cost increases in order to secure the membrane area. Therefore, the preferable outer diameter is 100 μm or more and less than 2000 μm, more preferably 150 μm or more and less than 1500 μm. It is. Also, if the film thickness is too thin, it will be difficult to provide effective crimping and maintain the quality of the hollow fiber membrane even if the present invention is applied. Conversely, if it is too thick, the raw material cost will increase and the performance as a membrane module will deteriorate. Therefore, the preferable film thickness is 10 μm or more and less than 150 μm, more preferably 15 μm or more and less than 100 μm.

  Further, in the present invention, a plurality of hollow fiber membranes that pass through the crimping device may be run together, but if there are too many bundles, the apparent diameter increases, The gap between the rods is not sufficiently secured, and flattening and blockage are likely to occur. Moreover, even if crimps are applied in a collective state, the crimp phase is synchronized, so that it is difficult to break, and the effects of the present invention may not be obtained. Therefore, when collecting the hollow fiber membranes when the crimping device is run, the number is preferably 10 or less, more preferably 4 or less. It is more preferable to run with a single yarn without putting them together.

  The material of the hollow fiber membrane in the present invention is not particularly limited, and examples thereof include cellulose derivatives or polysulfone or polyacrylonitrile polymers, polyamides, polymethyl methacrylate, ethylene vinyl alcohol copolymers, etc. A cellulose derivative or a polysulfone-based or polyacrylonitrile-based polymer has a high effect of the present invention and can be suitably used because it can exhibit permeation performance.

  Although the structure of the hollow fiber membrane in the present invention is not particularly limited, a hollow fiber membrane called an asymmetric membrane having a skin structure on the inside produced using an aqueous solution as the core liquid of the hollow fiber membrane can be produced in the form of cheese. The effect of the present invention is higher because it is difficult to impart an effective crimp with the prior art.

  Further, the hollow fiber membrane obtained by the present invention is assembled as a hollow fiber membrane module in a bundle of 1000 to 20000, but an appropriate number is selected depending on the housing diameter of the module and the outer diameter of the hollow fiber membrane. The When the filling rate is defined as (hollow fiber membrane outer shape) × (number of hollow fiber membranes) / (module housing end inner diameter) × 100 (%), the preferred filling rate is 30% to 75%. When the filling rate is smaller than 30%, an effective membrane area cannot be obtained for the module size, which is inefficient and the effect of the present invention is also small. On the other hand, when the filling rate increases to exceed 75%, the hollow fiber membranes in the module housing are in close contact with each other, and it is difficult not only to physically obtain a gap between the hollow fiber membranes, but also to be inserted into the case. This may cause other problems such as damage to the film due to contact.

  Hereinafter, preferred embodiments of the present invention will be described with reference to Examples. However, the present invention is not limited by these.

(Measurement method of hollow fiber membrane inner diameter and film thickness)
A sample of the cross section of the hollow fiber membrane can be obtained as follows. For the measurement, it is preferable to observe in a form in which the hollow fiber membrane is dried after washing and removing the core liquid. There is no limitation on the drying method. However, when the shape changes remarkably by drying, it is preferable to clean and remove the hollow forming material and then completely replace with pure water, and then observe the shape in a wet state. The inner diameter, outer diameter, and film thickness of the hollow fiber membrane are cut through a razor on the upper and lower surfaces of the slide glass so that the hollow fiber membrane does not fall out into the 3mmφ hole in the center of the slide glass. Then, after obtaining a hollow fiber membrane cross-section sample, it is obtained by measuring the short diameter and long diameter of the hollow fiber membrane cross section using a projector Nikon-12A. Measure the short axis and long axis in two directions for each cross section of hollow fiber membrane, and calculate the arithmetic average value of each as the inner diameter and outer diameter of one hollow fiber membrane cross section. The film thickness is calculated as (outer diameter-inner diameter) / 2. did. The same measurement was performed on five cross sections, and the average value was defined as the inner diameter and film thickness.

