Method for sealing a hollow fiber membrane bundle in a filter housing

Abstract

The present invention relates to a method of sealing the end of a hollow fiber membrane bundle to a filter housing using a sealing material by placing a sealing cap having a protrusion on at least one end region of the filter housing, wherein the curable sealing material is injected into the protrusion of the sealing cap, the curable sealing material flows across the terminal edge of the filter housing, and seals the end of the hollow fiber membrane onto the end face formed by the hollow fiber bundle.

Description

[Technical Field]

[0001] This application relates to a method for sealing the ends of a hollow fiber membrane bundle to a filter housing using a sealing material, an apparatus for carrying out this method, a special sealing cap for carrying out this method, a method for manufacturing a hollow fiber membrane filter, and a hollow fiber membrane filter. [Background technology]

[0002] Hollow fiber membrane filters are used in extracorporeal blood treatment, water treatment, or biological product processing for patients. In the production of hollow fiber membrane filters, bundles of pre-formed hollow fiber membranes, created through spinning and bundling processes, are inserted into the filter housing of the hollow fiber membrane filter. Cylindrical filter housings are commonly used as the filter housing type. The ends of the hollow fiber membranes are sealed to the end region of the filter housing using a curable sealant, usually polyurethane, thereby securing them within the housing. The end faces of the sealant are then partially cut away to expose the open ends of the hollow fiber membranes. Next, a filter cap is placed on the end section of the filter housing. Thus, two flow spaces are formed in the hollow fiber membrane filter. The two liquids can flow through their respective flow chambers and are in a mass transfer relationship with each other through the membrane walls of the hollow fiber membranes. Each liquid flows through its respective flow chamber through one liquid port on the filter cap and two liquid ports on the filter housing or two liquid ports on the filter cap. In extracorporeal hematopoiesis, the inside of the fibers is permeated with a first fluid, such as the patient's blood, and the internal space surrounding the hollow fiber membrane is permeated with a second fluid, such as dialysate.

[0003] One crucial step in the manufacturing process of hollow fiber membrane filters is the sealing of the ends of the hollow fiber membrane bundles into the filter housing. This step is critical to the productivity of hollow fiber membrane filter production. Many individual steps, such as fastening the filter housing into the sealing system, injecting a curable sealant into the end regions of the filter housing, and curing the sealant, must be performed during this production stage. Therefore, it is important that these production stages can be automated to enable efficient production of hollow fiber membrane filters on the large scale required.

[0004] In addition, sealing the hollow fiber membrane bundle within the filter housing also incurs a decisive cost in the production of hollow fiber membrane filters. Typically, a sealant that is fluid at room temperature is used to seal the ends of the hollow fiber membrane. Such sealants consist of several components, in particular, prepolymer components. These components are designed to cure into a resin under chemical reaction within a certain time after mixing. Such curable sealants suitable for the production of hollow fiber membrane filters are relatively expensive. Therefore, efforts continue to improve the industrial manufacturing process of hollow fiber membrane filters so that less sealant is required for the secure sealing of the hollow fiber membrane within the filter.

[0005] Furthermore, under heat treatment such as steam sterilization at 121°C, hollow fiber membrane filters induce material stress because the sealing material, filter housing, and hollow fiber membrane materials have different coefficients of thermal expansion. Such material stress can lead to production defects, which must be detected and resolved by appropriate quality control processes in industrial production processes. Therefore, it is desirable to reduce such material stress by using less sealing material, thereby reducing contact between materials with different coefficients of thermal expansion within the hollow fiber membrane filter.

[0006] In a typical industrial process, a curable sealant is injected into the end region of the filter housing, thereby rotating the filter housing around an axis perpendicular to its longitudinal axis, and the sealant is uniformly distributed across the end region of the filter housing between the hollow fiber membranes by centrifugal force. The amount of curable sealant required to securely seal the hollow fiber membrane bundle in the end region of the hollow fiber membrane filter depends on several factors. Essentially, the sealant forms a meniscus during the rotation and distribution process of the sealant in the end region of the filter housing. This means that the sealant on the side facing the axis of rotation conforms to the concave surface. At the center of the hollow fiber membrane bundle, the sealing height is therefore lower than that in the lateral region of the hollow fiber membrane bundle adjacent to the filter housing. Depending on the filter type, the meniscus may be noticeable to varying degrees. In the case of filters with numerous hollow fiber membranes, it may be necessary to introduce a large amount of curable sealant into the end regions of the filter housing so that, under given processing conditions, all fibers can be reliably sealed with the sealant at the center of the hollow fiber membrane bundle. The shape of the sealant meniscus during rotation may also depend on other processing conditions such as the rotation speed, diameter, and length of the filter housing. However, these processing conditions cannot be arbitrarily optimized without adequately ensuring the desired distribution of the curable sealant between the hollow fiber membranes, i.e., without ensuring the secure sealing of the hollow fiber membranes into the sealant. In particular, when increasing the packing density to increase the filtration surface, secure sealing becomes more difficult due to the resulting decrease in the next available packing volume between the hollow fibers.

[0007] European Patent EP 2 024 067 B1 describes a method for introducing a sealant into a filter device having two flow spaces, the first space being formed by the tubular passages of the fibers of a hollow fiber membrane bundle and the second space being formed by a housing enclosing the hollow fiber membrane bundle, wherein the end regions of the fibers are allocated within the sealant after sealing, and a sealing cap is fitted for the introduction of the sealant. The sealant is distributed from the sealing chamber through the sealing cap to the end of the filter device, rotating the sealing chamber and the filter device. In this process, the sealant is injected through the generated centrifugal force, starting from the sealing chamber and overcoming the gap between the sealing chamber and the sealing cap, so that the sealant is guided into the rotationally symmetric projections of each sealing cap.

