Coating for hollow-fiber membranes in medical engineering

Abstract

The present invention relates to a method for coating a preferably porous and / or hydrophilic hollow-fiber membrane (1) with a coating material (B), the method comprising the steps of: providing the hollow-fiber membrane (1) that has a coating side to be coated and an oppositely facing secondary side, providing the coating material (B) and applying the coating material (B) to the coating side, or exclusively to the latter.

Description

[0001] Description

[0002] Coating of hollow fiber membranes in medical technology

[0003] The present invention relates to a method for coating a preferably porous and / or hydrophilic hollow fiber membrane with a coating material according to claim 1, a hollow fiber membrane according to claim 21, a dialyzer according to claim 22 and a device according to claim 23 or according to the respective preambles or generic terms of these claims.

[0004] In ECLS (extracorporeal lung support), oxygen is added (ECMO = extracorporeal membrane oxygenation) and / or CO2 is removed (ECCO2R = extracorporeal CO2 removal) from the blood flowing extracorporeally in a gas exchange device, depending on the blood flow rate. This procedure represents a beneficial alternative and / or supplement to conventional mechanical ventilation for the patient in many ways.

[0005] An object of the present invention is to provide a method for producing a hollow fiber membrane suitable for this treatment method.

[0006] Furthermore, a membrane, in particular a hollow fiber membrane, a dialyzer and a device are to be specified.

[0007] The object of the invention is achieved by means of the method for coating a preferably porous and / or hydrophilic hollow fiber membrane with a coating material having the features of claim 1, by means of the hollow fiber membrane having the features of claim 21, and by means of the dialyzer having the features of claim 22. Furthermore, it is achieved by a device having the features of claim 23.

[0008] According to the invention, a method for coating a preferably porous and / or hydrophilic hollow fiber membrane with a coating material is proposed.

[0009] The method according to the invention comprises providing at least one hollow fiber membrane with a coating side to be coated and a secondary side opposite thereto, as well as providing the coating material.

[0010] The method further comprises applying the coating material to precisely one or at least one side of the hollow fiber membrane, namely the coating side, or only to this side, not also to the secondary side. The coating material can be suitable and applied to reduce the permeation of blood plasma through the pores of the hollow fiber membrane during subsequent use.

[0011] When reference is made herein to a hollow fiber membrane, what has been said in this regard also applies in some embodiments to a plurality of hollow fiber membranes that mostly run parallel to one another and are, for example, bundled, for example in a common housing, for example the filter housing, as shown in section in Fig. 2B of US 10,583,458 B2. They can be coated simultaneously using the present invention. If several hollow fibers or hollow fiber membranes are present, the coating side can correspond to the side facing the inner lumen of the hollow fiber; the secondary side would then be the outer surface of the hollow fibers, or alternatively, the entire space within the housing that is formed or (co-)delimited by the housing inner walls and the outer surfaces of the hollow fibers.

[0012] According to the invention, a hollow fiber membrane is proposed which has been coated by means of the method according to the invention.

[0013] According to the invention, a dialyzer with a hollow fiber membrane according to the invention is proposed. In this or any other embodiments, the coating side can be the blood side.

[0014] According to the invention, a device for coating a hollow fiber membrane is proposed, which is configured to carry out the method according to the invention.

[0015] Embodiments of the invention may comprise some, some or all of the following features in any combination, unless this is recognizably technically impossible for a person skilled in the art.

[0016] In all the following statements, the use of the expression "may be" or "may have" etc. is to be understood as synonymous with "is preferably" or "preferably has" etc. and is intended to explain embodiments of the invention.

[0017] Whenever numerical terms are mentioned herein, the person skilled in the art will understand them as indicating a numerical lower limit. Unless this leads to a contradiction recognizable to the person skilled in the art, the person skilled in the art will therefore always read "at least one" or "at least one" alongside the term "a" or "an." This understanding is encompassed by the present invention, as is the interpretation that a numerical word such as "a" can alternatively be meant as "exactly one," wherever this is recognizably technically possible to the person skilled in the art. Both are encompassed by the present invention and apply to all numerical terms used herein.

[0018] Whenever reference is made herein to spatial information such as "top," "bottom," "left," or "right," the skilled person understands this to refer to the arrangement in the figures attached here and / or in the state of use. "Bottom" is closer to the center of the earth or the lower edge of the figure than "top."

[0019] Advantageous further developments of the present invention are each the subject of subclaims and embodiments.

[0020] When an embodiment is mentioned herein, it represents an exemplary embodiment of the invention and is not to be understood as limiting.

[0021] If it is disclosed herein that the subject matter according to the invention has one or more features in a specific embodiment, it is also disclosed herein that the subject matter according to the invention expressly does not have precisely this or these features in other, likewise inventive embodiments, e.g., by way of a disclaimer. Thus, for each embodiment mentioned herein, the opposite embodiment, for example, formulated as a negation, is also disclosed.

[0022] If method steps are mentioned or disclosed herein, the device according to the invention is configured in some embodiments to carry out one, several or all of these method steps, in particular if these are automatically performable steps, in any combination, or to control corresponding devices, which are preferably based on the name of the respective method step (e.g. "determining" as a method step and "device for determining" for the device, etc.) and which can also be part of the device(s) according to the invention or can be connected thereto in signal communication.

