Method for coating a mass transfer device, and mass transfer device

Abstract

The invention relates to a method for coating at least one mass transfer device (1) comprising a transfer chamber (2), in which at least one mass-permeable membrane (3) is arranged and which is divided by the membrane (3) into a first and a second chamber region (2a, 2b), wherein a liquid coating agent (9) is introduced into one of the chamber regions (2a, 2b) and is deposited onto the surface and / or into the pores (3a) of the membrane (3) on the side of the membrane (3) associated with the chamber region (2a, 2b), whereupon excess coating agent (2a) is removed from the chamber region (2a, 2b), wherein a reservoir (7) containing the coating agent (9) is connected to an inlet port (8a) of one of the chamber regions (2a, 2b), wherein the volume of the coating agent (9) entering the chamber region (2a, 2b) to be coated is less than the total fillable volume of the chamber region (2b) to which the reservoir (7) is connected, and the coating agent (9) is propelled through the chamber region (2a, 2b) along the at least one membrane (3) as a bolus (5) from the inlet port (8a) to an outlet port (8b) of the chamber region (2a, 2b) by means of an acceleration force exerted on the coating agent (9), wherein the volume of the bolus (5) decreases while passing through the chamber region (2a, 2b) as coating agent (9) is deposited on the surface and / or coating agent (9) is embedded in the pores (3a) of the membrane (3), and a residual volume of the bolus (5) exits the chamber region (2a, 2b) through the outlet port (8b). The invention also relates to a mass transfer device.

Description

[0001] Method for coating a mass transfer device and mass transfer device

[0002] The invention relates to a method for coating at least one mass exchange device, comprising an exchange chamber in which at least one material-permeable, in particular porous, membrane is arranged, and in particular in which a plurality of material-permeable, in particular porous, hollow fibers are arranged, wherein the exchange chamber is divided by the at least one membrane into a first chamber area in which the at least one membrane can be contacted with a first exchange medium on a first membrane side and into a second chamber area in which the at least one membrane can be contacted with a second exchange medium on a second membrane side, wherein a liquid coating agent, in particular a coating agent comprising a silicone,The coating material is poured into one of the two chamber areas, thereby depositing it onto the membrane surface and / or into the pores of the at least one membrane on the side of the at least one membrane associated with the chamber area, after which excess coating material is removed from the chamber area.

[0003] The invention also relates to a mass exchange device comprising an exchange chamber in which at least one material-permeable, in particular porous, membrane is arranged, and in particular in which a plurality of material-permeable, in particular porous, hollow fibers are arranged, wherein the exchange chamber is divided by the at least one membrane into a first chamber region in which the at least one membrane can be contacted with a first exchange medium on a first membrane side, and into a second chamber region in which the at least one membrane can be contacted with a second exchange medium on a second membrane side, wherein a coating agent, in particular a coating agent comprising silicone, is deposited on the membrane surface and / or in the pores of the at least one membrane on at least one side of the at least one membrane that is associated with one of the chamber regions.in particular by a method according to the invention as described in the present disclosure.

[0004] The at least one membrane can be designed, for example, as a preferably flat membrane or as a hollow fiber whose tubular wall forms the membrane. Flat membranes are preferably sealed on two opposite sides to a respective wall area of ​​the exchange chamber, in particular so that the two chamber areas mentioned are located on both sides of such a flat membrane and are separated by it.

[0005] In the design of at least one membrane as hollow fibers, it is preferably provided that a plurality of hollow fibers are arranged in the exchange chamber, wherein the hollow fibers are sealed at their axial end regions to each other and at least partially to a wall region of the exchange chamber by means of a sealing agent. Mass exchange devices of the type mentioned above are generally known in the prior art.

[0006] Typically, and also preferably in the invention, hollow fibers are used in such devices whose walls form fabric-permeable membranes.

[0007] The two membrane sides of the hollow fibers mentioned at the beginning are, in this case, the outside and the inside of the hollow fiber. This means that a first exchange medium can be guided along the outside of the hollow fiber, and a second exchange medium can be guided through its interior. The first chamber area thus borders all the hollow fibers on the outside and carries the first exchange medium, while the second chamber area borders all the hollow fibers on the inside and carries the second exchange medium.

[0008] In mass transfer devices of the invention with hollow fibers, these hollow fibers can be grouped together as bundles or packages, e.g. as wound or folded mats of hollow fibers.