[0008] The principle of the process described in EP 2 024 067 B1 is based on a filter device having tabs at the ends of the housing. In this process, the injected curable sealant flows between the tabs into the end regions of the hollow fiber membrane and spreads between the hollow fiber membranes, sealing them with the sealant. While the process described in EP 2 024 067 B1 is significantly suitable for the production of hollow fiber membrane filters on a large industrial scale, this process is not suitable for reducing the amount of curable sealant required. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] European Patent EP 2 024 067 B1 Specification [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, based on the shortcomings of the prior art, there was a need to optimize the sealing process of the hollow fiber membrane into the filter housing so that the production cost and mechanical and thermal resistance of the hollow fiber membrane filter would be improved. [Means for solving the problem]

[0011] In a first aspect of the present invention, the problem is solved by a method for sealing the ends of the hollow fiber membrane bundle described in claim 1 to a filter housing.

[0012] In a second aspect of the present invention, the problem is solved by the apparatus for sealing a hollow fiber membrane bundle in a filter housing as described in claim 10.

[0013] In a third aspect of the present invention, the problem is solved by the sealing cap described in claim 12.

[0014] In a fourth aspect of the present invention, the problem is solved by a method for manufacturing a hollow fiber membrane filter as described in claim 13.

[0015] In a fifth aspect of the present invention, the problem is solved by the hollow fiber membrane filter described in claim 14.

[0016] Description of the present invention In the first aspect, the present invention is The step of inserting a hollow fiber membrane bundle into a tubular or cylindrical filter housing having a longitudinal extension axis, wherein the filter housing has an inner and outer side, and the filter housing has end regions at two open ends, each having an edge that terminates at the open end of the filter housing, and the hollow fiber membrane is inserted into the filter housing such that it forms an end face at the location where the hollow fiber membrane bundle terminates at the edge of the filter housing. The step of placing a sealing cap on at least one end region of the filter housing, wherein the sealing cap includes at least a first receiving portion for receiving the end face of the hollow fiber membrane bundle and at least one end region of the filter housing, and includes a projection extending over the at least one end region on the outside of the filter housing, The steps include injecting the curable sealant into the protrusion of the sealing cap such that the curable sealant flows between the outside of at least one end region of the filter housing and the sealing cap, Flowing the curable sealing material across the terminal edge of the first filter housing so that the curable sealing material flows onto the end face of the hollow fiber membrane bundle formed by the hollow fiber bundle; Sealing the end of the hollow fiber membrane of the hollow fiber membrane bundle to the filter housing; Curing the sealing material; A method for sealing the end of a hollow fiber membrane bundle to a filter housing using a sealing material, comprising: The filter housing having the hollow fiber membrane bundle is rotated about a rotational axis perpendicular to the longitudinal extension axis of the filter housing such that the overflow of the sealing material at the terminal edge of the filter housing and the inflow of the sealing material onto the end face of the hollow fiber membrane bundle are achieved by the centrifugal force resulting from the rotation of the filter housing.

[0017] This method has the advantage that the sealing process can be automated. In particular, this automation is enabled by the protrusion of the sealing cap that allows injecting the curable sealing material into the sealing cap without requiring strict assembly tolerances that are particularly difficult to execute during the rotation of the filter housing. Furthermore, the penetration of the curable sealing material between the fibers occurs from the direction of the end face of the hollow fiber membrane bundle. Thus, the penetration of the curable sealing material between the hollow fiber membranes occurs against the direction of the centrifugal force acting due to the rotation of the filter housing in which the hollow fiber membrane bundle is placed. The curable sealing material on the end face of the hollow fiber membrane is thereby pressed by the continuously flowing curable sealing material and distributed between the hollow fiber membranes. The penetration of the curable sealing material from the end face of the hollow fiber membrane against the dominant centrifugal force shortens the meniscus depth of the curable sealing material in the end region of the filter housing. The "meniscus depth" is the difference between the height of the seal adjacent to the filter housing and the seal height at the center of the hollow fiber membrane bundle. By this process, the sealing material is more evenly distributed within the end region of the filter housing, which means that the sealing height and thus the amount of the required sealing material can be reduced without impairing the secure sealing of the hollow fiber membrane into the sealing material.

[0018] For the purposes of the present application, the term "hollow fiber membrane bundle" means a plurality of hollow fiber membranes adjacent to each other substantially parallel to each other. The ends of the individual hollow fiber membranes are adjacent to each other within the hollow fiber membrane bundle.

[0019] According to the present application, the filter housing has an elongated extension and is particularly shaped in a tubular or cylindrical shape.

[0020] For the purposes of the present application, the term "elongated dimension" means that an object has a dimension that is larger in one direction than in the direction perpendicular thereto.

[0021] In the context of the present application, the term "end region of the filter housing" means an end region that extends longitudinally from the end to the center on the filter housing. The term "end region" indicates that it is a region that occupies only a small portion compared to its longitudinal extent on the filter housing. In particular, each of these end regions is shorter than one fifth, or shorter than one eighth, or shorter than one tenth, or shorter than one fifteenth of the total length of the filter housing.

[0022] The "terminal edge" is understood to be the circumferential edge at the end of the filter housing.

[0023] In the context of the present application, the "end face" of the hollow fiber membrane bundle is understood to be the end face of the hollow fiber membrane bundle where the ends of the hollow fiber membranes are substantially adjacent to each other such end face can be generated, for example, by cutting the hollow fiber membrane bundle perpendicular to the longitudinal extension.

[0024] In the context of the present application, the "sealing cap" is understood to be a cap that can be placed on the end region of the filter housing and thereby cover the end face of the hollow fiber membrane bundle. In this case, the sealing cap is designed such that the end region of the filter housing or a part thereof and the end face of the hollow fiber membrane bundle are received in the receiving portion of the sealing cap.

