JP2006068689A - Drying method for bundle of hollow fiber membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drying method for a bundle of hollow fiber membranes capable of suppressing deformation of the hollow fiber membrane in a drying step, enhancing uniformness of drying, reducing deterioration of a hollow fiber membrane component and manufacturing the bundle of the hollow fiber membranes with high performance, high safety and excellent storage stability and module assembling property, and to provide the bundle of the hollow fiber membranes having a characteristic suitable for a blood cleaning unit and a separation module with less left blood by the drying method. <P>SOLUTION: In the method for drying the bundle of the hollow fiber membranes in the wet state by irradiation with a micro wave, the bundle of the hollow fiber membranes is arranged and dried in a micro wave irradiation oven such that a longitudinal direction of the bundle of the hollow fiber membranes becomes an angle of 45° or less relatively to a horizontal direction in the drying method for the bundle of the hollow fiber membranes. Further, the bundle of the hollow fiber membranes comprising a polysulfone based resin containing polyvinylpyrrolidone in which variation ranges of length and quality of the hollow fiber membrane are specified in the bundle of the hollow fiber membrane after dried is provided by the drying method. Further, in the module in which both ends of the bundle of the hollow fiber membranes comprising the polysulfone based resin containing polyvinylpyrrolidone are fixed by a resin, the separation module having a specific characteristic is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for drying a wet hollow fiber membrane bundle, a hollow fiber membrane bundle, and a separation module. More specifically, the present invention relates to a method of drying a hollow fiber membrane bundle in a wet state, and suppresses deformation of the hollow fiber membrane in the drying process and improves the uniformity of drying and the hollow fiber membrane by a method simplified as compared with the prior art. The present invention relates to a method for drying a hollow fiber membrane bundle, which can produce a hollow fiber membrane bundle with reduced component deterioration, high performance, high safety, and excellent module assembly and storage stability. By this drying method, the hollow fiber membrane bundle suitable for the separation module and the loaded hollow fiber membrane bundle have high performance, high safety and stability of performance, excellent storage stability and low residual blood. We were able to provide a module.

  In recent years, technologies using selective permeable membranes have made remarkable progress, and so far a wide range of fields such as gas and liquid separation filters, hemodialyzers in the medical field, blood filters, blood component selective separation filters, etc. Practical use in is progressing. As the material of the membrane, cellulose resins (regenerated cellulose, cellulose acetate, chemically modified cellulose, etc.), polyacrylonitrile resins, polymethyl methacrylate resins, polysulfone resins, ethylene vinyl alcohol resins, polyamide resins and the like have been used. Of these, the polysulfone-based resin, in addition to its thermal stability, acid resistance, and alkali resistance, improves the blood compatibility by adding a hydrophilizing agent to the film-forming solution, so that it can be used as a semipermeable membrane material. Attention has been paid to research.

  In blood purification therapy for the treatment of renal failure, etc., hemodialyzers, hemofilters or hemodialyzers that use dialysis membranes or ultrafiltration membranes as separators to remove uremic toxins and waste products in the blood The module is widely used. In particular, modules using hollow fiber membranes as separation materials are important in the dialyzer field due to advantages such as reduction of the amount of blood circulating outside the body, high efficiency of removing substances in the blood, and productivity during module production. high.

  On the other hand, in order to produce a module by bonding the hollow fiber membrane bundle, it is necessary to dry the hollow fiber membrane bundle. However, the porous membrane made of organic polymer, especially dialysis membrane made of hydrophobic resin such as polysulfone In addition, it is known that when the ultrafiltration membrane is dried after film formation, the water permeation amount is remarkably reduced as compared with that before drying. Therefore, it was necessary to handle the membrane always in a wet state or in a state immersed in water.

  As a countermeasure against this problem, a conventional method has been to pack a low-volatile organic liquid such as glycerin in the pores in the porous film after film formation and before drying. However, since low-volatile organic liquids generally have high viscosity, it takes time for cleaning and removal, and even after the membrane is molded into a module, a small amount of effluent derived from low-volatile organic liquids (low-volatile organic liquids). There was a problem in that various derivatives produced by chemical reaction with liquid were found in the module sealing liquid.

As a method for drying without using a low-volatile organic liquid, a method using an inorganic salt such as calcium chloride in place of the low-volatile organic liquid is disclosed, but the necessity for washing and removing remains unchanged. Moreover, even if it is a trace amount, there is a concern that the remaining inorganic salt may adversely affect the dialysis patient (see Patent Document 1).
JP-A-6-277470

Moreover, as a method for drying the membrane, a method for producing a hollow fiber membrane in which microwave irradiation is performed while performing wet heat treatment with water vapor on the hollow fiber membrane is disclosed (see Patent Document 2). However, there is a disadvantage that it is necessary to lengthen the drying time because it is treated with steam to prevent deformation of the membrane while being dry, and further, drying after attaching a low volatile organic liquid such as glycerin Therefore, the object of reducing the effluent from the membrane is not achieved.
JP 11-332980 A

A hydrophilized film containing polyvinylpyrrolidone that has been dried without using a low-volatile organic liquid has been disclosed (see Patent Documents 3 and 4). The patent document discloses a technique for separating a plasma component from blood, but it is found that plasma protein permeates and is not effective as a dialysis membrane. In addition, since it is dried at a temperature at which polyvinylpyrrolidone is decomposed and modified, it is an extremely undesirable production method for the purpose of reducing the amount of eluate from the membrane.
JP-A-8-52331 Japanese Patent Publication No.8-9668

In addition, a method for producing a high-performance blood purification membrane by drying a wet membrane having a specific performance at a temperature of 120 ° C. or less without impregnating with a low-volatile organic liquid such as glycerin is disclosed (Patent Document). 5). However, it has been clarified by the same inventors that this method causes a slight difference in performance between the central portion and the outer peripheral portion of the yarn bundle when the yarn bundle is dried.
Japanese Patent No. 3281364

As a measure for solving the problem of the drying method disclosed in Patent Document 5 by the same inventors as Patent Document 5, a method of drying by irradiating microwaves is disclosed (see Patent Documents 6 to 9). These methods are preferable in that they are dried without impregnating the low-volatile organic liquid and can be dried without deteriorating the separation performance of the hollow fiber membrane bundle. However, any of these methods is a method in which a gas is passed through the hollow fiber membrane bundle to achieve uniform drying. In addition to the microwave irradiation mechanism, this method requires the installation of an auxiliary mechanism for ventilating the gas in the hollow fiber membrane bundle, and has a problem that the structure of the dryer becomes complicated. The method also requires that the hollow fiber membrane bundle to be dried be fixed to an auxiliary mechanism for venting gas into the hollow fiber membrane bundle, the structure of the fixing part becomes complicated, and the hollow fiber membrane bundle is There is a problem that the preparation for drying and the drying operation become complicated, such as setting in the above-mentioned place and controlling the air flow rate.
Another inventor has disclosed a method of drying a hollow fiber membrane bundle by irradiating microwaves while passing air through the hollow fiber membrane bundle under reduced pressure (see Patent Document 10). This method also has the same problem.
JP 2003-175320 A JP 2003-175321 A JP 2003-175322 A JP 2003-284931 A JP-A-9-888

  Further, since the method of the above-mentioned patent document uses ventilation drying together, if the ventilation conditions are not strictly controlled in the ventilation drying, the hollow to be dried in the drying process is caused by the non-uniformity of ventilation in the hollow fiber membrane bundle. Differences in deformation of the hollow fiber membrane such as contraction spots of the yarn membrane occur, causing breakage of the hollow fiber membrane, disorder of arrangement, variation in yarn length, and the like. When the hollow fiber membrane breaks or the arrangement is disrupted, the hollow fiber membranes at the embedding part by the adhesive are inclined during modularization.For example, when used for blood purification, blood drift occurs and residual blood Leads to outbreak. Further, when the hollow fiber membrane is broken or the arrangement is disturbed, the insertability of the hollow fiber membrane bundle into the container in the module assembling process is lowered, and the hollow fiber membrane is damaged or a crushed yarn in which the cross section of the hollow fiber membrane is deformed is generated. . Wounds can lead to blood leaks. In addition, the crushed thread causes blood drift and leads to the generation of residual blood thread. Regarding the yarn length variation, when a hollow fiber membrane with a large shrinkage rate and a short yarn length occurs, the adhesive tends to enter the end surface of the hollow fiber membrane with a short yarn length when embedding both ends with an adhesive. The inner hole of the part is blocked with an adhesive, leading to generation of clogging yarn, causing blood drift and generation of residual blood yarn. On the contrary, when a hollow fiber membrane having a low shrinkage rate and a long yarn length is generated, the hollow fiber membrane is broken or the arrangement is disturbed, causing the above-mentioned problems.

Moreover, the method of the said patent document lacks consideration with respect to the long-term storage stability of a hollow fiber membrane raw material, and the improvement is also required. When a hollow fiber membrane is used as a separation membrane for blood purification therapy, if the elution of the hydrophilic compound increases, the accumulation of the hydrophilic compound, which is a foreign substance for the human body, increases during long-term dialysis and may cause side effects and complications. The standard of UV (220-350 nm) absorbance in the extract of the hollow fiber membrane is set in the dialysis artificial kidney device manufacturing approval standard. Also in the method of the above-mentioned patent document, the representative value is measured.
The present inventors have confirmed that the extract extracted by the test method defined by the above-mentioned dialysis artificial kidney device manufacturing approval standard contains hydrogen peroxide that cannot be measured by conventionally known UV absorbance. I found it. It has been found that the presence of the hydrogen peroxide accelerates the oxidative degradation of, for example, polyvinyl pyrrolidone and increases the amount of the polyvinyl pyrrolidone eluted when the hollow fiber membrane bundle is stored. Furthermore, even if hydrogen peroxide is present in a specific part of the hollow fiber membrane bundle, the deterioration reaction of the hollow fiber membrane bundle material starts from that point and propagates to the entire hollow fiber membrane bundle, so it is used as a module. It has been found that the abundance of the hollow fiber membrane bundle in the longitudinal direction needs to ensure a certain amount or less over the entire region. When carried out by the method of the above-mentioned patent document, the amount of the hydrogen peroxide eluted increases, and when the hollow fiber membrane bundle is stored for a long period of time, the oxidative degradation of polyvinylpyrrolidone is promoted, and the UV (220 to 350 nm) absorbance over time. The problem that increases will occur.

  When implemented by the method of the above-mentioned patent document, non-uniform drying occurs in the longitudinal direction of the hollow fiber membrane bundle from the inlet side to the outlet side of the ventilation, and hydrogen peroxide is locally generated, leading to the occurrence of the above problems. .

  In addition, when the method of the above-mentioned patent document is used, since the ventilation is from one direction, non-uniform drying occurs in the longitudinal direction of the hollow fiber membrane bundle, and the UV (220 to 350 nm) absorbance is also measured with the hollow fiber. The subject that the fluctuation | variation of the longitudinal direction of a film bundle is large generate | occur | produces. This fluctuation leads to a decrease in safety. The fluctuation in UV (220 to 350 nm) absorbance also reflects the surface concentration of polyvinyl pyrrolidone on the outer surface of the hollow fiber membrane bundle, and when the wet hollow fiber membrane bundle is dried, the hollow fiber membrane bundle rises to dryness. This leads to a problem that partial sticking (adhesion) of the hollow fiber membranes occurs in a portion having a high polyvinylpyrrolidone concentration on the surface. If this partial sticking occurs, it will lead to problems such as deterioration of the module assemblability, so improvement is necessary. In the above patent document, no consideration is given to these problems.

  The above-described drying methods of Patent Documents 5 to 9 describe that the moisture content in the dried film is less than 1% by mass in Examples. In addition, any of the above known methods of drying by irradiating microwaves is a method of irradiating microwaves under normal pressure, and no mention is made of the effect of irradiating microwaves under reduced pressure. Absent.

  Suppressing the deformation of the hollow fiber membrane in the drying process by a method simplified compared to the prior art, improving the uniformity of drying and reducing deterioration of the hollow fiber membrane components, high performance, high safety, In addition, a hollow fiber membrane bundle drying method capable of producing a hollow fiber membrane bundle excellent in storage stability and assembling property of a separation module has been achieved. By this drying method, a hollow fiber membrane bundle suitable for a separation module is achieved. In addition, the hollow fiber membrane bundle loaded has high performance, high safety and stability of performance, excellent storage stability, and can provide a separation module with little residual blood.

The present invention is a method for drying a wet hollow fiber membrane bundle by microwave irradiation, and is arranged in a microwave irradiation oven so that the longitudinal direction of the hollow fiber membrane bundle is at an angle of 45 degrees or less with respect to the horizontal. And drying the hollow fiber membrane bundle.
The present invention also relates to a hollow fiber membrane bundle made of a polysulfone-based resin containing polyvinylpyrrolidone obtained by drying a wet hollow fiber membrane bundle by the method, and the length of the module container for loading the hollow fiber membrane bundle. Is A (mm), and the length of the hollow fiber membrane bundle at the time of assembling the module is B (mm). Per unit of the number of yarn membrane bundles, the ratio of the hollow fiber membrane length that is shorter than 1 mm longer than A + B (mm) and the length that is longer than 1 mm longer than A + B (mm) is 0.05% or less, respectively. It is possible to provide a hollow fiber membrane bundle.
Further, according to the present invention, a module in which both ends of a hollow fiber membrane bundle made of a polysulfone-based resin containing polyvinylpyrrolidone are fixed by a resin is fixed by a resin evaluated by the method described in the specification. After the hollow fiber membrane is stored at room temperature for one year in a state where the ratio of the number of hollow fiber membranes having a slope of 15 ° or more is 0.05% or less and the module is filled with a liquid mainly composed of water The hollow fiber membrane bundle was divided into 10 pieces in the longitudinal direction, and the UV (220-350 nm) absorbance in the hollow fiber membrane extract when each test was conducted according to the dialysis artificial kidney device manufacturing approval criteria was performed. A separation module having an average value of 0.10 or less can be provided.

  The drying method of the hollow fiber membrane bundle of the present invention can be used in combination with a conventionally known ventilation method for allowing gas to pass through the hollow fiber membrane bundle to make drying uniform, but it is not necessary to use it. However, since it is possible to dry sufficiently, the jig for applying this ventilation is not required, the structure of the dryer is simplified, and the hollow fiber membrane bundle to be dried is fixed to the jig for applying this ventilation. Therefore, the workability of placing the hollow fiber membrane bundle to be dried in the dryer is improved. In addition, the hollow fiber membranes such as broken and misaligned hollow fiber membranes in the drying process in the drying process due to the arrangement direction of the hollow fiber membrane bundles to be dried and the non-uniformity of the ventilation, which were conventionally known problems Since deformation and shrinkage spots are suppressed, the dry hollow fiber membrane bundle dried by the method of the present invention improves the insertability of the hollow fiber membrane bundle into the module container in the assembly process of the separation module, for example, Bonding workability at the time of module assembly in the next process is improved. Furthermore, the occurrence of defective hollow fiber membranes such as tilted hollow fiber membranes, crushed hollow fiber membranes and clogged hollow fiber membranes due to deformation and shrinkage spots is suppressed, and residual blood properties caused by these defects are improved. There is an advantage. In addition, since the hollow fiber membrane is prevented from being broken or damaged, blood leakage is improved.

  Further, since the non-uniform drying in the ventilation direction, that is, the longitudinal direction of the hollow fiber membrane bundle, which has been a conventionally known problem, is improved, the local degradation of polyvinyl pyrrolidone is reduced, and the excess generated by the degradation is reduced. Hydrogen oxide elution amount is suppressed. Therefore, since the hollow fiber membrane bundle obtained by the present invention suppresses deterioration of polyvinyl pyrrolidone and the like caused by the hydrogen peroxide, it is UV that is a dialysis type artificial kidney device manufacturing approval standard even after long-term storage. There is an advantage that the average value of (220-350 nm) absorbance can be maintained at 0.10 or less. Further, the uniform drying makes the variation in the degradation of polyvinyl pyrrolidone in the longitudinal direction of the hollow fiber membrane bundle small, suppresses the above UV (220-350 nm) absorbance variation in the longitudinal direction of the hollow fiber membrane bundle, and the hollow fiber membrane. Since the moisture content of the bundle is set in an appropriate range and the fluctuation rate is suppressed, the occurrence of partial sticking of the hollow fiber membrane bundle caused by these fluctuations is suppressed, and the module assembly property is excellent. The hollow fiber membrane bundle is characterized in that it can be produced stably. Moreover, suppression of UV (220-350 nm) absorbance fluctuations in the longitudinal direction of the hollow fiber membrane bundle also leads to an improvement in safety when used for blood purification. Therefore, there is an advantage that it is suitable as a method for drying a hollow fiber membrane bundle used for purifying blood having high water permeability used for the treatment of chronic renal failure. Further, the hollow fiber membrane bundle made of the polysulfone-based resin containing polyvinyl pyrrolidone of the present invention is improved in the problem characteristics of the hollow fiber membrane bundle obtained by the above-mentioned conventional technology, and is therefore preferably used for blood purification and the like. There is an advantage that you can. Furthermore, the separation module obtained in the present invention has the advantages that the loaded hollow fiber membrane bundle has high performance, high safety and stability of performance, excellent storage stability, and few residual blood yarns. It is possible to provide a product having the same.