[0009] The invention may provide that the at least one mass transfer device, in particular an uncoated mass transfer device, is already a commercially available and finished device, or that the at least one mass transfer device is a product stage of such a marketable / finished mass transfer device. Preferably, the at least one device to be coated comprises a housing containing the at least one membrane, in particular a cylindrical, longitudinally elongated housing comprising a bundle of hollow fibers which are bonded at their ends with a bonding agent, in particular to each other and to the inner wall of the housing.

[0010] "Verpotten" is a term commonly used by those skilled in the art in this field, meaning that a seal is achieved between the at least one membrane and the exchange chamber, in particular between the hollow fiber ends and the chamber housing wall, e.g., with a suitable material such as polyurethane or silicone. This separates the two chamber areas from each other on both sides of the at least one membrane.

[0011] When hollow fibers are used, it may be preferable to close their open ends before potting in order to prevent the potting agent from penetrating the hollow fibers.

[0012] When hollow fibers are used, it can preferably be provided that, after opening the sealed ends of the hollow fibers, such a mass transfer device is equipped, for example, with lid elements at the open ends, e.g., to form a finished, commercially marketable mass transfer device.

[0013] Mass transfer devices, and in particular the mass transfer devices according to the invention, are generally used to exchange substances between two exchange media, e.g., for the purpose of separation or targeted enrichment and / or depletion. To ensure this, membranes, e.g., flat membranes or hollow fibers, are used that possess a specific selectivity, in particular meaning that the membrane / hollow fiber walls are more permeable to certain substances compared to others. Such mass transfer devices, which can be coated or have been coated according to the invention, are generally also referred to as membrane contactors.

[0014] Hollow fibers with walls / membranes can be used for this purpose, in which mass transfer occurs by diffusion and / or through pores in the walls / membrane. The invention relating to the method and also to the mass transfer device relates to all possible types of membranes, in particular flat membranes or hollow fibers, especially porous, preferably microporous membranes, in particular whose pores are at least on average smaller than 1 micrometer in diameter.

[0015] Mass exchange devices of this type can, for example, be manufactured directly for use as blood oxygenators. The function of a blood oxygenator is such that blood flowing through one chamber is enriched with oxygen and depleted of carbon dioxide, while an oxygen-rich and carbon dioxide-poor gas or gas mixture flows through the other chamber, resulting in an equalization of the partial pressures of the gas components across at least one membrane. Such oxygenators can be used to support or replace lung function.

[0016] For this purpose, hydrophobic, especially semipermeable, hollow fibers are typically used, the walls of which form the membrane. The hydrophobic design prevents blood plasma from passing through the hollow fiber wall. Such oxygenators are well-established on the market and are considered high-priced. The membranes of these oxygenators are made, for example, of polymethylpentene. While the membrane is porous, it also has a thin, very unstable non-porous layer. Mass exchange thus occurs through diffusion.

[0017] Also known are mass transfer devices for use in dialysis. In contrast to their use in blood oxygenation, the membranes or hollow fibers used for dialysis are hydrophilic and porous. Commonly used hollow fibers are predominantly made of polysulfone or polyethersulfone, which are hydrophilized by a manufacturing-related proportion of polyvinylpyrrolidone. Due to the majority of polysulfone or polyethersulfone content, these devices are not hydrophilic.

[0018] Polyethersulfone hollow fibers are usually referred to simply as polysulfone hollow fibers. However, where the invention is described in relation to polysulfone fibers, both polysulfone and polyethersulfone are meant, particularly those containing polyvinylpyrrolidone.

[0019] Although these hollow fibers exhibit very good blood compatibility, they cannot be used for blood oxygenation because their hydrophilic nature makes them permeable to blood plasma. Due to their porous structure, the fibers would also be permeable to gas bubbles, potentially leading to gas bubble formation in the blood. Industrially manufactured mass transfer devices for dialysis are well-established on the market and significantly less expensive than those for blood oxygenation, primarily due to higher production volumes. However, because of the aforementioned hydrophilic properties of the fibers used, they cannot be used as oxygenators.

[0020] The invention can be used in mass transfer devices and in the process with all the aforementioned or even unmentioned types of hollow fiber and is not limited to mass transfer devices for blood treatment, but is preferably intended for use in these.

[0021] Against this background, prior art already included efforts to make mass transfer devices intended for dialysis hydrophobic by means of a coating, yet still selective for oxygen and / or carbon dioxide.