[0025] During the sealing stage, the curable sealant flows evenly between the hollow fiber membranes, starting from the end faces, so that the hollow fiber membranes are sealed by the sealant at each of their ends. The curable sealant is a self-rigid prepolymer mixture that reacts over a period of time, known as a sealing time, to form a cured polymer. The sealing time of the curable sealant is adjusted so that the sealant is fluid and can be handled in a liquid state during the sealing of the hollow fiber membranes. During sealing, the ends of the hollow fiber membranes are sealed within the sealant so that they are fixed to the end section of the filter housing. The sealant seals the end region of the filter housing. The sealant is substantially plate-shaped and positioned perpendicular to the longitudinal axis of the cylindrical housing within the end region of the filter housing.

[0026] In contrast to the processes described in the prior art, the sealant is not supplied on the inside of the filter housing and between the ends of the hollow fiber membrane bundle through a lateral opening in the end region of the filter housing. Preferably, the sealant is guided only from the end face of the hollow fiber membrane bundle between the ends of the hollow fiber membranes to achieve uniform distribution of the sealant between the hollow fiber membranes with only slight meniscus formation of the sealant.

[0027] In another embodiment of the first aspect, the projection of the sealing cap is a partially circumferential projection that extends partially circumferentially from outside the end region of the filter housing. The projection of the sealing material ensures that the curable sealant can be fully introduced into the sealing zone in the end region of the filter housing. By using this projection, it is no longer necessary to introduce the curable sealant into the sealing zone through the liquid connection. When the projection on the sealing cap is partially circumferential, no special alignment of the filter housing is required. Therefore, the sealing cap can be placed on the end region of the filter housing in an automated process.

[0028] In another embodiment of the first aspect, a sealing cap is securely fitted over the end region of the filter housing, and the curable sealant flows over the end face of the end of the hollow fiber membrane bundle through a through-opening between the sealing cap and the outside of the end region of the filter housing. Thus, the sealing cap can be securely fitted over the end section of the filter housing, while at the same time allowing for a continuous flow of the sealant onto the end face of the hollow fiber membrane bundle so that the curable sealant penetrates from the end face into the hollow fiber membranes against the direction of centrifugal force. A slot-shaped recess is provided on the inside of the cap to provide a through-opening when the cap is fitted.

[0029] In yet another embodiment of the first aspect, the sealing cap includes a second receiving portion that receives the end face of a second hollow fiber membrane bundle inserted into a second filter housing and the end region of the second filter housing, wherein a transfer channel is provided between the first and second receiving portions of the sealing cap through which a curable sealant flows from the first receiving portion into the second receiving portion over the end face of the second hollow fiber membrane bundle, and the ends of the hollow fiber membranes of the second hollow fiber membrane bundle are sealed within the second filter housing.

[0030] This embodiment of the process makes it possible to simultaneously assign two hollow fiber membrane bundles into two filter housings. Furthermore, the sealing cap can be configured to have first, second, and third receiving regions or first, second, third, and fourth receiving regions for the end regions of the filter housings, so that three or four hollow fiber membrane bundles can be simultaneously sealed into their respective filter housings using a curable sealant according to the method of the present invention. Thus, several filter housings can be assigned simultaneously into a single apparatus, thereby reducing the effort required to design the apparatus for sealing hollow fiber membrane bundles into filter housings.

[0031] In yet another embodiment of the first aspect, the sealant is injected simultaneously into the projections of two sealing caps, each placed on two filter housings, preferably positioned at an intersection, with the sealant stacked vertically on top of the other. Where possible, sealing caps having, for example, one, two, three, four, or five or more receiving sections can be used with transfer channels placed between each receiving section so that the curable sealant is transferred from the first receiving section to the second, third, and fourth, or further receiving sections. For example, two filter housings can be paired using two sealing caps, each having two receiving sections that intersect with each other. Similarly, three or four filter housings connected to a sealing cap having three or four receiving sections can be arranged in an intersecting, vertically stacked configuration with another three or four filter housings connected to a sealing cap having three or four receiving sections. Each of these arrangements serves to minimize the effort required for the design of the sealing apparatus.

[0032] In another embodiment according to the first aspect, the curable sealant is supplied within a sealing chamber, which rotates in synchronization with the rotation of one or more filter housings. The curable sealant is fed through a sealing channel radially with respect to the rotation axis of the filter housing in each case, toward the projection of the sealing cap. In this case, the sealing chamber is positioned at the center between two sealing caps, each mounted on the opposing end regions of one or more filter housings. In this embodiment, the curable sealant is discharged through the sealing channel by centrifugal force generated during rotation. The sealing channel is positioned so that the sealant is guided radially toward the sealing cap with respect to the rotation axis. In this case, the discharge of the curable sealant from the sealing chamber can be achieved solely by centrifugal force. The rotation of the filter housing and the rotation of the sealing chamber can be synchronized electronically or mechanically.

[0033] In another embodiment according to the first aspect, the curable sealant bypasses the void due to centrifugal force during injection into the projection of the sealing cap and is captured by the projection of the sealant. In particular, in yet another embodiment, the sealant is discharged from the sealing chamber through centrifugal force, flows radially through the sealing channel relative to the axis of rotation, and is injected through an opening at the end of the sealing channel. Therefore, it is not necessary to connect the sealing chamber and the sealing cap by a specially provided fluid connection channel.