Hereinafter, the present invention will be described in detail.
The present invention is a method for drying a wet hollow fiber membrane bundle by microwave irradiation, and is arranged in a microwave irradiation oven so that the longitudinal direction of the hollow fiber membrane bundle is at an angle of 45 degrees or less with respect to the horizontal. And drying. The angle is more preferably 30 degrees or less, and most preferably 0 degrees, that is, horizontal placement. When the angle is more than 45 degrees, for example, 90 degrees as disclosed in the prior art, the hollow fiber membrane bundle that has been constrained by water is less assembled as the hollow fiber membrane bundle is dried. Therefore, the degree of freedom of movement of the hollow fiber membrane bundle is increased, and for example, buckling, which is deformation due to its own weight, may occur. When the deformation occurs, the hollow fiber membrane bundle is bent. In addition, the arrangement of the hollow fiber membrane bundles is disturbed, the insertion property of the hollow fiber membrane bundle into the container is lowered during the assembly of the separation module, and the hollow fiber membrane bundle and the container or the hollow fiber membrane bundles are rubbed together during the insertion. Occurrence of scratches and crushed yarns due to hollow fiber membranes and workability in the bonding process of fixing the bundle of hollow fiber membranes after insertion to the container by adhesion, occurrence of poor adhesion due to adhesion work, and hollow fiber membrane inner hole of adhesive This leads to problems such as increased generation of clogged hollow fiber membranes due to the penetration of adhesive. Therefore, the present invention is preferably applied to drying of hollow fiber membrane bundles having a ratio L / D of 2 or more, which is the ratio of the diameter (D) to the length (L) of the hollow fiber membrane bundles. It is more preferable to apply to drying of hollow fiber membrane bundles having L / D of 3 or more.

  In the present invention, it is preferable that the hollow fiber membrane bundle to be dried is placed on a horizontally set table having a rotation function and dried while rotating. Further, it is a preferred embodiment that a plurality of the hollow fiber membrane bundles to be dried are arranged radially at equal intervals in a direction in which one end in the longitudinal direction is directed to the center point of the rotary table. Due to this correspondence, the uniformity of drying of the hollow fiber membrane bundle to be dried including the longitudinal direction of the hollow fiber membrane bundle to be dried can be improved by a synergistic effect with the implementation items described later. According to this method, since it can be installed only by placing it on the rotary table, the operation of installing the hollow fiber membrane bundle to be dried in the dryer can be performed very simply and efficiently. Further, by rotating the table, the energy of the microwave irradiated to the hollow fiber membrane bundle to be dried can be made uniform, and the drying uniformity of the hollow fiber membrane bundle to be dried can be improved. The rotation speed of the table is preferably 3 to 20 rpm. In addition, a hollow fiber membrane bundle shape recess is added to the position of the hollow fiber membrane bundle to be dried on the table, or conversely, a projection that can fix the hollow fiber membrane bundle is attached to specify and arrange the installation location of the hollow fiber membrane bundle. It is also a preferred embodiment to take measures such as improving the workability.

  The rotary table has a structure in which a plastic spacer having a thickness of 3 mm or more is installed on a metal rotary holder, and a tray is preferably installed on the spacer. The thickness of the spacer is more preferably 4 mm or more, and further preferably 5 mm or more. When the thickness of the plastic spacer is less than 3 mm, the microwave is reflected by the metal rotating holder that supports the plastic spacer, and the reflected microwave accelerates the drying of the hollow fiber membrane on the rotating holder side. In addition, the uniformity of heating of the hollow fiber membrane bundle to be dried may be reduced, and the effect of the present invention may be reduced. The material of the plastic spacer is not limited, and examples thereof include general-purpose resins such as polypropylene and polyethylene terephthalate. What consists of what is called engineering plastics, such as a group polyester, is preferable. Polysulfone resin is preferred. It is within the scope of the present invention to make the plastic including the rotating holder.

  The position of the rotary table in the present invention is preferably set so that the center of the hollow fiber membrane bundle installed in the dryer is near the center of the waveguide outlet of the microwave oscillator. When a large number of hollow fiber membrane bundles are arranged on each tray, it is preferable that the center of each hollow fiber membrane bundle is set to be near the center of the waveguide outlet of the microwave oscillator.

  In the present invention, unlike the prior art, drying is carried out without passing gas through the hollow fiber membrane bundle, so that the hollow fiber membrane bundle to be dried is placed and dried at any place in the dryer oven. Can do. In particular, in the case of horizontal placement, which is the most preferable arrangement, the hollow fiber membrane bundle may be simply arranged on the drying pedestal. Therefore, the workability of the arrangement of the hollow fiber membrane bundle to be dried in the dryer can be greatly simplified. The method for disposing the hollow fiber membrane bundle to be dried in the dryer is not limited, but it is preferable that the wet hollow fiber membrane bundle is constrained with a hollow package and disposed in the dryer. This further improves the workability of the arrangement. It is preferable to restrain the dried hollow fiber membrane bundle in consideration of the assembling property of the subsequent separation module. For example, the hollow fiber membrane bundle is constrained to the separation module with a package slightly smaller than the inner diameter of the container, the dried hollow fiber membrane bundle is inserted into the container together with the package, and only the package is inserted in the inserted state. Extraction is recommended as a particularly preferred method because it can suppress the workability of inserting the dry hollow fiber membrane bundle into the container and the occurrence of troubles such as scratches in the hollow fiber membrane in the work. In the method, it is preferable to set the unit length of the hollow fiber membrane bundle to be dried to a length corresponding to the length of the container of the module filled with the obtained dry hollow fiber membrane bundle. In this case, it is preferable to set the length of the hollow fiber membrane bundle to be dried in consideration of the shrinkage of the hollow fiber membrane bundle due to drying.

  The length of the hollow fiber membrane bundle to be dried is determined by setting the container length of the separation module loaded with the dried hollow fiber membrane bundle to A (mm), and the cutting margin at both ends of the hollow fiber membrane bundle when the module is assembled. The length after drying of the hollow fiber membrane bundle is preferably set to A + B (mm), where B is the combined length of B.

  In a preferred embodiment, the hollow package is made of a plastic having a circular cross-sectional shape, and its outer diameter is 70 to 99.9% of the inner diameter of the container of the module loaded with the dry hollow fiber membrane bundle. is there. The outer diameter of the hollow package is more preferably 80 to 99.0%, more preferably 90 to 98.0% of the inner diameter of the container of the module loaded with the dry hollow fiber membrane bundle. If it exceeds 99.9%, it may be difficult to load the package into a container. On the other hand, if it is less than 70%, the space occupied by the hollow fiber membrane bundle in the separation module becomes small, so a useless space is generated in the separation module or the position of the hollow fiber membrane bundle in the separation module is uneven. And dialysis fluid drift tends to occur, which may lead to a decrease in dialysis efficiency. Moreover, the workability | operativity of the adhesion process which fixes a hollow fiber membrane bundle in a container also falls.

  The thickness of the hollow package is preferably 0.05 to 1 mm. 0.1-0.8 mm is more preferable and 0.15-0.7 mm is still more preferable. If the thickness is less than 0.05 mm, the shape retainability is lowered and the shape is easily deformed, which may lead to the occurrence of shape deformation of the hollow fiber membrane bundle and the deterioration of workability of loading into the container. On the other hand, if the thickness exceeds 1 mm, the effect of improving the shape retention and loading workability is saturated, resulting in excessive quality.

  The filling density of the hollow fiber membrane bundle restrained by the hollow packaging body is the sum of the outer diameter cross-sectional areas of the hollow fiber membranes of the hollow fiber membrane bundle restrained relative to the cross-sectional area of the hollow packaging body. 40 to 90% is preferable. 43 to 80% is preferable, and 46 to 70% is more preferable. If it is less than 40%, it is not preferable because a useless space volume in the separation module after the separation module is assembled increases or the size of the separation module increases. In addition, for example, when used as a blood purifier, the dialysis fluid may drift, leading to a reduction in dialysis efficiency. On the other hand, if it exceeds 90%, the pullability when pulling out the hollow package during the loading operation of the dry hollow fiber membrane bundle into the container is deteriorated, and the hollow fiber membrane is crushed or damaged. It tends to occur and may lead to the generation of defective yarns. In addition, in the bonding step of fixing the hollow fiber membrane bundle in the container, the permeability of the adhesive between the hollow fiber membranes may be reduced, leading to an increase in the number of defective adhesion points.

  The hollow package for restraining the dried hollow fiber membrane bundle is preferably made of plastic. Further, the material is preferably selected from resins having a product of dielectric constant and dielectric loss tangent at 1 MHz of 0.02 or less. The resin is preferably a polyolefin resin. Use of the resin is preferable because microwave permeability is improved and drying uniformity of the hollow fiber membrane bundle is improved. Polyolefin-based resins are soft and have good slidability of the hollow fiber membrane bundle, and also have the advantage that the hollow fiber membrane bundle is not easily damaged when the hollow fiber membrane is inserted or removed. The package is preferably a method using a seamless tube-shaped package. For example, a hollow pipe or the like is preferably used. In particular, it is more preferable to fill a wet bundle of hollow fiber membranes into a film or sheet previously formed into a tube shape by a fusing seal or the like.

The restraint body of the hollow fiber membrane bundle may be dried by directly placing the restraint body in a dryer.
Further, the restraining body may be placed in a tray and placed in a dryer. The latter method is more preferable because the effect of further improving the workability of the drying process is exhibited.

  By satisfying the above-mentioned requirements of the present invention, it is possible to dry with a simpler apparatus and with a simpler method than the prior art, and the deformation of the hollow fiber membrane bundle is suppressed. In addition, the dry hollow fiber membrane bundle dried by the method of the present invention has improved insertion of the hollow fiber membrane bundle into a container in an assembly process for a blood purifier, and the hollow fiber in the process is suppressed. Generation | occurrence | production of the damage | wound of a film | membrane and a crushed thread | yarn is suppressed. Furthermore, this effect improves the workability of the subsequent bonding process, and suppresses the occurrence of the various defects described above. Due to these effects, a hollow fiber membrane bundle having the following excellent characteristics can be obtained.

  The first characteristic that the hollow fiber membrane bundle obtained by the method of the present invention should have is that the fluctuation range of the shrinkage rate in the longitudinal direction of the hollow fiber membrane in the hollow fiber membrane bundle during drying is in a specific range. That is, the hollow fiber membrane bundle length after drying is the ratio (short yarn ratio) in which the hollow fiber membrane length per hollow fiber membrane loaded in the separation module is shorter than 1 mm from A + B (mm) and A + B It is preferable that the ratio (long thread ratio) of the one longer than 1 mm by (mm) is 0.05% or less. Each of them is more preferably 0.04% or less, further preferably 0.03% or less, and particularly preferably 0%. If the hollow fiber membrane length is shorter than A + B (mm) by more than 1 mm, the adhesive penetrates into the hollow part of the hollow fiber membrane when the hollow fiber membrane bundle loaded in the container is embedded and fixed with the adhesive. This may lead to the generation of clogged yarn. Here, the occurrence of clogging yarn should be sufficient if the module length A (mm) is originally satisfied, but the adhesive enters the hollow portion from the end portion of the hollow fiber membrane by capillary action. . This penetration distance varies depending on the type of adhesive and the filling method of the adhesive, but generally exceeds the cutting allowance length. Of course, if the cutting allowance length B is set long, the generation of clogging yarn is suppressed. However, setting the cutting allowance length B long may result in loss of the hollow fiber membrane bundle, which is economically disadvantageous. is there. Therefore, the cutting allowance length B is preferably 30 mm or less. 25 mm or less is more preferable, and 20 mm or less is more preferable.

  On the other hand, if a length longer than 1 mm from A + B (mm) is present, the hollow fiber membrane in the separation module may be loosened, and the hollow fiber membrane may be inclined at the embedding portion with the adhesive. These disadvantages cause blood drift and lead to residual blood. Here, A (mm), which is the container length, is the container length after cutting when the container is cut to complete the separation module after the adhesive treatment for fixing the hollow fiber membrane bundle in the container. That's it.

In the present invention, satisfying the following requirements is also a preferred embodiment.
The inventors of the present invention, as described above, that the extract extracted by the test method defined by the dialysis-type artificial kidney device manufacturing approval standard contains hydrogen peroxide that cannot be measured by a conventionally known UV absorbance. I found. It has been found that the presence of the hydrogen peroxide accelerates the oxidative degradation of, for example, polyvinyl pyrrolidone and increases the amount of the polyvinyl pyrrolidone eluted when the hollow fiber membrane bundle is stored. Furthermore, even if hydrogen peroxide is present in a part of the hollow fiber membrane bundle, the deterioration reaction of the hollow fiber membrane bundle material starts from that location and propagates throughout the hollow fiber membrane bundle. It was found that it is necessary to secure a certain amount or less over the whole area. When carried out by a conventionally known method, the elution amount of the hydrogen peroxide increases, and when the hollow fiber membrane bundle is stored for a long period of time, the oxidative deterioration of the polyvinyl pyrrolidone is promoted and UV (220 to 350 nm) with time It has been found that the problem of increased absorbance occurs.

Moreover, when it is carried out by a conventionally known method, the longitudinal variation of the hollow fiber membrane bundle is evaluated even when evaluated by UV (220 to 350 nm) absorbance, which is a test method defined by the dialysis-type artificial kidney device manufacturing approval standard. It has been found that there is a problem that is large. This fluctuation leads to a decrease in safety. The fluctuation in UV (220 to 350 nm) absorbance also reflects the surface concentration of polyvinyl pyrrolidone on the outer surface of the hollow fiber membrane bundle, and when the wet hollow fiber membrane bundle is dried, the hollow fiber membrane bundle rises to dryness. This leads to a problem that partial sticking (adhesion) of the hollow fiber membranes occurs in a portion having a high polyvinylpyrrolidone concentration on the surface. Furthermore, it has been found that the partial fixation is affected by the moisture content of the dried hollow fiber membrane bundle and the fluctuation of the moisture content in the longitudinal direction of the hollow fiber membrane bundle. If this partial sticking occurs, it will lead to problems such as deterioration of the module assemblability, so improvement is necessary.
Furthermore, regarding the occurrence of the above-mentioned problems, it has been found that the wet hollow fiber membrane bundle in the manufacturing process of the hollow fiber membrane bundle is greatly affected by the drying method and drying conditions. In particular, it has been found that it is important to suppress the oxidative degradation of polyvinylpyrrolidone in the drying step and to improve the drying uniformity.

  That is, it is preferable to obtain a hollow fiber membrane bundle having the following characteristics. That is, the second characteristic that the hollow fiber membrane bundle obtained by the method of the present invention should have is a characteristic relating to the hydrogen peroxide elution amount of the hollow fiber membrane bundle that governs the storage stability of the hollow fiber membrane bundle. When the membrane bundle is divided into 10 pieces in the longitudinal direction, and each of them is subjected to the test defined by the dialysis-type artificial kidney device manufacturing approval standard, the concentration of hydrogen peroxide in the extract at all the divided portions is 10. It is preferable that it is 5 ppm or less. Here, the elution test of the dialysis-type artificial kidney device manufacturing approval standard measures 1 g from the divided hollow fiber membrane bundle. 100 ml of RO water was added to this, and extraction was performed at 70 ° C. for 1 hour to measure UV (220-350 nm) absorbance of the extract. This was determined by quantifying hydrogen peroxide in the extract. It is.

The hydrogen peroxide elution amount is more preferably 4 ppm or less, and further preferably 3 ppm or less. When the elution amount of the hydrogen peroxide exceeds 5 ppm, the storage stability is deteriorated due to oxidative degradation caused by hydrogen peroxide, for example, the elution amount of polyvinylpyrrolidone may increase when stored for a long period of time. . As for storage stability, the increase in the amount of polyvinylpyrrolidone eluted is the most remarkable phenomenon. In addition, the deterioration of the polysulfone-based polymer causes the hollow fiber membrane bundle to become brittle, or the polyurethane system used for module assembly. There is a possibility that the deterioration of the adhesive is promoted, the amount of elution of the deteriorated product is increased, and the safety is lowered. The increase in the amount of elution due to deterioration caused by the oxidizing action of hydrogen peroxide in the long-term storage can be evaluated by measuring UV (220-350 nm) absorbance set by the dialysis artificial kidney device manufacturing approval standard.
Therefore, in the present invention, when the separation module assembled using the hollow fiber membrane bundle obtained by the present invention is stored at room temperature for one year, and then the test defined by the dialysis-type artificial kidney device manufacturing approval standard is performed. It is preferable that the UV (220-350 nm) absorbance in the hollow fiber membrane extract is 0.10 or less. More preferably, the UV (220 to 350 nm) absorbance is kept at 0.08 or less. In addition, UV (220-350 nm) absorbance after storage is evaluated by an average value when the hollow fiber membrane bundle is divided into 10 pieces in the longitudinal direction and measured for each.