[0022] Publication DE 100 34 098 A1 by Fresenius Medical Care Deutschland GmbH already describes a process of the type mentioned above, in which porous hollow fibers, e.g., made of polysulfone, are coated with a hydrophobic layer, e.g., of silicone, which eliminates the hydrophilic property of the underlying hollow fiber. Silicone as a possible coating also proves to be diffusion-permeable to oxygen and carbon dioxide, particularly with a selectivity suitable for blood oxygenation, so that the mass exchange required for blood oxygenation appears to be fundamentally possible in silicone-coated dialyzers. The aforementioned publication, besides stating the fundamental possibility of such a procedure, does not mention any essential features for carrying out the process and provides no guidance for those skilled in the art regarding the practical implementation of the silicone coating.

[0023] Publication DE 10 2021 116 764 A1 of the same applicant further describes a method for coating hollow fibers with, for example, silicone as a coating, in which a coating agent is circulated through the mass transfer device to be coated. This process requires a large quantity of coating agent and thus results in correspondingly high consumption and costs. Due to the long contact time of the coating agent on the at least one membrane during the circulating process, the quantity of coating agent deposited on and / or into the membrane is difficult to control. This can also lead to an unnecessarily high quantity of coating agent introduced, which would not be required to achieve a seal against convective passage of an exchange medium through the at least one membrane and can, moreover, limit the exchange rate of the exchange medium by diffusion.For example, measurements on mass transfer devices coated with a recirculating coating agent showed that quantities of more than 20 grams of coating agent per square meter of membrane surface were introduced into the mass transfer device.

[0024] Against this background, it is an object of the invention to further develop the aforementioned method in such a way that coating is reliably possible even with small amounts of coating agent. It is also an object to provide mass transfer devices coated with a coating agent that offer a tightness against convective passage with smaller amounts of coating agent and whose exchange rate for diffusion is improved.

[0025] This problem is solved in the method by connecting a reservoir containing the coating agent to an inlet port of one of the two chamber areas, preferably to an inlet port of the second chamber area of ​​the at least one mass transfer device, wherein the volume of the coating agent entering the chamber area to be coated of the at least one mass transfer device is smaller than the total fillable volume of the chamber area of ​​the at least one mass transfer device to which the reservoir is connected, and by means of an acceleration force exerted on the coating agent, the coating agent is driven as a bolus from the inlet port to an outlet port of the chamber area along the at least one membrane through the chamber area.wherein the volume of the bolus of coating material decreases as it passes through the chamber area due to the deposition of coating material on the membrane surface and / or the incorporation of coating material into the pores of the at least one membrane, and the bolus of coating material with a residual volume exits the chamber area at the outlet connection, in particular being collected in a collection container.

[0026] Any coating agent suitable for creating a coating on the membrane surface and / or for being embedded in the pores of the at least one membrane is suitable. Preferably, an agent comprising or consisting of silicone is used, which is deposited by the method on the wall of the at least one membrane / hollow fiber and / or in the pores of the at least one membrane / hollow fiber. The invention can also provide for the deposition of other agents and is therefore not limited to silicone, although the latter is preferred.

[0027] The coating material can be, for example, a solution of a silicone material with a solvent; n-heptane can be used as the solvent. Suitable silicone materials for dilution with n-heptane include, for example, Rausik from Raumedic or SILPURAN 2400 A / B from Wacker.

[0028] Advantageously, a proportion of 0.2 volume parts silicone material to 2 volume parts silicone material, preferably 0.5 volume parts silicone material to 1 volume part silicone material in 10 volume parts of total coating material (silicone material plus solvent, in particular n-heptane) is used.

[0029] Unlike the aforementioned and known method of circulating a coating agent, which requires sufficiently good flowability and pumpability of the coating agent and therefore its dilution with a solvent, the invention preferably allows the use of a coating agent not diluted with a solvent. This is particularly advantageous because the acceleration force makes it possible to propel such coating agents along the membrane surface through a chamber. Preferably, the acceleration can be adapted to the coating agent used. For example, the product Elastosil RT 604 A / B from Wacker can be used as a solvent-free coating agent.

[0030] The use of coating material without dilution by a solvent can lead to a seal against convective passage of an exchange medium through a membrane even with small amounts of coating material, since no solvent components leave the created coating and thus a decrease in the material density of the coating due to solvent loss and any associated cavities in the coating do not occur.