[0034] In another embodiment according to the first aspect, the filter housing and sealing chamber are arranged on a mounting table, which rotates around a rotation axis (R). In this embodiment, the filter housing can be fixed on the mounting table by a holding device, and the sealing chamber is also mounted on the mounting table by a fixing means. In this case, the rotation of the sealing chamber and the rotation of the filter housing are mechanically coupled. Therefore, it is no longer necessary to synchronize the rotation of the sealing chamber and the rotation of the filter housing. In an alternative embodiment, the sealing chamber and the mounting table can be mounted separately, and the rotation of the sealing chamber and the rotation of the filter housing can be electronically synchronized. This is particularly applicable when several, for example, two, four, six, eight, or ten filter housings are arranged on the assembly table.

[0035] A further embodiment of the first aspect is characterized in that at least one further filter housing (200), for example, a second filter housing (200), a third filter housing (300), and a fourth filter housing (400), each containing a bundle of hollow fiber membranes, are placed on the mounting table. The arrangement of several filter housings on the assembly table enables economical production, in particular when several filter housings are connected to one another by sealing caps having several receiving areas.

[0036] In this embodiment, it is advantageous that the end faces of the ends of the first hollow fiber membrane bundle and at least one further hollow fiber membrane bundle, for example, the second, third, and fourth hollow fiber membrane bundles, and the end regions of the first filter housing and at least one further filter housing, for example, the second filter housing, the third filter housing, and the fourth filter housing, are respectively received in the first and second receiving portions of the sealing cap, and the ends of the first hollow fiber membrane bundle and at least one further hollow fiber membrane bundle, for example, the ends of the second hollow fiber membrane bundle, the ends of the third hollow fiber membrane bundle, and the ends of the fourth hollow fiber membrane bundle are simultaneously sealed in the first filter housing and at least one further filter housing, for example, the second filter housing, the third filter housing, and the fourth filter housing.

[0037] In a second aspect, the present invention relates to an apparatus for sealing a hollow fiber membrane bundle in a filter housing by carrying out a method according to an embodiment of the first aspect, the apparatus comprising an assembly having a mounting table having at least one retaining device for the at least one filter housing, in which a hollow fiber membrane bundle is placed and which has an elongated extension, particularly a tubular elongated extension, along a longitudinal extension axis, and on which a sealing cap is fitted on each end region thereof; and a sealing chamber in which the mounting table is mounted so as to be rotatable about a rotation axis perpendicular to the longitudinal extension axis of the filter housing.

[0038] In particular, in one embodiment, the apparatus is characterized in that the sealing chamber is fixedly mounted on a mounting table and therefore performs the same rotation as the filter housing mounted within the mounting table and holding device. In this embodiment, the curable sealant can be discharged radially with respect to the axis of rotation (R) through the sealing channel toward the sealing cap and injected through the void from the terminal opening on the sealing channel into the projection of the sealing cap. Advantageously, the sealing chamber and filter housing are positioned on the mounting table such that the rotation of the assembly table around the axis of rotation passes through the center of gravity of the sealing chamber and one or more filter housings.

[0039] In an alternative embodiment according to the second aspect, the mounting table of the device for sealing includes a retaining device for an even number of filter housings, in particular two, four, six, eight, or ten filter housings. It is particularly advantageous that the mounting table has a retaining device for each sealing cap having two receiving areas, and optionally three or four receiving areas, in pairs, and optionally three or four arrangements.

[0040] In a third aspect, the present invention relates to a sealing cap for sealing at least two hollow fiber membrane bundles using a curable sealant, each placed in a first filter housing and a second filter housing, the sealing cap comprising a first receiving portion for receiving an end region of the first filter housing and a first hollow fiber membrane bundle placed in the first filter housing, and at least one second receiving portion for receiving an end region of the second filter housing and a second hollow fiber membrane bundle placed in the second filter housing, the first and second receiving portions being connected to a transfer passage that allows the curable sealant to flow from the first receiving portion into the second receiving portion, and the sealing cap having at least partially circumferential projections that allow the curable sealant injected through a void to be captured and flowed into the first receiving portion.

[0041] Using a sealing cap, two filter housings can be sealed simultaneously according to the method of the present invention. In an alternative embodiment, such a sealing cap may include third and fourth receiving portions and further include transfer channels between the second and third receiving portions and between the third and fourth receiving portions. The sealing cap is designed to be securely fitted simultaneously to the end regions of the first filter housing and the end regions of the second filter housing. The sealing material flows through through openings placed in active seating portions between the sealing cap and the end sections of the filter housings within the sealing cap to the end faces of the hollow fiber membrane bundle.

[0042] In a fourth aspect, the present invention relates to a method for manufacturing a hollow fiber membrane filter, comprising the steps of a method according to an embodiment of the first aspect, further comprising the steps of: exposing the lumen of the hollow fiber membrane by cutting away a layer of sealant at the sealed end of the hollow fiber membrane; and sealingly attaching filter caps to each end region of the filter housing so as to form two flow spaces: a first flow space including the internal volume of the hollow fiber membrane and a second flow space including the volume between the hollow fiber and the filter housing.

[0043] This method allows for the production of a hollow fiber membrane filter with a low sealing height, as it creates a relatively inconspicuous meniscus depth when the hollow fiber membrane is sealed within the filter housing according to the method of the first embodiment.

[0044] In a fifth aspect, the present invention relates to a hollow fiber membrane filter including a filter housing, the filter housing having two end regions, each having two terminal edges, a hollow fiber membrane bundle placed in the filter housing and having its ends sealed within a sealant by the filter housing within the end regions of the filter housing, and filter caps sealed to the two end regions of the filter housing, the hollow fiber membrane filter having two flow spaces, a first flow space including the internal volume of the hollow fiber membrane and a second flow space including the volume between the hollow fiber membrane and the filter housing, wherein the sealing height of the sealant is 3 mm to 7 mm, particularly 4 mm to 6 mm or 4.5 mm to 5.5 mm. The sealing height is lower at the center of the hollow fiber membrane bundle than at the edges of the hollow fiber membrane bundle adjacent to the filter housing. The sealing height is the thickness of the thinnest sealant within the sealing zone.