The third characteristic to be provided is that the hollow fiber membrane bundle after drying is divided into 10 pieces in the longitudinal direction with respect to partial fixation of the hollow fiber membrane bundle, and each is determined by the dialysis-type artificial kidney device manufacturing approval standard. When the test was carried out, the maximum value of UV (220 to 350 nm) absorbance in the hollow fiber membrane extract was less than 0.10, and the difference between the maximum value and the minimum value in the same hollow fiber membrane bundle was 0. It is also important to make it 05 or less.
The maximum value of the UV absorbance is preferably 0 because the content of the hydrophilic polymer on the outer surface that affects the fixation is small and there is no eluate to be extracted. However, in the present invention, the maximum value of UV absorbance is preferably 0.03 or more and less than 0.1. If it is less than 0.03, the content of the hydrophilic polymer on the inner surface of the film is not sufficient, so the film wettability is poor, and the film performance may not be fully exhibited. More preferably, it is 0.04-0.09, More preferably, it is 0.05-0.08, Most preferably, it is 0.06-0.07.
The UV (220 to 350 nm) absorbance in the extract is an indicator of the polyvinylpyrrolidone content on the surface of the hollow fiber membrane that adversely affects the fixation of the hollow fiber membrane bundle, and the extract in the longitudinal direction of the hollow fiber membrane bundle. By suppressing UV (220-350 nm) absorbance fluctuations in the glass fiber, fluctuations in the content of polyvinyl pyrrolidone on the hollow fiber membrane surface in the longitudinal direction of the hollow fiber membrane bundle are suppressed, so that occurrence of partial sticking of the hollow fiber membrane bundle is suppressed. Is done. Moreover, since the suppression of the fluctuation leads to keeping the elution amount of polyvinyl pyrrolidone in the entire hollow fiber membrane bundle at a low level, the safety is improved when it is used in a blood purifier. Therefore, 0.04 or less is preferable, 0.03 or less is more preferable, and 0.02 or less is even more preferable.

  Examples of the constituent material of the hollow fiber membrane bundle in the present invention include cellulose such as regenerated cellulose, cellulose acetate, and cellulose triacetate, polysulfone such as polysulfone and polyethersulfone, polyacrylonitrile, polymethyl methacrylate, and ethylene vinyl alcohol copolymer. However, a cellulose type or a polysulfone type is preferable. Moreover, what consists of hydrophobic polymer containing a hydrophilic polymer is preferable. In particular, a system composed of a polysulfone-based resin containing polyvinylpyrrolidone is preferable because a selective permeable separation membrane having excellent biocompatibility and excellent water permeability and separation characteristics can be obtained.

Polysulfone resin is a generic term for resins having a sulfone bond, and is not particularly limited. For example, polysulfone resins and polyethersulfone resins having repeating units represented by chemical formulas 1 and 2 are widely available as polysulfone resins. It is preferable because it is easily available.

  Polyvinyl pyrrolidone is a water-soluble polymer compound obtained by vinyl polymerization of N-vinyl pyrrolidone. The product names are “Collidon” from BASF, “Prasdon” from ISP, and “Pittscall” from Daiichi Kogyo Seiyaku. There are products of various molecular weights that are commercially available. In general, it is preferable to use a low molecular weight in terms of imparting hydrophilicity, while a high molecular weight is preferable in terms of reducing the amount of elution, but in accordance with the required characteristics of the hollow fiber membrane bundle of the final product. It is selected appropriately. Those having a single molecular weight may be used, or two or more products having different molecular weights may be mixed and used. Moreover, you may use what refine | purified a commercial product and sharpened molecular weight distribution, for example. As the molecular weight of polyvinylpyrrolidone, those having a mass average molecular weight of 10,000 to 1,500,000 can be used. Specifically, for example, those having a molecular weight of 9,000 (K17) commercially available from BASF, and the same shall apply hereinafter, 45,000 (K30), 450,000 (K60), 900,000 (K80), 1,200 000 (K90) is preferable, and in order to obtain the intended use, characteristics, and structure, each may be used alone, or two or more may be used in combination as appropriate.

  The content of the polyvinyl pyrrolidone in the polysulfone-based resin in the present invention is not particularly limited as long as the hydrophilic property can be imparted to the hollow fiber membrane, and can be arbitrarily set. The proportion of pyrrolidone is preferably 1 to 20% by mass, and more preferably 3 to 15% by mass. If it is less than 1% by mass, the hydrophilicity-imparting effect of the film may be insufficient. On the other hand, if it exceeds 20% by mass, the effect of imparting hydrophilicity is saturated, and the elution amount of the hydrophilic polymer from the membrane may increase and the safety may decrease.

  Although the manufacturing method of the hollow fiber membrane bundle in this invention is not limited at all, For example, the method which is known by Unexamined-Japanese-Patent No. 2000-300663 is illustrated. For example, 16% by mass of polyethersulfone (4800P, manufactured by Sumitomo Chemical Co., Ltd.), 5% by mass of polyvinylpyrrolidone (K-90, manufactured by BASF), 74% by mass of dimethylacetamide and 5% by mass of water were mixed and dissolved, and defoamed. As a spinning solution, 50% dimethylacetamide aqueous solution is used as the core solution, and this is simultaneously discharged from the outside and inside of the double tube orifice. A guided hollow fiber membrane bundle can be formed and scraped after washing with water to produce a wet hollow fiber membrane bundle.

  The drying method in the present invention is a preferred embodiment that is applied to a wet hollow fiber membrane bundle obtained by the above method, for example.

  In the present invention, as described above, it eliminates the ventilating method for allowing gas to pass through the hollow fiber membrane bundle, which has been conventionally known, to achieve uniform drying, and drying can be performed by a simplified method, Various problems caused by the ventilation method are improved, but in order to stably obtain the characteristics that the hollow fiber membrane bundle obtained in the present invention should have, the hollow fiber membrane bundle is dried in addition to the above achievement requirements. It is preferable to incorporate means for achieving the homogenization. Hereinafter, this measure will be mentioned.

  It is preferable to install a microwave oscillator on the side wall of the microwave irradiation oven and irradiate the microwave from the side surface direction of the rotary table. In addition, a microwave oscillator in which the ratio (Er / Ei) of the energy Ei of the incident wave from the microwave oscillator to the oven and the energy Er of the reflected wave reflected from the oven and returning to the oscillator is 0.2 or less is used. It is more preferable to heat by irradiating with microwaves. The measurement of the energy Ei of the incident wave from the microwave oscillator toward the oven and the energy Er of the reflected wave reflected from the oven and returning from the oven to the oven is performed by, for example, microwaves as disclosed in Japanese Patent Application Laid-Open No. 11-83325. The energy detector was installed in the waveguide section from the oscillator toward the oven, and was measured and determined. When Er / Ei exceeds 0.2, the energy of the microwaves hitting the hollow fiber membrane bundle becomes non-uniform, and the effects of the present invention are fully exhibited even if various means for uniform heating described below are taken. This is not preferable because it cannot be performed. If Er / Ei is large, the magnetron of the oscillator may be destroyed by the reflected wave. Er / Ei is more preferably 0.15 or less, and further preferably 0.10 or less. In the present invention, the method for reducing the above Er / Ei to 0.1 or less is not limited, but it is a preferred embodiment to employ various measures disclosed in Japanese Patent Laid-Open No. 2000-340356.

  The above-mentioned correspondence and the arrangement of the hollow fiber membrane bundle to be dried make the intensity distribution of the microwaves irradiated to the hollow fiber membrane bundle to be dried uniform, and the drying of the hollow fiber membrane bundle is made uniform. The preferable characteristic which a hollow fiber membrane bundle should have can be provided.

  In the present invention, it is preferable to stop the microwave irradiation at the time when the water content in the hollow fiber membrane bundle is reduced to 10 to 20% by mass and subsequently dry by far infrared irradiation. 10-15 mass% is more preferable. Polyvinylpyrrolidone is susceptible to oxidative degradation as the water content decreases, so drying with microwave irradiation to a water content of less than 10% by mass increases the degradation of polyvinylpyrrolidone and increases the amount of hydrogen peroxide extracted. There is a possibility that the storage stability of the hollow fiber membrane bundle is lowered. Moreover, the moisture content in the longitudinal direction of the hollow fiber membrane bundle and the fluctuation rate of UV (220 to 350 nm) absorbance increase, and the occurrence of partial sticking of the hollow fiber membrane bundle may increase. On the other hand, if microwave irradiation is stopped at a point in time when the amount is more than 20% by mass, the total drying time until the end of drying becomes longer, leading to an increase in cost.

  Total drying is completed by drying with far-infrared irradiation after the above-described microwave irradiation in the present invention. It is preferable that the moisture content in the hollow fiber membrane bundle after completion of the drying is 1 to 7% by mass. Moreover, it is preferable that each moisture content fluctuation | variation rate which divided this dry hollow fiber membrane bundle into 10 in the longitudinal direction is less than 10%. Only by obtaining a dry hollow fiber membrane bundle having such a water content can the properties that the hollow fiber membrane bundle of the present invention has to hold be provided. In addition, when the moisture content exceeds 10% by mass, it becomes easy for bacteria to grow during storage, thread crushing occurs due to the weight of the hollow fiber membrane, or adhesive failure of the adhesive during module assembly (foaming of adhesive resin) ) May occur.

The moisture content of the hollow fiber membrane bundle in the present invention was calculated by the following formula.
Moisture content (mass%) = 100 × (Ww−Wd) / Wd
Here, Ww is the weight (g) of the hollow fiber membrane before drying, and Wd is the weight (g) of the hollow fiber membrane after being dried for 2 hours in a dry heat oven at 120 ° C. (after completely dried). Here, by setting Ww within the range of 1 to 2 g, it can be in an absolutely dry state (a state in which there is no further weight change) after 2 hours.

  On the other hand, it is preferable to dry by microwave irradiation until the moisture content in the hollow fiber membrane bundle becomes 10 to 20% by mass. Microwave drying is a useful method for drying a hollow fiber membrane bundle because it has good permeability to the material to be dried and high energy, and thus can be efficiently dried, but has a final moisture content of 1 When drying by microwave irradiation is continued until it becomes ˜7% by mass, fluctuations in the degree of degradation of polyvinyl pyrrolidone and fluctuations in water content in the longitudinal direction in the hollow fiber membranes increase, and the hollow fiber membranes intended by the present invention This is not preferable because a bundle cannot be obtained. The cause of the deterioration of the polyvinylpyrrolidone in the longitudinal direction of the hollow fiber membrane and the increase in fluctuation of the water content by irradiating with microwaves in a state where the moisture content in the hollow fiber membrane bundle is low has not been clarified. Drying is performed by directly exciting water molecules with microwaves, and the moisture in the hollow fiber membrane has a strong affinity for polyvinylpyrrolidone and contributes to the localization of polyvinylpyrrolidone. It is presumed that That is, this water localization increases with a decrease in water content, heat generation in the portion where the water is localized increases, leads to non-uniformity in the temperature and dryness of the hollow fiber membrane, and the periphery of the water molecule It is presumed that deterioration is promoted due to the presence of polyvinylpyrrolidone. On the other hand, since far-infrared drying and the like have lower excitation energy than microwaves, it is considered that the occurrence of the above problems is suppressed.

  The water content management method is not limited. Online measurement may be performed by an infrared absorption method or the like, or offline measurement by sampling may be performed.

  In the present invention, as described above, it is important to suppress oxidative degradation of polyvinylpyrrolidone in the drying step. Therefore, it is preferable to carry out the above-described microwave irradiation or far-infrared irradiation in an inert gas atmosphere such as nitrogen gas, but it is economically disadvantageous. On the other hand, a method of suppressing oxidation deterioration by performing microwave drying or far-infrared drying under reduced pressure leads to an improvement in drying efficiency and is recommended. The most preferred embodiment is that both drying operations are performed under reduced pressure. For example, as a drying condition for microwave drying, it is preferable to irradiate microwaves with an output of 0.1 to 100 KW under a reduced pressure of 20 KPa or less. Moreover, the frequency of this microwave is 1,000-5,000 MHz, and it is a preferable embodiment that the highest ultimate temperature of the hollow fiber membrane bundle during a drying process is 90 degrees C or less. If a means of decompression is additionally provided, drying of moisture is promoted by itself, so there is an advantage that the output of microwave irradiation can be suppressed and the irradiation time can be shortened, but the temperature rise can also be made relatively low. Therefore, the influence on the performance degradation of the hollow fiber membrane bundle is small as a whole. Furthermore, drying accompanied by means of reduced pressure has the advantage that the drying temperature can be relatively lowered, and has a significant point that deterioration and decomposition of the hydrophilic polymer can be remarkably suppressed. An appropriate drying temperature is sufficient from 20 to 80 ° C. More preferably, it is 20-70 degreeC, More preferably, it is 20-60 degreeC, More preferably, it is 30-50 degreeC.

  The fact that the pressure is reduced means that the low pressure acts uniformly on the center portion and the outer peripheral portion of the hollow fiber membrane bundle, the moisture evaporation is promoted uniformly, and the hollow fiber membrane is uniformly dried. Therefore, the failure of the hollow fiber membrane bundle due to non-uniform drying is corrected. In addition, heating by microwaves also acts almost equally on the entire center and outer periphery of the hollow fiber membrane bundle, so it functions synergistically in uniform heating, and is unique in drying the hollow fiber membrane bundle. It will be of significance. The degree of vacuum may be appropriately set according to the output of the microwave, the total moisture content of the hollow fiber membrane bundle, and the number of hollow fiber membrane bundles, but the degree of vacuum is 20 kPa to prevent the temperature of the hollow fiber membrane bundle during drying. Hereinafter, it is performed more preferably at 15 kPa or less, and further preferably at 10 kPa or less. If it is 20 kPa or more, not only the water evaporation efficiency is lowered, but also the temperature of the polymer forming the hollow fiber membrane bundle may be increased and deteriorated. Moreover, although the one where a pressure reduction degree is higher is preferable in the meaning which suppresses a temperature rise and raises drying efficiency, since the cost concerning maintaining the sealing degree of an apparatus becomes high, 0.1 kPa or more is preferable. More preferably, it is 0.25 kPa or more, and further preferably 0.4 kPa or more.

In consideration of shortening the drying time, a higher microwave output is preferable.For example, in hollow fiber membrane bundles containing polyvinylpyrrolidone, degradation or decomposition of polyvinylpyrrolidone occurs due to overdrying or overheating, and wettability decreases during use. Therefore, it is preferable not to increase the output so much. Further, the hollow fiber membrane bundle can be dried even with an output of less than 0.1 kW, but there is a possibility that a problem of reduction in throughput due to an increase in drying time may occur. The optimum value of the combination of the degree of decompression and the microwave output varies depending on the water content of the hollow fiber membrane bundle and the number of processed hollow fiber membrane bundles, and it is preferable to obtain a set value as appropriate through trial and error.
For example, as a temporary guide for carrying out the drying conditions of the present invention, when 20 hollow fiber membrane bundles having a moisture content of 50 g per hollow fiber membrane bundle are dried, the total moisture content is 50 g × 20 fibers = 1,000 g. At this time, it is appropriate that the microwave output is 1.5 kW and the decompression degree is 5 kPa.

  A more preferable microwave output is 0.1 to 80 kW, and a more preferable microwave output is 0.1 to 60 kW. The output of the microwave is determined by, for example, the total number of hollow fiber membranes and the total water content, but when suddenly high-power microwaves are irradiated, drying is completed in a short time, but the hollow fiber membrane is partially denatured. And may cause deformation such as curling. When drying using microwaves, for example, when using something like a water retention agent in the hollow fiber membrane, high power and extreme drying using microwaves will disappear due to scattering of the water retention agent It becomes the cause of. In consideration of the influence on the hollow fiber membrane, especially under conditions under reduced pressure, conventionally, irradiation with microwaves under reduced pressure was not intended. Irradiation of microwaves under reduced pressure according to the present invention means that the evaporation of aqueous liquid is active even in a relatively low temperature state, so that degradation of polyvinylpyrrolidone and deformation of hollow fiber membranes due to high output microwaves and high temperatures Thus, a double effect of preventing damage to the hollow fiber membrane is obtained.

  Although the present invention enables one-stage drying in which the microwave output is constant, i.e., drying by microwaves under reduced pressure, as another embodiment, the microwave output is sequentially changed according to the progress of drying. So-called multi-stage drying, which lowers in stages, is included as a preferred embodiment. Therefore, the significance of multi-stage drying will be described as follows. When drying with microwaves at a relatively low temperature of about 30 to 90 ° C. under reduced pressure, multi-stage drying in which the output of the microwaves is sequentially reduced in accordance with the progress of drying of the hollow fiber membrane bundle. The method is excellent. The degree of pressure reduction, temperature, microwave output, and irradiation time may be determined in consideration of the total amount of hollow fiber membranes to be dried, industrially acceptable drying time, and the like. Multistage drying can be performed in any number of stages, for example, 2 to 6 stages, but it is appropriate to use 2 to 3 stages of drying that is industrially appropriate in consideration of productivity. Depending on the total amount of water contained in the hollow fiber membrane bundle, when relatively large, multistage drying is performed at a temperature of 90 ° C. or lower, for example, at a reduced pressure of about 5 to 20 kPa, and the first stage is 30 to 100 kW. The range can be determined in consideration of the microwave irradiation time such that the second stage is in the range of 10 to 30 kW and the third stage is in the range of 0.1 to 10 kW. When the output of the microwave is large, such as 90 kW in the high part and 0.1 kW in the low part, the number of stages for reducing the output may be increased to 4 to 8 stages, for example. In the case of the present invention, since technical consideration is given to the microwave irradiation called decompression, there is an advantage that the microwave output can be relatively lowered. For example, the first stage is about 10 to 100 minutes by 10 to 20 kW microwave, the second stage is about 3 to 10 kW and about 5 to 80 minutes, and the third stage is about 0.1 to 3 kW and about 1 to 60 minutes. Dry in stages. It is preferable that the microwave output and irradiation time of each stage are lowered in conjunction with the reduction in the total amount of moisture contained in the hollow fiber membrane. This drying method is a very gentle drying method for hollow fiber membrane bundles and cannot be expected in the prior arts of the above-mentioned Patent Documents 8 to 10, and thus makes the effects of the present invention significant.

