JP4807608B2 - Method for drying hollow fiber membrane bundle - Google Patents

Description

  The present invention relates to a method for drying a wet hollow fiber membrane bundle, a hollow fiber membrane bundle, and a blood purification module. More specifically, regarding a method for drying a hollow fiber membrane bundle in a wet state, it is excellent in workability by a method simplified as compared with the prior art, and the deformation of the hollow fiber membrane in the drying process is suppressed and the drying is suppressed. The present invention relates to a method for drying a hollow fiber membrane bundle, which can produce a hollow fiber membrane bundle with improved uniformity and reduced deterioration of the hollow fiber membrane components, which can produce a high performance, high safety, and excellent module assembly property and storage stability. . More specifically, the present invention relates to a method for drying a hollow fiber membrane bundle with high cost performance that can balance the drying efficiency of the hollow fiber membrane bundle with the uniformity of drying between the hollow fiber membrane bundles and the quality of the hollow fiber membrane bundle after drying.

  In recent years, technology using membranes with selective permeability has made remarkable progress, and so far in a wide range of fields such as gas and liquid separation filters, hemodialyzers, blood filters, blood component separation filters in the medical field. Is being put to practical use. As the material of the membrane, resins such as cellulose (regenerated cellulose, cellulose acetate, chemically modified cellulose, etc.), polyacrylonitrile, polymethyl methacrylate, polysulfone, polyethylene vinyl alcohol, and polyamide are used. I came. 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 using 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 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 polyvinyl pyrrolidone that has been dried without using a low-volatile organic liquid is disclosed (see Patent Documents 3 and 4). These describe the ability to separate plasma components from blood, but it is found that plasma proteins permeate and are not effective as dialysis membranes. 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 when this method is dried in the form of a yarn bundle, there is a slight difference in performance between the central portion and the outer peripheral portion of the yarn bundle.
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 parts at both ends of the adhesive are inclined when modularized.For example, when used for blood purification, blood drift occurs and residual blood It leads to the generation of yarn. Further, when the hollow fiber membrane is broken or the arrangement is disturbed, the insertability of the hollow fiber membrane bundle into the module housing in the module assembling process is lowered, and the hollow fiber membrane is damaged or the crushed yarn in which the cross section of the hollow fiber membrane is deformed. appear. 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, if a hollow fiber membrane with a large shrinkage rate and a short yarn length occurs, the adhesive can easily enter the hollow portion of the hollow fiber membrane when embedding both ends with an adhesive, leading to the generation of clogged yarn. This causes blood drift and the generation of residual blood thread. 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 and the arrangement is disturbed, causing the above-mentioned problems.

Moreover, the method of the said patent document lacks consideration with respect to 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 as a foreign substance in the human body increases during long-term dialysis, which may cause side effects and complications. In the dialysis-type artificial kidney device manufacturing approval standard, UV (220 to 350 nm) absorbance standards for hollow fiber membrane extracts are set. 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 hydrogen peroxide accelerates the oxidative degradation of polyvinylpyrrolidone, for example, and increases the elution amount of polyvinylpyrrolidone 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 carried out by the method of the above 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, resulting in the occurrence of the above problem It leads to.

  Moreover, when implemented by the method of the above-mentioned patent document, the longitudinal direction of the hollow fiber membrane bundle from the inlet side to the outlet side of the ventilation is made non-uniform in drying, so that the UV (220 to 350 nm) absorbance is also measured for the hollow fiber membrane bundle. The problem that the fluctuation | variation of the longitudinal direction of this 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. 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 irradiating and drying 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.

  The process simplified in comparison with the prior art is excellent in workability in the drying process, suppresses the deformation of the hollow fiber membrane in the drying process, improves the uniformity of drying and reduces the deterioration of the components of the hollow fiber membrane. High performance, high safety, hollow fiber membrane bundles with excellent storage stability and module assemblability can be manufactured. It is an object of the present invention to provide a method for drying a hollow fiber membrane bundle with high cost performance that can balance the quality and quality of the hollow fiber membrane bundle after drying.

In the present invention, a plurality of wet hollow fiber membrane bundles are arranged in parallel on a tray, and are 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. In the method of drying, the distance between adjacent hollow fiber membrane bundles when the diameter of the unit hollow fiber membrane bundle is d is arranged at a position 1.5 to 3.0 d away from the center of the hollow fiber membrane bundle. This is a method for drying a hollow fiber membrane bundle.
In addition, a plurality of wet hollow fiber membrane bundles are arranged in parallel on the tray, and are placed in a microwave irradiation oven so that the longitudinal direction of the hollow fiber membrane bundles is at an angle of 45 degrees or less with respect to the horizontal. When the unit hollow fiber membrane bundle has a diameter d and the distance between adjacent hollow fiber membrane bundles is 1.5d or less, the distance between the center of the hollow fiber membrane bundles is 1. The hollow fiber membrane bundle drying method is characterized in that the number of hollow fiber membrane bundles arranged within 5d is within two.

  The drying method of the hollow fiber membrane bundle of the present invention can be used in combination with a conventionally known technique of passing a gas through the hollow fiber membrane bundle to make the drying uniform, but it is not used intentionally. However, since it is possible to perform sufficient drying, 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, hollow fiber membranes such as broken or misaligned hollow fiber membranes in a 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 ventilation, which has been a problem of the prior art 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 module assembly process for blood purification, for example. Adhesion work 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, in the present invention, since the wet hollow fiber membrane bundle is restrained by the hollow package, the workability of placing the hollow fiber membrane bundle to be dried in the dryer is improved, and the dried hollow fiber membrane bundle is It is restrained by a hollow packaging body as a unit of number to be loaded into a module to be assembled using a yarn membrane bundle. The membrane bundle can be loaded into the module container, and the workability of the loading can be greatly improved, and there is an advantage that generation of defective yarns during loading is suppressed. In addition, since a plurality of the hollow fiber membrane bundles to be dried restrained by the packaging body are fixed to the tray and arranged in the dryer, the workability of arranging the hollow fiber membrane bundles to be dried in the dryer is further improved. And the arrangement | positioning is specified so that the uniformity of drying between the several hollow fiber membrane bundles can be expressed, and it has the advantage that the cost performance of a drying process is high.

  Furthermore, since the non-uniformity of drying in the ventilation direction, that is, the longitudinal direction of the hollow fiber membrane bundle, which has been a problem of the prior art, is improved, the local degradation of polyvinyl pyrrolidone is reduced and the degradation is generated by the degradation. Hydrogen peroxide 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 fluctuation 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 in a blood purifier having high water permeability used for the treatment of chronic renal failure. In addition, the hollow fiber membrane bundle made of the polysulfone-based resin containing polyvinylpyrrolidone of the present invention has improved the problem characteristics possessed by the hollow fiber membrane bundle obtained by the above-mentioned conventionally known technology, so it is suitable for blood purifiers and the like. There is an advantage that it can be used. Furthermore, the blood purification module obtained by the present invention has the advantages that the loaded hollow fiber membrane bundle has high performance, high safety and stability, excellent storage stability, and few residual blood threads. There is.

Hereinafter, the present invention will be described in detail.
In the present invention, a plurality of wet hollow fiber membrane bundles are arranged in parallel on a tray, and are 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. In the method of drying, the distance between adjacent hollow fiber membrane bundles when the diameter of the unit hollow fiber membrane bundle is d is arranged at a position 1.5 to 3.0 d away from the center of the hollow fiber membrane bundle. In other words, it is preferable that the number of hollow fiber membrane bundles arranged within 1.5d when arranged at a position within 1.5d be within two.
The angle of the hollow fiber membrane bundle is more preferably 30 degrees or less, and most preferably 0 degree, that is, horizontal placement. If the angle is more than 45 degrees, for example, 90 degrees disclosed in the prior art, the assembly of the hollow fiber membrane bundle restrained by water decreases as the drying of the hollow fiber membrane bundle progresses. The degree of freedom of movement of the hollow fiber membrane bundle increases, and the possibility that buckling, which is deformation due to its own weight, for example, increases. When the deformation occurs, the hollow fiber membrane bundle is bent. Moreover, it leads to the disorder of the arrangement between the hollow fiber membrane bundles, the insertability of the hollow fiber membrane bundle into the module container at the time of module assembly, and the friction between the hollow fiber membrane bundle and the module container or the hollow fiber membrane bundle at the time of insertion. Occurrence of flaws and crushing of hollow fiber membranes and bonding of hollow fiber membrane bundles after insertion to a module container by bonding, poor adhesion due to bonding operations, generation of inclined hollow fiber membranes and adhesives This leads to problems such as increased generation of clogged hollow fiber membranes due to the penetration of the adhesive into the hollow fiber membrane inner holes. 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 drying site, the inventors often arrange a plurality of wet hollow fiber membrane bundles in a wet state in parallel on a tray and randomly introduce them into a microwave irradiation oven for drying. As a result of examining what drying specifications make the drying of the hollow fiber membrane bundle uniform and contributing to quality control, the arrangement of the hollow fiber membrane bundle in the microwave irradiation oven is also greatly related. It has been found that. This is a novel finding that is found in the relationship of a special object called a hollow fiber membrane bundle to be dried in a specific drying apparatus called a microwave irradiation oven apparatus.