[0045] In yet another embodiment of the fifth aspect, the meniscus depth of the cured sealing cap is less than 3 mm, 2 mm, or 1 mm. In this context, the meniscus depth refers to the difference in sealing thickness between the point of thinnest thickness within the sealing zone and the thickness of the sealing material at the edge of the hollow fiber bundle.

[0046] In one embodiment, the inner diameter of the filter housing of the hollow fiber membrane filter according to the present invention is 25 mm to 45 mm, preferably 30 mm to 40 mm. In particular, the hollow fiber membrane filter is 1.2 m 2 2.5m 2 6,000 to 15,000, preferably 9,000 to 15,000 hollow fiber membranes can be placed in the filter housing of the hollow fiber membrane filter so that it can have a membrane surface area of ​​up to 15,000. The filter housing of the hollow fiber membrane filter is preferably tubular, especially cylindrical. The "membrane surface area" is calculated from the product of the inner area of ​​the hollow fiber membrane and the number of hollow fiber membranes placed in the cylindrical housing of the hollow fiber membrane filter. The inner area of ​​the hollow fiber membrane is calculated from the product of the inner diameter of the hollow fiber membrane, pi (π), and effective length.

[0047] In an alternative embodiment, the membrane surface area of the hollow fiber membrane filter of the present invention is from 1.3 m 2 to 1.9 m 2 ; from 1.3 m 2 to 1.8 m 2 ; or from 1.4 m 2 to 1.7 m 2 .

[0048] In certain embodiments, the hollow fiber membrane filter of the present invention has an aspect ratio of 8.0 to 10.0 with a membrane surface area of from 1.6 m 2 to 2.0 m 2 . In an alternative embodiment, the hollow fiber membrane filter has an aspect ratio of 8.5 to 9.5 with a membrane surface area of from 1.3 m 2 to 1.6 m 2 . In the context of the present application, the "aspect ratio" is understood as the ratio of the effective length of the hollow fiber membrane to the inner diameter of the cylindrical housing of the hollow fiber membrane filter.

[0049] In the context of the present application, the "effective length" of the hollow fiber membrane filter is understood as the distance between the sealing materials at the point of the minimum sealing thickness at which mass transfer can substantially occur by the hollow fiber membrane. In certain embodiments, the hollow fiber membrane filter according to the present invention has an aspect ratio of 8 to 12, 8.5 to 11, 8.5 to 10, or 9 to 10.

[0050] The effective length of the hollow fiber membrane in these embodiments is correspondingly from 270 mm to 320 mm. In an advantageous embodiment of the present invention, the hollow fiber membrane filter is characterized in that the effective length of the hollow fiber membrane is from 280 mm to 320 mm, particularly from 285 mm to 310 mm or from 290 mm to 310 mm. In particular, the selection of the aspect ratio, membrane surface area, and effective length within the ranges described so far enables effective removal of middle molecules in extracorporeal blood purification therapies such as hemodialysis or hemofiltration. In this context, serum proteins having a molecular weight of from 10,000 daltons to 50,000 daltons are referred to as middle molecules. On the one hand, while enabling effective removal of middle molecules, the above-described selection also prevents an excessive pressure drop over the length of the hollow fiber membrane lumen on the lumen side that would cause excessive erythrocyte lysis or membrane blockage.

[0051] The effective length of the hollow fiber membrane is increased by reducing the sealing height of the cured sealant. Therefore, with a filter housing of the same length, high performance parameters of the hollow fiber membrane filter can be achieved by the low sealing height according to the first, fourth, or fifth aspect of the present invention.

[0052] The inner diameter of the cylindrical housing can be reduced to 25-35 mm, 25-33 mm, or 28-33 mm within the aspect ratio defined by the present invention, so that an improved inflow flow of the hollow fiber membrane in the second flow chamber can be generated.

[0053] Preferably, a hollow fiber membrane made of polysulfone and polyvinylpyrrolidone is used to produce the hollow fiber membrane filter according to the present invention.

[0054] The sealing material used to seal the hollow fiber diaphragm and seal each end region of the cylindrical housing is preferably polyurethane.

[0055] The filter housing and filter cap are preferably made of polypropylene material. The polypropylene housing is advantageously suitable for receiving long fiber bundles in a production-safe manner.

[0056] In an advantageous embodiment of the present invention, the hollow fiber membrane filter is characterized by a packing density of the hollow fiber membrane being greater than 50%, preferably greater than 57%, preferably greater than 60%, and more preferably greater than 62%. In certain embodiments, the packing density does not exceed 70%. In the context of this application, “packing density” is understood as the proportion occupied by the hollow fiber membrane within the cylindrical housing. The packing density is calculated from the percentage ratio of the sum of the cross-sectional areas of the hollow fiber membrane, measured by the outer diameter of the fibers, to the cross-sectional area of ​​the cylindrical housing of the hollow fiber membrane filter, in which case the cross-sectional area of ​​the cylindrical housing is understood as simply the cross-sectional area provided by the inner diameter measured at the narrowest point of the housing. Sealing during the manufacture of the hollow fiber membrane filter is particularly difficult when the packing density is particularly high. In contrast, the separation characteristics, measured as spacing with respect to low molecular weight substances, are particularly high when the packing density is high, and optionally the aspect ratio is also high. The teachings of the present invention have been shown to be particularly advantageous with respect to such hollow fiber membrane filters. The manufacturing process becomes simpler, costs are reduced, and material consumption, especially that of sealants, decreases.