  To explain another aspect, when the so-called moisture content of the hollow fiber membrane bundle is relatively small, that is, a so-called moisture content of 400% by mass or less, irradiation with a low output microwave of 12 kW or less may be excellent. For example, when the amount of water in the total amount of the hollow fiber membrane bundle is about 1 to 7 kg, the output is 12 kW or less under a reduced pressure of about 3 to 10 kPa at a temperature of 80 ° C. or less, preferably 60 ° C. or less. For example, irradiation with a microwave of about 1 to 5 kW for 10 to 240 minutes, irradiation with a microwave of less than 0.5 to 1 kW for about 3 to 240 minutes, and irradiation with a microwave of less than 0.1 to 0.5 kW for about 1 to 240 minutes If the irradiation output and the irradiation time of the microphone mouth wave are adjusted according to the degree of drying, drying is performed uniformly. The degree of vacuum is set to 0.1 to 20 kPa for each stage, but the first stage having a relatively high moisture content of the hollow fiber membrane is increased to 0.1 to 5 kPa, for example, and the microwave output is increased. The degree of pressure reduction at each stage, in which the microwave is irradiated at a pressure slightly higher than the first stage of 0.1 to 5 kW under a reduced pressure of 5 to 20 kPa in the second stage and the third stage. It is possible to arbitrarily set the appropriate adjustment in accordance with the change in consideration of the transition of the total moisture content and the moisture content of the hollow fiber membrane bundle. In each stage, the operation of changing the degree of reduced pressure further increases the significance of irradiating microwaves under reduced pressure according to the present invention. Of course, it is necessary to always consider the uniform irradiation and exhaust of the microwave in the microwave irradiation apparatus.

  The maximum temperature of the hollow fiber membrane bundle during drying can be measured by applying an irreversible thermolabel to the side of the package that protects the hollow fiber membrane bundle, drying it, and checking the display after taking it out. it can. At this time, the maximum reached temperature of the hollow fiber membrane bundle during drying is preferably 90 ° C. or lower, more preferably 80 ° C. or lower. More preferably, it is 70 degrees C or less. If the maximum temperature reaches 90 ° C. or higher, the film structure is likely to change, which may cause performance degradation or oxidative degradation. In particular, in a hollow fiber membrane bundle containing polyvinylpyrrolidone, it is necessary to prevent the temperature rise as much as possible because polyvinylpyrrolidone is easily decomposed by heat. Temperature rise can be prevented by optimizing the degree of decompression and microwave output and irradiating intermittently. Moreover, although the one where a drying temperature is lower is preferable, 30 degreeC or more is preferable from the surface of the maintenance cost of pressure reduction degree, and the shortening of drying time.

  The microwave irradiation frequency is preferably 1,000 to 5,000 MHz in consideration of the suppression of irradiation spots on the hollow fiber membrane bundle and the effect of extruding water in the pores from the pores. More preferably, it is 1,500-4,000 MHz, More preferably, it is 2,000-3,000 MHz.

  In drying by microwave irradiation, it is important to uniformly heat and dry the hollow fiber membrane bundle. In the above-described microwave drying, nonuniform heating due to reflected waves generated during microwave irradiation occurs, so it is important to take measures to reduce nonuniform heating due to the reflected waves. The method is not limited and is arbitrary. For example, a method of providing a reflector in an oven disclosed in Japanese Patent Application Laid-Open No. 2000-340356 to reflect reflected waves and uniformize heating is a preferred embodiment. One.

  On the other hand, in the case of drying by far-infrared irradiation performed after the completion of microwave drying, unlike the case of microwave drying, the discharge phenomenon does not occur even if irradiation is performed under reduced pressure. It can be carried out. From the point of drying efficiency, 2 kPa or less is preferable and 1 kPa or less is more preferable. The energy of the far-infrared irradiation is preferably controlled so as to be 80 ° C. or lower at a temperature detected by a thermocouple provided at the center of the oven. It is more preferable to control at 70 ° C. or lower.

  The far-infrared irradiation may be started after the microwave irradiation is completed, or may be performed simultaneously with the microwave irradiation, and the microwave drying and the far-infrared drying may be performed simultaneously. By performing the microwave and far infrared irradiation simultaneously, the evaporation of water that has been excited by the microwave irradiation and moved to the surface of the hollow fiber membrane is accelerated by the far infrared irradiation, leading to an improvement in drying efficiency. Further, this efficient evaporation of the surface moisture is preferable because the variation in the concentration of polyvinylpyrrolidone on the surface of the hollow fiber membrane induced by the surface moisture is suppressed, and the occurrence of partial sticking is suppressed. As described above, microwave drying is preferably performed under reduced pressure. Therefore, microwave drying and far-infrared drying are simultaneously performed under reduced pressure, and microwave irradiation is performed when the moisture content is reached. A method of stopping the drying by continuing far-infrared irradiation while maintaining a reduced pressure state and continuing further drying is preferable. At this time, after the microwave irradiation is completed, the degree of decompression of the system may be lowered, and after conditioning, the degree of decompression may be raised again to start far-infrared irradiation. Therefore, in the present invention, it is a preferred embodiment that drying is performed using a microwave dryer in which a far-infrared heater is attached in the heating oven and an exhaust system capable of reducing the pressure of the heating oven is attached.

  In this invention, it is preferable that the irradiation wavelength of a far infrared ray is 1-30 micrometers. Since water and organic matter have a high absorption rate of far-infrared rays with a wavelength of 3 to 12 μm, it is difficult to increase the temperature of the object to be dried if the wavelength of far-infrared rays is too short or too long. Such costs may increase. Therefore, the wavelength of the far infrared ray to be irradiated is more preferably 1.5 to 26 μm, further preferably 2 to 22 μm, and further preferably 2.5 to 18 μm.

In the present invention, as a radiation medium for irradiating far-infrared rays, a stainless steel medium having a metal oxide film on the surface is preferably used. For example, an austenitic stainless steel powder as described in JP-A-10-5265 is coated with a metal oxide such as Al ₂ O ₃ , Fe ₂ O ₃ , TiO ₂ , CaO, MgO, K ₂ O and Na ₂ O. It is a more preferable embodiment to use a far-infrared radiator coated with, because far-infrared rays can be extracted efficiently at low cost.

  On the other hand, in the case of drying by far-infrared irradiation performed after the completion of microwave drying, unlike the case of microwave drying, the discharge phenomenon does not occur even if irradiation is performed under reduced pressure. It can be carried out. From the point of drying efficiency, 5 kPa or less is preferable, 4 kPa or less is more preferable, 3 kPa or less is more preferable, and 2 kPa or less is more preferable. The irradiation energy of the far-infrared irradiation is preferably controlled so as to be 80 ° C. or lower at a temperature detected by a thermocouple provided at the center of the oven. It is more preferable to control at 70 ° C. or lower.

  The far-infrared irradiation may be started after the end of microwave irradiation, or may be performed at the time of microwave irradiation, and microwave drying and far-infrared drying may be performed simultaneously. By performing microwave and far-infrared irradiation at the same time, evaporation of water that has been excited by microwave irradiation and moved to the surface of the hollow fiber membrane is accelerated by irradiation with far-infrared radiation, leading to improved drying efficiency. Further, this efficient evaporation of the surface moisture is preferable because the variation in the concentration of polyvinylpyrrolidone on the surface of the hollow fiber membrane induced by the surface moisture is suppressed, and the occurrence of partial sticking is suppressed. As described above, microwave drying is preferably performed under reduced pressure. Therefore, microwave drying and far-infrared drying are simultaneously performed under reduced pressure, and microwave irradiation is performed when the moisture content is reached. A method of stopping, continuing the far-infrared irradiation while maintaining the reduced pressure state, and continuing further drying is preferable. At this time, after the microwave irradiation is completed, the degree of decompression of the system may be lowered and conditioning may be performed, and then the degree of decompression may be increased again to start far-infrared irradiation. Therefore, in the present invention, it is preferable to perform drying using a microwave dryer in which a far-infrared heater is attached in the heating oven and an exhaust system capable of reducing the pressure (vacuum) in the heating oven is attached. It is an aspect.

  In the present invention, it is a preferred embodiment that an inert gas such as nitrogen gas is used when the inside of the drying system is returned to normal pressure after drying. Immediately after the drying, the temperature of the hollow fiber membrane bundle is high, so when returning the inside of the drying chamber to atmospheric pressure, when a gas containing oxygen such as air is fed, in the case of a hollow fiber membrane containing polyvinylpyrrolidone, polyvinylpyrrolidone May undergo oxidative degradation due to the effects of oxygen and heat. Therefore, when the inside of the drying chamber is returned to normal pressure after the drying is completed, the oxidative deterioration of the polyvinyl pyrrolidone in the hollow fiber membrane bundle is suppressed by feeding the inert gas.

  For the drying of the hollow fiber membrane bundle, the use of microwaves and far-infrared rays for an unlimited time does not affect the quality. This is because the effects of thermal degradation of the hydrophobic polymer or the hydrophilic polymer material constituting the hollow fiber membrane bundle and environmental degradation such as oxygen, water, and steam can be considered. Therefore, from the viewpoint of industrial production, it is necessary to consider an appropriate time that is naturally allowed for the drying time. From the viewpoint of protecting the quality of the hollow fiber membrane subjected to relatively harsh drying conditions such as microwaves and far infrared rays, from the viewpoint of industrial productivity, the inventors of the present invention are from the start to the end of drying. The drying time is preferably within 3 hours. More preferably within 2.5 hours, still more preferably within 2 hours.

  In the hollow fiber membrane bundle according to the present invention, it is preferable that the elution amount of hydrogen peroxide is suppressed as described above. Regarding the provision of this property, it is important to select the drying method and conditions described above, but the quality and handling of polyvinyl pyrrolidone, the causative agent of hydrogen peroxide generation, are also important factors and considerations are required. is necessary. For example, it is preferable to produce using polyvinyl pyrrolidone having a hydrogen peroxide content of 300 ppm or less. By setting the hydrogen peroxide content in the polyvinylpyrrolidone used as a raw material to 300 ppm or less, the hydrogen peroxide elution amount of the hollow fiber membrane bundle after film formation can be suppressed to 5 ppm or less, and the hollow fiber membrane of the present invention This is preferable because the bundle quality can be stabilized. Therefore, the hydrogen peroxide content in the polyvinylpyrrolidone used as a raw material is more preferably 250 ppm or less, further preferably 200 ppm or less, and further preferably 150 ppm or less.

  It is estimated that hydrogen peroxide contained in polyvinylpyrrolidone used as the raw material is generated in the process of oxidative degradation of polyvinylpyrrolidone. Therefore, to reduce the hydrogen peroxide content to 300 ppm or less, it is effective to take measures to suppress the oxidative degradation of polyvinylpyrrolidone in the production process of polyvinylpyrrolidone. It is also effective and recommended to take measures to suppress deterioration during transportation and storage of polyvinylpyrrolidone. For example, it is preferable to use an aluminum foil laminated bag to shield the light and enclose it with an inert gas such as nitrogen gas, or to enclose and store an oxygen scavenger together. In addition, it is preferable that the measurement and preparation when the package is opened and subdivided be performed after inert gas replacement, and the above-mentioned measures are taken for the storage. Also, in the manufacturing process of the hollow fiber membrane bundle, it is also recommended as a preferred embodiment to take a means such as replacing the supply tank or the like in the raw material supply system with an inert gas. In addition, it is not excluded to take a method of reducing the amount of hydrogen peroxide by a recrystallization method or an extraction method.

  Also, when stirring and dissolving a spinning solution composed of a polysulfone resin, polyvinyl pyrrolidone, and a solvent, if hydrogen peroxide is contained in the polyvinyl pyrrolidone, the influence of oxygen present in the dissolution tank and the heating during dissolution It was found that hydrogen peroxide increased explosively due to the influence. Therefore, when charging the raw material into the dissolution tank, it is preferable to input the raw material into the dissolution tank that has been previously replaced with an inert gas. As the inert gas, nitrogen, argon or the like is preferably used. Moreover, although a solvent, and a non-solvent may be added depending on the case, it is also a preferable embodiment that oxygen dissolved in these solvent and non-solvent is replaced with an inert gas.

  As a method for controlling the elution amount of hydrogen peroxide to the above regulated range, for example, as described above, it is effective to make the amount of hydrogen peroxide in polyvinylpyrrolidone used as a raw material 300 ppm or less. Since the hydrogen peroxide is also generated during the manufacturing process of the hollow fiber membrane described above, it is necessary to strictly control the manufacturing conditions of the hollow fiber membrane. In particular, since the contribution of the production in the drying process when producing the hollow fiber membrane is large, it is important to optimize the drying conditions. In particular, the optimization of the drying conditions is important because it greatly contributes to the suppression of hydrogen peroxide production. Furthermore, the optimization of the drying conditions is an effective means for reducing the fluctuation in the elution amount in the longitudinal direction of the hollow fiber membrane.

  In addition, as another method for suppressing the generation of hydrogen peroxide, it is an important requirement to dissolve the film forming solution in a short time. For this purpose, it is usually sufficient to increase the dissolution temperature and / or increase the stirring speed. However, when it does so, degradation and decomposition of polyvinyl pyrrolidone will proceed due to the influence of temperature, stirring linear velocity and shearing force. In fact, according to the study by the inventors, the molecular weight of polyvinylpyrrolidone in the film-forming solution moves in the direction of decomposition (shifts to the low molecular side) as the dissolution temperature increases, or the low molecular side. The appearance of a shoulder that appears to be a decomposition product was observed. From the above, increasing the temperature for the purpose of improving the dissolution rate of the raw material accelerates the degradation and decomposition of polyvinylpyrrolidone, and consequently blends the degradation product of polyvinylpyrrolidone into the selectively permeable separation membrane. When the obtained hollow fiber membrane is used for blood purification, the degradation product is eluted in the blood, so that it is not excellent in terms of product quality safety. Then, it tried to mix a raw material at low temperature in order to suppress decomposition | disassembly of polyvinylpyrrolidone. Even if it is low-temperature dissolution, it is usually preferable to have a temperature of 5 ° C. or higher and 70 ° C. or lower because it requires a running cost under extreme conditions that are below freezing. 60 degrees C or less is more preferable. However, simply lowering the melting temperature causes degradation of polyvinylpyrrolidone due to the longer melting time, lowering the operability and increasing the size of the equipment, which causes problems in industrial implementation.

  As a result of examining the dissolution conditions for dissolving at low temperature without taking time, it was found that it is preferable to knead the components constituting the spinning solution prior to dissolution, and the present invention was reached. The kneading may be performed by kneading components such as polysulfone polymer, polyvinyl pyrrolidone and a solvent at once, or kneading polyvinyl pyrrolidone and polysulfone polymer separately. As mentioned above, polyvinylpyrrolidone is accelerated by contact with oxygen and leads to the generation of hydrogen peroxide. Therefore, consideration must be given to suppressing contact with oxygen, such as in an atmosphere substituted with an inert gas, even during kneading. It is preferable to carry out in a separate line. A method of supplying only the polyvinyl pyrrolidone and the solvent and supplying the polysulfone polymer directly to the dissolution tank without pre-kneading is also included in the scope of the present invention.

  The kneading may be performed by providing a kneading line separately from the dissolving tank, and the kneaded product may be supplied to the dissolving tank, or both the kneading and dissolving may be performed in a dissolving tank having a kneading function. The type and form of the kneading apparatus in the former separate apparatus are not limited. Either a batch system or a continuous system may be used. A static method such as a static mixer may be used, or a dynamic method such as a kneader or a stirring kneader may be used. The latter is preferred from the efficiency of kneading. The kneading method in the latter case is not limited, and any type such as a pin type, a screw type, and a stirrer type may be used. Screw type is preferred. What is necessary is just to select suitably the shape and rotation speed of a screw from the balance of kneading | mixing efficiency and heat_generation | fever. On the other hand, the type of dissolution tank when using a dissolution tank having a kneading function is not limited. For example, there is a kneading and dissolving machine of a type that expresses a kneading effect by so-called planetary motion in which two frame-type blades rotate and revolve. Recommended. For example, a planetary mixer or a trimix manufactured by Inoue Seisakusho Co., Ltd. corresponds to this method.

  The ratio of the resin component such as polyvinyl pyrrolidone or polysulfone polymer and the solvent during kneading is not limited. A resin / solvent mass ratio of 0.1 to 3 is preferred. 0.5-2 are more preferable.