[0023] When reference is made herein to programmed or configured, these terms may be interchangeable in some embodiments.

[0024] The control device can initiate the execution of all or substantially all method steps. The method according to the invention can be carried out substantially or entirely by the control device. It can be carried out partially by the control device; in particular, those steps that do not require or involve human intervention and / or provision can be carried out by the control device. The control device can serve as a pure control device or also as a regulating device. In some embodiments of the method according to the invention, the coating material is or comprises a solution, preferably a silicone solution.

[0025] In some embodiments of the method, the at least one hollow fiber membrane is arranged in a housing, such as a filter housing.

[0026] In some embodiments, the at least one hollow fiber membrane is arranged in the housing, or filter housing, of a dialyzer.

[0027] In these embodiments, the volume adjacent to or surrounding the side of the hollow fiber membrane not to be coated, also referred to herein as the secondary side, is preferably fluidically separated from the exterior of the housing or dialyzer, e.g., by means of the housing. The housing can have fluid line connections such as the compressed gas inlet or compressed gas outlet mentioned below, but can otherwise be fluidically separated.

[0028] In some embodiments, the method of the invention further comprises subjecting the hollow fiber membrane to a centrifugal force during application of the coating material.

[0029] In some embodiments, the hollow fiber membrane has a longitudinal direction with two longitudinally opposite ends, referred to herein as the first and second ends, respectively. The coating material is brought into contact with the hollow fiber membrane at the first end for application to the hollow fiber membrane to coat it. In some embodiments, the first end is positioned closer to a centrifugation rotation axis than the second end.

[0030] In some embodiments of the method, the coating material is not brought into contact with the hollow fiber membrane until the centrifugal force begins, e.g., not before, or not before at least 10% of the subsequent maximum value of the centrifugal force has been reached. Another advantage here can be that the coating material does not come into contact with the hollow fiber membrane too early and does not penetrate uncontrollably into the membrane material to be coated.

[0031] In some embodiments of the method, the hollow-fiber membrane is held in or on a first holding device for coating. The coating material is arranged such that it is guided by centrifugal force along a feed line, e.g., along the first holding device, for example, through a lumen of the feed line or the first holding device, to the first end of the hollow-fiber membrane. The feed line can run inside or outside the first holding device. It can be identical to the first holding device or be part of it.

[0032] In some embodiments, the feed line is arranged and / or configured such that the coating material must first overcome a height difference to reach the first end of the hollow fiber membrane. For example, a minimum flow rate—and thus a minimum fill level for the coating material—and / or a minimum centrifugal force are required for the coating material to enter the clamped hollow fiber membrane while overcoming the height difference.

[0033] In some embodiments, the course of the supply line includes the elevation difference, or a portion thereof. Such an elevation difference can be an inclination of the supply line relative to a horizontal line or can be caused by this. The inclination can refer to the entire supply line, which, for example, runs upwards from bottom to top. The inclination can refer to a section of the supply line in which the supply line, e.g., in a side view, runs in an S-shape, is curved, etc.

[0034] In some embodiments, the height difference, or a portion thereof, is provided (in the sense of being present) in the lumen of the supply line or is caused by its design. The height difference may be, or be caused by, a step, a barrier, or the like that must be overcome. The height difference may, for example, be, or be caused by, a lumen constriction, especially in the lower region of the cross-section containing the constriction.

[0035] In some embodiments of the method, the hollow-fiber membrane is held in or on a second holding device for coating. A drain line is arranged, via which excess coating material is discharged from the hollow-fiber membrane via the second end of the membrane by means of centrifugal force along the drain line, e.g., along the second holding device, for example, through a lumen of the feed line or the second holding device. The drain line can run inside or outside the second holding device. It can be identical to the second holding device or be part of it.

[0036] In some embodiments, the drain line is arranged and / or configured such that the coating material overcomes a second height difference when flowing off, or after flowing off, from the second end of the hollow fiber membrane.

[0037] In some embodiments, the path of the drain line includes or causes the second elevation difference, or a portion thereof.

[0038] In some embodiments, the second height difference, or a portion thereof, is provided in the lumen of the drain line.

[0039] What is stated herein regarding the first height difference (of the inlet line) also applies in some embodiments to the second height difference (of the outlet line), and vice versa.

[0040] In some embodiments, the inlet line and / or the outlet line have a first vent port and / or a second vent port, respectively, through which gas can flow passively, e.g., as atmospheric air, into the inlet line during coating or can be actively supplied, and / or gas can flow passively out of the outlet line or can be actively discharged. In some embodiments, the first vent port and / or the second vent port are each fluidly connected to the inlet line or the outlet line in the upper half of the cross section of the inlet line or the outlet line. This means that the gas is supplied or discharged in the upper half of that cross section of the inlet line or the outlet line.

[0041] This possibility of passive or active ventilation can serve to avoid negative pressure, which could make it difficult for coating material to flow towards the hollow fiber membrane.