[0057] The present invention will be explained in more detail below with reference to the figures. [Brief explanation of the drawing]

[0058] [Figure 1] This is a schematic diagram of a filter housing with a seated sealing cap and a flow path for a curable sealant. [Figure 2] This is a schematic diagram of a sealing cap and a flow path for a curable sealant, which has two receiving sections where two filter housings are positioned. [Figure 3] This is a schematic diagram of a cylindrical filter housing with sealing material positioned at each end region. [Figure 4] This is a schematic diagram of a part of a filter housing where the sealing material is located in the edge region. [Figure 5] This is a diagram of the mounting table for the apparatus according to the present invention, in which four filter housings are held. [Modes for carrying out the invention]

[0059] Figure 1 illustrates an internal view of a portion of a cylindrical filter housing 100 having an end region 105 and a terminal edge 107 surrounding an open end 103. Furthermore, Figure 1 shows a cross-sectional view of a sealing cap 109 that is securely mounted on the end region 105 and covers the end face 108 of the hollow fiber membrane bundle, which is not shown in Figure 1. The receiving portion 110 of the sealing cap exposes the end face 108 of the hollow fiber membrane bundle and a portion of the end region 105 of the filter housing. The sealing cap 109 includes a projection 111 that extends over the end region 105 and a portion of the filter housing 100. Furthermore, a schematic diagram with arrows shows the inflow path 112 of the curable sealant. Figure 1 illustrates a filter housing 100 having a lateral opening 101. These openings are provided to allow the hollow fiber membrane filter to flow into or out of its second flow chamber during functional use. Advantageously, these openings 101 are located on the side of the filter housing 100 facing the viewer in this figure. These openings are not relevant in the context of the method according to the first aspect of the present invention. Furthermore, Figure 1 illustrates a sealing channel 511 that allows the curable sealant to be discharged through an opening 512. Between the opening 512 and the projection 111 is a void that is bypassed by the curable sealant during the sealing process. The discharged curable sealant is captured by the projection 111 of the sealing cap 109. As a result, as shown in Figure 1, the curable sealant flows between the outer region of the end region 105 of the filter housing 100 and the wall of the sealing cap, overflowing at the end edge 107, and consequently flowing onto the end face 108. As shown in Figure 1, the sealant flows from this face into the end of the hollow fiber membrane bundle and is distributed between the hollow fiber membranes, which are not shown in Figure 1. The discharge of the curable sealant through the sealing channel 511 and opening 512, as well as the flow of the curable sealant through the sealing cap, is caused by rotation performed around the rotation axis R.

[0060] Figure 2 illustrates a schematic cross-sectional view of yet another embodiment for sealing a hollow fiber membrane bundle into a filter housing. The sealing cap 209 shown in Figure 2 has two receiving portions 210a and 210b and is securely fitted to the end regions 105 and 205 of two filter housings 100 and 200. In a symmetrical arrangement, the sealing cap 209 has two projections 211a and 211b. However, in the illustrated embodiment, only projection 211a is used to introduce the curable sealant into the sealing cap, as indicated by the arrows in Figure 2 that show the flow path of the curable sealing cap. The sealing cap 209 is securely fitted onto the end regions 105 and 205 of the filter housings 100 and 200 and covers the respective end faces of the hollow fiber membrane bundle shown in Figure 2, which are not shown or visible in this cross-sectional view. Using reference numerals 214a and 214b shown in Figure 2, one of several through-openings is illustrated that allows the curable sealant to flow between the sealing cap and the outside of the end region of the filter housing to reach the end face of the hollow fiber membrane. As indicated by the arrows in the illustration, the released curable sealant is captured by the projection 211a and flows between the wall of the sealing cap and the outer section of the end region 105 of the filter housing 100 across the terminal edge 107, reaching the surface of the hollow fiber membrane bundle of the first filter housing 100, where it is distributed between the hollow fiber membranes. In this process, the curable sealant reaches the surface of the hollow fiber membrane bundle through opening 214a. In this case, the sealant flows through the first receiving portion 210a, flows through the transfer channel 213 into the second receiving portion 210b, and reaches the surface of the hollow fiber membrane bundle of the second filter housing 200 through opening 214b. In the embodiment shown in Figure 2, two hollow fiber membrane bundles can be simultaneously sealed within a first filter housing and a second filter housing, respectively. Similar to the embodiment in Figure 1, the release of the curable sealant through the sealing channels and openings, and the flow of the curable sealant through the sealing cap, are caused by rotational movement performed around the rotation axis R.

[0061] Figure 3 is a side view of an embodiment of the filter housing 100 as used in a process according to the present invention and rotated around a rotation axis R. The filter housing has a cylindrical shape along a longitudinal extension axis L. In the illustrated embodiment, the filter housing 100 includes openings 101a and 101b in their respective end regions 105 and 106. These openings are used in a hollow fiber membrane filter constructed to allow a liquid, for example, dialysate if the hollow fiber membrane filter is a dialyzer for extracorporeal blood treatment, into a second flow space of the hollow fiber membrane filter that includes space between the hollow fiber membranes inside the filter housing. Furthermore, Figure 3 schematically shows sealants 113a and 113b located inside the end regions 105 and 106 at their respective ends 103 and 104 of the filter housing. The sealants are plate-shaped and seal the hollow fiber membrane bundle (not shown in Figure 3) and engage airtightly with the respective end regions 105 and 106 of the filter housing 100. The surface of the sealant curves concavely in the direction of the rotation axis R to form a typical meniscus. Furthermore, Figure 3 illustrates the terminal edges 107a and 107b of the filter housing in the respective end regions 105 and 106. As described above, in the method according to the present invention, the sealant flows to the end faces 108a and 108b shown in Figure 3, and further overflow occurs at the terminal edges outside the end regions so that it flows between the hollow fiber membranes inside the end sections 105 and 106. Care is taken in the process of the present invention to ensure that the openings 101a and 101b are not covered by the curable sealant. Based on the method according to the present invention, the sealing height and meniscus depth of the sealant in the end regions 105 and 106 can be kept sufficiently low so that the illustrated openings 101a and 101b are not covered.