(Method for measuring the number of crimps of hollow fiber membranes)
The number of crimps applied to the hollow fiber membrane is measured as follows. When the hollow fiber membrane is cut out about 20cm and placed so that the length direction of the hollow fiber membrane is vertical, the number of peaks on the wavy part is counted (the number of valleys is not counted) The number per unit length is calculated from the length of the cut hollow fiber membrane. Measure in the same manner for five hollow fiber membranes and use the average value. At this time, the apparent length when the hollow fiber membrane is hung vertically downward is used as the length of the hollow fiber membrane.

(Measurement method of amplitude of hollow fiber membrane)
The amplitude applied to the hollow fiber membrane is measured as follows. Cut 10-30 cm of the hollow fiber membrane, measure the width of the wavy portion with respect to the length direction of one crest and the next trough, and calculate a half value thereof. Measure in the same manner for five hollow fiber membranes and use the average value.

(Measurement method of roundness of hollow fiber membrane)
In order to evaluate the flatness of the hollow fiber membrane, the roundness of the hollow fiber membrane was measured. The roundness is the ratio of the minor axis / major axis of the inner diameter of the hollow fiber membrane in the cross section of the hollow fiber membrane. For example, the roundness is 1 for a perfect circle. Using an image analysis software “Image-Pro Plus” (Media Cybernetics), measurement was performed by image analysis on an arbitrary 100 cross-sections of hollow fiber membranes in the module end face, and the average value was obtained.

(Measurement method of hollow fiber membrane crushing)
In order to evaluate the blockage of the hollow fiber membrane, the collapse of the hollow fiber membrane was measured. Hollow fiber membrane crushing is defined as the extreme flatness of the minor axis / major axis ratio of the hollow fiber inner diameter in the hollow fiber membrane cross section being less than 1/3 or the hollow part being substantially collapsed. The number present in the end face was counted, and the existence ratio was determined from the total number of hollow fiber membranes contained in the end face.

(Measurement method of urea clearance of hollow fiber membrane module)
The urea clearance of the hollow fiber membrane module was measured according to the dialyzer performance evaluation standard published by the Japanese Society for Dialysis Medicine and converted to a value per membrane area of 1.0 m ² .
It was dissolved in dialysate (Kindaly diluted solution) at a concentration of 1.0 g / L of urea to obtain a measurement solution. A 37 ° C measurement solution (hereinafter referred to as B solution) is introduced at a rate of 200 ml / min from the blood side inlet of the module, and a dialysate (hereinafter referred to as D solution) maintained at 37 ° C from the dialysate side inlet is 500 ml / min. It was introduced countercurrently to the B liquid at min. B liquid inlet and outlet pressure (P _Bi and P _Bo respectively) and D liquid inlet and outlet pressure (P _Di and P _Do respectively) are measured, and the transmembrane pressure difference (TMP) 100mmHg shown in Equation 1 Measurements were made at
TMP = (P _Bi + P _Bo ) / 2− (P _Di + P _Do ) / 2 (Formula 1)
While confirming that there was no flow rate change during the measurement, the liquid at the inlet and outlet of the liquid B and the liquid at the outlet of the liquid D were sampled. The concentration of the sampling solution was determined using Urea Nitrogen Test Wako B manufactured by Wako Pure Chemical Industries, and clearance (CL) was calculated from these values using Equations 2 and 3.
CL = (C _Bi × Q _Bi −C _Bo × Q _Bo ) / C _Bi (Formula 2)
Where C _Bi is the B solution inlet solute concentration (g / ml), Q _Bi is the B solution inlet flow rate (ml / min), C _Bo is the B solution outlet solute concentration (g / ml), Q _Bo is the B solution outlet Flow rate (ml / min). For these values, those with a mass balance error (MBE) of 5% or less were adopted. MBE was calculated from Equation 2 below.
MBE = (Q _Bi x C _Bi- Q _Bo x C _Bo- Q _Do x C _Do ) / (Q _Bi x C _Bi- Q _Bo x C _Bo ) (Formula 3)
Here, Q _Do is the D solution outlet flow rate, and C _Do is the D solution outlet concentration.
By employing the hollow fiber membrane production method of the present invention, a high-quality hollow fiber membrane having a urea clearance variation (σ) of 15 or less measured using five modules can be obtained with high accuracy. More preferably, the variation is 10 or less, and further preferably 7 or less.