  In the present invention, it is necessary to place a plurality of wet hollow fiber membrane bundles in a wet state in parallel with the tray and introduce them into the microwave irradiation oven. In this case, from the viewpoint of the efficiency of the dryer, it is preferable to introduce and place it in the dryer so that the hollow fiber membrane bundle is packed as closely as possible. However, in the drying method using microwave irradiation according to the present invention, if a plurality of tubes are dried in a close-packed arrangement, there is a difference in microwave irradiation energy depending on the arrangement location, and the uniformity of drying between the hollow fiber membrane bundles is reduced. I encountered a challenge to do. The present inventors have intensively studied to solve this problem and completed the present invention. That is, it has been found that it is necessary to provide a specified space between adjacent hollow fiber membrane bundles in order to balance drying efficiency and drying uniformity, that is, to improve cost performance.

The first method of the present invention is a position where the distance between adjacent hollow fiber membrane bundles when the diameter of the unit hollow fiber membrane bundle is d is 1.5 d or more and 3.0 d or less in the distance between the hollow fiber membrane bundle centers. It is preferable to arrange in. The interval needs to be satisfied in any of the vertical, horizontal, and diagonal directions. 1.7 d or more is more preferable, and 1.9 d or more is more preferable. When the number is less than 1.5d, when the number is 3 or more, there is a difference in drying speed between the outer hollow fiber membrane bundle and the middle hollow fiber membrane bundle, and the uniformity of drying between the hollow fiber membrane bundles is increased. descend. The drying speed of the hollow fiber membrane bundle in the middle part is slow. Therefore, if the drying is controlled in accordance with the moisture content of the hollow fiber membrane bundle outside the group of hollow fiber membrane bundles, the hollow fiber membrane bundle in the middle part becomes insufficiently dried. Conversely, when the drying is controlled in accordance with the moisture content of the hollow fiber membrane bundle in the middle part, the outer hollow fiber membrane bundle is overdried, and the moisture content of the entire hollow fiber membrane bundle is controlled within the preferred range required by the present invention. I can't do that. In this case, if there are two hollow fiber membrane bundles close to each other within 1.5d, this phenomenon does not occur and is allowed. Therefore, when the second method of the present invention is arranged at a position within 1.5 d, it is preferable that the number of hollow fiber membrane bundles arranged within 1.5 d is within two. These two arrangements must be satisfied in any of the vertical, horizontal and diagonal directions. In other words, regarding the total of four blocks in the vertical and horizontal directions, the above problem can be avoided by setting the distance between the blocks to 1.5 d or more. The second method is more preferable because it is close to the closest packing and has high cost performance.

  The interval between the bundles based on the diameter d of the unit hollow fiber membrane bundle is sequentially changed. Measure its moisture content. Table 5 shows the degree of variation calculated based on the maximum difference in the measured moisture content of the bundle. And about one hollow fiber membrane is sampled from the central part, middle part and outer peripheral part of the bundle, and the part of the position of the same condition such as the end part and the middle part in the longitudinal direction is collected. It is useful in raising the confidence value of the balance. When the distance between the hollow fiber membrane bundles exceeds a certain value, that is, 1.5 d, the maximum difference in the measured values of the moisture content of the hollow fiber membranes at the center, middle, and outer periphery of the bundle becomes small, and the stable moisture content This means that a dry hollow bundle is obtained. However, on the other hand, if the distance between the hollow fiber membrane bundles is increased, there is a risk that the microwave for drying will concentrate on a specific hollow fiber membrane bundle with few microwaves, and that specific hollow fiber membrane bundle will be significantly damaged. . Furthermore, when the distance between the hollow fiber membrane bundles is increased, the number of hollow fiber membrane bundles stored in the dryer for drying is reduced, which significantly impedes productivity. Considering the balance, 1.5d or more and 1.7d or more are more preferable, and 1.9d or more are more preferable. It is possible that the maximum value is 2.0d, and in some cases, about 3.0d.

  The bundle interval based on the diameter d of the hollow fiber membrane bundle is sequentially changed, and from the measured value of the moisture content of the hollow fiber membrane at the center portion s, the middle portion m, and the outer peripheral portion u of the bundle, The water content of the smallest measured value is the minimum water content L, and the average of the three points is the average water content M (s + m + u / 3). Find the difference between the average moisture content M and the maximum moisture content U (UM) and the difference between the average moisture content M and the minimum moisture content L (ML), and adopt the value with the larger absolute value. This is the variation degree (± ΔB). FIG. 9 shows the relationship between the bundle interval and the variation based on the diameter d. As can be seen from the tendency shown in FIG. 9, when the interval is 1.5d or more, the variation degree is acceptable. However, the variation degree converges to a constant value when the distance between the bundles becomes 2d or more. . That the degree of variation is large also means that the difference in the moisture content of the hollow fiber membranes at the center portion s, the middle portion m and the outer peripheral portion u of the bundle is large, and uniform drying of the entire bundle is not achieved. It also becomes an indicator. For example, when the water content in the center of the hollow fiber membrane is 2% by mass and the water content in the outer peripheral part is 4% by mass, the partial stickiness of the hollow fiber membrane due to the difference in water content can be different. Since the difference in moisture content is based on the difference in drying conditions, it has a considerable influence on the various characteristics shown in the attached table, such as the cause of the generation of hydrogen peroxide and the ratio of the inclined hollow fiber membrane. As a problem before that, it is obvious that in the drying of the hollow fiber membrane bundle, the unraveling of the drying itself becomes a problem.

Although the reason why the uniformity of drying between a plurality of hollow fiber membrane bundles arranged on a tray can be ensured by the above method is not clear, the penetration distance of microwaves into the hollow fiber membrane bundle is involved. I guess. That is, when the distance between the hollow fiber membrane bundles exceeds 1.5 d, the microwaves are evenly irradiated from the entire surface of each hollow fiber membrane bundle, but when the distance between the hollow fiber membrane bundles is less than 1.5 d When the microwave shielding effect by the adjacent hollow fiber membrane bundle is generated, and the microwave reaching the hollow fiber membrane bundle in the middle part is attenuated, the irradiation energy is reduced and the drying speed of the hollow fiber membrane bundle in the middle part is slowed down. I guess.

  Therefore, the diameter d of the unit hollow fiber membrane bundle is preferably 25 to 50 mm. 30 to 45 mm is more preferable.

In the present invention, the moisture content of the dried hollow fiber membrane bundle is preferably 1 to 5% by mass. 1.5-4 mass% is more preferable, and 2-3 mass% is further more preferable.
The moisture content of the hollow fiber membrane bundle in the present invention was calculated by the following formula.
Moisture content% = 100 × (Ww−Wd) / Wd
Here, Ww is the weight of the selectively permeable separation membrane before drying (g), and Wd is the weight of the selectively permeable separation membrane after drying for 2 hours (after absolutely dry) in a dry heat oven at 120 ° C. (g). 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.

  When dried so that the moisture content is less than 1% by mass, the degradation of polyvinyl pyrrolidone of the hollow fiber membrane bundle material increases, the elution amount of the degraded product increases, and the elution amount in the longitudinal direction of the hollow fiber membrane bundle The fluctuation of the pressure increases, leading to a decrease in safety when used for blood purification, for example. In addition, the variation in the surface concentration of the hydrophilic compound such as the deteriorated product on the outer surface of the hollow fiber membrane bundle in the longitudinal direction of the hollow fiber membrane bundle becomes large, and the surface concentration of the hydrophilic compound in the hollow fiber membrane bundle is high. This leads to the problem that partial sticking occurs. If the partial sticking occurs, it will lead to problems such as deterioration in module assembly. Furthermore, the elution amount of hydrogen peroxide increases, and the variation of the elution amount in the longitudinal direction of the hollow fiber membrane bundle increases. In the presence of hydrogen peroxide, for example, the oxidative degradation of polyvinyl pyrrolidone is promoted, and the amount of the polyvinyl pyrrolidone eluted increases when the hollow fiber membrane bundle is stored. That is, storage stability deteriorates. Even if hydrogen peroxide is present in a specific part of the hollow fiber membrane bundle, the degradation reaction of the hollow fiber membrane bundle material starts from that location and propagates to the entire hollow fiber membrane bundle. It is necessary to ensure a certain amount or less of the film bundle in the longitudinal direction over the entire region. Therefore, an increase in the hydrogen peroxide elution amount leads to a decrease in safety even if it is localized. On the other hand, if it exceeds 5% by mass, the bacteria may proliferate during storage, the hollow fiber membrane may be crushed by its own weight, or adhesive failure of the adhesive may occur during module assembly. It is not preferable. Moreover, it leads to that a microbe becomes easy to proliferate at the time of a preservation | save, or a thread crushing generate | occur | produces by the dead weight of a hollow fiber membrane.

  The method for managing the moisture content at the end of drying 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, it is preferable to constrain with a hollow package and place it on a tray. This improves the handleability of the hollow fiber membrane bundle and improves the workability of the arrangement. In this case, it is preferable to restrain the wet hollow fiber membrane bundle in consideration of module assembly in the next step. That is, the number of units of the hollow fiber membrane bundle required for the module is constrained by a package that is slightly smaller than the inner diameter of the module housing, and the dried hollow fiber membrane bundle is inserted into the housing for each package. It is recommended as a particularly preferable method because it is possible to suppress the occurrence of troubles such as the workability of inserting the dry hollow fiber membrane bundle into the housing and the occurrence of scratches on the hollow fiber membrane in the work by pulling out only the package in a state where The In this 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 housing 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 degree of shrinkage of the hollow fiber membrane bundle due to drying.

  The length of the wet hollow fiber membrane bundle is set by setting the length of the module housing for loading the dried hollow fiber membrane bundle to A (mm). When the combined length is B (mm), it is preferably set to A + B (mm) after the hollow fiber membrane bundle is dried.