[0031] The invention may also provide for the inclusion of further functional additives in the coating material, e.g., medications, e.g., anticoagulants, e.g., heparin. It may also provide for the inclusion of additives that improve thermal conductivity or for the use of a coating material, in particular a silicone-based coating material, which has better thermal conductivity compared to (pure) silicone. If such a silicone with better thermal conductivity is not approved for medical use, it may be possible to apply the coating in two stages, in particular by using an unapproved silicone and an approved silicone successively as coating materials.

[0032] The invention achieves that a quantity is sufficient as a coating agent for a single coating of at least one mass transfer device of the type mentioned for flow through the chamber area to be coated, which is smaller in volume than the total filling volume of the chamber area to be coated of the single mass transfer device connected to a reservoir or of the respective mass transfer device.

[0033] This is achieved by driving the coating agent through the chamber area to be coated as a bolus, i.e., depending on the chamber area, as a continuous plug of liquid or as a plug divided into the number of internal volumes of the hollow fibers, whereby the coating agent is deposited from the bolus onto the membrane surface and / or into the pores of the at least one membrane as the bolus moves through the chamber area, and thus the volume of the bolus effectively decreases from a starting volume as it passes through the chamber area, i.e., the bolus is consumed, wherein according to the invention the starting volume is defined such that a residual amount of bolus exits the chamber area to be coated.

[0034] This ensures that the bolus is not completely consumed within the chamber area and that no uncoated areas remain at the flow end of the chamber. The amount of coating material entering a chamber area from a reservoir is therefore always calculated to be large enough to coat all membrane areas to be coated, leaving a residual volume that then exits the chamber. This residual volume of the bolus can, for example, be collected in a container at the outlet of the at least one mass transfer device.

[0035] Preferably, the invention provides that during the coating process there is a period in which the bolus is entirely contained only within the chamber area to be coated. Thus, both the leading liquid front and the trailing liquid front of the bolus (or of all bolus components distributed across the internal volumes of the hollow fibers) are present in this chamber area. During this period, the reservoir is therefore already empty, but the collection container is not yet filled with the remainder of the bolus.

[0036] The initial volume of the bolus of coating material entering a respective chamber area to be coated is always smaller than the total filling volume of the respective chamber area to be coated and preferably less than or equal to 75%, further preferably less than or equal to 50%, further preferably less than or equal to 33% of the filling volume of the respective chamber area to be coated.

[0037] The invention advantageously reveals that the contact time of the coating agent on the membrane can be controlled and, in particular, kept shorter than would be possible if the coating agent were conveyed through the mass transfer device in a closed loop. Specifically, the contact time at each location on the membrane is determined by the period during which a membrane location is in contact with the bolus between the leading and trailing liquid fronts. This contact time can be readily controlled by the selected acceleration rate.

[0038] A preferred embodiment provides that, during the coating process, the bolus is subjected to an acceleration greater than 10 times the acceleration due to gravity, preferably greater than 100 times the acceleration due to gravity, preferably greater than 200 times the acceleration due to gravity, and more preferably greater than 300 times the acceleration due to gravity. Such accelerations can preferably be achieved using a centrifuge.

[0039] In particular, the invention can provide that, for coating a mass transfer device on one side of the at least one membrane, a bolus of coating agent is driven only once through the chamber area adjacent to that side. However, it is also possible to carry out the coating by driving a bolus of coating agent through a chamber area at least twice in succession. In a preferred embodiment, the invention provides that the reservoir is connected to a single mass transfer device and that the volume of the coating agent in the reservoir is smaller than the total volume to be filled of the chamber area to be coated of this single mass transfer device.

[0040] The invention can also provide that the reservoir is connected to several mass transfer devices, in particular to several identical mass transfer devices, and that the volume of the coating agent in the reservoir is smaller than the sum of all the volumes to be filled in the chamber areas to be coated in all mass transfer devices. Thus, it is provided that several mass transfer devices are coated simultaneously or in parallel with the coating agent in one reservoir, whereby the coating agent exiting the reservoir is distributed at least substantially evenly / in equal proportions among the respective chamber areas to be coated in all mass transfer devices. In this way, many mass transfer devices can be coated per unit of time, which is of interest for industrial applications.In one possible embodiment, the invention may provide that the acceleration force acting on the bolus of coating material is formed exclusively by the mass of the bolus of coating material subject to acceleration, i.e., acceleration force = mass η x acceleration.

[0041] Due to the consumption of the bolus through material deposition on the membrane surface / in the pores of at least one membrane / hollow fibers, the volume and thus the mass of the bolus decreases. This can cause the driving force to decrease as the bolus passes through the chamber, especially assuming constant acceleration.