[0042] The design and / or arrangement of the vent connections in the upper half of the inlet line or the outlet line can advantageously help prevent coating material from escaping through these vent connections while the centrifugal force acts on the coating material. For this purpose, for example, an advantageous angle of inclination of at least 10° of the vent connections relative to the perpendicular or vertical, e.g., inclined toward or away from the centrifuge's rotation axis, can be selected.

[0043] Any connections to the dialysis fluid compartment can be open or closed.

[0044] In some embodiments of the method, a purge gas is introduced into the hollow fiber membrane along the longitudinal direction of the hollow fiber membrane and in contact with the coating side to remove excess coating material from the

[0045] Hollow fiber membrane. In some embodiments, the purge gas is introduced during centrifugation or during a period during which centrifugation is not taking place or is no longer taking place.

[0046] In some embodiments, the purge gas is introduced via a rotary union or by means of a line arranged according to the "Adams unique jump rope" principle. The purge gas can be introduced via a guide that is secured against rotation during rotation.

[0047] A rotary union enables fluids (gases, liquids) to pass in a sealed manner between a stationary body and a rotating body, or between bodies rotating against each other.

[0048] A flow-through centrifuge without a sliding seal and having a line for supplying and / or discharging at least one fluid from the separation unit to a stationary connection point is disclosed, for example, in EP 0 933133 B1 of Fresenius AG, the relevant disclosure of which is incorporated herein by reference in its entirety.

[0049] In some embodiments, the excess coating material is first expelled by means of the purge gas at a first pressure, e.g., over a predetermined first duration, and then at a second pressure, e.g., over a predetermined second duration.

[0050] In some embodiments of the method, pressure is applied to the hollow fiber membrane by means of compressed gas, bypassing the inlet line, which pressure acts on it, for example, along the circumferential direction of the hollow fiber membrane, preferably on that side of the hollow fiber membrane which is not the coating side. For this purpose, compressed gas can be introduced into the housing or filter housing described herein in such a way that it exerts pressure on the hollow fiber membrane via the secondary side of the hollow fiber membrane. The compressed gas can flow along the longitudinal direction of the hollow fiber and exert pressure along the longitudinal and / or circumferential direction. The compressed gas does not flow through the inlet line, or not only through that side.

[0051] In some embodiments, the pressurized gas is discharged bypassing the drain line, for example, from the housing surrounding the hollow fiber membrane. The pressurized gas does not flow through the drain line, or not exclusively through it.

[0052] In some embodiments, the compressed gas is introduced onto the hollow fiber membrane via a compressed gas inlet or, for example, into the housing and discharged again via a compressed gas outlet. If the housing is designed as a dialyzer housing, the compressed gas inlet and compressed gas outlet can be the inlet and outlet lines of the dialysis fluid compartment, respectively, or the connections therefor.

[0053] In some embodiments, the compressed gas outlet is not closed for or during the discharge of the compressed gas, but at most throttled, for example by means of a throttle. In some embodiments, compressed gas flowing into the housing surrounding the hollow fiber membrane is therefore not located in the housing but flows through it. In some embodiments, it is never prevented from flowing out of the housing. Allowing gas to flow past the membrane of the hollow fiber, i.e. on the secondary side, serves to immediately remove substances or products of the coating process from the side of the hollow fiber membrane facing the secondary side from the housing. These substances, which should no longer be present in the housing during later use of the hollow fiber membrane, can be partially removed from the housing in this way, which can shorten the time required for subsequent priming or rinsing.If the brushing is carried out under increased pressure, this can already counteract the transfer of coating material from the coating side to the secondary side.

[0054] In this way, in some embodiments, the penetration depth of the coating material on the coating side and into it can be influenced in a controlled manner. Furthermore, the time required for a coating process can be advantageously shortened by increasing gas flow rates, which initially results in an increase in pressure due to the flow resistance. By also increasing the pressure on the secondary side, a change in penetration depth can thus be advantageously counteracted.

[0055] In some embodiments, the hollow fiber membrane is held in a first position prior to centrifugation in order to be brought into contact with the coating material or to be brought into contact for the first time, such as at its first end. For centrifugation and / or by centrifugation, the hollow fiber membrane is brought into a second position different from this first position.

[0056] In some embodiments, the hollow fiber membrane is arranged more upright or vertically in the first position than in the second position. In some embodiments of the method, excess coating material is expelled by means of the purge gas at a first pressure, for example, over a predetermined first duration. The first pressure can be, for example, between 100 hPa and 400 hPa (0.1 bar and 0.4 bar), for example, 200 hPa (0.2 bar). When diluting, for example, the silicone as a coating material or parts thereof with solvent, or with some other coating materials, in some embodiments the solvent is subsequently expelled at a second pressure, for example, over a predetermined second duration. In the present example, this is done to promote the crosslinking of the silicone via air or ambient humidity. The second pressure can be, for example, above 400 hPa (0.4 bar) and below 1000 hPa (1 bar), for example,at 500 hPa (0.5 bar). This pressure can lead to a back pressure in front of the hollow fiber membrane, which contributes to generating a volume flow.

[0057] In some embodiments of the device according to the invention, it comprises a control device for controlling or regulating the centrifugation, the introduction of the coating material, the gas, the purge gas and / or the compressed gas, in particular as described herein.