  In a preferred embodiment, the hollow package is made of plastic having a circular cross-sectional shape, and the outer diameter thereof is 70 to 99.9% of the inner diameter of the housing 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 housing of the module loaded with the dry hollow fiber membrane bundle. If it exceeds 99.9%, it becomes difficult to load the package into the module housing. On the other hand, if it is less than 70%, the space occupied by the bundle of hollow fiber membranes in the module becomes small, so a useless space is created in the module, or the position of the hollow fiber membrane bundle is uneven in the module. When used as a purifier, the dialysis fluid is liable to drift, leading to a reduction in dialysis efficiency. Moreover, the workability | operativity of the adhesion | attachment process which fixes a hollow fiber membrane bundle in a housing 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 further more preferable. If the thickness is less than 0.05 mm, the shape retainability is lowered, the shape is easily deformed, the shape deformation of the hollow fiber membrane bundle is generated, and the workability of loading into the housing is deteriorated. 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% by volume is preferred. 43-80 volume% is preferable and 46-70 volume% is more preferable. If it is less than 40% by volume, useless space volume in the module after assembling the module is increased, and the diameter of the module is increased. Also, for example, when used as a blood purifier, the dialysate drifts and leads to a decrease in dialysis efficiency, which is not preferable. On the other hand, if it exceeds 90% by volume, the workability of extraction when the hollow packaging body is extracted when the dry hollow fiber membrane bundle is loaded into the housing is deteriorated, and the hollow fiber membrane is crushed or damaged. Is likely to occur, leading to the generation of defective yarns. In addition, in the bonding step of fixing the hollow fiber membrane bundle in the housing, the permeability of the adhesive into the space between the hollow fiber membranes is lowered, leading to an increase in the number of defective bonding points, which is not preferable.

The material of the hollow package that restrains the wet hollow fiber membrane bundle is preferably selected from resins whose product of dielectric constant and dielectric loss tangent at 1 MHz is 0.02 or less. 0.018 or less is more preferable, and 0.016 or less is more preferable. Examples of the resin include polyolefin resins such as polyethylene and polypropylene, polyethylene terephthalate resins, polysulfone resins such as polysulfone resins and ether sulfone resins, polyether ether ketone resins, and polyimide resins. Use of the resin is preferable because microwave permeability is improved and drying uniformity of the hollow fiber membrane bundle is improved. Polyolefin resin has a very low product of dielectric constant and dielectric loss tangent at 1 MHz of 0.0005 or less, is soft, and has a good sliding property of the hollow fiber membrane bundle. This is particularly preferable because it also has the advantage that the film bundle is hardly damaged.
On the other hand, if a resin whose dielectric constant and dielectric loss tangent at 1 MHz exceeds 0.02, such as polyvinyl chloride resin, polymethyl methacrylate resin, and polycarbonate resin, the microwave transmission is reduced. When the package is heated, the temperature of the constrained hollow fiber membrane bundle and the hollow fiber membrane in contact with or in the vicinity thereof increases, and the deterioration of polyvinylpyrrolidone in the hollow fiber membrane increases or the longitudinal direction of the hollow fiber membrane increases. This is not preferable because the drying uniformity and shrinkage of the hollow fiber membrane increase.

  The package is preferably a method using a seamless tube-shaped package. For example, it is preferable to use a hollow pipe or the like. In particular, it is more preferable to fill a hollow fiber membrane bundle in a wet state into a film or sheet that has been previously formed into a tube shape by a fusing seal or the like.

  The structure of the tray for fixing the hollow fiber membrane bundle is not limited as long as it can be fixed in an arrangement that satisfies the above requirements. There is no limitation on the shape of the tray, and a method of fixing the package by attaching a recess in the shape of the package in which a bundle of hollow fiber membranes in a wet state is constrained, or by attaching a protrusion that can fix the package, Examples include a method of storing and fixing the package in the space. From the viewpoint of workability, it is preferable to attach a semicircular recess according to the shape of the package on the upper surface of the tray and fix the dried hollow fiber membrane bundle restrained by the package in this recess. Even if the tray has a configuration in which a plurality of hollow fiber membrane bundles are arranged in both the horizontal direction and the vertical direction, a plurality of divided trays are arranged only in the horizontal or vertical direction, and in the opposite direction are single pieces. A unit tray may be combined. From the viewpoint of handling, a method of stacking a plurality of divided trays arranged in a horizontal direction to form a unit tray is recommended.

  The number of hollow fiber membrane bundles arranged on the set tray is not limited as long as the above requirements are satisfied, and may be appropriately selected depending on the size and structure of the microwave dryer, but 2 to 4 vertically and 2 to 6 horizontally. Books are preferred. That is, it is preferable that 2 to 4 unit trays each having 2 to 6 hollow fiber membrane bundles fixed in parallel in the lateral direction are stacked to form a set tray.

  The material of the tray is preferably selected from resins having a product of a dielectric constant and a dielectric loss tangent at 1 MHz of 0.02 or less, like the material of the hollow packaging body that restrains the hollow fiber membrane bundle. 0.018 or less is more preferable, and 0.016 or less is more preferable. Examples of the resin include polyolefin resins such as polyethylene and polypropylene, polyethylene terephthalate resins, polysulfone resins such as polysulfone resins and polyethersulfone resins, polyetheretherketone resins, and polyimide resins. Use of the resin is preferable because microwave permeability is improved, heat generation of the tray is suppressed, and drying uniformity of the hollow fiber membrane bundle is improved. Since it is necessary to use it repeatedly, it is preferable to use a polysulfone resin or a polyether ether ketone resin having excellent heat resistance. On the other hand, if a resin whose dielectric constant and dielectric loss tangent at 1 MHz exceeds 0.02, such as polyvinyl chloride resin, polymethyl methacrylate resin, and polycarbonate resin, the microwave transmission is reduced. The heat generation of the tray increases, the temperature of the package in the part in contact with the tray and the hollow fiber membrane bundle in the vicinity thereof increases, the deterioration of polyvinylpyrrolidone in the hollow fiber membrane of the part increases, and the hollow fiber membrane This is not preferable because the uniformity of drying in the longitudinal direction is lowered, the shrinkage of the hollow fiber membranes is increased, and the quality variation in each hollow fiber membrane bundle is increased.

  In the present invention, it is preferable that the hollow fiber membrane bundle to be dried fixed by the tray is placed on a horizontally set table having a rotation function and dried while rotating. Moreover, it is preferable to arrange | position a tray on a rotary table so that a hollow fiber membrane bundle may become substantially radial with respect to a rotation center. More preferably, they are arranged at substantially equal intervals. 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 arrange | position only by putting on a rotary table, the operation | work of arrangement | positioning of the to-be-dried hollow fiber membrane bundle to a 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. Take measures such as adding a dent in the shape of the tray to the location of the tray on the table, or conversely, adding a protrusion that can fix the tray to identify the location of the tray and improve the workability of the placement. Is also a preferred embodiment. In the case of the divided tray system, the unit tray may be assembled in advance and then fixed to the rotary table, or the unit tray may be assembled on the rotary table. In addition, the centrifugal dehydration process tray, which is the previous process of drying, is shared with the drying process tray, the hollow fiber membrane bundle is fixed to the tray used for the main drying process, centrifugal dehydration is performed, and the flow is directly passed to the drying process. May be. This method is recommended as a preferred embodiment because it improves 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 is lowered, and the effect of the present invention is lowered. The material of the plastic spacer is not limited and may be a general-purpose resin such as polypropylene or polyethylene terephthalate. However, from the viewpoint of heat resistance, polycarbonate, polysulfone resin, polyether ether ketone, polyphenylene sulfide, aramid Those made of so-called engineering plastics such as wholly aromatic polyesters are preferred. Polysulfone resin is preferred. It is also included in 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 point of the dry hollow fiber membrane bundle group of the unit tray is near the center of the waveguide outlet of the microwave oscillator.

  As described above, the first characteristic of the hollow fiber membrane bundle obtained by the method of the present invention is that, as described above, the moisture content in the hollow fiber membrane bundle after drying of the hollow fiber membrane bundle in the unit tray is from 1 to all. It is preferably 5% by mass.

As for the second characteristic that the hollow fiber membrane bundle obtained by the method of the present invention should have, it is preferable 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, it is preferable that the difference in the average value of the hollow fiber membrane length between the outer peripheral portion and the inner peripheral portion of the hollow fiber membrane bundle constrained by the hollow package after the drying is within 3 mm.
Here, the outer peripheral portion of the hollow fiber membrane bundle refers to an outer peripheral portion of ¼ of the radius from the center point in the circular cross section of the hollow fiber membrane bundle. Further, the inner peripheral portion means an inner peripheral portion having a quarter of the radius from the center point. The average value of the length of the hollow fiber membrane is that 500 pieces are randomly sampled from the hollow fiber membranes sampled from the outer peripheral portion and the inner peripheral portion, and the yarn length is measured for all 500 pieces by the following method. The average value is obtained.
(Measurement method of yarn length)
Each hollow fiber membrane is sandwiched between KOKUYO W clip mouth width 15 mm and beans (Kokuyo Co., Ltd .: Cree J36), 5 mm from both ends of each hollow fiber membrane, one clip is fixed, and the other clip is free Suspend and measure the yarn length with a ruler in this state.