[0042] In one embodiment, the invention may also provide that the acceleration force acting on the bolus of coating material is formed by the sum of the mass of the coating material and the mass of an accelerating mass following the coating material in the flow direction and acting on the coating material, in particular contacting it, which is subject to acceleration.

[0043] Such an accelerating mass can be formed, for example, by a piston that is slidably mounted in the reservoir of the coating material due to the acceleration and that propels the coating material forward in the direction of the acting acceleration. For example, the reservoir can be designed as a cylinder with such a slidable piston.

[0044] When the accelerating mass is formed by a piston, it is preferably provided that a region located between the coating material and the piston is ventable, e.g. by a valve arranged in the piston or in the reservoir, in particular a valve permeable to gas / air and impermeable to liquid, or a valve that is closed at positive pressure relative to the environment and open at negative pressure relative to the environment, in particular to ensure that after the piston reaches an end position in the reservoir, the aforementioned region in the flow direction in front of the piston, or between the piston and the coating material, is subject to pressure equalization and thus the coating material can be driven further by the acceleration when the effect of the piston on the coating material or the bolus ceases.Such an accelerating mass can preferably also be formed by a liquid accelerating agent that propels the coating agent in the direction of the acting acceleration. The accelerating mass can preferably be stored in the reservoir together with the coating agent in any embodiment.

[0045] If several mass transfer devices are coated from a single reservoir and a liquid accelerating mass acts on the coating agent in addition to its own mass, it is preferably provided that the liquid accelerating mass, like the coating agent, is also divided among the several chamber areas to be coated, in particular at least substantially in equal proportions.

[0046] Another preferred embodiment provides that during the passage of the bolus of coating material through the mass transfer device or its chamber area to be coated, the mass of the accelerating mass, in particular the mass of the liquid accelerating material which follows the bolus of coating material in the direction of flow, is increased.

[0047] For example, this can compensate for a mass loss caused by the coating in the bolus of the coating material. Likewise, this can ensure that a change in the viscosity of the coating material is at least partially compensated.

[0048] Such a change in viscosity, particularly an increase, can occur, for example, when a solvent is separated from the bolus through the pores of at least one membrane / the walls of the hollow fibers as the bolus passes through the chamber area, for example, if the pores have a higher permeability for the solvent than for the dissolved coating material. An increase in viscosity would reduce the velocity of the bolus with increasing distance traveled in the chamber area to be coated, and the increase in the mass of the accelerating mass would counteract this by increasing the driving force. The invention can also provide, particularly in combination with at least one of the aforementioned embodiments, that the acceleration, particularly with regard to its magnitude, is changed during the passage of the coating material bolus through the mass transfer device.This is particularly possible if the acceleration acting on the bolus and / or the accelerating mass is artificially generated, e.g. in a centrifuge.

[0049] A preferred embodiment provides that the acceleration force is generated solely by the acceleration due to gravity, which is exerted on the bolus of the coating material, and in particular on the acceleration mass, within the chamber. In this embodiment, no separate devices are required to generate acceleration.

[0050] The invention preferably also provides that the acceleration force is generated in a centrifuge by the centrifugal acceleration exerted on the bolus of the coating material, and in particular on the acceleration mass, within the chamber. This has the advantage that the acceleration can be specifically controlled.

[0051] For example, it can be provided that the rotational speed or rotational speed of the centrifuge and / or the radius on which the mass transfer device to be coated is moved by the centrifuge is changed as the bolus of coating agent and / or accelerant passes through the chamber, e.g., depending on the distance traveled by the bolus within the chamber. For example, the distance traveled by the bolus can be detected by an optical sensor through the exchange chamber wall, and the rotational speed and / or radius of the centrifuge can be changed based on the sensor reading.

[0052] For example, it may be provided that as the path of the bolus through the chamber area increases, which increases the radius of centrifugation and thus the effective acceleration, the rotational speed of the centrifuge is reduced, particularly to compensate for the increase in acceleration.

[0053] However, using a centrifuge to generate acceleration can also offer the advantage that the increase in acceleration associated with the increasing radius during bolus passage at least partially compensates for, or even overcompensates for, the mass loss of the bolus and / or an increase in the viscosity of the coating material. Depending on the requirements, it may also be possible to increase the rotational speed of the centrifuge as the bolus travels through the chamber.