[0058] In some embodiments, the dialyzer according to the invention is designed for use in dialysis, hemodialysis, hemofiltration, or hemodiafiltration, in particular for acute or chronic renal replacement therapy or continuous kidney replacement therapy (CKRT). In some embodiments, no pump is used to introduce the coating material into or onto the hollow fiber membrane.

[0059] In some embodiments, the hollow fiber membrane consists of polysulfone, polyvinylpyrrolidone or a mixture thereof, or comprises at least one of these materials or the mixture, in particular before its coating.

[0060] In some embodiments, the hollow fiber membrane is designed as in DE 10034 098 C2, the disclosure of which is hereby incorporated by reference in its entirety.

[0061] Some or all embodiments of the invention may have one, several or all of the advantages mentioned above and / or below.

[0062] In recent years, CO2 removal from the blood has increasingly come into focus, not least due to the COVID-19 pandemic and the ever-increasing prevalence of COPD. When using a hollow-fiber membrane coated according to the invention in an ultra-low-flow procedure, the blood flow can be, for example, less than 1000 ml / min or even less than 500 ml / min, but is not limited to this. This makes treatment "minimally invasive" compared to standard treatment (low-flow ECMO), as it can be performed using a smaller catheter for vascular access than in ECMO, such as the one used for dialysis (e.g., the Shaldon catheter (11-13.5 Fr).

[0063] The field of application of the present invention can therefore be, in particular, the treatment of patients with chronic obstructive pulmonary disease (COPD), including those suffering from an acute exacerbation, i.e., a significant worsening of the clinical picture of their disease. The present invention and its advantages can thus benefit a wide range of patients.

[0064] State-of-the-art gas exchangers can be used to treat these patients. Gas exchangers are typically produced in much smaller quantities than dialyzers. Their production therefore has a low degree of automation. For this reason, gas exchangers are comparatively expensive to manufacture. One advantage of the present invention may therefore be that the coating process can be automated, i.e., without human intervention. This can help save time and costs.

[0065] A further advantage may be that a large number of coated dialyzers according to the invention can be produced, since several modules can be coated simultaneously using the present invention. Since this can accelerate the production of dialyzers suitable for gas exchange, this can also help save time and costs.

[0066] During the coating process on the coated side of the hollow fiber membrane, the air located there is displaced through the membrane toward the secondary side. If the secondary side were prevented from flowing out of the housing, air pockets could form in the hollow fiber membrane, which could be dangerous for a patient during subsequent treatment using the coated hollow fiber membrane. The present invention can advantageously prevent or at least reduce this. This can contribute to increased patient safety.

[0067] A further advantage of the present invention may be that solvent from the coating material, which filters through the hollow fiber membrane toward the secondary side and evaporates there during coating of the coating side, can escape from the housing. This avoids solvent residues that would otherwise remain in the dialyzer housing. This can also advantageously contribute to increasing patient safety and optimizing the quality of the coating.

[0068] All advantages achievable with the methods according to the invention can also be achieved without reduction with the devices according to the invention in certain embodiments according to the invention, and vice versa.

[0069] The present invention is described below purely by way of example with reference to the accompanying figures. In these figures, identical reference numerals designate identical or similar components. The following applies:

[0070] Fig. 1 shows an exemplary sequence of a method according to the invention for coating a preferably porous and / or hydrophilic hollow fiber membrane with a coating material in an exemplary embodiment;

[0071] Fig. 2 shows an exemplary arrangement for carrying out the method according to the invention in one embodiment using a device according to the invention in a first exemplary embodiment;

[0072] Fig. 2a shows a characteristic diagram determined in the experiment, which can help in the design of the construction of the device according to the invention, for example Fig. 2;

[0073] Fig. 2b shows an exemplary arrangement of the inlet line to illustrate the operating point;

[0074] Fig. 3 shows an exemplary arrangement for carrying out the method according to the invention in one embodiment using a device according to the invention in a second exemplary embodiment;

[0075] Fig. 4a shows a further exemplary arrangement for carrying out the method according to the invention in a further embodiment using a device according to the invention in a third exemplary embodiment, which is shown in a first position;

[0076] Fig. 4b shows the arrangement of Fig. 4a in a second position;

[0077] Fig. 5 shows the sequential principle of the anti-twist mechanism, also known as "Adam's unique jump rope"; and Fig. 6 shows an exemplary procedure within the scope of an embodiment of the method according to the invention, wherein only the expulsion of excess coating material B by introducing purge gas S is described here.

[0078] Fig. 1 shows an exemplary sequence of a method according to the invention for coating a preferably porous and / or hydrophilic hollow fiber membrane 1 with a coating material B in an exemplary embodiment.

[0079] Reference is made to the reference numerals of the device 100 and components in the following figures.

[0080] Method step M1 represents a provision of the hollow fiber membrane 1. The hollow fiber membrane 1 can be arranged in a housing, such as a filter housing 50, for example of a dialyzer, for example as shown in the following figures.

[0081] Process step M2 represents a provision of the coating material B. The coating material B can be or comprise a solution, preferably a silicone solution.