  The difference in the average value of the hollow fiber membrane length is more preferably 2 mm or less, and further preferably 1 mm or less. If the difference in the average value of the hollow fiber membrane length exceeds 3 mm, when the hollow fiber membrane bundle is used as a module, the ratio of the inclined hollow fiber membrane and the ratio of clogged yarn increase as described later. This is not preferable because it leads to an increase in residual blood thread when used for blood purification, for example.

  The above characteristics can be easily achieved by carrying out the drying method of the present invention. Although expressed as an effect of the sum of the constituent requirements of the drying method of the present invention, the contribution of the effect of selecting the material of the package or tray described above is significant.

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 hydrogen peroxide accelerates the oxidative degradation of polyvinylpyrrolidone, for example, and increases the elution amount of polyvinylpyrrolidone 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 a conventionally known method, the elution amount of the hydrogen peroxide increases, and when the hollow fiber membrane bundle is stored for a long time, the oxidative degradation of polyvinylpyrrolidone is promoted, and the UV (220 to 350 nm) absorbance increases with time. We found that the problem of increasing would occur.

  That is, it is preferable to obtain a hollow fiber membrane bundle having the following characteristics. That is, the third 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 preferably 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 pure water is added to this, extraction is performed at 70 ° C. for 1 hour, and the UV (220-350 nm) absorbance of the extract is measured. It is obtained by quantifying hydrogen peroxide in the extract. It is a thing.

The hydrogen peroxide elution amount is more preferably 4 ppm or less, and further preferably 3 ppm or less. When the elution amount of hydrogen peroxide exceeds 5 ppm, the storage stability is deteriorated due to oxidative degradation due to hydrogen peroxide, and the elution amount of polyvinylpyrrolidone may increase when stored for a long period of time, for example. 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, the dry hollow fiber membrane bundle obtained by the present invention is stored in a dry box (atmosphere is air) at room temperature for 3 months, and then the hollow fiber membrane bundle is divided into 10 pieces in the longitudinal direction, When each of them is subjected to a test defined by the dialysis artificial kidney device manufacturing approval criteria, the UV (220 to 350 nm) absorbance in the hollow fiber membrane extract is preferably 0.10 or less on average. More preferably, the above properties are maintained even after storage for 5 months or longer. Therefore, the UV (220 to 350 nm) absorbance after storage for 3 months is more preferably 0.08 or less, and further preferably 0.06 or less. In consideration of storing the hollow fiber membrane bundle in a dry state in the manufacturing process of the hollow fiber membrane bundle, transportation and storage for inventory, etc., it is preferable to give the above characteristics.

  The fourth characteristic to be provided is the characteristic that governs the partial fixation of the hollow fiber membrane bundle. The hollow fiber membrane bundle after drying divides the hollow fiber membrane bundle into 10 pieces in the longitudinal direction. When the test defined by the dialysis-type artificial kidney device manufacturing approval standard is carried out, the maximum value of UV (220 to 350 nm) absorbance in the extract of the hollow fiber membrane is less than 0.10, and within the same hollow fiber membrane bundle It is also important that the difference between the maximum value and the minimum value is 0.05 or less. 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 UV in the extract in the longitudinal direction of the hollow fiber membrane bundle. (220 to 350 nm) By suppressing the fluctuation in absorbance, the fluctuation of the content of polyvinylpyrrolidone on the surface of the hollow fiber membrane in the longitudinal direction of the hollow fiber membrane bundle is suppressed, so that the occurrence of partial sticking of the hollow fiber membrane bundle is suppressed. . 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 for blood purification. Therefore, 0.04 or less is preferable, 0.03 or less is more preferable, and 0.02 or less is even more preferable.

  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. When less than 0.03, the content of the hydrophilic polymer on the inner surface of the film is not sufficient, so that the film has poor wettability, 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.

  In the present invention, as described above, the outermost layer of the bundle of hollow fiber membranes in contact with the package and the hollow fiber membrane in the vicinity thereof are selected unless the material having the characteristics specified in the present invention is selected as the material of the package or tray. Therefore, the hollow fiber membranes at the outer periphery of the bundle of hollow fiber membranes must have the above characteristics. Here, the outer peripheral portion refers to a range of ¼ radius from the outer periphery in the circular cross section of the hollow fiber membrane bundle.

  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. Cellulose type and polysulfone type are 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. 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 composition ratio of polyvinylpyrrolidone in the membrane relative to the polysulfone resin in the present invention is not particularly limited as long as it is within a range that can impart sufficient hydrophilicity and high water content to the hollow fiber membrane, but can be arbitrarily set, The mass ratio of polyvinylpyrrolidone to the polysulfone resin is preferably 1 to 20 mass%, more preferably 3 to 15 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 amount of elution from the membrane of the hydrophilic polymer increases, resulting in a decrease in safety.

  Although the manufacturing method of the hollow fiber membrane bundle in this invention is not limited at all, For example, the method 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 has, the hollow fiber membrane bundle can be 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 toward the oven and the energy Er of the reflected wave reflected from the oven toward the oscillator is 0.2 or less is used. It is more preferable to heat by irradiating with microwaves. 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 toward the oscillator is performed by installing an energy detector in the waveguide section from the microwave oscillator toward the oven. Measured and obtained. 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. In this case, in the present invention, since the drying uniformity between the hollow fiber membrane bundles in the tray is high, the above switching may be performed by paying attention to the moisture content of the hollow fiber membrane bundle at any position. It is preferable to perform switching by paying attention to any one of the hollow fiber membrane bundles located at the outermost part of the fiber. 10-15 mass% is more preferable. Drying by microwave irradiation to a moisture content of less than 10% by mass is not preferable because degradation of polyvinylpyrrolidone increases, the amount of hydrogen peroxide extracted increases, and the storage stability of the hollow fiber membrane bundle decreases. Further, 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 increases, which is not preferable. On the contrary, if microwave irradiation is stopped when it exceeds 20% by mass, the total drying time until drying to the final moisture content becomes longer, which is not preferable.

  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 improvement in drying efficiency and is recommended because it is economical. In the most preferred embodiment, 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 also 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 20-60 degreeC, More preferably, it is 20-50 degreeC, More preferably, it is 30-40 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 raises temperature rise suppression and 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 a hollow fiber membrane bundle containing polyvinylpyrrolidone, the polyvinylpyrrolidone is deteriorated or decomposed due to overdrying or overheating, and the wettability during use is reduced. It is preferable not to raise the output much because there are problems such as occurring. 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 reached by the hollow fiber membrane bundle during drying can be measured by attaching an irreversible thermolabel to the side surface of the hollow fiber membrane bundle restraint body, drying, and taking out and confirming the display after drying. 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 a reflected wave that occurs accompanying the generation of microwaves occurs. Therefore, it is important to take measures to reduce the nonuniform heating due to the reflected wave. 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. What is the irradiation energy of far-infrared irradiation? It is preferable to control so that the temperature detected by a thermocouple provided at the center of the oven is 80 ° C. or lower. 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 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 surface moisture suppresses the concentration fluctuation of the surface of the hollow fiber membrane of polyvinylpyrrolidone induced by the surface moisture, which is preferable because it leads to suppression of partial sticking. 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 drying by continuing far-infrared irradiation while maintaining a reduced pressure state and continuing further drying is preferable. In this case, 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 having a wavelength of 3 to 12 μm, it is difficult to increase the temperature of the object to be dried even if the wavelength of the 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 simultaneously, 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 surface moisture suppresses the concentration fluctuation of the surface of the hollow fiber membrane of polyvinylpyrrolidone induced by the surface moisture, which is preferable because it leads to suppression of partial sticking. 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 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 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 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 influence 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, in view 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.

  The appropriate drying time of the hollow fiber membrane bundle is a value obtained by adding a drying region by far infrared rays to a drying region time by microwave, of course, in this case, a drying means using both of them may be included, The present inventors have analyzed the behavior of whether the switching state between the drying region time by microwaves and the drying region by far infrared rays is most dependent on the technical conditions. If it demonstrates based on FIG. 1, if it dries within the range enclosed by the area | region enclosed with 1 and 2 of a continuous line, it is that a product with comparatively good quality is easily obtained. For example, if it becomes the area | region of the broken lines (1) and (2) of FIG. 1, it will have a considerable influence on the quality of a hollow fiber membrane bundle. This can be easily understood by taking into account the statistical interpretation shown in FIG.

  Looking closely at such an analysis, as a method of drying a hollow fiber membrane having a relatively high moisture content, microwave drying is optimal in this case, microwave drying under reduced pressure is suitable for it, It can also be said that the drying by far-infrared including conditioning is appropriate drying. As a result of examination by the inventors about this switching, the moisture content of the hollow fiber membrane bundle is 5 to 30% by mass, more preferably 8 to 25% by mass, and further preferably 10 to 20% by mass by drying with microwaves. The fact that it is most suitable to switch at the stage of reaching is found.

  For example, when the moisture content of the hollow fiber membrane bundle is relatively high, such as 60 to 400% by mass, it is forcibly reduced to a predetermined moisture content by applying a reduced pressure by a microwave in some cases. The present inventors have found that a technique using infrared rays is most suitable. The appropriate range of 10 to 20% by mass of water content is slightly different depending on the polymer material, structure, etc., but within this range, it can be said that it can be applied to drying of general-purpose hollow fiber membrane bundles.

  FIG. 2 shows an analysis of an example in which the range of 10 to 20% by mass of the dry switching affects the quality of the hollow fiber membrane bundle. Based on Examples and Comparative Examples, several examples are plotted. It can be easily understood that this tendency influences the variation of the hollow fiber membrane bundle, with the water content of the hollow fiber membrane bundle being 10 to 20% by mass as a boundary. The idea of using far-infrared rays in combination with microwaves is based on the knowledge of the present inventors. This is based on the knowledge of the present inventors and is a new idea.