  As described above, the technical point of the present invention is to suppress the degradation of polyvinyl pyrrolidone and perform efficient dissolution. Therefore, a system in which at least polyvinylpyrrolidone is present is a preferred embodiment in which the system is kneaded and dissolved at a low temperature of 70 ° C. or lower in a nitrogen atmosphere. When the polyvinyl pyrrolidone and the polysulfone polymer are kneaded in separate lines, this requirement may be applied to the polysulfone polymer kneading line. The efficiency of kneading and dissolution and heat generation are two contradictory phenomena. Selection of an apparatus and conditions that avoid the trade-off as much as possible is an important element of the present invention. In this sense, the cooling method in the kneading mechanism is important and needs attention.

Subsequently, the material kneaded by the above method is dissolved. Although the dissolution method is not limited, for example, a dissolution method using a stirring type dissolution apparatus can be applied. In order to dissolve at a low temperature for a short time (within 3 hours), the Froude number (Fr = n ² d / g) is 0.7 to 1.3 and the stirring Reynolds number (Re = nd ² ρ / μ) is It is preferable that they are 50 or more and 250 or less. Here, n is the blade rotation speed (rps), ρ is the density (Kg / m ³ ), μ is the viscosity (Pa · s), g is the gravitational acceleration (= 9.8 m / s ² ), and d is the stirring blade diameter. (M). If the Froude number is too large, the inertial force becomes strong, so that the raw material scattered in the tank adheres to the walls and ceiling, and the desired film-forming solution composition may not be obtained. Therefore, the fluid number is more preferably 1.25 or less, further preferably 1.2 or less, and further preferably 1.15 or less. On the other hand, if the fluid number is too small, the inertial force is weakened, so that the dispersibility of the raw material is lowered, and in particular, polyvinylpyrrolidone becomes a spatter, which makes it difficult to dissolve further or requires a long time for uniform dissolution. Sometimes. Therefore, the fluid number is more preferably 0.75 or more, and further preferably 0.8 or more.

  Since the film-forming solution in the present invention is a so-called low-viscosity fluid, if the stirring Reynolds number is too large, the defoaming time becomes long due to entrapment of bubbles in the film-forming solution during stirring, or the defoaming is insufficient. Problems may occur. Therefore, the stirring Reynolds number is more preferably 240 or less, further preferably 230 or less, and still more preferably 220 or less. On the other hand, when the stirring Reynolds number is too small, the stirring force becomes small, so that dissolution may be easily made nonuniform. Therefore, the stirring Reynolds number is more preferably 35 or more, further preferably 40 or more, still more preferably 55 or more, and particularly preferably 60 or more. Further, when a hollow fiber membrane is formed with such a spinning solution, the operation is deteriorated due to a decrease in spinnability due to bubbles, and in terms of quality, the portion becomes defective due to the entrapment of bubbles in the hollow fiber membrane, and the membrane is not confidential. It has been found that this causes problems such as decreased sex and burst pressure. Defoaming of the spinning solution is an effective countermeasure, but it may involve a change in the composition of the spinning solution due to viscosity control of the spinning solution or evaporation of the solvent.

Furthermore, since polyvinylpyrrolidone tends to undergo oxidative degradation due to the influence of oxygen in the air, it is preferable to dissolve the spinning solution in an inert gas enclosure. Nitrogen, argon, etc. are raised as the inert gas, but nitrogen is preferably used. At this time, the residual oxygen concentration in the dissolution tank is preferably 3% or less. If the nitrogen filling pressure is increased, the melting time can be shortened. However, in order to increase the pressure, the equipment cost is increased, and from the viewpoint of work safety, atmospheric pressure and 2 kgf / cm ² or less are preferable.

  In addition, as the shape of the stirring blade used for dissolving the low-viscosity film forming solution used in the present invention, a radial turbine blade such as a disk turbine type, a paddle type, a curved blade fan turbine type, an arrow blade turbine type, or a propeller type An axial-flow type wing such as an inclined paddle type or a fiddler type is included, but is not limited thereto.

  By using the low-temperature dissolution method as described above, it is possible to obtain a highly safe hollow fiber membrane in which the degradation degradation of the hydrophilic polymer is suppressed. In addition, it is preferable to use a spinning solution having a residence time of 24 hours or less after dissolution of the raw material for film formation. This is because thermal energy was accumulated while the film forming solution was kept warm, and a tendency to cause deterioration of the raw material was recognized.

  Although the other characteristic of the hollow fiber membrane bundle in this invention is not limited, For example, it is preferable that the content rate in the outer surface of the hollow fiber membrane bundle of polyvinylpyrrolidone is 25-50 mass%. 27-45 mass% is more preferable, and 30-45 mass% is further more preferable. If the content of polyvinyl pyrrolidone on the outer surface is less than 25% by mass, the content of polyvinyl pyrrolidone on the entire membrane, particularly on the inner surface of the membrane will be too low, and blood compatibility and permeation performance may be deteriorated. Even if the drying method of the present invention is applied, the priming property may be lowered. When the hemodialyzer is used for blood purification therapy, it is necessary to perform wetting and defoaming by allowing physiological saline or the like to flow inside and outside the hollow fiber membrane bundle of the hemodialyzer. In this priming operation, the roundness of the hollow fiber membrane bundle, edge crushing, deformation, hydrophilicity of the membrane material, etc. are thought to affect the priming properties. However, the hollow fiber made of polysulfone polymer and polyvinylpyrrolidone In the case of a yarn membrane bundle and a dry membrane module, the hydrophilic / hydrophobic balance of the hollow fiber membrane bundle greatly affects the priming property. If the content of polyvinylpyrrolidone on the outer surface exceeds 50% by mass, the endotoxin (endotoxin) contained in the dialysate may enter the blood, leading to side effects such as fever, or drying the membrane. When this is done, polyvinyl pyrrolidone present on the outer surface of the membrane intervenes and the hollow fiber membrane bundles are fixed to each other, which may cause problems such as deterioration in module assembly.

  As a method for imparting the above properties, for example, the composition ratio of polyvinyl pyrrolidone with respect to the polysulfone-based polymer can be set to the above range, or the film forming conditions of the hollow fiber membrane bundle can be optimized. It is also an effective method to wash the formed hollow fiber membrane bundle. As film forming conditions, humidity adjustment of the air gap part at the nozzle outlet, stretching conditions, temperature of the coagulation bath, optimization of the composition ratio of the solvent and the non-solvent in the coagulation liquid, etc. Washing, alcohol washing, centrifugal washing and the like are effective. Among these methods, as the film forming conditions, optimization of the humidity of the air gap and the composition ratio of the solvent and the non-solvent in the external coagulating liquid is particularly effective as the cleaning method.

  As the internal coagulation liquid, a 0 to 80% by mass dimethylacetamide (DMAc) aqueous solution is preferable. More preferably, it is 15-70 mass%, More preferably, it is 25-60 mass%, More preferably, it is 30-50 mass%. If the concentration of the internal coagulation solution is too low, the dense layer of the blood contact surface becomes thick, which may reduce the solute permeability. On the other hand, if the concentration of the internal coagulating liquid is too high, the formation of the dense layer tends to be incomplete, and the fractionation characteristics may be deteriorated. The external coagulation liquid is preferably a 0 to 50% by weight DMAc aqueous solution. If the concentration of the external coagulation solution is too high, the outer surface open area ratio and outer surface average pore area will become too large, which may increase the backflow of endotoxin to the blood side during dialysis and decrease the burst pressure. is there. Therefore, the external coagulation liquid concentration is more preferably 40% by mass or less, further preferably 30% by mass or less, and still more preferably 25% by mass or less. If the concentration of the external coagulation liquid is too low, it is necessary to use a large amount of water to dilute the solvent brought in from the spinning solution, and the cost for waste liquid treatment increases. Therefore, the lower limit of the external coagulation liquid concentration is more preferably 5% by mass or more.

  In the production of the hollow fiber membrane bundle, it is preferable that stretching is not substantially performed before the hollow fiber membrane bundle structure is completely fixed. “Substantially no stretching” means that the roller speed during the spinning process is controlled so that the spinning solution discharged from the nozzle does not become slack or excessively tensioned. The discharge linear speed / coagulation bath first roller speed ratio (draft ratio) is preferably in the range of 0.7 to 1.8. If the ratio is less than 0.7, the running hollow fiber membrane bundle may be slack and lead to a decrease in productivity. Therefore, the draft ratio is more preferably 0.8 or more, more preferably 0.9 or more, and 0 .95 or more is even more preferable. If it exceeds 1.8, the membrane structure may be destroyed, for example, the dense layer of the hollow fiber membrane bundle is torn. Therefore, the draft ratio is more preferably 1.7 or less, still more preferably 1.6 or less, still more preferably 1.5 or less, and particularly preferably 1.4 or less. By adjusting the draft ratio to this range, deformation and destruction of the pores can be prevented, clogging of blood protein into the membrane pores can be prevented, and performance stability over time and sharp fractionation characteristics can be expressed. Is possible.

The hollow fiber membrane bundle that has passed through the water-washing bath is wound into a basket in a wet state to form a bundle of 3,000 to 20,000. Next, the obtained hollow fiber membrane bundle is washed to remove excess solvent, polyvinylpyrrolidone. As a method for washing the hollow fiber membrane bundle, in the present invention, it is preferable to treat the hollow fiber membrane bundle by immersing it in hot water at 70 to 130 ° C. or room temperature to 50 ° C. and 10 to 40 vol% ethanol or isopropanol aqueous solution. .
(1) In the case of hot water washing, the hollow fiber membrane bundle is immersed in excess RO water and treated at 70 to 90 ° C. for 15 to 60 minutes, and then the hollow fiber membrane bundle is taken out and subjected to centrifugal dehydration. This operation is repeated three or four times while updating the RO water to perform the cleaning process.
(2) A method of treating a hollow fiber membrane bundle immersed in excess RO water in a pressurized container at 121 ° C. for about 2 hours may be employed.
(3) When using an ethanol or isopropanol aqueous solution, it is preferable to repeat the same operation as in (1).
(4) It is also a preferable washing method that the hollow fiber membrane bundle is radially arranged in the centrifugal washer, and centrifugal washing is performed for 30 minutes to 5 hours while spraying washing water at 40 ° C. to 90 ° C. from the rotation center in a shower shape. .
Two or more cleaning methods may be combined. In any of the methods, if the processing temperature is too low, it is necessary to increase the number of times of cleaning, which may lead to an increase in cost. On the other hand, if the treatment temperature is too high, the decomposition of polyvinylpyrrolidone is accelerated, and conversely, the cleaning efficiency may be reduced. By performing the above-described cleaning, it is possible to optimize the content of the outer surface polyvinyl pyrrolidone, thereby suppressing sticking and reducing the amount of eluate.

  In this invention, it is preferable that the content rate in the outer surface of the hollow fiber membrane of a hydrophilic polymer is 25-50 mass%. If the content of the hydrophilic polymer on the outer surface is less than 25% by mass, the proportion of the hydrophilic polymer on the entire membrane, particularly the inner surface of the membrane, becomes too low, and blood compatibility and permeation performance may be degraded. . In the case of a dry film, wettability may be reduced. When the hemodialyzer is used for blood purification therapy, it is necessary to perform wetting and defoaming by allowing physiological saline or the like to flow inside and outside the hollow fiber membrane of the hemodialyzer. In this priming operation, roundness of the hollow fiber membrane, edge crushing, deformation, hydrophilicity of the membrane material, etc. are thought to affect the priming properties, but it consists of a hydrophobic polymer and a hydrophilic polymer. In the case of a hollow fiber membrane and a dry membrane module, the hydrophilic / hydrophobic balance of the hollow fiber membrane greatly affects the priming property. Therefore, the more preferable content of the hydrophilic polymer is 27% by mass or more, and more preferably 30% by mass or more. If the content of the hydrophilic polymer on the outer surface exceeds 50% by mass, the endotoxin (endotoxin) contained in the dialysate may enter the blood side, leading to side effects such as fever, When the membrane is dried, a hydrophilic polymer existing on the outer surface of the membrane is interposed, and the hollow fiber membranes stick to each other (adhere), which may cause problems such as deterioration in module assembly. Therefore, a more preferable content rate is 47 mass% or less, More preferably, it is 45 mass% or less.

  In addition, the content rate of the hollow polymer membrane surface outermost layer of the above-mentioned hydrophilic polymer was measured and calculated by the ESCA method as described later, and the outermost layer portion (depth number from the surface layer) of the hollow fiber membrane surface was calculated. The absolute value of the existence ratio of ˜several tens of meters) is obtained. Usually, the ESCA method (outermost layer) can measure the hydrophilic polymer (PVP) content up to about 10 nm (100 mm) deep from the blood contact surface.

  Moreover, in this invention, it is effective in order to provide an above described property that the porosity of the outer surface of a hollow fiber membrane is 8-25%, and is a preferable embodiment. If the open area ratio is less than 8%, the water permeability may be lowered. Further, when the membrane is dried, the hydrophilic polymer existing on the outer surface of the membrane is interposed, and the hollow fiber membranes are fixed to each other, causing problems such as deterioration in module assemblability. Therefore, the open area ratio is more preferably 9% or more, and further preferably 10% or more. On the other hand, when the open area ratio exceeds 25%, the burst pressure may decrease or endotoxin from the dialysate side to the blood side may enter during hemodialysis. Therefore, the porosity is more preferably 23% or less, further preferably 20% or less, still more preferably 17% or less, and particularly preferably 15% or less.

  The film thickness of the hollow fiber membrane is preferably 10 μm or more and 60 μm or less. If it exceeds 60 μm, the permeability of medium to high molecular weight substances having a low movement speed may be lowered even if the water permeability is high. The thinner the film thickness is, the higher the substance permeability is, and it is more preferably 55 μm or less, further preferably 50 μm or less, and still more preferably 47 μm or less. On the other hand, when the film thickness is less than 10 μm, the burst pressure may be lowered even if the film strength is low and the thickness deviation is 0.6 or more. Therefore, the film thickness is more preferably 20 μm or more, further preferably 25 μm or more, still more preferably 30 μm or more, and particularly preferably 35 μm or more.

  The hollow fiber membrane bundle of the present invention has the above characteristics and can be suitably used as a separation membrane for a blood purifier, for example.

  The separation module of the present invention is a module in which both ends of a hollow fiber membrane bundle made of a polysulfone-based resin containing polyvinylpyrrolidone are fixed with a resin.

The shape of the separation module is illustrated in FIG.
The separation module 1 is loaded with a hollow fiber membrane bundle 3 in a cylindrical container 2, and both ends of the hollow fiber membrane bundle 3 are fixed to both ends of the container 2 with an adhesive or the like 4. Is covered with caps 5a and 5b. A dialysate inlet 6a for introducing dialysate into the container 2 is provided near one end of the side of the container 2, and a dialysate outlet 6b for discharging dialysate is provided near the other end. Each is formed to protrude. One cap 5a is formed with a blood introduction port 7a for introducing blood into the container 2, and the other cap 5b is formed with a blood discharge port 7b for discharging blood.

  The blood enters the space formed by the cap 5a and one end surface of the hollow fiber membrane bundle 3 from the blood introduction port 7a as indicated by the arrow A, and passes through the hollow fibers of the hollow fiber membrane bundle 3 As shown, the hollow fiber bundle 3 enters the space formed by the other end face of the hollow fiber bundle 3 and the cap 5b, and is discharged from the blood outlet 7b as shown by an arrow B. On the other hand, the dialysate enters the container 2 from the dialysate inlet 6a as shown by the arrow C, flows outside the hollow fiber of the hollow fiber membrane bundle 3, and as shown by the arrow D, the dialysate outlet 6b. Discharged from. At this time, the flow of blood and the flow of dialysate are so-called opposite flows (cross flow) in opposite directions. During this time, waste in the blood flowing in the hollow fiber membrane is dialyzed into the outer dialysate through the hollow fiber membrane.

  Examples of the material for the container and the cap include polycarbonate, polyester, and polypropylene. Examples of the adhesive material used for fixing both ends include polyurethane resin, epoxy resin, and silicone resin.

  The method of injecting the adhesive used for fixing both ends into the fixing portion is not limited, but a centrifugal bonding method in which an adhesive resin is injected using a centrifugal force generated by rotating a module to be injected is recommended. The method of the centrifugal bonding method is not limited. For example, sealing jigs are attached to both ends of a container in which a dried hollow fiber membrane bundle is loaded, and set in a centrifugal bonding machine. A predetermined amount of uncured adhesive resin is injected from the dialysate inlets 6a and 6b at a temperature near room temperature while rotating the centrifugal adhesive machine at a predetermined rotational speed, and then the temperature of the centrifugal adhesive machine is injected. The curing temperature is raised and the curing is terminated, or at least the resin is precured until the fluidity of the resin is lost, and the centrifugal bonding machine is stopped. In the latter case, heating is performed in a stationary state, post-curing is performed, and curing is terminated. This centrifugal bonding method may be a two-layer centrifugal bonding method in which the hollow fiber membrane at the bonding interface is reinforced by covering the inside of the bonding portion of the hollow fiber membrane bundle with a flexible resin layer.