[0082] An application of the coating material B to exactly one or at least one side of the hollow fiber membrane 1, which serves as the coating side, is carried out in process step M A represents the procedure M A may consist of or include one or more of the following process steps. It should be noted that the terms "side" and "end" of the hollow fiber membrane 1 have different meanings, as explained herein, and are therefore not equivalent.

[0083] The volume adjacent to the secondary side of the hollow fiber membrane 1 not to be coated is preferably separated from the exterior of a housing, e.g., the filter housing 50, or a dialyzer.

[0084] The method step M3 comprises subjecting the hollow fiber membrane 1 to a centrifugal force during the application of the coating material B to one or at least one side of the hollow fiber membrane 1.

[0085] The centrifugal force causes the coating material B, which is first brought into contact with a first end 10 of the hollow fiber membrane 1 for its application, which is closer to a rotation axis R of the centrifugation than a second end 20 of the hollow fiber membrane 1, to move toward the second end 20. The second end 20 is arranged opposite the first end 10 in the longitudinal direction L of the hollow fiber membrane 1.

[0086] The coating material B is preferably brought into contact with the hollow fiber membrane 1 only upon the onset of the centrifugal force, represented by method step M4. This may include, for example, that the coating material B cannot come into contact with the hollow fiber membrane 1 before the onset of the centrifugal force, or not before at least 10% of the later maximum value of the centrifugal force has been reached. For this purpose, some embodiments of the method may provide that the coating material B must first overcome a first height difference H1 in order to reach the first end 10 of the hollow fiber membrane 1.

[0087] In some embodiments, the hollow fiber membrane 1 can be held in or on a first holding device 60 for its coating, wherein the coating material B is arranged to be guided by centrifugal force along an inlet line 65, e.g., along the first holding device 60, for example, through a lumen of the inlet line 65, to the first end 10 of the hollow fiber membrane 1. It can be provided that the arrangement (see Fig. 2) of the inlet line 65 or the configuration of the inlet line 65 or its lumen (see Fig. 3) represents the first height difference H1 that the coating material B has to overcome.

[0088] In this method step M4, the hollow fiber membrane 1 is optionally further held in or on a second holding device 70, wherein a drain line 75 is arranged in or on this, via which the coating material B is discharged by means of centrifugal force along the drain line 75, e.g., along the second holding device 70, from the second end 20 of the hollow fiber membrane 1.

[0089] In some embodiments, the drain line 75 is arranged and / or configured such that the coating material B, when flowing from the second end 20 of the hollow fiber membrane 1, overcomes a second height difference H2, which prevents a backflow of the coating material B to the second end 20 of the hollow fiber membrane 1 (after overcoming the second height difference H2). It can be provided that the arrangement (see Fig. 2) of the drain line 75 or the configuration of the drain line 75 or its lumen (see Fig. 3) represents the second height difference H2 that the coating material B must overcome.

[0090] In some embodiments, the inlet line 65 and / or the outlet line 75 may each have a ventilation connection 80, in particular in the upper half of the cross section thereof, which is in fluid communication with the ventilation connection 80, wherein gas is supplied into the inlet line 65 during coating and / or wherein gas is discharged from the outlet line 75.

[0091] In the optional process step M5, a purge gas S is introduced into the hollow fiber membrane 1 in the longitudinal direction L along the coated side to displace excess coating material B from the hollow fiber membrane 1. This step can be performed during centrifugation, i.e., while the centrifuge is still running and a centrifugal force is still acting. The purge gas S can be supplied via an optional rotary union at the vent port 80 or a line, which is optionally arranged according to the "Adams unique jump rope" principle at the vent port 80.

[0092] Fig. 2 shows an exemplary arrangement for carrying out the method according to the invention in one embodiment using a device 100 according to the invention in a first exemplary embodiment.

[0093] At least one, preferably porous and / or hydrophilic, hollow-fiber membrane 1 is arranged in a filter housing 50. It has a longitudinal direction L with two ends 10, 20 opposite one another in the longitudinal direction L. At its first end 10, the hollow-fiber membrane 1 is connected to a first holding device 60. The hollow-fiber membrane 1 is fluidically connected to an inlet line 65. In this inlet line 65, at least at the beginning of the method according to the invention, a coating material B, which can be or comprise silicone or a silicone solution, is provided. At its second end 20, the hollow-fiber membrane 1 is optionally connected to a second holding device 70. The hollow-fiber membrane 1 is optionally fluidically connected to an outlet line 75. The outlet line 75 will be discussed in more detail below.

[0094] If the device 100 shown is now rotated about a rotation axis R, i.e. here, for example, in a plane which is perpendicular to the plane of the drawing, with the first end 10 being arranged closer to the rotation axis R than the second end 20, a centrifugal force acts on the coating material B provided in the feed line 65 and presses it outwards and upwards against the first end 10 of the hollow fibre membrane 1. This is illustrated by the upwardly pointing white block arrow in Fig. 2, whereby Fig. 2 not entirely accurately shows two volumes of coating material B on the right-hand side, one at the first end 10, one at the beginning of the feed line 65. In fact, during the rotation, a continuous film would be expected between these two volumes, but not an interruption of the flow of coating material B between them, which is created by the centrifugation.The coating material B continues its path along the coating side of the hollow fiber membrane 1 and through the filter housing 50 to the second end 20. A portion of the coating material B remains adhering to the coating side of the hollow fiber membrane 1 as a coating. Any excess coating material B that is not required for this purpose is pressed by centrifugal force over the second end 20 of the hollow fiber membrane 1 and the second holding device 70 into the drain line 75, where it is advantageously collected. This is represented by the downward-pointing white block arrow.