  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 making the hydrogen peroxide content in polyvinyl pyrrolidone used as a raw material 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 It is preferable because the bundle quality can be stabilized. Therefore, the hydrogen peroxide content in the polyvinyl pyrrolidone 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.

  In addition, when a spinning solution comprising a polysulfone resin, polyvinyl pyrrolidone, and a solvent is stirred and dissolved, if polyvinyl pyrrolidone contains hydrogen peroxide, the effects 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, and it has not been 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 or more and 1.3 or less, 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, a long defoaming time or insufficient defoaming occurs due to entrapment of bubbles in the film-forming solution during stirring. 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. Furthermore, 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 sealing pressure is increased, the melting time can be shortened. However, in order to increase the pressure, the equipment cost increases, and from the viewpoint of work safety, it is preferably from atmospheric pressure to 2 kgf / cm ² .

  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 proportion of polyvinylpyrrolidone present on the outer surface exceeds 50% by mass, 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 on 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 not stretching” means controlling the roller speed during the spinning process 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 traveling 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, further preferably 0.9 or more, 0 .95 or more is even more preferable. When 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 abundance of the outer surface polyvinyl pyrrolidone, thereby suppressing sticking and reducing the amount of eluate.

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

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

The shape of the blood purification module is illustrated in FIG.
The blood purification module 10 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 4 to both ends of the container 2 with an adhesive or the like. The part 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 to be dialyzed and the flow of dialysate are opposite so-called opposite flows. 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. Moreover, polyurethane etc. are mentioned as a material of the adhesive agent used for both ends fixing.

  The method of injecting the adhesive used for fixing both ends into the fixing portion is not limited, but a centrifugal bonding method is recommended in which injection is performed using the centrifugal force generated by rotating the module container to be injected. The method of the centrifugal bonding method is not limited. For example, sealing jigs are attached to both ends of the housing loaded with the dried hollow fiber membrane bundle 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, post-curing is performed to complete the curing. Further, the injection of the adhesive may be carried out by being divided into two or more times.

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 part 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 warping treatment is effective in 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 unnecessary.
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 filling density of the hollow fiber membrane bundle restrained by the hollow package when the dry hollow fiber membrane bundle is inserted into the housing 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 housing 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 blood purification module of the present invention is a blood purification 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 ratio of the number of hollow fiber membranes having a degree of inclination of the hollow fiber membrane of 15 degrees or more is 0.05% or less. (2) The ratio of the number of clogged yarns measured by the following method is 0.05. % Is preferably satisfied at the same time.

[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, the fixing jigs are attached to both ends of the housing and set in the 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 blood purifier 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 bundle exceeds 15 degrees, it becomes difficult for blood to flow, and drift occurs and leads to the generation of residual blood hollow fiber membranes. 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 hollow fiber membranes increases, which causes anxiety to dialysis patients. In the present invention, it is preferable that this characteristic is satisfied on both end faces.

[Percentage of clogged hollow fiber membrane]
The end surface of the sample prepared by the above method is colored with red magic ink (R), and the end surface is marked with 8 divisions in a radial pattern. The entire 8 end portions are microscopes with a national light (light scope 100, magnification: 100 times, manufactured by Matsushita Electric Industrial Co., Ltd.) and the number of clogged hollow fiber membranes is counted. The ratio of the clogged hollow fiber membrane is calculated by the following formula.
Ratio of clogged hollow fiber membranes (%) = (number of clogged hollow fiber membranes / total number of hollow fiber membranes on the sample end face) × 100
Here, both the number of clogged hollow fiber membranes and the total number of hollow fiber membranes on the sample end surface are total counts of all end surfaces divided into eight.

  The ratio of the clogged hollow fiber membrane is more preferably 0.04% or less, and further preferably 0.03% or less. 0% is particularly preferred. When the ratio of the clogged hollow fiber membrane exceeds 0.05%, it is not preferable because blood becomes difficult to flow, blood drifts and leads to the generation of residual blood hollow fiber membranes. In the present invention, it is preferable that this characteristic is satisfied on both end faces.

Further, in the blood purification module of the present invention, the ratio of the number of crushed hollow fiber membranes evaluated by observing and evaluating the outermost surface portion of the portion where the hollow fiber membrane bundle on the end surface of the module is fixed with an adhesive is 0.00. It is preferable that it is 05% or less. In the present invention, it is preferable that this characteristic is satisfied on 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 number of crushed hollow fiber membranes exceeds 0.05%, blood becomes difficult to flow, blood drifts and leads to the generation of residual blood yarn.
[Method for evaluating the ratio of hollow hollow fiber membranes]
The end face (module end face side) of the sample used for the evaluation of the ratio of the above-mentioned inclined hollow fiber membrane was radially marked with 8 divisions, and the total number of crushing was counted by observing all 8 divided end faces at a magnification of 200 times. . 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 collapsed hollow fiber membrane 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 hollow fiber 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.

In the blood purification module of the present invention, the ratio of residual blood yarn 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 evaluation method of residual blood hollow fiber membrane]
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 hollow fiber membrane (%) = (number of residual blood hollow fiber membranes / total number of hollow fiber membranes in module) × 100

  Furthermore, in the present invention, 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 divided into 10 pieces in the longitudinal direction, and each is divided into dialysis artificial kidney devices. It is preferable that the UV (220 to 350 nm) absorbance of the hollow fiber membrane extract when the test defined by the manufacturing approval standard is performed is 0.10 or less. More preferably, the UV (220 to 350 nm) absorbance of the hollow fiber membrane extract is 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 blood purifier 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. In addition, the liquid filled in the module during the storage evaluation of the above-mentioned module may be sodium pyrosulfite or sodium sulfite for preventing deterioration of the hollow fiber membrane bundle material during the γ-ray sterilization treatment of the module with water alone. And an aqueous solution in which sodium bisulfite, acetone sodium bisulfite, sodium formaldehyde sulfoxylate, ascorbic acid, glycerin and the like are dissolved.

  Although the achievement means which gives the characteristic preferable to comprise as said blood purification module is not limited, For example, it can achieve by using the above-mentioned hollow fiber membrane bundle of this invention.

  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%. When the content of the hydrophilic polymer on the outer surface is less than 25% by mass, the content 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 decrease. . 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 is likely to 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 content ratio of ˜several tens of liters) is obtained. Normally, 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 hollow fiber membrane outer surface is 8 to 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. Conversely, 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.

  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 selectively permeable separation membrane in the present invention was calculated by the following equation.
Moisture content% = 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 is equally divided into 10 pieces of 2.7 cm in the longitudinal direction, and 1 g of the dry hollow fiber membrane bundle is weighed from each part. The water content was measured by the above method 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 100 g of pure water was added to 1 g of a hollow fiber membrane bundle, which is a method stipulated in the manufacturing standard for dialysis-type artificial kidney apparatus, and the extracted liquid was extracted at 70 ° C. for 1 hour. Absorbance in the wavelength range of 200 to 350 nm was measured using U-3000) manufactured by Seisakusho Co., 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 bundle in a dry state was weighed from each portion 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 passed 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 measurement was performed using the dry membrane.

4. Determination of hydrogen peroxide Hydrogen chloride solution of TiCl ₄ and 4- (2-pyridylazo) mixed in an equimolar ratio with ammonium chloride buffer (PH 8.6) 0.2 ml in 2.6 ml of the extract extracted by the above method ) Add 0.2 ml of coloring reagent prepared to 0.4 mM of a mixed solution of resorcinol with Na salt solution, heat at 50 ° C. for 5 minutes, cool to room temperature, and measure absorbance at 508 nm. 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 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. If the fused state is severe, replace the blade to be cut as appropriate.

6. Shrinkage fluctuation of hollow fiber membrane bundles In the circular cross section of the hollow fiber membrane bundle after drying, it is divided into an outer peripheral part of ¼ radius from the central point and an inner peripheral part of ¼ radius from the central point. And sampled. 500 pieces of each of the hollow fiber membranes sampled from the outer peripheral portion and the inner peripheral portion were randomly sampled, and the yarn lengths of all 500 pieces were measured by the following method to determine the average value. The difference between the two average lengths was determined and judged according to the following criteria. ◎ and ○ were accepted.
(Measurement method of yarn length)
Each hollow fiber membrane is sandwiched between KOKUYO W clip mouth width 15 mm and beans (Kokuyo Co., Ltd .: Cree J36), 5 mm from both ends of each hollow fiber membrane, one clip is fixed, and the other clip is free Suspend and measure the yarn length with a ruler in this state.
(Determination of shrinkage fluctuation)
A: The difference in the average value of the hollow fiber membrane length between the outer peripheral portion and the inner peripheral portion is less than 1 mm. ○: The difference in the average value of the hollow fiber membrane length between the outer peripheral portion and the inner peripheral portion is 1 mm to 3 mm or less. The difference in the average value of the hollow fiber membrane length between the outer peripheral part and the inner peripheral part exceeds 3 mm

7. Storage stability of dried hollow fiber membrane bundle The dried hollow fiber membrane bundle was stored in a dry box (atmosphere: air) conditioned at 50% humidity for 3 months at room temperature, and then UV (220- 350 nm) absorbance was measured. 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 housing having an inner diameter of 31 and a length of 255 mm, and the hollow fiber membrane is fixed while being packaged. Extracted. In this state, sealing jigs were attached to both ends of the housing 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 taken out and post-cured overnight at room temperature, and then 5 mm at each end of the module end was 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 eight parts, and the whole end face divided into eight parts at a magnification of 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 number of crushed hollow fiber membranes was obtained by the following formula.
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: Less than 0.03% of hollow hollow fiber membrane
○: Ratio of collapsed hollow fiber membrane 0.03-0.05%
X: Ratio of crushing hollow fiber membrane exceeding 0.05% ◎ and ○ were regarded as acceptable.