[0054] In one possible embodiment, the invention preferably provides that, in the case of coating under the exclusive influence of gravity, the mass transfer device is positioned in an initial position such that the direction of the spacing between the inlet and outlet connections is oriented parallel to the effect of gravity, wherein the inlet connection is arranged below the outlet connection, in particular wherein the extent of the at least one membrane, preferably the axial extent of the hollow fibers, is oriented parallel to the effect of gravity, and the coating agent is injected in the initial position against the effect of gravity from the reservoir through the inlet connection up to the height range of the lower reservoir, in particular up to the upper edge of the lower reservoir.

[0055] The vertical region of the liner is preferably understood to be the region where at least one membrane is sealed against the exchange chamber wall to divide the exchange chamber, and in particular where several membranes are also sealed to each other. In the case of hollow fibers, this is particularly the case in a respective axial end region of the hollow fibers.

[0056] The mass transfer device is then rotated 180 degrees from its initial position to an end position in which the inlet is positioned above the outlet and the bolus is driven through the mass transfer device in the chamber solely by gravity. This can be done with or without the effect of an additional accelerating mass, in particular a liquid accelerating agent.

[0057] Filling the chamber area up to the height of the underlying potting unit has the advantage of ensuring that all membranes are initially wetted with coating agent, in particular that all hollow fibers have an initial partial filling, but only up to an area of ​​the potting unit where the membrane(s), especially the walls of the hollow fibers, are coated with coating agent and are therefore not effective in mass transfer anyway.

[0058] In the case of any type of generated or existing natural acceleration, the invention preferably provides that the entry of the coating agent from the reservoir into the at least one mass transfer device or the chamber area to be coated is controlled. For example, this can be achieved by controlling a valve arranged between the reservoir and the respective mass transfer device.

[0059] For example, in the case of a coating process under the influence of gravity, such control can be achieved manually or electronically. In a centrifuge or with other artificially generated acceleration, the control can be achieved, for example, electronically or by exceeding a limit acceleration, and in particular also automatically.

[0060] Particularly when acceleration is artificially generated, e.g. in a centrifuge, it can be ensured that the coating agent from the reservoir is only fed to the inlet of the respective chamber area of ​​the at least one mass transfer device when the required or desired acceleration has been reached, e.g. at a minimum speed of the centrifuge.

[0061] A preferred design, in all possible variations, provides that the bolus of coating material, along with its remaining volume, enters a collection container connected to the drain via a cross-sectionally reduced section or a one-way valve. The cross-sectional reduction or one-way valve ensures that the remaining volume cannot flow back into the previously coated chamber area after the driving acceleration ceases.

[0062] The invention preferably provides that, during the coating process in one chamber area to be coated, the other chamber area on the opposite side of the at least one membrane is open to the external environment. A further embodiment preferably provides that, during the coating process in one chamber area to be coated, the other chamber area on the opposite side of the at least one membrane is sealed off from the external environment, in particular by means of a fluid with a differential pressure, preferably an overpressure, compared to the chamber area in which the coating takes place.

[0063] In particular, this allows control over whether a significant amount of coating material enters the pores of at least one membrane, especially the hollow fibers, during the coating process. By applying overpressure in the other chamber area or on the other side of the membrane, the penetration of the coating material into the pores can be prevented or at least reduced.

[0064] The invention can also provide that, after coating in one of the chamber areas, in particular before solidification of the coating agent, this chamber area is pressurized by means of a fluid, in particular a gas or a liquid, preferably a solvent, such as n-heptane, whereby the coating agent located on the at least one membrane and / or in the pores of the at least one membrane is driven through the at least one membrane into the pores on the membrane side in the other chamber area.

[0065] Preferably, the coating agent is then removed from the chamber area where the coating was previously applied, in particular by rinsing with a solvent (n-heptane) or blowing with a gas.

[0066] This embodiment is preferably used when the at least one membrane to be coated, in particular hollow fibers to be coated, has an asymmetrical cross-sectional distribution of pores across the thickness of the hollow fiber wall, i.e., when the membrane side in one of the chamber regions has (at least on average) smaller pores than the membrane side in the other chamber region. This can be the case, for example, with polysulfone hollow fibers. The problem here would be that if the membrane is coated in the chamber region with the larger pores, the coating material would be lost too quickly into the depths of the pores, and the bolus could be used up too quickly.In such a case, the invention provides to carry out the coating in the chamber area in which the membrane side with the (at least on average) smaller pores is located and then to transfer the coating agent into the pores of the other side as described.