(Example 1)
Polyethersulfone (Sumitomo Chemtec Co., Ltd. Sumika Excel (registered trademark) 4800P) 17.5% by mass, Polyvinylpyrrolidone (BASF Koridone (registered trademark) K-90) 3.0% by mass, non-solvent 5.5% by mass water, dimethyl solvent A solution obtained by uniformly dissolving 74.0% by mass of acetamide was used as a spinning dope, and a 44.5% by mass dimethylacetamide aqueous solution was used as a core solution. Using a spinneret with a double-pipe structure, a spinning stock solution was discharged from the outside, and a core solution was discharged from the inside in a vertically downward direction to form a hollow fiber membrane. After passing through a steam atmosphere of 620 mm in length, it is immersed in a coagulation bath, passed through a washing bath and hot water bath, then passed through a crimping device with a single yarn, and wound with a casserole at a winding speed of 40 m / min. It was. At that time, the yarn path passing through the crimping device is S-shaped as shown in FIG. 3 (the angle at which the hollow fiber membrane runs along the roll before and after the roll biting portion of the crimping device: 180 ° before biting) 180 ° after biting), and at a middle portion, the crimping device was sandwiched between φ2.0 mm rods arranged at a pitch of 7.9 mm with a biting depth of 2.5 mm. The tension in the crimping equipment was 1.0 gf per hollow fiber membrane.
A bundle of 10100 wound hollow fiber membranes was inserted into a polyethylene pipe, cut perpendicularly to the length direction into a bundle, and dried. The hollow fiber membrane was taken out from the dried bundle, and the crimp was measured. Moreover, the bundle after drying was assembled in the module, and crush evaluation and urea clearance measurement were performed.
The results are shown in Table 1. However, five modules were prepared, and urea clearance indicates an average value measured excluding modules with poor adhesion. Moreover, the filling rate of the hollow fiber membrane with respect to the module diameter was in the range of 55 to 65%.

(Example 2)
A hollow fiber membrane was formed in the same manner as in Example 1, and wound with a cassette at a winding speed of 75 m / min. As shown in FIG. 4, the yarn path passing through the crimping device has a saddle shape (the angle at which the hollow fiber membrane runs along the roll before and after the roll biting portion of the crimping device: 90 ° before biting, biting 90 °), and the intermediate portion was sandwiched between the 2.0 mm-diameter rods arranged at a pitch of 4.8 mm with a crimping depth of 1.0 mm. The tension in the crimping equipment was 1.6 gf per hollow fiber membrane.
A bundle of 10100 wound hollow fiber membranes was inserted into a polyethylene pipe, cut perpendicularly to the length direction into a bundle, and dried. The hollow fiber membrane was taken out from the dried bundle, and the crimp was measured. Moreover, the bundle after drying was assembled in the module, and crush evaluation and urea clearance measurement were performed.
The results are shown in Table 1. However, five modules were prepared, and urea clearance indicates an average value measured excluding modules with poor adhesion. Moreover, the filling rate of the hollow fiber membrane with respect to the module diameter was in the range of 55 to 65%.