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

11. Residual blood hollow fiber membrane 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, and the blood bag and the module are tubed 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.
Rate of change = correction value (60 minutes) / value before circulation start x 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 hollow fiber membrane (%) = (number of residual blood hollow fiber membranes / total number of hollow fiber membranes in module) × 100
The following quality classification was judged by the ratio of clogged hollow fiber membranes.
A: Ratio of residual blood hollow fiber membrane less than 0.03%
○: Ratio of residual blood hollow fiber membrane 0.03-0.05%
X: Ratio of residual blood hollow fiber membrane exceeding 0.05% ◎ and ○ were accepted.

12. Water permeability The blood outlet circuit (outlet side from the pressure measurement point) of the dialyzer 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 suppress coagulation is sent to a blood purifier at 200 mL / min, and the blood is filtered at a rate of 10 mL / min (m ² ). At this time, the filtrate is returned to blood to be a circulatory system. After 60 minutes, the filtrate from the blood purifier is collected, and the red color resulting from red blood cell leakage is visually observed. In this blood leak test, 30 blood purifiers were used in each example and comparative example, and the number of blood leaked modules was examined.

15. Storage stability of hollow fiber membrane bundle of blood purifier The module prepared by the same method as the ratio evaluation method of tilted hollow fiber membrane was filled with RO water and irradiated with γ-rays at an absorbed dose of 25 kGy and subjected to crosslinking treatment . 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.

16. Content on the outer surface of the hydrophilic polymer The content of the hydrophilic polymer relative to the hydrophobic polymer was determined by X-ray photoelectron spectroscopy (ESCA method). A measurement method in the case of using polysulfone-based polymer as the hydrophobic polymer and polyvinylpyrrolidone as the hydrophilic polymer is exemplified.
One hollow fiber membrane was attached to a sample stage, and measurement was performed by X-ray photoelectron spectroscopy (ESCA method). The measurement conditions are as follows.
Measuring device: ULVAC-Phi ESCA5800
Excitation X-ray: MgKα ray X-ray output: 14 kV, 25 mA
Photoelectron escape angle: 45 °
Analysis diameter: 400μmφ
Pass energy: 29.35 eV
Resolution: 0.125 eV / step
Degree of vacuum: about 10 ⁻⁷ Pa or less From the measured value of nitrogen (N) and the measured value of sulfur (S), the PVP content on the surface was calculated by the following formula.
<In case of PVP-added PES (polyethersulfone) membrane>
PVP content (Hpvp) [%]
= 100 × (N × 111) / (N × 111 + S × 232)
<In the case of PVP-added PSf (polysulfone) membrane>
PVP content (Hpvp) [%]
= 100 × (N × 111) / (N × 111 + S × 442)

17. Content of hydrophilic polymer in membrane An example of a measurement method using polyvinyl pyrrolidone (PVP) as the hydrophilic polymer is illustrated. The sample was dried at 80 ° C. for 48 hours using a vacuum dryer, and 10 mg of the sample was analyzed with a CHN coder (manufactured by Yanaco Analytical Industrial Co., Ltd., MT-6 type). Calculated with
PVP content (mass%) = nitrogen content (mass%) × 111/14

18. Opening ratio of outer surface of hollow fiber membrane The outer surface of the hollow fiber membrane is observed with an electron microscope of 10,000 times and a photograph (SEM photograph) is taken. The image was processed with image analysis processing software to obtain the porosity of the outer surface of the hollow fiber membrane. The image analysis processing software is measured using, for example, Image Pro Plus (Media Cybernetics, Inc.). The emphasis / filtering operation is performed on the captured image so that the hole and the blockage are identified. Thereafter, the holes are counted, and when the lower polymer chain can be seen inside the holes, the holes are combined and counted as one hole. The area (A) of the measurement range and the cumulative area (B) of the areas of the pores within the measurement range were determined, and the area ratio (%) = B / A × 100. This was carried out for 10 views and the average was obtained. Scale setting is performed as an initial operation, and holes on the measurement range boundary are not excluded during counting.

19. Membrane thickness of hollow fiber membrane A cross section of the hollow fiber membrane is projected with a projector having a magnification of 200 times, and the inner diameter (A) and outer diameter (A) and outer diameter (maximum, minimum, and medium) of the hollow fiber membrane within each field of view ( B) is measured, and the film thickness of each hollow fiber membrane is obtained by the following formula,
Film thickness = (B−A) / 2
The average of the film thickness of 90 hollow fiber membranes in 30 fields of view was calculated.

(Example 1)
1 part by weight of polyethersulfone (manufactured by Sumika Chemtex, Sumika Excel (R) 5200P), 0.145 parts by weight of polyvinylpyrrolidone (Collidon (R) K-90 by BASF), 1.5 parts by weight of DMAc are biaxial. It knead | mixed with the screw-type kneader. The obtained kneaded material was added to a stirring type dissolver charged with 2.96 parts by mass of DMAc and 0.17 parts 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 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 (thickness 0.2 mm, dielectric loss tangent: 0.0002, dielectric constant and dielectric) of 10,000 of the hollow fiber membranes and having a textured surface on the hollow fiber membrane bundle side surface (0.2 mm) The product is inserted into a hollow packaging body (outer diameter 36 mm) having a circular cross-sectional shape (product with tangent: 0.00046), cut to a length of 270 mm, and 30 minutes × 4 in hot water at 80 ° C. Washed twice. A package body in which the washed hollow fiber membrane bundle is constrained is placed in a recess portion of a tray made of a polysulfone resin in which a semicircular recess conforming to the shape of the package body is provided on the upper surface of the tray, and then a centrifugal dehydrator. Centrifugal dehydration was performed at 140 rpm for 20 minutes to obtain a dehydrated hollow fiber membrane bundle having a water content of 300% by mass. The length in the width direction of the tray was 210 mm, a space having a width of 46 mm was provided at the center of the tray, and two hollow fiber membrane bundles were arranged on the left and right sides thereof at a center distance of 41 mm.

  The resulting dehydrated hollow fiber membrane bundle is installed with a tray and a microwave oscillator on the side wall of the heating oven, the microwave can oscillate in the horizontal direction, has a horizontal rotating table inside the oven, has a far infrared heater and oven Five sets of trays are arranged at approximately 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 depressurization. And arranged so as to be substantially radial. The unit trays are arranged in two layers to form one set. The distance between the upper and lower centers was 41 mm. FIG. 5 shows a conceptual diagram of the arrangement of one set of the hollow fiber membrane bundle and the hollow fiber membrane bundle. The rotary table has a structure in which a polypropylene plate having a thickness of 6 mm is fixed on a metal holding jig, and the center point of the two-layer stack in the height direction is the center of the waveguide of the microwave oscillator. It was installed to be a part.

  The rotary table was dried under the following conditions while rotating at 8 rpm. After heating the hollow fiber membrane bundle for 25 minutes at a pressure of 1.5 kW under a reduced pressure of 7 KPa, the microwave irradiation was stopped and simultaneously the pressure was increased 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 moisture content in the hollow fiber membrane bundle after the microwave irradiation was 13% by mass. After stopping the microwave irradiation, the degree of vacuum was increased to 0.5 kPa, only far infrared rays were irradiated, 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. The Er / Ei of the irradiated microwave was 0.05. The moisture content of the hollow fiber membrane bundle before drying was about 340% by mass. The water content after the final drying was 2.5% by mass. The water content was controlled by paying attention to the outermost single hollow fiber membrane bundle. The moisture content of all the hollow fiber membrane bundles in one set of trays was in the range of 2.3 to 2.7% by mass, and the drying uniformity between the hollow fiber membranes was good. The obtained hollow fiber membrane bundle had an inner diameter of 198 μm and a film thickness of 28 μm. The filling rate of the dry hollow fiber membrane bundle in the package was 50% by volume. 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.

  One dried hollow fiber membrane bundle was selected at random from one set of trays, and the difference between the average values of the hollow fiber membrane lengths of the outer peripheral portion and the inner peripheral portion was determined. The shrinkage variation of the hollow fiber membrane was small and 0.5 mm or less. In addition, another sample was used to sample the hollow fiber membrane at the outer peripheral portion of the hollow fiber membrane bundle (in the range of a quarter of the radius), and the sample was equally divided into 10 pieces of 2.7 cm in the longitudinal direction. From this, 1 g of a hollow fiber membrane in a dry state was weighed 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 elution amount and UV (220-350 nm) absorbance in the extract were measured. The variation of moisture content was small. Further, the elution amount of hydrogen peroxide and the 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. 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 constrained by the polyethylene film obtained by the above method were inserted into a module housing having an inner diameter of 31 mm and a length of 255 mm, and made of a polyethylene film while fixing the hollow fiber membrane. The package was removed. In this state, sealing jigs were attached to both ends of the housing 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 pure water degassed in advance, and γ-rays were irradiated at an absorbed dose of 25 kGy for crosslinking treatment. The dry hollow fiber membrane bundle obtained in this example is not deformed 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 bundle, and there is also partial adhesion Since it did not occur, 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.