[0067] Further development preferably provides that at least one further bolus of a liquid component, in particular a bolus of at least two components layered in the direction of acceleration, is accelerated through the chamber area before and / or after the bolus of coating material.

[0068] Before the actual bolus of coating agent, for example, a conditioning agent for at least one membrane, especially the hollow fiber walls, can be driven through the chamber area, e.g., pure solvent such as n-heptane.

[0069] Following the bolus of coating material, at least one liquid component can serve as an accelerating mass acting on the bolus of coating material, whereby the at least one component can also have functional effects, such as washing out excess coating material, e.g., if one liquid component represents the solvent mentioned, e.g., n-heptane.

[0070] Such a liquid component can also perform anticoagulant conditioning of at least one membrane, particularly before and / or after the bolus of coating material.

[0071] Preferably, it is provided that the volume of the bolus of one liquid component and / or the volume of each component in a layered bolus is smaller than the total fillable volume of the chamber area to be coated.

[0072] Another preferred embodiment provides that, prior to the entry of the coating bolus into the chamber area, the coating bolus is formed by mixing at least two liquid components in a mixing arrangement located upstream of the inlet connection. The components are driven through this mixing arrangement, in particular by the same acceleration that also drives the mixed coating bolus formed thereafter. It can be provided that the components yet to be mixed are driven before the mixing arrangement with the same acceleration but with a different force than the bolus of the mixed coating material, for example, by applying an accelerating mass to the components yet to be mixed at the same acceleration, the mass of which is added to the masses of the two components in the resulting force.

[0073] Another embodiment may provide that a mass transfer device is coated according to the invention and, after coating, is divided into smaller units, in particular by cuts perpendicular to the longitudinal direction of the at least one membrane, in particular the longitudinal direction of hollow fibers in the coated mass transfer device.

[0074] This is particularly advantageous when the coated mass transfer device is not itself a commercially marketable product or directly usable in one, but rather a semi-finished product from which the finished end product is manufactured through further steps. In this way, several finished products can be produced from a single coated mass transfer device. It is preferably possible to recoat the side of the cut mass transfer device facing the cutting plane. This is especially feasible when the coating is applied inside hollow fibers, as the coating allows the coating agent to adhere to the outer surface of the hollow fibers in the usual manner without impairing its adhesion.

[0075] It is further preferably provided that, with the coating method according to the invention, an amount of less than 2 grams of coating agent per square meter of membrane surface, in particular silicone material per square meter of membrane surface, preferably less than 1 gram per square meter of membrane surface, preferably less than 0.5 grams per square meter of membrane surface, is deposited in the mass transfer device. Preferably, the membrane surface is considered on only one side of the membrane.

[0076] The problem is thus also solved by a mass transfer device of the type mentioned above, in which an amount of less than 2 grams of coating material per square meter of membrane surface, in particular silicone material per square meter of membrane surface, preferably less than 1 gram of coating material per square meter of membrane surface, preferably less than 0.5 grams of coating material per square meter of membrane surface, is deposited in the mass transfer device, in particular in / on the membrane. Here, too, the deposition on only one side of the membrane is preferably considered. A mass transfer device designed in this way can preferably be produced using the method according to the invention; in particular, according to the applicant's current knowledge, such a small deposited amount of coating material can only be achieved using the method according to the invention.

[0077] Preferably, even with such small quantities, compared to a coating where the coating agent is circulated through the mass transfer device, a seal against convective passage of an exchange medium through the membrane is achieved. Due to the small deposited amounts of coating agent, the diffusive passage of an exchange medium through the at least one membrane is further significantly improved compared to membranes with a higher deposited coating agent.

[0078] Preferably, the thickness of the coating produced with the coating material on the surface of the at least one membrane and / or in the pores of the at least one membrane can be less than 4 micrometers, preferably less than 3 micrometers, and more preferably less than 2 micrometers. In particular, the thickness is considered in a direction perpendicular to the membrane surface, and in the case of hollow fibers, especially in a radial direction perpendicular to their longitudinal extent. It is further preferred that the layer of coating material deposited on the membrane surface and a layer embedded in the pores of the membrane are both less than 1 micrometer, resulting in a total coating thickness of less than 2 micrometers.

[0079] The invention more preferably provides that a solvent-free coating agent, particularly one that is solvent-free at the time of coating application, is deposited on at least one side of the at least one membrane. Such a solvent-free coating agent preferably has a denser structure within the volume of the finished coating compared to a solvent-based coating agent. This preferably results in fewer voids in the volume of the coating produced, and in particular, improved sealing, or the achievement of sealing with lower quantities of the coating agent compared to solvent-based coatings. The invention is explained in more detail with reference to the following figures.