(Example 3)
As the spinning dope, 19.0% by mass of cellulose triacetate manufactured by Daicel Chemical Industries, 68.9% by mass of N-methyl-2-pyrrolidone, and 12.1% by mass of triethylene glycol were mixed and dissolved at 180 ° C. This was discharged vertically downward from the outer annular part of the spinneret with a double pipe structure. At the same time, water was supplied to the inner tube as a core liquid to form a hollow fiber membrane. After passing through a 30 mm steam atmosphere, this hollow fiber membrane was passed through a coagulation bath and a water washing bath, passed through a crimping device with a single yarn, and wound with a casserole at a winding speed of 60 m / min. At that time, the yarn path passing through the crimping device is S-shaped as shown in FIG. 5 (the angle at which the hollow fiber membrane runs along the roll before and after the roll biting portion of the crimping device: 210 ° before biting, At 210 ° after biting, the crimping device was sandwiched between the φ2.0 mm rods arranged at a pitch of 7.9 mm with a biting depth of 3.5 mm. The tension in the crimp application facility was 1.3 gf per hollow fiber membrane.
A bundle of 10800 wound hollow fiber membranes was inserted into a polyethylene pipe, cut perpendicularly to the length direction to form a bundle, and dried. The hollow fiber membrane was taken out from the dried bundle, and the crimp was measured. Moreover, the bundle after drying was assembled in the module, and crush evaluation and urea clearance measurement were performed.
The results are shown in Table 1. However, five modules were prepared, and urea clearance indicates an average value measured excluding modules with poor adhesion. Moreover, the filling rate of the hollow fiber membrane with respect to the module diameter was in the range of 55 to 65%.

Example 4
A hollow fiber membrane was formed in the same manner as in Example 1, and wound with a cassette at a winding speed of 40 m / min. The yarn path passing through the crimping device was formed in an S shape as shown in FIG. 3, and the hollow fiber membrane was sandwiched between the φ3.5 mm rods with a depth of 3.0 mm. The pitch between the rods was 7.9 mm. The tension in the crimping equipment was 0.9 gf per hollow fiber membrane.
A bundle of 10100 wound hollow fiber membranes was inserted into a polyethylene pipe, cut perpendicularly to the length direction into a bundle, and dried. The hollow fiber membrane was taken out from the dried bundle, and the crimp was measured. Moreover, the bundle after drying was assembled in the module, and crush evaluation and urea clearance measurement were performed.
The results are shown in Table 1. However, five modules were prepared, and urea clearance indicates an average value measured excluding modules with poor adhesion. Moreover, the filling rate of the hollow fiber membrane with respect to the module diameter was in the range of 55 to 65%.

(Comparative Example 1)
A hollow fiber membrane was formed in the same manner as in Example 1, and wound with a cassette at a winding speed of 40 m / min. As a crimping device, a belt-like facility having a large number of rods on the upper and lower sides as shown in FIG. 6 was used, and the hollow fiber membrane was sandwiched between φ4.5 mm rods with a depth of 4.5 mm. The pitch between the rods was 20.0 mm. The tension in the crimping equipment was 2.6 gf per hollow fiber membrane.
A bundle of 10100 wound hollow fiber membranes was inserted into a polyethylene pipe, cut perpendicularly to the length direction into a bundle, and dried. The hollow fiber membrane was taken out from the dried bundle, and the crimp was measured. Moreover, the bundle after drying was assembled in the module, and crush evaluation and urea clearance measurement were performed.
The results are shown in Table 1. However, five modules were prepared, and urea clearance indicates an average value measured excluding modules with poor adhesion. Moreover, the filling rate of the hollow fiber membrane with respect to the module diameter was in the range of 55 to 65%.

(Comparative Example 2)
A hollow fiber membrane was formed in the same manner as in Example 3, and wound with a cassette at a winding speed of 60 m / min. The yarn path passing through the crimping device was straight as shown in FIG. 7 and was sandwiched between φ2.0 mm rods arranged at a pitch of 7.9 mm in the crimping device at a depth of 4.0 mm. The tension in the crimp application facility was 1.3 gf per hollow fiber membrane.
A bundle of 10800 wound hollow fiber membranes was inserted into a polyethylene pipe, cut perpendicularly to the length direction to form a bundle, and dried. The hollow fiber membrane was taken out from the dried bundle, and the crimp was measured. Moreover, the bundle after drying was assembled in the module, and crush evaluation and urea clearance measurement were performed.
The results are shown in Table 1. However, five modules were prepared, and urea clearance indicates an average value measured excluding modules with poor adhesion. Moreover, the filling rate of the hollow fiber membrane with respect to the module diameter was in the range of 55 to 65%.