Fresh bovine blood to which citric acid was added was flowed to the blood purifier at a blood flow rate of 200 mL / min and a filtration rate of 10 mL / min (m ² ). There was no leak. These results are shown in Table 4.

  The blood purifier was stored at room temperature for 1 year. When the hollow fiber membrane bundle was cut out from the blood purifier 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, various characteristic value evaluations were performed with a hollow fiber membrane bundle randomly selected from one set of trays as in this example, unless otherwise specified.

(Comparative Example 1)
In Example 1, except that one hollow fiber membrane bundle is disposed also in the space in the center of the unit tray, and the five hollow fiber membrane bundles are fixed in parallel at a center distance of 41 mm. In the same manner as in Example 1, a dry hollow fiber membrane bundle of Comparative Example 1 was obtained. The conceptual diagram of arrangement | positioning of 1 set of trays and hollow fiber membrane bundles is shown in FIG. Drying was controlled by paying attention to the moisture content of the hollow fiber membrane bundle located at the center of the unit tray. The moisture content of the hollow fiber membrane bundle on the outer side of one set of trays was 0.4% by mass, and was overdried. Various characteristic values were evaluated for the outermost hollow fiber membrane bundle.

(Comparative Example 2)
In the method of Comparative Example 1, the drying was controlled by paying attention to the moisture content of the outermost single unit tray. Drying was stopped when the water content reached 2.5% by mass. The water content of the hollow fiber membrane bundle at the center was 7% by mass and was insufficiently dried. When the module was assembled in the same manner as in Example 1, the hollow fiber membrane bundle at the center portion was foamed with urethane resin, causing poor adhesion. This is presumably because the hollow fiber membrane bundles were arranged close to each other, so that there was a portion where the microwave did not reach the hollow fiber membrane bundle at the center.

(Comparative Example 3)
In Example 1, the packaging body and the tray material that restrain the wet hollow fiber membrane bundle are polycarbonate resin having a dielectric constant of 2.9, a dielectric loss tangent of 0.009, and a product of dielectric constant and dielectric loss tangent of 0.0261. The hollow fiber membrane bundle of Comparative Example 3 was obtained in the same manner as in Example 1 except that the tray arrangement direction was changed so that the hollow fiber membrane bundle to be dried was perpendicular to the rotary table. . In the case of this comparative example, since the package and the tray are made of polycarbonate resin having low microwave drying permeability, the package and the tray generate a large amount of heat generated by the microwaves, and the hollow fiber membrane bundle outer peripheral portion and inner peripheral portion The temperature difference between the hollow fiber membranes of each of the hollow fiber membranes increases, and this causes a difference in shrinkage rate, and the shrinkage of the hollow fiber membranes on the outer peripheral portion, which is greatly affected by the heat generation, is larger than that on the inner peripheral portion. The difference in film length was 4 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. Here, the hydrogen peroxide concentration and the UV absorbance measurement values are evaluated for the hollow fiber membranes in the outer peripheral portion (in the range of ¼ radius) of the hollow fiber membrane bundle. In the method of this comparative example, deterioration of polyvinyl pyrrolidone, which is a component of the hollow fiber membrane, increases due to an increase in the temperature of the outer peripheral portion of the hollow fiber membrane bundle, and the drying uniformity in the longitudinal direction of the hollow fiber membrane bundle decreases. Therefore, the hydrogen peroxide elution amount of the hollow fiber membrane bundle obtained in this comparative example was high, and the variation in the hydrogen peroxide elution amount depending on the sampling location was large and the quality was low. 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 blood purifier was assembled in the same manner 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 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. Moreover, since the shrinkage spots of the hollow fiber membrane were large as described above, 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. Further, 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 blood purifier, and the average value of UV (220-350 nm) absorbance is dialyzed in about 2 months. The value of 0.10, which is the standard value for manufacturing type artificial kidney device, has been exceeded. The results are shown in Table 4.

(Comparative Example 4)
In Example 1, the arrangement direction of the tray was changed so that the hollow fiber membrane bundle to be dried was perpendicular to the rotary table, and microwave drying was performed at an atmospheric pressure and an output of 2.0 kW for 45 minutes, and then the same A hollow fiber membrane bundle was obtained by the same method as in Example 1 except that irradiation was performed at an output of 0.9 kW for 15 minutes, and far-infrared irradiation was changed to dry for 3 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 of 264 mm or less and hollow fiber membranes of 268 mm or more.

  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. Here, the hydrogen peroxide concentration and the UV absorbance measurement values are evaluated for the hollow fiber membranes in the outer peripheral portion (in the range of ¼ radius) of the hollow fiber membrane bundle. 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. 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 hollow fiber membrane bundle in a dry state obtained in this comparative example had an average value of 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 blood purifier was assembled in the same manner 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 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. 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. Further, 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 blood purifier, 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 5)
In the method of Comparative Example 3, 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 Er / Ei of the microwave to be irradiated was changed to a microwave oscillator having a value of 0.3, and the hollow fiber membrane bundle was dried for 20 minutes at a normal pressure and an output of 2.0 kW at a normal pressure. A hollow fiber membrane bundle was obtained in the same manner as in Comparative Example 1 except that it was changed to two-stage microwave drying with irradiation of 10 minutes at an output of .9 kW and far-infrared irradiation was also performed to dry for 20 minutes under normal pressure. . The moisture content of the hollow fiber membrane bundle at the time of switching to drying was 23% by mass. 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.
In addition, the blood purifier was assembled by the same method as in Example 1, but as with the hollow fiber membrane bundle obtained in Comparative Example 3, the arrangement of the hollow fiber membranes in the hollow fiber membrane bundle was disturbed, and the packaging body 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 1.3. 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.

  A polypropylene film (dielectric constant: 2.2, dielectric loss tangent: 0.0002, dielectric constant and dielectric loss tangent) of 10,080 hollow fiber membranes having a thickness (0.2 mm) whose surface on the hollow fiber bundle side is textured. The product is inserted into a package made of a hollow package (diameter: 36 mm) having a circular cross-sectional shape (product: 0.00044), and then immersed and washed in a 40 vol% isopropanol aqueous solution at 30 ° C. for 30 minutes × 2 times. The dielectric constant is 3.3, the dielectric loss tangent is 0.003, and the product of the dielectric constant and the dielectric loss tangent is 0.0099. 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. Similar to Example 1, the variation in the moisture content between all the hollow fiber membrane bundles in the unit tray was small.

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.
In addition, a blood purifier was obtained by the same method as in Example 1 using the obtained dry hollow fiber membrane bundle. The obtained blood purifier was also of high quality like the blood purifier obtained in Example 1. The results are shown in Table 4.

(Example 3)
In the same manner as in Example 1, polysulfone (Amoco P-3500) 18% by mass, polyvinylpyrrolidone (BASF K-60) 9% by mass, dimethylacetamide (DMAc) 68% by mass, water 5% by mass A film forming solution was obtained. In addition, as said polyvinylpyrrolidone, the hydrogen peroxide content rate 100ppm was used. The obtained film-forming solution was passed through two types of filters 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 1.1. 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 hollow fiber membrane bundle after washing is inserted into a package made of the same polyethylene film as in Example 1, fixed to the same tray as used in Example 1, and then this is a method according to the drying method of Example 1. A dried hollow fiber membrane bundle having a moisture content of 2.0% by mass 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. Similar to Example 1, the variation in the moisture content between all the hollow fiber membrane bundles in the unit tray was small.

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.
In addition, a blood purifier was obtained by the same method as in Example 1 using the obtained dry hollow fiber membrane bundle. The obtained blood purifier was also of high quality like the blood purifier 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) 68% by mass, water 5% by mass A film forming solution was obtained. The polyvinyl pyrrolidone used was a hydrogen peroxide content of 120 ppm. The obtained film-forming solution was passed through two types of filters 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 packaging body and tray material for restraining the hollow fiber membrane bundle after washing were changed to polyethylene terephthalate resin having a dielectric constant of 3.2, a dielectric loss tangent of 0.0021, and a product of dielectric constant and dielectric loss tangent of 0.00672. It dried until the moisture content became 1.5 mass% according to Example 1. The resulting hollow fiber membrane had an inner diameter of 201 μm and a film thickness of 43 μm. Similar to Example 1, the variation in the moisture content between all the hollow fiber membrane bundles in the unit tray was small.

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.
In addition, a blood purifier was obtained by the same method as in Example 1 using the obtained dry hollow fiber membrane bundle. The obtained blood purifier was also of high quality like the blood purifier obtained in Example 1. The results are shown in Table 4.

(Comparative Example 6)
In the method of Example 4, the material of the package that restrains the wet hollow fiber membrane bundle is a polycarbonate resin having a dielectric constant of 2.9, a dielectric loss tangent of 0.009, and a product of dielectric constant and dielectric loss tangent of 0.0261. 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. The hollow fiber membrane bundle is fixed to a fixing jig having a ventilation function so as to be perpendicular to the horizontal, and dehumidified air (humidity 10% or less) at a wind speed of 8 m / sec from the lower part of the hollow fiber membrane bundle. Was blown from the lower part to the upper part of the hollow fiber membrane bundle and irradiated with a microwave of 2.0 kW at normal pressure for 40 minutes 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 of 264 mm or less and hollow fiber membranes of 268 mm or more. 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, the drying method of this comparative example requires that the hollow fiber membrane bundle is a single product and set on a fixing jig in the dryer, so that the workability in the drying process is inferior and the working time is greatly increased.
A blood purifier was obtained in the same manner as in Example 1 using the dry hollow fiber membrane bundle obtained in this comparative example. The obtained blood purifier was also of low quality, similar to the blood purifiers obtained in Comparative Examples 1 and 2. The results are shown in Table 4.