[0062] The sealing height and meniscus depth produced by the method according to the present invention are illustrated in more detail in Figure 4. Figure 4 illustrates an enlarged view of the upper portion of the filter housing 100 in Figure 3. Figure 4 illustrates that the sealing height of the sealing material 113a laterally adjacent to the end region 105 of the filter housing 100 is 6.0 mm. At the center of the sealing material, the sealing height is 5.0 mm. Therefore, the meniscus depth is 1 mm. This meniscus depth is calculated by subtracting the lowest sealing height from the highest sealing height.

[0063] Figure 5 illustrates an embodiment of a mounting table 501 of the apparatus according to the present invention for receiving four filter housings 100, 200, 300, and 400 for sealing hollow fiber membrane bundles in each filter housing. In the illustrated embodiment, these filter housings are mounted in pairs to the end regions of the filter housings through closure caps 209, each having two receiving portions. The closure caps are designed in detail as shown in Figure 2. Reference numbers are shown for two of the four caps shown in Figure 5. The pairs of filter housings are fastened in a cross-shaped manner within the mounting table by retaining devices 502A, 502B, 502C, and 502D. The mounting table is mounted rotatably so that it can perform rotation around a rotation axis R. Bearings for rotational movement are not shown in Figure 5. The rotation axis R shown in Figure 5 is perpendicular to the longitudinal axis L of the filter housing, which is shown in Figure 5 only with respect to filter housing 200. In the arrangement shown in Figure 5, the axis of rotation is also perpendicular to the longitudinal extension axes of the other filter housings 100, 300, and 400, which have axes not shown in Figure 5. The mounting table 501 and the filter housing arrangement are positioned so that the rotation occurs around the center of gravity of each filter housing. In Figure 5, reference numeral 510 is assigned to the sealing chamber. During sealing, the sealing chamber confines a curable sealant for sealing the hollow fiber membrane bundle to the filter housing. The hollow fiber membrane bundle is not shown in Figure 5. Sealing channels 511A, 511B, 511C, and 511D extend from the sealing chamber 501, and the orientation of these sealing channels is such that the sealant is discharged radially relative to the axis of rotation by the rotation of the sealing chamber around the axis of rotation R. Openings 512A, 512B, 512C, and 512D are located at the ends of the sealing channels 511A, 511B, 511C, and 511D. The sealing material flows out through these openings under rotation and is injected into the protrusions 211a of the sealing cap 209. As shown in Figure 5, the sealing material thereby bypasses the gaps during the rotation of the mounting table 501 and is captured by each protrusion of the sealing cap 209. The sealing chamber 510 is connected to the mounting table by one or more fasteners 513.The position of the sealing chamber on the assembly table is selected such that the axis of rotation passes through the center of gravity of the sealing chamber. As shown in the figure, the sealing chamber is positioned above a pair of filter housings arranged in a cross pattern. The mounting table, filter housings, and sealing chamber therefore perform the same rotational movement during rotation.

Claims

1. The step of inserting a hollow fiber membrane bundle into a filter housing (100) which is a tubular or cylindrical filter housing having a longitudinal extension axis (L) and is open at two ends (103, 104), wherein the filter housing has an inner and outer side, and the filter housing has end regions (105, 106) at the two open ends (103, 104) of the filter housing, each having terminal edges (107, 107a, 107b), and the hollow fiber membrane is inserted into the filter housing such that the hollow fiber membrane bundle (101) terminates at the edge (101) of the filter housing (100), forming an end face (108), and The step of placing a sealing cap (109, 209) on at least one end region (105) of the filter housing (100), wherein the sealing cap (109, 209) includes at least a first receiving portion (110, 210a) for receiving the end face (108) of the hollow fiber membrane bundle and the at least one end region (105) of the filter housing (100), and includes a projection (111, 211a) that extends outwards from the filter housing (100) over the at least one end region (105), The steps include: injecting a curable sealant into the protrusions (111, 211) of the sealing caps (109, 209) such that the curable sealant flows between the outside of at least one end region (105) of the filter housing (100) and the sealing caps (109, 209); The steps include: flowing the curable sealant over the terminal edges (107, 107a, 107b) of the first filter housing (100) so that the curable sealant flows over the end faces (108) of the hollow fiber membrane bundle formed by the hollow fiber bundle (101); The steps include sealing the ends of the hollow fiber membranes of the hollow fiber membrane bundle to the filter housing (100), The stage of curing the sealant, A method for sealing the ends of a hollow fiber membrane bundle to a filter housing (100) using a sealing material, including, The filter housing (100) having the hollow fiber membrane bundle is rotated around a rotation axis (R) perpendicular to the longitudinal extension axis (L) of the filter housing, such that overflow of the sealing material from the terminal edges (107, 107a) of the filter housing (100) and inflow of the sealing material onto the end face (108) of the hollow fiber membrane bundle are achieved by centrifugal force resulting from the rotation of the filter housing (100). A method characterized by the following:

2. The method according to claim 1, characterized in that the protrusions (111, 211a) of the sealing caps (109, 209) are partially circumferential protrusions that partially extend circumferentially over the outside of at least one end region (105) of the filter housing (100).

3. The method according to one of claims 1 to 2, characterized in that the sealing caps (109, 209) are securely attached to the end region (105) of the filter housing (100), and the curable sealing material flows onto the end face (108) of the hollow fiber membrane bundle through a through opening between the sealing caps and the outside of the end region (105) of the filter housing.