In the case of the centrifugal bonding method, it is important that the adhesive is uniformly injected into the entire space in the hollow fiber membrane bundle. If this injection becomes non-uniform and a portion where the injection amount of the adhesive is insufficient is produced, it leads to poor adhesion. In particular, if there is a portion where the hollow fiber membranes are fixed, penetration of the adhesive is inhibited. Therefore, in order to unravel the adhering portion, for example, so-called yarn trimming treatment in which air is blown from the nozzle onto the end surface of the hollow fiber membrane bundle is performed. Certainly, the present yarn setting treatment is effective for unraveling the fixed hollow fiber membrane, but this treatment is not preferable because the hollow fiber membrane bundle at the end face portion is deformed and the inclined hollow fiber membrane is generated.
The hollow fiber membrane bundle of the present invention is characterized in that the uniformity of the injection of the adhesive is ensured without performing the yarn setting treatment because partial adhesion during drying is suppressed. Therefore, the yarn setting process is not necessary.
However, since it is important to ensure the uniformity of the injection of the adhesive, it is preferable to implement the following measures. For example, it is preferable to select a low viscosity brand as the adhesive. The viscosity after 2 minutes of mixing the two liquids is preferably 2000 mPa · s or less. 1600 mPa · s or less is more preferable. Moreover, it is preferable to lower the packing density of the hollow fiber membrane bundle restrained by the hollow package when the dry hollow fiber membrane bundle is inserted into the container used for module assembly.

  The number of hollow fiber membranes and the length of the hollow fiber membrane bundle to be filled are appropriately set according to market requirements and hollow fiber membrane bundle characteristics. The length and diameter of the container are set so as to match the size of the hollow fiber membrane bundle to be filled. The hollow fiber membrane bundle to be filled is preferably, but not limited to, the hollow fiber membrane bundle of the present invention described above.

The separation module of the present invention is a ratio of the number of hollow fiber membranes whose inclination of the hollow fiber membrane is 15 ° or more in the portion fixed by the adhesive resin evaluated by the method described below (hereinafter referred to as the inclined hollow fiber membrane). The hollow fiber membrane bundle after being stored for 1 year at room temperature in a state where the module is filled with a liquid mainly composed of water is 0.05% or less and is divided into 10 pieces in the longitudinal direction. The UV (220 to 350 nm) absorbance in the hollow fiber membrane extract when each of the tests defined by the dialysis-type artificial kidney device manufacturing approval standard is performed is preferably 0.10 or less.
In addition, the liquid filled in the module during the storage evaluation of the above-mentioned module is only water or sodium pyrosulfite, sodium sulfite for preventing deterioration of the hollow fiber membrane bundle material during γ-ray sterilization treatment of the module. And an aqueous solution in which sodium bisulfite, acetone sodium bisulfite, sodium formaldehyde sulfoxylate, ascorbic acid, glycerin and the like are dissolved.

[Evaluation method of proportion of inclined hollow fiber membrane]
A dry hollow fiber membrane bundle restraint body in which a predetermined number of hollow fiber membranes (for example, 10000) is restrained by a hollow packaging body made of a polyethylene film having a thickness of 0.2 mm, the surface of the hollow fiber bundle side being textured. It is inserted into a module container having a predetermined shape (for example, an inner diameter of 31 mm and a length of 255 mm), and a package made of a polyethylene film is pulled out while fixing the hollow fiber membrane. In this state, sealing jigs are attached to both ends of the container and set in a centrifugal bonding machine. While rotating the centrifugal bonding machine at a rotation speed of 500 rpm, a potting agent (two-component curable polyurethane resin manufactured by Sanyo Kasei Co., Ltd., main agent: Polymedica MA-200, curing agent: Polymedica MB, from the dialysate inlets 6a and 6b. -200, blending ratio: 52/48, viscosity after 2 minutes of mixing of two liquids: 1400 mPa · s) at 25 ° C., 20 g was injected at 0.8 g / sec per end face. Cure for 30 minutes at 50 ° C. and stop the centrifugal bonding machine. After taking out this module and carrying out post-curing overnight at room temperature, 5 mm each of both ends of the module end are cut and opened to obtain a hollow fiber membrane bundle module. The module end face is cut at a thickness of about 0.2 mm to produce a sample for evaluation. The above-described method for producing the sample for evaluation is an example and is not limited. For example, when evaluating a modularized separation module product, the end surface of the module may be cut to a thickness of about 0.2 mm to obtain an evaluation sample. This end face is enlarged and projected by a projector, and a hollow fiber membrane whose inclination with respect to the normal of the end face is 15 degrees or more is defined as an inclined hollow fiber membrane. The specific measurement method is as follows. That is, first, the thickness (d) of the sample is measured, and a value of d × tan 15 degrees is calculated. The sample is enlarged and projected by a projector about 20 to 50 times. If a tilted hollow fiber membrane is present, a shadow of the tilted portion occurs. The length of the shift of the shadow portion is measured. The number of hollow fiber membranes whose length is greater than the above d × tan 15 degrees is counted. A conceptual diagram is shown in FIG.
The ratio of the inclined hollow fiber membrane is calculated by the following formula.
Ratio of inclined hollow fiber membrane (%) = (number of hollow fiber membranes inclined at 15 degrees or more / total number of hollow fiber membranes on the sample end face) × 100

  When the degree of inclination of the hollow fiber membrane exceeds 15 degrees, it becomes difficult for blood to flow, and drift occurs, leading to the generation of residual blood thread. The proportion of the inclined hollow fiber membrane is more preferably 0.04% or less, and further preferably 0.03% or less. 0% is particularly preferred. If it exceeds 0.05%, the number of residual blood threads increases, which gives anxiety to dialysis patients. In the present invention, it is preferable that this characteristic is satisfied on both end faces.

  The UV (220-350 nm) absorbance in the hollow fiber membrane extract is more preferably maintained even when stored for 2 years or longer. For this purpose, the UV (220-350 nm) absorbance after storage for 1 year is more preferably 0.08 or less, and further preferably 0.06 or less. This is preferable because the long-term safety of the separation module can be maintained. In addition, UV (220-350 nm) absorbance after storage is evaluated by an average value when the hollow fiber membrane bundle is divided into 10 pieces in the longitudinal direction and measured for each.

Further, in the separation module of the present invention, it is preferable that the ratio of the collapsed hollow fiber membrane in which the hollow fiber membrane bundle on the module end surface is fixed with an adhesive is observed by the following method is 0.05% or less. In the present invention, it is preferable that this characteristic satisfies both end faces. 0.04% or less is more preferable, and 0.03% or less is more preferable. 0% is particularly preferred. When the ratio of the collapsed hollow fiber membrane exceeds 0.05%, blood becomes difficult to flow, blood drifts and leads to the generation of residual blood thread.
[Method for evaluating the ratio of hollow hollow fiber membranes]
The end face (module end face) of the sample used for the evaluation of the ratio of the above-described inclined hollow fiber membrane was radially marked with 8 divisions, and the entire end face obtained by dividing the 8 divisions was observed at a magnification of 200 times to count the number of crushed yarns. The standard of crushing is to measure the short diameter and long diameter of each hollow fiber membrane, and the one whose ratio is flatter than 1: 2 is regarded as a crushing hollow fiber membrane. The ratio of the number of crushed hollow fiber membranes is obtained by the following equation.
Ratio of collapsed hollow fiber membranes (%) = (number of collapsed hollow fiber membranes / total number of hollow fiber membranes on the sample end face) × 100
Here, both the number of crushed yarns and the total number of hollow fiber membranes on the sample end face are total counts of all the end faces divided into eight.

Furthermore, it is preferable that the separation module of the present invention has a clogging yarn ratio measured by the following method of 0.05% or less. 0.04% or less is more preferable, and 0.03% or less is more preferable. 0% is particularly preferred. When the ratio of the clogged yarn exceeds 0.05%, it is not preferable because blood becomes difficult to flow and blood drifts and leads to the generation of residual blood yarn. In the present invention, it is preferable that this characteristic satisfies both end faces.
[Percentage of clogged yarn]
The end surface of the sample prepared by the above method is colored with red magic ink (R), and the end surface is radially marked into eight parts, and the whole end surface divided into eight parts is a microscope with a national light (light scope 100, magnification: 100). Counts the number of clogged yarns using a Matsushita Electric Industrial Co., Ltd.). The ratio of clogged yarn is calculated by the following formula.
Clogging yarn ratio (%) = (number of clogging yarns / total number of hollow fiber membranes on the sample end face) × 100
Here, both the number of clogged yarns and the total number of hollow fiber membranes on the sample end face are total counts of all end faces divided into eight.

In the separation module of the present invention, the ratio of residual blood thread measured by the following method is preferably 0.05% or less with respect to the total number of hollow fibers per module. 0.04% or less is more preferable, and 0.03% or less is more preferable. 0% is particularly preferred. If it exceeds 0.05%, the number of residual blood threads increases, which gives anxiety to dialysis patients.
[Rate blood thread ratio evaluation method]
The dialyzate side of the module obtained by the above method is filled with physiological saline, 200 ml of heparinized blood collected from a healthy person is packed in a blood bag, the blood bag and the module are connected by a tube, and the blood flow rate is 100 ml / Cycle for 1 hour. Blood samples before the start of circulation and 60 minutes of circulation are sampled, and the white blood cell count and platelet count are measured. The measured value is corrected with the value of hematocrit.
Correction value = measured value (60 minutes) x hematocrit (0 minutes) / hematocrit (60 minutes)
The rate of change of white blood cells and platelets is calculated from the correction value.
Change rate = correction value (60 minutes) / value before circulation start × 100
After circulation for 60 minutes, the blood is returned with physiological saline, and the number of remaining blood is counted. The ratio of residual blood thread is calculated by the following formula.
Ratio of residual blood thread (%) = (number of residual blood threads / total number of hollow fiber membranes in module) × 100

  The achievement means for imparting the above properties is not limited, but can be achieved, for example, by using the hollow fiber membrane bundle of the present invention described above.

  Hereinafter, the effectiveness of the present invention will be described with reference to examples, but the present invention is not limited thereto. In addition, the evaluation method of the physical property in the following examples is as follows.

1. Water content of hollow fiber membrane bundle The water content of the hollow fiber membrane bundle in the present invention was calculated by the following equation.
Moisture content (mass%) = 100 × (Ww−Wd) / Wd
Here, Ww is the weight (g) of the hollow fiber membrane before drying, and Wd is the weight (g) of the hollow fiber membrane after being dried for 2 hours in a dry heat oven at 120 ° C. (after completely dried). Here, by setting Ww within the range of 1 to 2 g, it can be in an absolutely dry state (a state in which there is no further weight change) after 2 hours.

2. Moisture content fluctuation rate of hollow fiber membrane bundle The hollow fiber membrane bundle was equally divided into 10 pieces of 2.7 cm in the longitudinal direction, and 1 g of the dried hollow fiber membrane bundle was weighed from each part, and water content was obtained by the above method. The rate was measured and calculated by the following formula.
Moisture content fluctuation rate (%) = {(maximum moisture content value−minimum moisture content value) / average moisture content value} × 100

3. UV (220-350 nm) absorbance The method defined in the dialysis artificial kidney device production standard, that is, 100 ml of pure water was added to 1 g of a hollow fiber membrane and extracted at 70 ° C. for 1 hour. The obtained extract was measured for absorbance at a wavelength of 200 to 350 nm using a spectrophotometer (U-3000, manufactured by Hitachi, Ltd.), and the maximum absorbance in this wavelength range was determined.
In the measurement, the hollow fiber membrane bundle was equally divided into 10 pieces of 2.7 cm in the longitudinal direction, and 1 g of the hollow fiber membrane in a dry state was weighed from each part and measured for all samples.
In the case of the wet hollow fiber membrane module, physiological saline was passed through the dialysate side channel of the module at 500 mL / min for 5 minutes, and then passed through the blood side channel at 200 mL / min. Thereafter, the solution was allowed to pass through for 3 minutes while filtering from the blood side to the dialysate side at 200 mL / min, and then freeze-dried to obtain a dry membrane, and the above quantification was performed using the dry membrane.

4. Determination of hydrogen peroxide A hydrogen chloride solution of TiCl ₄ mixed with 2.6 ml of an ammonium chloride buffer (PH 8.6) in an equimolar ratio with 2.6 ml of the extract extracted in the same manner as 3 above and 4- 0.2 ml of a coloring reagent prepared by adjusting the mixed solution of (2-pyridylazo) resorcinol with an aqueous Na salt solution to 0.4 mM was added, heated at 50 ° C. for 5 minutes, cooled to room temperature, and the absorbance at 508 nm was measured. It quantified with the analytical curve calculated | required similarly using the sample and calculated | required.
In the measurement, the hollow fiber membrane bundle was equally divided into 10 pieces of 2.7 cm in the longitudinal direction, and 1 g of the hollow fiber membrane bundle in a dry state was weighed from each portion and measured for all samples.
In the case of a wet hollow fiber membrane type separation module, measurement was performed using a dry membrane obtained by processing in the same manner as the measurement of UV (220-350 nm) absorbance.

5. Partial fixing property of hollow fiber membrane bundle Using a SK cutter so that the hollow fiber membrane bundles are not fused by heat generated during cutting of the dry hollow fiber membrane bundle constrained by the package, the longitudinal direction of the hollow fiber membrane bundle Cut into 2 cm widths. While neutralizing the ring-shaped hollow fiber membrane bundle (SJ-F020, manufactured by Keyence Corporation), it was slowly dropped onto the paper surface of the desk, and it was visually confirmed whether or not a plurality of lumps were generated. In addition, when visually confirming, the thing which the lump produced by fusion | melting of the cut surface clearly was classified as not partial adhesion. When the fused state is severe, a cutting tool is appropriately selected.

6. Shrinkage variation of the hollow fiber membrane bundle (1) Ratio of short yarn Measure the length of all hollow fiber membranes of the dried hollow fiber membrane bundle loaded in the container, and measure the reference length [container length A (mm) And the total length of the length B (mm) including the cutting allowance of the hollow fiber membrane bundle end at the time of assembling the separation module], the number of hollow fiber membranes shorter than 1 mm was determined.
The length is measured by sandwiching both ends of each hollow fiber membrane 5 mm from the end with a KOKUYO W clip mouth width of 15 mm and beans (manufactured by KOKUYO: Cree J36), fixing one clip, and fixing the other clip The hollow fiber membrane was suspended as free, and the yarn length was measured with a ruler in this state.
The proportion of short yarn was determined by the following formula.
Short yarn ratio (%) = (number of short yarns / total number of hollow fiber membranes in a bundle of hollow fiber membranes) × 100
The following quality classification was determined based on the ratio of the short yarn.
A: Ratio of short yarn is less than 0.03%
○: Ratio of short yarns 0.03-0.05%
X: Ratio of short yarn exceeding 0.05% ◎ and ○ were regarded as acceptable.
(2) Ratio of long yarn Measure the length of all hollow fiber membranes of the dried hollow fiber membrane bundle loaded in the container, and measure the reference length [container length A (mm) and hollow fiber when assembling the separation module. The total number of hollow fiber membranes exceeding 1 mm from the total length of the length B (mm) including the cutting allowance at the end of the membrane bundle was determined.
The length was measured by the same method as the evaluation method for the proportion of the short yarn.
The length of the long yarn was determined by the following formula.
Ratio of long yarn (%) = (number of short yarns / total number of hollow fiber membranes in a bundle of hollow fiber membranes) × 100
The following quality classification was determined based on the ratio of the long yarn.
A: Ratio of long yarn less than 0.03%
○: Ratio of long yarn 0.03-0.05%
X: The ratio of long yarn exceeding 0.05% ◎ and ○ were accepted.

7. Storage stability of the dried hollow fiber membrane bundle The dried samples used for the measurement of the various elution amounts described above were placed in a dry box (atmosphere: air) conditioned at a humidity of 50% for 3 months at room temperature. After storage, UV (220-350 nm) absorbance was measured by the above method. Stability was determined by the degree of increase in UV (220-350 nm) absorbance due to the storage. The degree of increase was determined by dividing the hollow fiber membrane bundle into 10 pieces of 2.7 cm in the longitudinal direction, measuring each sample, and determining the average value. Those whose average value did not exceed 0.1 were regarded as acceptable.

8. Inclined Hollow Fiber Membrane Ratio Evaluation Method The dry hollow fiber membrane bundle restraint obtained in the examples and comparative examples is inserted into a module container having an inner diameter of 31 mm and a length of 255 mm, and the hollow fiber membrane is fixed and packaged. I extracted my body. In this state, sealing jigs were attached to both ends of the container and set in a centrifugal bonding machine. While rotating the centrifugal bonding machine at a rotation speed of 500 rpm, a potting agent (two-component curable polyurethane resin manufactured by Sanyo Kasei Co., Ltd., main agent: Polymedica MA-200, curing agent: Polymedica MB, from the dialysate inlets 6a and 6b. -200, blending ratio: 52/48, viscosity after 2 minutes of mixing of two liquids: 1400 mPa · s) at 25 ° C., 20 g was injected at 0.8 g / sec per end face. The centrifugal bonding machine was stopped by curing at 50 ° C. for 30 minutes. This module was taken out and post-cured overnight at room temperature, and then 5 mm each of both ends of the module end were cut and opened to obtain a hollow fiber membrane bundle module. The module end face was cut to a thickness of about 0.2 mm to prepare an evaluation sample. This end face was enlarged and projected by a projector, and a hollow fiber membrane having an inclination of 15 degrees or more with respect to the normal of the end face was defined as an inclined hollow fiber membrane. The specific measurement method is as follows. That is, first, the thickness (d) of the sample was measured, and a value of d × tan 15 degrees was calculated. The sample is enlarged and projected by a projector about 20 to 50 times. If a tilted hollow fiber membrane is present, a shadow of the tilted portion occurs. The length of the shift of the shadow portion was measured. The number of hollow fiber membranes whose length is greater than the above d × tan 15 degrees is counted. A conceptual diagram is shown in FIG.
The ratio of the inclined hollow fiber membrane is calculated by the following formula.
Ratio of inclined hollow fiber membrane (%) = (number of hollow fiber membranes inclined at 15 degrees or more / total number of hollow fiber membranes on the sample end face) × 100
The following quality classification was determined by the ratio of the inclined hollow fiber membrane.
A: Ratio of inclined hollow fiber membrane is less than 0.03%
○: Ratio of inclined hollow fiber membrane 0.03 to 0.05%
X: The proportion of the inclined hollow fiber membrane exceeds 0.05%.