[0095] In the example of Fig. 2, the inlet line 65 is arranged and / or designed to rise from bottom to top. Thus, in order to reach the first end 10 of the hollow fiber membrane 1, the coating material B, coming from the right in Fig. 2 (e.g., from a container or a source), must first overcome a first height difference H1. Thus, for example, a minimum flow—and thus a minimum fill level for the coating material B—and / or a minimum centrifugal force is required for the coating material B to enter the clamped hollow fiber membrane 1. This advantageously prevents the coating material B from coming into contact with the hollow fiber membrane 1 before the device 100 begins to rotate.

[0096] This can prevent uncontrolled, even temporary, penetration of the coating material into the membrane material to be coated. This ensures that as many fibers of the hollow-fiber membrane 1 as possible come into contact with the coating material B simultaneously or immediately one after the other. Otherwise, the solvent contained in the coating material might filter out uncontrollably through the hollow fibers of the hollow-fiber membrane 1 and lead to a thickening of the coating material B, which is usually present as a solution.

[0097] Furthermore, in the example of Fig. 2, the drain line 75 is arranged and / or configured to slope downwards from top to bottom. Thus, when the coating material B exits the second end 20 of the hollow-fiber membrane 1, it first overcomes a second height difference H2. This advantageously prevents the coating material B from flowing back to or into the hollow-fiber membrane 1 when the rotation of the device 100 slows down or stops.

[0098] In the example of Fig. 2, the inlet line 65 further has a first vent port 80 at its upper cross-section, and the outlet line 75 has a second vent port 90, also at its upper cross-section. During coating, gas, e.g., as atmospheric air, can flow passively into the inlet line 65 through the first vent port 80 or can be actively supplied, e.g., as purge gas S as shown in Fig. 6, and / or gas can flow passively out of the outlet line 75 through the second vent port 90 or can be actively discharged.

[0099] The arrangement and fluidic connection of the venting ports 80, 90 with the inlet line 65 and the outlet line 75, respectively, in the upper half of the cross-section can advantageously help prevent coating material B from escaping via these venting ports 80, 90 while the centrifugal force acts on the coating material B. The possibility of passive venting and de-aeration (represented by black block arrows in Fig. 2) can serve to avoid negative pressure, which could complicate the flow of coating material B towards the hollow fiber membrane 1. The possibility of active venting and de-aeration (represented by black block arrows in Fig. 2) can serve to expel excess coating material B from the hollow fiber membrane 1.

[0100] In a very simplified schematic, a control device 101 for carrying out the method and / or for controlling and / or regulating the device 100 is arranged next to it. This can be or include controlling or regulating the centrifugation, the introduction of the coating material B, the gas, the purge gas S, and / or the compressed gas D (see Fig. 6), in particular as described herein.

[0101] Fig. 2a shows a characteristic diagram determined in the experiment, which can help in the design of the construction of the device 100 according to the invention in Fig. 2.

[0102] The maximum gradient angle of the inlet line 65 that can be overcome by the coating material B is determined using a formula by equating the horizontal component of the slope force on the slope with the centrifugal force at this operating point A (see Fig. 2b).

[0103] The distance radius r of the operating point A from the rotation axis R is marked on the x-axis in millimeters [mm], and the pitch angle of the inlet line in degrees [°] is marked on the y-axis. For various rotation speeds in the unit of revolutions per minute [rpm], the characteristic curves K1 to K2 are shown.

[0104] K8.

[0105] In the diagram of Fig. 2a:

[0106] K1 50 rpm,

[0107] K2 100 rpm,

[0108] K3 150 rpm,

[0109] K4 200 rpm,

[0110] K5 250 rpm,

[0111] K6 300 rpm,

[0112] K7 350 rpm, and

[0113] K8 400 rpm

[0114] Fig. 2b shows an exemplary arrangement of the

[0115] Inlet line 65 to illustrate the operating point A.

[0116] Operating point A represents the highest contact point of coating material B in storage container 30 when rotation is present. A parabolic filling curve forms in storage container 30, which also depends on x and the rotation speed. Operating point A describes the point at which this filling level is exceeded and coating material B flows from storage container 30 into feed line 65.

[0117] Fig. 3 shows a further exemplary arrangement for carrying out the method according to the invention in one embodiment using a device 100 according to the invention in a further exemplary embodiment.

[0118] Reference is made to the reference numerals and the description for Fig. 2. In contrast to Fig. 2, in the example in Fig. 3 both of the height differences H1, H2 are provided in the lumen of the inlet line 65 and the outlet line 75, respectively. The height difference H1, H2 can be a step, a barrier or the like, or be caused by one, which must be overcome. The height difference H1, H2 can, for example, be a lumen constriction, especially in the lower region of the cross-section having the constriction, or be caused by one. In the examples in Fig. 2 and Fig. 3, H1 = H2 applies; this can be different in other embodiments.