4. The method according to any one of claims 1 to 3, wherein the sealing cap (209) includes a second receiving portion (210b) that receives the end face of a second hollow fiber membrane bundle inserted into a second filter housing (200) and an end region (205) of the second filter housing, and a transfer channel (213) is positioned between the first and second receiving portions (210b) of the sealing cap (209), through which the curable sealant flows from the first receiving portion (210a) into the second receiving portion (210b) and onto the end face of the second hollow fiber membrane bundle, and the end of the hollow fiber membrane of the second hollow fiber membrane bundle is sealed to the second filter housing.

5. The method according to any one of claims 1 to 4, characterized in that the curable sealant is supplied to a sealing chamber (510), the sealing chamber is rotated in synchronization with the rotation of the filter housing (100), and is guided radially with respect to the rotation axis (R) of the filter housing in the direction of the projection (111) of the sealing cap (109) through at least one sealing channel (511A, 511B, 511C, 511D).

6. The method according to 5, characterized in that the curable sealant starts from the opening of the at least one sealing channel (512A, 512B, 512C, 512D), bypasses the void during injection into the protrusion (111) of the sealing cap (109), and is captured by the protrusion (111) of the sealant.

7. The method according to claim 5 or 6, characterized in that the at least one filter housing (100) and the sealing chamber (510) are arranged on a mounting table (301), and the mounting table (501) is rotated around a rotation axis (R).

8. The method according to 7, characterized in that at least one further filter housing (200), for example, second (200), third (300), and fourth (400) filter housings, each containing a hollow fiber membrane bundle, are arranged on the mounting table.

9. The method according to claim 8, wherein the end faces of the ends of the first and at least one further hollow fiber membrane bundles, for example, the end faces of the ends of the second, third, and fourth hollow fiber membrane bundles, and the end regions (105, 204) of the first and at least one further filter housings (100, 200), for example, the end regions of the second (200), third (300), and fourth filter housings (400), are respectively received by the first (110) and second (210) receiving portions of the sealing cap according to claim 4, and the ends of the first and at least one further, for example, the second, third, and fourth hollow fiber membrane bundles, into the respective first (100) and at least one further, for example, the second (200), third (300), and fourth (400) filter housings, are simultaneously sealed.

10. An apparatus for sealing a hollow fiber membrane bundle in a filter housing (100) by carrying out the method described in any one of claims 1 to 9, A hollow fiber membrane bundle is arranged therein in a filter housing (100) having an elongated extension, particularly a tubular elongated extension, along a longitudinal extension axis (L), wherein the sealing cap (109) includes an assembly having a mounting table (501) having a retaining device (502) for the at least one filter housing (100) placed on each of the end regions (105) of the filter housing (100), A sealing chamber (510) comprising the sealing chamber (510) on which the mounting table (501) is rotatably mounted about a rotation axis (R) that is perpendicular to the longitudinal extension axis (L) of the filter housing, Device.

11. The apparatus according to claim 10, characterized in that the mounting table (501) includes a retaining device (502) for an even number of filter housings, particularly 2, 4, 6, 8, or 10 filter housings.

12. A sealing cap (213) for sealing at least two hollow fiber membrane bundles using a curable sealing material (112) disposed in the first (100) and second (200) filter housings, respectively, The sealing cap (209) has a first receiving portion (210a) for receiving the end region (105) of the first filter housing (100) and the first hollow fiber membrane bundle disposed therein, and at least a second receiving portion (210b) for receiving the end region (205) of the second filter housing (200) and the second hollow fiber membrane bundle disposed therein, The first receiving portion (210a) and the second receiving portion (210b) are connected to a transfer passage (213), thereby allowing the curable sealant to flow from the first receiving portion (210a) into the second receiving portion (210b). The sealing cap (209) has at least partially circumferential projections (211) so that the curable sealant injected through the void can be captured and flow into the first receiving portion (210a). Sealing cap (213).

13. A method for manufacturing a hollow fiber membrane filter, comprising the steps of the method described in claims 1 to 9, The steps include: exposing the lumen of the hollow fiber membrane by removing the layer of the sealing material from the surface of the sealed end of the hollow fiber membrane; A step of sealingly attaching filter caps to each of the end regions of the filter housing in order to form two flow spaces, wherein the first flow space includes the internal volume of the hollow fiber membrane, and the second flow space includes the volume between the hollow fiber membrane and the filter housing, A method that further includes this.

14. A hollow fiber membrane filter including a filter housing, The filter housing is Two end regions (105, 106) each having two terminal edges (107a, 107b), A bundle of hollow fiber membranes is arranged in the filter housing, and in the end region of the filter housing, the ends of the hollow fiber membranes are sealed with a sealing material by the filter housing, Filter caps are sealed and attached to the two end regions of the filter housing, Includes, The hollow fiber membrane filter has two flow spaces, the first of which includes the internal volume of the hollow fiber membrane, and the second of which includes the volume between the hollow fiber membrane and the filter housing. The hollow fiber membrane filter, The sealing height of the sealing material is 3 to 7 mm, particularly 4 to 6 mm or 4.5 to 5.5 mm. A hollow fiber membrane filter characterized by the following features.

15. The hollow fiber membrane filter according to claim 16, characterized in that the meniscus depth is less than or equal to 3 mm, preferably less than or equal to 2 mm, and more preferably less than or equal to 1 mm.

16. The hollow fiber membrane filter according to claim 14 or 15, characterized in that the aspect ratio between the effective length of the hollow fiber membrane and the inner diameter of the cylindrical housing is 8 to 12.

17. The hollow fiber membrane filter according to claims 14 to 16, characterized in that the packing density of the hollow fibers in the filter housing is higher than 57%, more particularly higher than 60%, and more specifically higher than 62%.

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