(Comparative Example 7)
In the method of Comparative Example 3, the packaging material and the tray material that restrain the wet hollow fiber membrane bundle are made of vinyl chloride having a dielectric constant of 3, a dielectric loss tangent of 0.01, and a product of dielectric constant and dielectric loss tangent of 0.030. A hollow fiber membrane bundle of Comparative Example 7 was obtained in the same manner as Comparative Example 3 except that the resin was changed. The hollow fiber membrane bundle and blood purifier obtained in this comparative example were of low quality, similar to the hollow fiber membrane bundle and blood purifier obtained in comparative example 3.

(Example 5)
In Example 1, using a tray made of a polysulfone resin having a hollow space in which three hollow fiber membrane bundles can be inserted and fixed each at a center distance of 60 mm both in the top, bottom, left and right of the hollow fiber membrane bundle, A hollow fiber membrane bundle of Example 5 was obtained in the same manner as in Example 1 except that the hollow fiber membrane bundle restrained by a restraint composed of nine polyethylene films was inserted and fixed in the space. . FIG. 7 shows a conceptual diagram of the arrangement of one set of trays and hollow fiber membrane bundles. Similar to Example 1, the variation in the moisture content between all the hollow fiber membrane bundles in the unit tray was small.
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. In addition, a blood purifier was obtained by the same method as in Example 1 using the obtained dry hollow fiber membrane bundle. The obtained blood purifier was also of high quality like the blood purifier obtained in Example 1. The results are shown in Tables 1-4.

(Comparative Example 8)
A hollow fiber membrane bundle of Comparative Example 7 was obtained in the same manner as in Example 5 except that the distance between the centers of the hollow fiber membrane bundles was all reduced to 41 mm by the method of Example 5. FIG. 8 shows a conceptual diagram of the arrangement of one set of trays and hollow fiber membrane bundles. Drying was controlled by paying attention to the moisture content of the hollow fiber membrane bundle located at the center of the unit tray. The moisture content of the hollow fiber membrane bundle on the outer periphery of one set of trays was 0.1% by mass, and was overdried. The results are shown in Tables 1-4. These results displayed the result evaluated about the over-dried hollow fiber membrane bundle of the outer peripheral part.

(Comparative Example 9)
In the method of Comparative Example 8, the drying was controlled by paying attention to the moisture content of one outer peripheral corner of the unit tray. Drying was stopped when the water content of one hollow fiber membrane bundle reached 2.5% by mass. The water content of the hollow fiber membrane bundle at the center was 9% by mass and was insufficiently dried. When the module was assembled in the same manner as in Example 1, the hollow fiber membrane bundle at the center portion was foamed with urethane resin, causing poor adhesion.

  The method for drying a hollow fiber membrane bundle according to the present invention excludes a ventilation method for allowing gas to pass through the hollow fiber membrane bundle, which has been conventionally known, to achieve uniform drying, and a jig for applying this ventilation. The structure of the dryer is not required, and it is not necessary to fix the hollow fiber membrane bundle to be dried to a jig for applying this ventilation. Improves. In addition, hollow fiber membranes such as broken or misaligned hollow fiber membranes in a 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 ventilation, which has been a problem of the prior art 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 housing in the module assembly process for a blood purifier, for example. At the same time, the bonding work 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, in the present invention, since the wet hollow fiber membrane bundle is restrained by the hollow package, the workability of placing the hollow fiber membrane bundle to be dried in the dryer is improved, and the dried hollow fiber membrane bundle is The hollow fiber body is restrained by a hollow packaging body as a unit of number to be loaded into a module to be assembled using the thread membrane bundle, and the dried hollow fiber membrane bundle is loaded as it is into the housing of the module, and then the hollow body is pulled out. The membrane bundle can be loaded into the housing, the workability of the loading can be greatly improved, and there is an advantage that generation of defective yarns during loading is suppressed. In addition, since the plurality of dried hollow fiber membrane bundles restrained by the packaging body are fixed to the tray and placed in the dryer, the workability of placing the dried hollow fiber membrane bundle on the dryer is further improved. And the arrangement | positioning is specified so that the uniformity of drying between the several hollow fiber membrane bundles can be expressed, and it has the advantage that the cost performance of a drying process is high. Furthermore, since the non-uniformity of drying in the ventilation direction, that is, the longitudinal direction of the hollow fiber membrane bundle, which has been a problem of the prior art, is improved, the local degradation of polyvinyl pyrrolidone is reduced and the degradation is generated by the degradation. Hydrogen peroxide 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 fluctuation 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 hemodialysis hollow fiber blood purifiers having high water permeability used for the treatment of chronic renal failure. In addition, 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 conventionally known technology, and therefore suitable for blood purifiers and the like. There is an advantage that it can be used. Furthermore, the blood purifier module obtained in the present invention has the advantage that the loaded hollow fiber membrane bundle has high performance, high safety and stability of performance, excellent storage stability, and few residual blood threads. There is. Therefore, it is important to contribute to the industry.

The schematic diagram which shows the correlation with the drying time and moisture content of a hollow fiber membrane bundle. The schematic diagram which shows the relationship between a dry switching moisture content and the variation degree of quality. It is sectional drawing of a hollow fiber type blood purifier. It is a conceptual diagram of the ratio evaluation method of an inclination hollow fiber membrane. FIG. 3 is a conceptual diagram of an arrangement of a set of trays and hollow fiber membrane bundles in Example 1. The conceptual diagram of arrangement | positioning of 1 set of tray and hollow fiber membrane bundle | flux in the comparative example 1. FIG. The conceptual diagram of arrangement | positioning of 1 set of tray and hollow fiber membrane bundle | flux in Example 5. FIG. The conceptual diagram of arrangement | positioning of 1 set of tray and hollow fiber membrane bundle | flux in the comparative examples 8 and 9. FIG. Schematic showing distance between hollow fiber membrane bundles and moisture content variation

Explanation of symbols

1: Blood purifier 2: Housing 3: Hollow fiber membrane bundle 4: Adhesive resin 5: Cap 6a: Dialysate inlet 6b: Dialysate outlet 7a: Blood inlet 7b: Blood outlet 8: Tray

Claims (12)

A method of arranging a plurality of wet hollow fiber membrane bundles in parallel on a tray and placing them in a microwave irradiation oven so that the longitudinal direction of the hollow fiber membrane bundles is at an angle of 45 degrees or less with respect to the horizontal. , Wherein the distance between adjacent hollow fiber membrane bundles when the diameter of the unit hollow fiber membrane bundle is d is arranged at a position 1.5 to 3.0 d away from the center of the hollow fiber membrane bundle. A method for drying a hollow fiber membrane bundle.   A method of arranging a plurality of wet hollow fiber membrane bundles in parallel on a tray and placing them in a microwave irradiation oven so that the longitudinal direction of the hollow fiber membrane bundles is at an angle of 45 degrees or less with respect to the horizontal. When the diameter of the unit hollow fiber membrane bundle is d, the distance between adjacent hollow fiber membrane bundles is 1.5d or less when the distance between the centers of the hollow fiber membrane bundles is 1.5d. The method for drying a hollow fiber membrane bundle is characterized in that the number of hollow fiber membrane bundles arranged within is within two.   The method for drying a hollow fiber membrane bundle according to claim 1 or 2, wherein the hollow fiber membrane bundle is constrained by a hollow package.   4. The packaging body and tray material for constraining a wet hollow fiber membrane bundle are made of a resin having a product of dielectric constant and dielectric loss tangent at 1 MHz of 0.02 or less. A method for drying a hollow fiber membrane bundle according to claim 1.   The method for drying a hollow fiber membrane bundle according to any one of claims 1 to 4, wherein the tray is placed on a horizontally set table having a rotation function and is dried while being rotated.   6. The method for drying a hollow fiber membrane bundle according to claim 5, wherein the tray on which the hollow fiber membrane bundle is placed is arranged on a rotary table so as to be substantially radial with respect to the rotation center.   The hollow according to any one of claims 1 to 6, wherein a microwave oscillator is installed on a side wall of the microwave dryer, the microwave is oscillated in the horizontal direction, and the microwave is irradiated to the dried hollow fiber membrane bundle. A method for drying the yarn membrane bundle.   Microwave using a microwave oscillator in which the ratio (Er / Ei) between 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 toward the oscillator is 0.2 or less The method for drying a hollow fiber membrane bundle according to claim 7, wherein the hollow fiber membrane bundle is heated by irradiation.   It dries under reduced pressure of 20 kPa or less, The drying method of the hollow fiber membrane bundle in any one of Claims 1-8 characterized by the above-mentioned.   It is characterized in that microwave irradiation is stopped in a state where the moisture content in the hollow fiber membrane of the hollow fiber membrane bundle located at the outermost part of the tray is 10% by mass or more, followed by irradiation with far infrared rays under reduced pressure and drying. A method for drying a hollow fiber membrane bundle.   The method for drying a hollow fiber membrane bundle according to any one of claims 1 to 10, wherein the hollow fiber membrane bundle is made of a polysulfone resin containing polyvinylpyrrolidone. The method for drying a hollow fiber membrane bundle according to any one of claims 1 to 11, wherein the moisture content of all the hollow fiber membrane bundles dried simultaneously is 1 to 5% by mass.