[0119] The height differences H1 and H2 also serve the purpose indicated in Fig. 2 in the embodiment of Fig. 3.

[0120] Fig. 4a shows an exemplary arrangement for carrying out the method according to the invention in one embodiment using a device 100 according to the invention in a third exemplary embodiment.

[0121] Reference is made to the reference numerals and embodiments of Fig. 2 and Fig. 3.

[0122] In the example of Fig. 4a, the hollow fiber membrane 1 is held in the housing 50 in a first, here upright, position before centrifugation, and is placed on a container containing coating material B and fluidically connected thereto. The container can function as an inlet line 65 and have a first vent connection 80.

[0123] For centrifuging and / or by centrifuging, the

[0124] Hollow fiber membrane 1 is brought into a different second position (see Fig. 4b), represented by the curved arrow.

[0125] Fig. 4b shows the arrangement of Fig. 4a in the second position into which it was brought for centrifugation and / or by centrifugation.

[0126] Figure 4b is supplemented by a drain line 75 at the second end 20 of the hollow fiber membrane 1, which was omitted in Figure 4a for reasons of space. The drain line 75 has a second vent port 90, which in this arrangement is preferably located in the lower cross-section of the drain line 75 to prevent the escape of coating material B during centrifugation.

[0127] In the second position, the hollow fiber membrane 1 can come into contact with the coating material B or come into contact for the first time, for example at its first end.

[0128] It can be seen from Fig. 4a and Fig. 4b that the hollow fiber membrane 1 is arranged more upright or vertically in the first position than in the second position.

[0129] Fig. 5 shows a sketch of the sequential principle of the anti-rotation mechanism.

[0130] For better clarity, the rotating disk has been marked with an arrow and the front and back of the "rope" have been contrasted differently. The arrangement in a corresponds to the arrangement when the disk is rotated by 0°, in b by 90°, in c by 180° and so on up to 720° in i. It can be seen from the figure that the arrangement at 0° (a) corresponds to the arrangement at 720° (i), ie the "rope" is not twisted any further.

[0131] The disc, or other rotating structure, can be connected on its upper side to the "rope", a band, a cord, a cable, or the like, in a first connection point in a rotationally fixed manner, while the "rope" on the underside (or vice versa) of the disc, which rotates about its longitudinal axis during use, is fixedly connected to, for example, a stationary housing section, directly or indirectly to the support surface on the floor, etc., in a second connection point. The "rope" is guided at least in sections past a circumferential surface of the disc between these two connection points without being connected to the circumferential surface of the disc.

[0132] Fig. 6 shows an exemplary procedure within the scope of an embodiment of the method according to the invention, wherein only the expulsion of excess coating material B by introducing purge gas S is described here, a process which follows or concludes the actual coating.

[0133] In the procedure according to Fig. 6, an external pressure P is applied to the purge gas line, which is in fluid communication with the inlet line 65 via the first vent connection 80 upstream of the hollow fiber membrane 1.

[0134] At the same time, an external pressure P is applied to the compressed gas inlet 85, which does not exceed the first

[0135] The aeration connection 80 is not in fluid communication with the inlet line 65 upstream of the hollow fiber membrane 1, but directly with the hollow fiber membrane 1, here preferably with its secondary side.

[0136] In this way, a gas which does not serve to flush out excess coating material B is applied to generate pressure on the secondary side, which is why it is also referred to herein as pressure gas D.

[0137] The external pressure P, as mentioned in the two previous paragraphs, can be the same, but this is not mandatory.

[0138] If it is desired that the external pressure P is the same in both the inlet line 65 and the compressed gas inlet 85, then the line coupling shown in Fig. 6, for example, is suitable, by means of which both the purge gas S and the compressed gas D are supplied via a common source and are therefore at the same pressure P. This is clearly the case in Fig. 6, which is also evident from the arrow indicating a gas flow with reference symbols D+S, which breaks downstream into an arrow for a flow only from D and an arrow for a flow only from S.

[0139] Thus, an almost uniform pressure P prevails on both sides of the hollow fiber membrane 1, which protects against leaks as well as against further penetration of the coating material B onto the coating side.

[0140] A compressed gas outlet 95 for the compressed gas D is shown in Fig. 6 downstream of the compressed gas inlet 85. In the embodiment shown here, the compressed gas outlet 95 is not closed. As also shown by way of example in Fig. 6, it can be provided with a flow-limiting or flow-reducing element, which here is designed, for example, as a throttle 97.

[0141] List of reference symbols

[0142] 1 hollow fiber membrane

[0143] 10 first end

[0144] 20 second end

[0145] 30 storage containers

[0146] 50 filter housings

[0147] 60 first holding device

[0148] 65 Inlet line

[0149] 70 second holding device

[0150] 75 drain line

[0151] 80 first ventilation connection for purge gas

[0152] 85 Compressed gas inlet for compressed gas

[0153] 90 second ventilation connection for purge gas

[0154] 95 Compressed gas outlet for compressed gas

[0155] 97 Thrush

[0156] 100 device

[0157] 101 Control device

[0158] A operating point

[0159] B Coating material

[0160] D Compressed gas H1 first height difference

[0161] H2 second height difference

[0162] K1 to K8 characteristics

[0163] L longitudinal direction

[0164] M A procedural section;

[0165] Applying the coating material

[0166] M1 to M5 process steps

[0167] P external pressure

[0168] R Rotation axis r Distance radius to rotation axis

[0169] S Spülgas

Claims

Claims 1. A method for coating a, preferably porous and / or hydrophilic, hollow fiber membrane (1) with a coating material (B), comprising the steps of: - providing the hollow fiber membrane (1) with a coating side to be coated and a secondary side opposite it; - providing the coating material (B); and - applying the coating material (B) to the coating side of the hollow fiber membrane (1) or only to it.