(Comparative Example 3)
A hollow fiber membrane was formed in the same manner as in Example 3, and wound with a cassette at a winding speed of 60 m / min. At that time, the yarn path passing through the crimping device is curved at the crimping portion as shown in FIG. 8 (the angle at which the hollow fiber membrane runs along the roll before and after the roll biting portion of the crimping device: biting At 30 ° before and 30 ° after biting), the crimping device was sandwiched between φ2.0 mm rods arranged at a pitch of 7.9 mm at a biting depth of 3.5 mm. The tension in the crimping equipment was 1.2 gf per hollow fiber membrane.
A bundle of 10800 wound hollow fiber membranes was inserted into a polyethylene pipe, cut perpendicularly to the length direction to form a bundle, and dried. The hollow fiber membrane was taken out from the dried bundle, and the crimp was measured. Moreover, the bundle after drying was assembled in the module, and crush evaluation and urea clearance measurement were performed.
The results are shown in Table 1. However, five modules were prepared, and urea clearance indicates an average value measured excluding modules with poor adhesion. Moreover, the filling rate of the hollow fiber membrane with respect to the module diameter was in the range of 55 to 65%.

  By using the present invention, it can be seen that poor adhesion at the time of module assembly can be prevented, and that it is possible to achieve both suppression of poor quality of the hollow fiber membrane such as flatness and blockage and expression of stable high dialysis efficiency.

  According to the method for producing a hollow fiber membrane of the present invention, it is possible to provide an effective crimp for reducing adhesion failure when assembling a hollow fiber membrane module and preventing drift when the module is used, so that stable and high permeation performance can be expressed. It becomes possible to obtain a hollow fiber membrane with a high yield. In addition, when crimping is mechanically applied, the risk of flattening, crushing, and breakage of the hollow fiber membrane has been a big problem in the past, but the production method of the present invention suppresses the occurrence frequency of such defective products. Is possible. Furthermore, the energy required for heat fixing is not required, which is effective for cost saving and simplification of equipment. Therefore, it is suitable as a method for producing a hollow fiber membrane that is particularly required to maintain its quality, and can greatly contribute to the industry.

It is an example which shows the whole hollow fiber membrane manufacturing process of this invention. It is an enlarged view which shows one example of the crimp provision apparatus of this invention. It is a schematic diagram which shows the embodiment (Examples 1 and 4) of this invention. It is a schematic diagram which shows another embodiment (Example 2) of this invention. It is a schematic diagram which shows another embodiment (Example 3) of this invention. 6 is a schematic diagram showing an embodiment of Comparative Example 1. FIG. 6 is a schematic diagram showing an embodiment of Comparative Example 2. FIG. 10 is a schematic diagram showing an embodiment of Comparative Example 3. FIG.

Explanation of symbols

1: Rod 2: Biting depth 3: Pitch between rods

Claims (7)

  A hollow fiber membrane manufacturing method for applying a crimp by passing the hollow fiber membrane through a crimp applying device comprising at least a pair of rolls having a large number of rods on the outer peripheral surface, the hollow fiber membrane on the outer peripheral surface of the roll A hollow fiber membrane manufacturing method, wherein the hollow fiber membrane is sandwiched in a meshing portion between rolls, meandering, and crimped while changing a traveling direction while traveling along the rod.   The method for producing a hollow fiber membrane according to claim 1, wherein the meshing portions between the rolls do not contact each other.   The method for producing a hollow fiber membrane according to claim 1 or 2, wherein a pitch between the rods is 15 mm or less.   The method for producing a hollow fiber membrane according to any one of claims 1 to 3, wherein the outer diameter of the rod is 1 to 5 mmφ.   The method for producing a hollow fiber membrane according to any one of claims 1 to 4, wherein the rod rotates freely.   The method for producing a hollow fiber membrane according to any one of claims 1 to 5, wherein the surface of the rod is mirror-finished. The method for producing a hollow fiber membrane according to any one of claims 1 to 6, wherein a biting depth by which the hollow fiber membrane is sandwiched between meshing portions between the rolls is 0.3 to 5.0 mm.

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