9. Ratio evaluation method of collapsed hollow fiber membrane The end surface (module end surface side) of the sample used for the ratio evaluation of the above-mentioned inclined hollow fiber membrane is radially divided into 8 divisions, and the entire end surface divided into 8 parts is multiplied by 200 times. The number of crushing was counted by observation. The standard for crushing was to measure the short diameter and long diameter of each hollow fiber membrane, and the one whose ratio was flatter than 1: 2 was defined as a crushing hollow fiber membrane. The ratio of the collapsed hollow fiber membrane was determined by the following equation.
Ratio of collapsed hollow fiber membranes (%) = (number of collapsed hollow fiber membranes / total number of hollow fiber membranes on the sample end face) × 100
Here, both the number of crushed yarn membranes and the total number of hollow fiber membranes on the sample end surface are total counts of all the end surfaces divided into eight.
The following quality classification was determined based on the ratio of the collapsed hollow fiber membrane.
A: Ratio of short yarn is less than 0.03%
○: Ratio of short yarns 0.03-0.05%
X: Ratio of short yarn exceeding 0.05% ◎ and ○ were regarded as acceptable.

10. Ratio of clogged yarn The end surface of the sample prepared by the above method is colored with red magic ink (R), and the end surface is radially marked with 8 divisions, and the whole end surface divided into 8 is a microscope with a national light. The number of clogged yarns was counted using a light scope 100 (magnification: 100 times, manufactured by Matsushita Electric Industrial Co., Ltd.). The ratio of clogged yarn was calculated by the following formula.
Clogging yarn ratio (%) = (number of clogging yarns / total number of hollow fiber membranes on the sample end face) × 100
Here, both the number of clogged yarns and the total number of hollow fiber membranes on the sample end face are total counts of all end faces divided into eight.
The following quality classification was judged by the percentage of clogged yarn.
A: Clogging yarn ratio less than 0.03%
○: Clogging thread ratio 0.03 to 0.05%
X: The ratio of clogging yarn exceeds 0.05%.

11. Residual blood thread ratio evaluation method Fill the dialysate side of the module obtained by the above method with physiological saline, fill 200ml of heparinized blood collected from a healthy person into a blood bag, and connect the blood bag and the module with a tube. And circulate at 37 ° C. for 1 hour at a blood flow rate of 100 ml / min. Blood samples before the start of circulation and 60 minutes of circulation are sampled, and the white blood cell count and platelet count are measured. The measured value was corrected with the value of hematocrit.
Correction value = measured value (60 minutes) x hematocrit (0 minutes) / hematocrit (60 minutes)
The change rate of leukocytes and platelets was calculated from the correction value.
Change rate = correction value (60 minutes) / value before circulation start × 100
After the circulation for 60 minutes, the blood was returned with physiological saline, and the number of remaining blood was counted. The ratio of residual blood thread was calculated by the following formula.
Ratio of residual blood thread (%) = (number of residual blood threads / total number of hollow fiber membranes in module) × 100
The following quality classification was judged by the percentage of clogged yarn.
A: Ratio of residual blood thread less than 0.03%
○: Ratio of residual blood thread 0.03-0.05%
X: Ratio of residual blood thread exceeding 0.05% A and B were accepted.

12. Water permeability The blood outlet circuit of the dialyzer (the outlet side from the pressure measurement point) was sealed with forceps. Purified water kept at 37 ° C is put into a pressurized tank, and while controlling the pressure with a regulator, pure water is sent to the blood flow path side of the dialyzer kept at 37 ° C constant temperature bath, and the amount of filtrate flowing out from the dialysate side is measured. It was measured. The transmembrane pressure difference (TMP) is TMP = (Pi + Po) / 2
And Here, Pi is the dialyzer inlet side pressure, and Po is the dialyzer outlet side pressure. The TMP is changed at four points, the filtration flow rate is measured, and the water permeability (mL / hr / mmHg) is calculated from the slope of the relationship. At this time, the correlation coefficient between TMP and the filtration flow rate must be 0.999 or more. In order to reduce the pressure loss error due to the circuit, TMP is measured in the range of 100 mmHg or less. The water permeability of the hollow fiber membrane bundle is calculated from the membrane area and the water permeability of the dialyzer.
UFR (H) = UFR (D) / A
Here, UFR (H) is the water permeability of the hollow fiber membrane bundle (mL / m ² / hr / mmHg), UFR (D) is the water permeability of the dialyzer (mL / hr / mmHg), and A is the membrane area of the dialyzer. (M ² ).

13. Calculation of membrane area The membrane area of the dialyzer is determined as a reference for the inner diameter of the hollow fiber.
A = n × π × d × L
Here, n is the number of hollow fibers in the dialyzer, π is the circumference, d is the inner diameter (m) of the hollow fiber, and L is the effective length (m) of the hollow fiber in the dialyzer.

14. Blood Leak Test A 37 ° C. bovine blood to which citric acid has been added to prevent coagulation is fed to the separation module at 200 mL / min, and the blood is filtered at a rate of 20 mL / min. At this time, the filtrate is returned to blood to be a circulatory system. After 60 minutes, the filtrate of the separation module is collected, and the red color caused by red blood cell leakage is visually observed. In this blood leak test, 30 separation modules were used in each of the examples and comparative examples, and the number of separation modules leaking blood was examined.

15. Storage stability of separation of hollow fiber membrane bundle of separation module Module prepared by the same method as the ratio evaluation method of tilted hollow fiber membrane is filled with pre-degassed RO water and irradiated with γ-rays with an absorbed dose of 25 kGy Crosslinking treatment was performed. After storing the module after γ-ray irradiation for one year at room temperature, UV (220-350 nm) absorbance was measured by the method described above. Stability was determined by the degree of increase in UV (220-350 nm) absorbance due to the storage. The degree of increase was obtained by equally dividing the hollow fiber membrane bundle into 10 pieces in the longitudinal direction, measuring each sample, and determining the average value. Those whose average value did not exceed 0.10, which is the reference value of the dialysis artificial kidney device manufacturing standard, were regarded as acceptable.

Example 1
Polyethersulfone (Sumika Chemtex Co., Ltd., Sumika Excel (R) 5200P) 17.3 mass%, Polyvinylpyrrolidone (BASF Kollidon (R) K-90) 2.5 mass%, DMAc 26.0 mass% 2 It knead | mixed with the screw type kneading machine of the axis | shaft. The obtained kneaded product was added to a stirring type dissolver charged with 51.3% by mass of DMAc and 2.9% by mass of water, and dissolved by stirring for 3 hours. The kneading and dissolution were cooled so that the internal temperature did not rise above 30 ° C. The system was then depressurized to -500 mmHg using a vacuum pump, and the system was immediately sealed and allowed to stand for 15 minutes so that the solvent etc. evaporated and the film forming solution composition did not change. This operation was repeated three times to degas the film forming solution. After the defoaming was completed, the inside of the system was again purged with nitrogen and maintained in a weakly pressurized state. As the polyvinyl pyrrolidone, one having a hydrogen peroxide content of 110 ppm was used, and the supply tank in the raw material supply system and the dissolution tank were replaced with nitrogen gas. Further, the Froude number and the stirring Reynolds number at the time of dissolution were 1.1 and 120, respectively. The membrane-forming solution was passed through a two-stage sintered filter of 10 μm and 5 μm in order, and then degassed at −700 mmHg for 30 minutes in advance from a tube-in orifice nozzle heated to 75 ° C. for 60 mass at 50 ° C. After passing through a 400 mm dry section cut off from the outside air by discharge and spinning tube using a% DMAc aqueous solution, it was coagulated in a 20 mass% DMAc aqueous solution at 60 ° C., and was rolled up in a wet state. The nozzle slit width of the tube-in-orifice nozzle used was an average of 60 μm, the maximum 61 μm, the minimum 59 μm, the ratio of the maximum and minimum slit widths was 1.03, and the draft ratio was 1.2.

  A film made of polyethylene having a thickness of 0.2 mm and having a hollow fiber bundle side surface treated with 10,000 hollow fiber membranes (dielectric constant: 2.3, dielectric loss tangent: 0.0002, and dielectric constant and dielectric loss tangent) The product was inserted into a hollow package (outer diameter: 36 mm) having a circular cross-sectional shape (product: 0.00046), cut to a length of 270 mm, and washed in hot water at 80 ° C. for 30 minutes × 4 times. . The washed hollow fiber membrane bundle was placed in a tray made of polysulfone resin and dehydrated at 140 rpm for 20 minutes with a centrifugal dehydrator to obtain a wet hollow fiber membrane bundle having a water content of 300% by mass. The obtained wet hollow fiber membrane bundle is installed on the side wall of the heating oven with a microwave oscillator, the microwave can oscillate in the horizontal direction, has a horizontal rotary table inside the oven, and the far-infrared heater and oven are decompressed. 10 hollow fiber membrane bundles are arranged at equal intervals in the direction in which the longitudinal direction of the hollow fiber membrane bundle is horizontal on the rotary table of a microwave dryer having an exhaust system for the center of the rotary table. It was arranged radially to face. The rotary table has a structure in which a 6 mm-thick polypropylene plate is fixed on a metal holding jig, and the upper surface of the table is placed about 30 mm below the center of the waveguide of the microwave oscillator. ing. The rotary table was dried under the following conditions while rotating at 8 rpm. After heating the hollow fiber membrane bundle under a reduced pressure of 7 kPa at an output of 1.5 kW for 25 minutes, the microwave irradiation was stopped and at the same time the pressure was reduced to 1.5 kPa and maintained for 3 minutes. Subsequently, the degree of vacuum was returned to 7 kPa, the microwave was irradiated and the hollow fiber membrane bundle was heated at an output of 0.5 kW for 8 minutes, and then the microwave was cut to increase the degree of vacuum and maintain 0.7 kPa for 3 minutes. Furthermore, the degree of vacuum was returned to 7 kPa, and microwave irradiation was performed for 5 minutes at an output of 0.2 kW to heat the hollow fiber membrane bundle. The water content in the hollow fiber membrane bundle after the microwave irradiation was 11% by mass. After microwave cutting, the degree of vacuum was increased to 0.5 kPa, irradiation with far infrared rays alone was performed, and the drying of the hollow fiber membrane bundle was completed by maintaining for 10 minutes. During drying, the output of the far-infrared heater was adjusted so that the temperature detected by a thermocouple provided at the center of the drying oven was 50 ° C. over the entire period. The maximum temperature reached on the surface of the hollow fiber membrane bundle at this time was 65 ° C. Note that the waveguide of the microwave oscillator of the above microwave dryer has a cross-sectional area that gradually increases in the direction of microwave travel, and a conical reflector at the exit of the waveguide. It had the structure installed in the direction facing the inside, and Er / Ei of the irradiated microwave was 0.05. Further, the moisture content after the final drying was 2.5% by mass. The obtained hollow fiber membrane bundle had an inner diameter of 198 μm and a film thickness of 28 μm. During the spinning process, all the rollers with which the hollow fiber membrane bundle contacts were mirror-finished on the surface, and the guides were all finished with a satin finish.

  The drying process processed 6 samples simultaneously. One sample of the obtained dry hollow fiber membrane bundle was equally divided into 10 pieces of 2.7 cm in the longitudinal direction, and 1 g of dry hollow fiber membranes were weighed from each part, and the water content was measured. Moreover, the extract was obtained according to the dialysis type artificial kidney apparatus manufacture approval reference test, and the hydrogen peroxide concentration and UV (220-350 nm) absorbance in the extract were measured. The variation of moisture content was small. Moreover, hydrogen peroxide and UV (220-350 nm) absorbance were stable at a low level in all sites. Further, the dried hollow fiber membrane bundle length was assumed to be 265 mm, and the wet hollow fiber membrane bundle length was set to 270 mm and dried. Using one sample of the obtained dry hollow fiber membrane bundle, the yarn length of all hollow fiber membranes of the hollow fiber membrane bundle was measured. There were no hollow fiber membranes shorter than 264 mm and hollow fiber membranes longer than 266 mm. These results are summarized in Tables 1-3. Further, one sample of the obtained hollow fiber membrane bundle was stored in a dry state, and the storage stability was evaluated. The storage stability in a dry state is good, and the maximum UV (220-350 nm) absorbance of the extract obtained from each part obtained by dividing the bundle of hollow fiber membranes after storage for 3 months into 10 is 0.03. Yes, even at the maximum value, the reference value of 0.10 or less was maintained. Furthermore, the UV absorbance level at each site was stable at a low level.

  The remaining three samples of the dry hollow fiber membrane bundle restrained by the polyethylene film obtained by the above method were inserted into a container having an inner diameter of 31 mm and a length of 255 mm, and the package was removed while fixing the hollow fiber membrane. In this state, sealing jigs were attached to both ends of the container and set in a centrifugal bonding machine. While rotating the centrifugal bonding machine at a rotation speed of 500 rpm, a potting agent (two-component curable polyurethane resin manufactured by Sanyo Kasei Co., Ltd., main agent: Polymedica MA-200, curing agent: Polymedica MB, from the dialysate inlets 6a and 6b. -200, blending ratio: 52/48, viscosity after 2 minutes of mixing of two liquids: 1400 mPa · s) at 25 ° C., 20 g was injected at 0.8 g / sec per end face. The centrifugal bonding machine was stopped by curing at 50 ° C. for 30 minutes. The module was removed and post-cured overnight at room temperature. The end face was cut and opened to obtain a hollow fiber membrane module. The module was filled with degassed RO water and irradiated with γ rays at an absorbed dose of 25 kGy for crosslinking. The dried hollow fiber membrane bundle obtained in this example has no deformation such as bending of the hollow fiber membrane bundle in the drying step, there is little disorder in the arrangement of the hollow fiber membranes in the hollow fiber membrane, and partial sticking also occurs As a result, the package could be removed smoothly. Also, the workability of the adhesion treatment was good. The number of inclined hollow fiber membranes and collapsed hollow fiber membranes by observation of the cross-section of the hollow fiber membranes on the bonded end face was zero. Moreover, the clogged yarn evaluated by the above method was not detected. Therefore, there was no residual blood thread and the quality was high.

In this separation module, citrated fresh bovine blood was flowed to the separation module at a blood flow rate of 200 mL / min and a filtration rate of 10 mL / min (m ² ). It was not seen. These results are shown in Table 4.

  The separation module was stored at room temperature for 1 year. When the hollow fiber membrane bundle was cut out from the separation module after storage and subjected to the eluate test, the UV (220-350 nm) absorbance was 0.04 in terms of the maximum value. Some 0.10 or less was maintained.

  Also in the following examples and comparative examples, 6 samples were simultaneously dried in the same manner as in this example and subjected to various evaluations.

(Comparative Example 1)
In Example 1, the hollow fiber membrane bundle to be dried was changed so as to be arranged vertically, and microwave drying was performed for 40 minutes at an output of 2.0 kW at normal pressure, and then for 10 minutes at an output of 0.9 kW. Thus, a hollow fiber membrane bundle was obtained by the same method as in Example 1 except that irradiation with far-infrared radiation was changed to dry for 20 minutes under normal pressure. In this comparative example, since the hollow fiber membrane bundles to be dried were arranged vertically, the obtained dry hollow fiber membrane bundles were bent due to buckling that occurred during drying. Using one sample of the obtained dry hollow fiber membrane bundle, the yarn length of all hollow fiber membranes of the hollow fiber membrane bundle was measured. There were many hollow fiber membranes shorter than 264 mm and hollow fiber membranes longer than 266 mm.

  In addition, Tables 1 to 3 show the water content, the hydrogen peroxide concentration, and the UV absorbance measured values of the dry hollow fiber membrane bundle obtained in this Comparative Example. In the method of this comparative example, the deterioration of the polyvinyl pyrrolidone component of the hollow fiber membrane is large and the uniformity of drying in the longitudinal direction of the hollow fiber membrane bundle is inferior. Therefore, the excess of the hollow fiber membrane bundle obtained in this comparative example is The amount of elution of hydrogen oxide was high, and the amount of elution of hydrogen peroxide varied greatly depending on the sampling location. Furthermore, since the hollow fiber membrane bundle of this comparative example had a high hydrogen peroxide elution amount, the storage stability was inferior. The dried hollow fiber membrane bundle obtained in this comparative example had a UV (220-350 nm) absorbance exceeding 0.10 after storage for about 30 days. In addition, the UV (220-350 nm) absorbance of the dried hollow fiber membrane bundle varied greatly depending on the sampling site, partial sticking occurred, and the module assembly workability was poor.