2. The method of claim 1, wherein the coating material (B) is or comprises a solution, preferably a silicone solution.

3. Method according to one of the preceding claims, wherein the hollow fiber membrane (1) is arranged in a housing, for example a filter housing (50).

4. Method according to any of the preceding claims, further comprising the step of: - Exposing the hollow fiber membrane (1) to a centrifugal force during the application of the coating material (B).

5. Method according to any one of the preceding claims, wherein the hollow fiber membrane (1) has a longitudinal direction (L) with two oriented longitudinally (L) opposite first and second ends (10, 20), wherein the coating material (B) is brought into contact with the hollow fiber membrane (1) at the first end (10) for its application, and wherein the first end (10) is positioned closer to an axis of rotation (R) of the centrifugation than the second end (20).

6. Method according to claim 4 or 5, wherein the coating material (B) is brought into contact with the hollow fiber membrane (1) only upon application of the centrifugal force.

7. Method according to any one of claims 4 to 6, wherein the hollow fiber membrane (1) is held in or on a first holding device (60) for its coating, wherein the coating material (B) is arranged to be guided to the first end (10) of the hollow fiber membrane (1) by means of the centrifugal force along a feed line (65). 8.A method according to claim 7, wherein the inlet line (65) is arranged and / or configured such that the coating material (B) must first overcome a first height difference (H1) in order to reach the first end (10) of the hollow fiber membrane (1).

9. A method according to claim 8, wherein the course of the inlet line (65) includes the height difference (H1), or a portion thereof.

10. A method according to at least one of claims 8 or 9, wherein the height difference (H1), or a portion thereof, is provided or present in the lumen of the inlet line (65).

11. A method according to any one of claims 4 to 9, wherein the hollow fiber membrane (1) is held in or on a second holding device (70) for coating, wherein a drain line (75) is arranged, through which excess coating material (B) is discharged from the hollow fiber membrane (1) via the second end (20) by means of centrifugal force along the drain line (75).

12. A method according to claim 11, wherein the drain line (75) is arranged and / or configured such that the coating material (B), during or after flowing from the second end (20) of the hollow fiber membrane (1), overcomes a second height difference (H2).

13. A method according to claim 12, wherein the course of the drain line (75) includes the second height difference (H2), or a portion thereof.

14. Method according to at least one of claims 12 or 13, wherein the second height difference (H2), or a part thereof, is provided or present in the lumen of the discharge line (75).

15. Method according to any one of claims 7 to 14, wherein the inlet line (65) and / or the outlet line (75) has a first vent connection (80) or a second vent connection (90), wherein a gas is enabled to flow into the inlet line (65) during coating, or to be supplied to it, and / or wherein the gas is enabled to escape. to flow out of the drain pipe (75), or to be discharged from it.

16. Method according to claim 15, wherein the first ventilation connection (80) and / or the second ventilation connection (90) is located in the upper half of the cross-section of the inlet pipe (65) or the The outlet line (75) is in fluid connection with the inlet line (65) or the outlet line (75).

17. Method according to any of the preceding claims, wherein a purge gas (S) is introduced into the hollow fiber membrane (1) along the longitudinal direction (L) of the hollow fiber membrane (1) and into contact with the coating side in order to displace excess coating material (B) from the hollow fiber membrane (1).

18. Method according to one of claims 7 to 17, wherein pressure is applied to the hollow fiber membrane (1) by means of pressurized gas (D), e.g. perpendicular to the longitudinal direction (L) of the hollow fiber membrane (1), which is introduced by bypassing the supply line (65), preferably on the secondary side of the hollow fiber membrane (1).

19. Method according to claim 18, wherein a pressurized gas outlet (95) for or during the discharge of the pressurized gas (D) from the housing is not closed, but is at most throttled, for example by means of a throttle (97).

20. Method according to any one of claims 4 to 19, wherein the hollow fiber membrane (1) is held in a first position before centrifugation in order to be brought into contact with the coating material (B), and wherein the hollow fiber membrane (1) is moved into a second position for centrifugation, the hollow fiber membrane (1) being arranged more upright in the first position than in the second.

21. Hollow fiber membrane (1) coated by the method according to any one of the preceding claims.

22. Dialyzer with a hollow fiber membrane (1) according to claim 21.

23. Device (100) for coating a hollow fiber membrane (1), configured to carry out the method according to any one of claims 1 to 20.

24. Device (100) according to claim 23, comprising a control device (101) for controlling or regulating the centrifugation, the introduction of the coating material (B), the gas, the purge gas (S) and / or the pressurized gas (D).

Images