  Further, the separation module was assembled by the same method as in Example 1, but the arrangement of the hollow fiber membranes in the hollow fiber membrane bundle was disturbed, and the package could not be removed smoothly. Therefore, it takes time and effort to align the end faces of the hollow fiber membrane bundle loaded after the polyethylene film is pulled out, and the filling property of the adhesive is poor and the workability is inferior due to the disordered arrangement of the hollow fiber membrane bundle. A large number of inclined hollow fiber membranes, collapsed hollow fiber membranes, and clogged yarns were detected. For this reason, many residual blood threads were generated and the quality was low. Furthermore, the hollow fiber membrane bundle of this comparative example has a high hydrogen peroxide elution amount level of the hollow fiber membrane bundle and poor storage stability of the separation module, and the average value of UV (220-350 nm) absorbance is about 2.5 months. As a result, the dialysis artificial kidney device manufacturing approval standard value of 0.10 was exceeded. The results are shown in Table 4.

(Comparative Example 2)
In the method of Comparative Example 1, the waveguide of the microwave oscillator of the microwave dryer has a structure in which the cross-sectional area is constant facing the traveling direction of the microwave, and the reflector at the waveguide outlet is not installed. The microwave irradiation is changed to a microwave oscillator having an Er / Ei of 0.3, the hollow fiber membrane bundle is dried for 40 minutes at a normal pressure with an output of 2.0 kW, and then 0 A hollow fiber membrane bundle was obtained in the same manner as in Comparative Example 1, except that irradiation was performed for 10 minutes at an output of .9 kW, and that far-infrared irradiation was changed to dry for 20 minutes under normal pressure. The characteristics of the obtained hollow fiber membrane bundle are shown in Tables 1-3. In the hollow fiber membrane bundle obtained in this comparative example, deformation of the hollow fiber membrane in the drying process occurred in the same manner as the hollow fiber membrane bundle obtained in comparative example 1, and the structure of the microwave drying oscillator and the drying Since the non-uniformity of drying of the hollow fiber membrane bundle was increased by changing the conditions, the quality was inferior to that of the hollow fiber membrane bundle obtained in Comparative Example 1. For example, the dried hollow fiber membrane bundle obtained in this comparative example was stored for 25 days, and the UV (220-350 nm) absorbance of the extract prepared according to the test method of the dialysis artificial kidney device manufacturing approval standard The average value of exceeded the reference value of 0.10. Further, the UV (220-350 nm) absorbance of the dried hollow fiber membrane bundle varies greatly depending on the sampling site, partial sticking occurs, and the module assembly workability is higher than that of the hollow fiber membrane bundle obtained in Comparative Example 1. It was inferior.
Further, the separation module was assembled by the same method as in Example 1, but the arrangement of the hollow fiber membranes in the hollow fiber membrane bundle was disturbed similarly to the hollow fiber membrane bundle obtained in Comparative Example 1, and the package. It was not possible to pull out smoothly. Therefore, it takes time and effort to align the end faces of the hollow fiber membrane bundle loaded after the package is pulled out, and the filling property of the adhesive is poor and the workability is inferior due to the disordered arrangement of the hollow fiber membrane bundle. As a result of observation of the bonded end face, a large number of inclined hollow fiber membranes, collapsed hollow fiber membranes and clogged yarns were detected. Therefore, many residual blood threads were observed and the quality was low. The results are shown in Table 4.

(Example 2)
In the same manner as in Example 1, polyethersulfone (Sumika Chemtex, Sumika Excel (R) 4800P) 18% by mass, polyvinylpyrrolidone (BASF Kollidon (R) K-90) 3.8% by mass, dimethyl A film forming solution consisting of 73.2% by mass of acetamide (DMAc) and 5% by mass of water was obtained. As the polyvinyl pyrrolidone, one having a hydrogen peroxide content of 90 ppm was used. The obtained film-forming solution was passed through a two-stage filter of 15 μm and 15 μm, and then degassed at −700 mmHg for 2 hours in advance from a tube-in orifice nozzle heated to 70 ° C. for 50 mass at 60 ° C. The solution was discharged at the same time as the% DMAc aqueous solution, passed through a 350 mm air gap portion cut off from the outside air by a spinning tube, and then coagulated in water at 60 ° C. The average nozzle slit width of the tube-in-orifice nozzle used was 45 μm, the maximum was 45.5 μm, the minimum was 44.5 μm, the ratio of the maximum and minimum slit widths was 1.02, and the draft ratio was 1.2. It was. The hollow fiber membrane bundle pulled up from the coagulation bath was passed through a water washing tank at 85 ° C. for 45 seconds to remove the solvent and excess polyvinylpyrrolidone, and then wound up.

  After being inserted into a package made of the same polyethylene film as in Example 1 around the bundle of 10,080 hollow fiber membranes, it was immersed and washed in a 40 vol% isopropanol aqueous solution at 30 ° C. for 30 minutes × 2 times. A hollow fiber membrane bundle having a water content of 3.0% by mass was obtained by drying according to the drying method of Example 1. The roller for changing the yarn path during the spinning process was a mirror-finished surface, and the fixing guide was a satin-finished surface. The resulting hollow fiber membrane had an inner diameter of 199 μm and a film thickness of 27 μm.

The hollow fiber membrane bundle obtained in this example was of high quality like the hollow fiber membrane bundle of Example 1. The results are shown in Tables 1-3.
Moreover, the module for separation was obtained by the same method as Example 1 using the obtained dry hollow fiber membrane bundle. The obtained separation module was of high quality as was the separation module obtained in Example 1. The results are shown in Table 4.

(Example 3)
In the same manner as in Example 1, from 18% by mass of polysulfone (P-3500 manufactured by Amoco), 9% by mass of polyvinylpyrrolidone (K-60 manufactured by BASF), 68% by mass of dimethylacetamide (DMAc), and 5% by mass of water A film forming solution was obtained. As the polyvinyl pyrrolidone, one having a hydrogen peroxide content of 100 ppm was used. The obtained film-forming solution was passed through a two-stage filter of 15 μm and 15 μm, and simultaneously with a 35 mass% DMAc aqueous solution at 60 ° C. which was degassed in advance as a hollow forming agent from a tube-in orifice nozzle heated to 40 ° C. After discharging and passing through a 600 mm air gap portion cut off from the outside air by a spinning tube, it was solidified in 50 ° C. water. The nozzle slit width of the tube-in-orifice nozzle used was an average of 60 μm, the maximum 61 μm, the minimum 59 μm, the ratio of the maximum and minimum slit widths was 1.03, and the draft ratio was 1.2. The hollow fiber membrane bundle pulled up from the coagulation bath was passed through a water washing tank at 85 ° C. for 45 seconds to remove the solvent and excess polyvinylpyrrolidone, and then wound up. A bundle of about 10,000 hollow fiber membranes was immersed in pure water and washed in an autoclave at 121 ° C. for 1 hour. After being inserted into a package made of the same polyethylene film as in Example 1 around the washed hollow fiber membrane bundle, this was dried by a method according to the drying method of Example 1, and the water content was 2.0% by mass. A dry hollow fiber membrane bundle was obtained. The roller for changing the yarn path during the spinning process was a mirror-finished surface, and the fixing guide was a satin-finished surface. The obtained hollow fiber membrane bundle had an inner diameter of 201 μm and a film thickness of 44 μm.

The hollow fiber membrane bundle obtained in this example was of high quality like the hollow fiber membrane bundle of Example 1. The results are shown in Tables 1-3.
Moreover, the module for separation was obtained by the same method as Example 1 using the obtained dry hollow fiber membrane bundle. The obtained separation module was of high quality as was the separation module obtained in Example 1. The results are shown in Table 4.

Example 4
In the same manner as in Example 1, polysulfone (Amoco P-1700) 17% by mass, polyvinylpyrrolidone (BASF K-60) 5% by mass, dimethylacetamide (DMAc) 73% by mass, water 5% by mass A film forming solution was obtained. As the polyvinyl pyrrolidone, one having a hydrogen peroxide content of 120 ppm was used. The obtained film-forming solution was passed through a two-stage filter of 15 μm and 15 μm, and simultaneously with a 35 mass% DMAc aqueous solution at 65 ° C. degassed as a hollow forming agent from a tube-in orifice nozzle heated to 40 ° C. After discharging and passing through a 600 mm air gap portion cut off from the outside air by a spinning tube, it was solidified in 50 ° C. water. The nozzle slit width of the tube-in-orifice nozzle used was an average of 60 μm, the maximum 61 μm, the minimum 59 μm, the ratio of the maximum and minimum slit widths was 1.03, and the draft ratio was 1.2. The hollow fiber membrane bundle pulled up from the coagulation bath was passed through a water washing tank at 85 ° C. for 45 seconds to remove the solvent and excess polyvinylpyrrolidone, and then wound up. A bundle of about 10,000 hollow fiber membranes was immersed in pure water and washed in an autoclave at 121 ° C. for 1 hour. The roller for changing the yarn path during the spinning process was a mirror-finished surface, and the fixing guide was a satin-finished surface.

  The washed hollow fiber membrane bundle was inserted into the same package as used in Example 1, and then dried according to Example 1 so that the moisture content was 1.5% by mass. The resulting hollow fiber membrane had an inner diameter of 201 μm and a film thickness of 43 μm.

The hollow fiber membrane bundle obtained in this example was of high quality like the hollow fiber membrane bundle of Example 1. The results are shown in Tables 1-3.
Moreover, the module for separation was obtained by the same method as Example 1 using the obtained dry hollow fiber membrane bundle. The obtained separation module was of high quality as was the separation module obtained in Example 1. The results are shown in Table 4.

(Comparative Example 3)
In the method of Example 4, a hollow fiber membrane bundle was obtained in the same manner as in Example 4 except that the drying of the hollow fiber membrane bundle was changed as follows. Dehumidified air (humidity of 10% or less) from the lower part of the hollow fiber membrane bundle at a wind speed of 8 m / sec. Irradiated to obtain a hollow fiber membrane bundle having a water content of 18% by mass. The hollow fiber membrane bundle was transferred to a hot air drier and dried under normal pressure at a temperature of 87 ° C. for 1.5 hours to obtain a dry hollow fiber membrane bundle having a water content of 0.7 mass%. The characteristics of the obtained hollow fiber membrane bundle are shown in Tables 1-3.

  Using one sample of the obtained dry hollow fiber membrane bundle, the yarn length of all hollow fiber membranes of the hollow fiber membrane bundle was measured. There were many hollow fiber membranes shorter than 264 mm and hollow fiber membranes longer than 266 mm. Moreover, the fluctuation | variation of the moisture content of the hollow fiber membrane bundle obtained by this comparative example was high. Furthermore, the hydrogen peroxide elution amount was high, and the amount of hydrogen peroxide elution amount varied greatly depending on the sampling location, resulting in low quality. Furthermore, since the hollow fiber membrane bundle of this comparative example had a high hydrogen peroxide elution amount, the storage stability was inferior. The hollow fiber membrane bundle in the dry state obtained in this comparative example was stored for about 20 days, and the average value of UV (220-350 nm) absorbance exceeded the standard value of 0.10. In addition, the UV (220-350 nm) absorbance of the dried hollow fiber membrane bundle varied greatly depending on the sampling site, partial sticking occurred, and the module assembly workability was poor.

  Further, a separation module was obtained by the same method as in Example 1 using the dry hollow fiber membrane bundle obtained in this Comparative Example. The obtained separation module was also of low quality like the separation modules obtained in Comparative Examples 1 and 2. The results are shown in Table 4.

  The method for drying a hollow fiber membrane bundle of the present invention can be used in combination with a conventionally known method for ventilating gas in a hollow fiber membrane bundle to achieve uniform drying. Since sufficient drying can be performed, the jig for applying this ventilation is not required, the structure of the dryer is simplified, and the hollow fiber membrane bundle to be dried must be fixed to the jig for applying this ventilation. Therefore, the workability of placing the hollow fiber membrane bundle to be dried on the dryer is improved. In addition, deformation and contraction spots of the hollow fiber membranes such as breakage or disorder of the hollow fiber membrane bundles to be dried in the drying process due to the arrangement direction of the hollow fiber membrane bundles to be dried and the non-uniformity of ventilation, which were conventionally known problems. Therefore, the dry hollow fiber membrane bundle dried by the method of the present invention improves the insertability of the hollow fiber membrane bundle into the module container in the assembly process of the separation module, for example. Bonding work during module assembly is improved. Furthermore, the occurrence of defective hollow fiber membranes such as tilted hollow fiber membranes, crushed hollow fiber membranes and clogged hollow fiber membranes due to deformation and shrinkage spots is suppressed, and residual blood properties caused by these defects are improved. There is an advantage. In addition, since the hollow fiber membrane is prevented from being broken or damaged, blood leakage is improved. Furthermore, the performance degradation of the hollow fiber membrane in the drying step and the degradation of the hollow fiber membrane component, particularly polyvinylpyrrolidone, are improved, and the hydrogen peroxide elution amount generated by the degradation is suppressed. Therefore, the hollow fiber membrane bundle obtained by the present invention is prevented from deterioration such as polyvinyl pyrrolidone when the hollow fiber membrane bundle caused by the hydrogen peroxide is stored for a long time. In addition, there is an advantage that UV (220-350 nm) absorbance, which is a dialysis-type artificial kidney device manufacturing approval standard, can be maintained at a reference value of 0.10 or less. In addition, the variation in degradation of polyvinylpyrrolidone in the longitudinal direction of the hollow fiber membrane bundle is small, the above UV (220-350 nm) absorbance variation in the longitudinal direction of the hollow fiber membrane bundle is suppressed, and the moisture content of the hollow fiber membrane bundle is moderate. Since the fluctuation rate is suppressed and the rate of change is suppressed, partial sticking of the hollow fiber membrane bundle caused by this change is suppressed, and a hollow fiber membrane bundle excellent in module assembly is stably manufactured. It has the feature that it can. Moreover, suppression of UV (220-350 nm) absorbance fluctuations in the longitudinal direction of the hollow fiber membrane bundle also leads to an improvement in safety when used for blood purification. Therefore, there is an advantage that it is suitable as a method for drying a hollow fiber membrane bundle used for blood purifiers having high water permeability used for the treatment of chronic renal failure. Moreover, since the hollow fiber membrane bundle obtained by the drying method of the present invention has the above characteristics, it can be suitably used for a blood purifier. Further, the separation module obtained by the present invention has the characteristics that the loaded hollow fiber membrane bundle has high performance, high safety and stability of performance, excellent storage stability, and few residual blood yarns. . Therefore, it is important to contribute to the industry.

It is sectional drawing of the module for hollow fiber type | mold isolation | separation. It is a conceptual diagram of the ratio evaluation method of an inclination hollow fiber membrane.

Explanation of symbols

1: Separation module 2: Container 3: Hollow fiber membrane bundle 4: Adhesive resin 5: Cap 6a: Dialysate inlet 6b: Dialysate outlet 7a: Blood inlet 7b: Blood outlet

Claims (10)

  A method of drying a wet hollow fiber membrane bundle by microwave irradiation, which is placed in a microwave irradiation oven and dried so that the longitudinal direction of the hollow fiber membrane bundle is at an angle of 45 degrees or less with respect to the horizontal. A method for drying a hollow fiber membrane bundle, comprising:   The method for drying a hollow fiber membrane bundle according to claim 1, wherein the hollow fiber membrane bundle to be dried is placed on a horizontally set table having a rotation function and dried while rotating.   The method for drying a hollow fiber membrane bundle according to claim 1 or 2, wherein the hollow fiber membrane bundle to be dried is arranged and dried radially from the center of the rotary table.   The method for drying a hollow fiber membrane bundle according to any one of claims 1 to 3, wherein the microwave is irradiated from a side surface direction of the rotary table.   A microwave oscillator having a ratio (Er / Ei) of energy Ei of an incident wave directed from the microwave oscillator toward the oven and energy Er of a reflected wave reflected from the oven toward the oscillator is 0.2 or less is used. The drying method of the hollow fiber membrane bundle in any one of Claims 1-4.   The hollow fiber membrane according to any one of claims 1 to 5, wherein L / D, which is a ratio of the diameter (D) to the length (L) of the wet bundle of hollow fiber membranes, is 2 or more. How to dry the bundle.   The method for drying a hollow fiber membrane bundle according to any one of claims 1 to 6, wherein drying is performed under a reduced pressure of 20 kPa or less.   The hollow fiber membrane according to any one of claims 1 to 7, wherein the microwave irradiation is stopped when the water content of the hollow fiber membrane is reduced to 10 to 20% by mass, and subsequently dried by far infrared irradiation. How to dry the bundle.   The drying method of the hollow fiber membrane bundle according to any one of claims 1 to 8, wherein the drying is terminated when the moisture content of the hollow fiber membrane becomes 1 to 7% by mass. The method for drying a hollow fiber membrane bundle according to any one of claims 1 to 9, wherein the hollow fiber membrane bundle comprises a polysulfone resin containing polyvinylpyrrolidone.