[0080] Figure 1 schematically visualizes the basic principle of the invention.

[0081] A mass transfer device 1 with an exchange chamber 2 is shown schematically. In this example, a plurality of hollow fibers 3 are arranged as at least one membrane in the chamber, the axial ends 4a and 4b of which are sealed to each other and to the wall of the exchange chamber 2 with a sealing compound 4c. Thus, a first chamber region 2a is formed in the exchange chamber 2, which borders the walls of the hollow fibers 3 on the outside, and a second chamber region 2b, which borders the walls of the hollow fibers 3 on the inside.

[0082] In an oxygenator application, for example, blood can flow around the hollow fibers 3 in the first chamber area 2a, and a gas (oxygen / air) can flow through the hollow fibers 3 in the second chamber area 2b. The chamber areas 2a and 2b are illustrated in Figure 2 using a hollow fiber 3 as a guide.

[0083] According to the invention, a bolus 5 of coating material is driven through one of the chamber regions, e.g. through the second chamber region 2b, which comprises the interior of the hollow fibers 3, via an inlet connection 8 (not shown here) with the acceleration due to gravity acting in the axial direction of the hollow fibers 3.

[0084] Bolus 5 is symbolically represented as a strip of equal width with different heights, which visualizes the decrease in volume of bolus 5 as it passes through the chamber area.

[0085] It can be seen that the bolus 5 enters the chamber region as an initial bolus 5a with an initial volume and loses volume during its stepwise passage through the chamber region, as shown here, due to the coating of the walls and the pores of the hollow fibers 3 during the passage, whereby the bolus 5 exits the chamber region as an end bolus 5b with a non-zero final volume. According to the invention, the initial volume is smaller than the total filling volume of the chamber region to be coated, here, for example, chamber region 2b.

[0086] Figure 1 also illustrates that the bolus is completely located within the chamber area during a certain period of time.

[0087] Figure 2 visualizes this situation using a single hollow fiber 3. The bolus, driven through the second chamber region 2b, which borders the interior of all hollow fibers 3, by acceleration, passes as a partial bolus 5' through each of the individual hollow fibers 3 of the entire hollow fiber bundle of the mass transfer device 1. The behavior of the partial bolus 5' in each hollow fiber 3 corresponds to the behavior of the entire bolus 5 passing through the second chamber region 2b in Figure 1. In particular, the volume of a partial bolus 5' within a single hollow fiber 3 is equal to the total volume of the bolus 5 in the chamber region 2b divided by the number of hollow fibers in the second chamber region 2b.

[0088] In step 1, it can be seen that the partial bolus 5'a enters the hollow fiber 3 with an initial volume. Through contact of the coating agent of the partial bolus 5' with the wall of the hollow fiber 3, a coating 6 is deposited on the wall of the hollow fiber 3 and / or coating agent is deposited into the pores of the wall. As a result, the volume and mass of the partial bolus 5' decrease continuously until, at the end of step 4, the partial bolus 5'b exits from the drain connection with its remaining volume.

[0089] Figure 3 illustrates a coating process in the Earth's gravitational field; thus, only the acceleration due to gravity acts on the bolus 5 of the coating agent 9. The upper row of illustrations shows that the mass transfer device 1 is oriented such that its inlet connection 8a is initially located below the upper outlet connection 8b. The hollow fibers 3 are oriented with their axial extent parallel to the direction of gravity, i.e., the acceleration due to gravity. Initially, the coating agent 9 is filled from the reservoir 7 through the inlet connection 8a into the second chamber 2b, which is connected to the interior of the hollow fibers 3, against the effect of the acceleration, i.e., from bottom to top. The coating agent 9 is filled to below the upper edge 0 of the reservoir 4c located at the lower axial end 4b of the hollow fibers 3.

[0090] After this filling, the mass transfer device is rotated 180 degrees, corresponding to the position shown in the bottom row of Figure 3. The coating agent 9 is now driven by gravity as a bolus, divided among all hollow fibers 3, through the second chamber section 2b and exits at the bottom as a final bolus 5b with the remaining volume from chamber section 2b. During this passage, the walls of all hollow fibers are coated and, if necessary,

[0091] Coating agent deposited in the pores of the walls.

[0092] In the lower row of Figure 3, the left illustration additionally shows that by changing the height of the initial bolus 5a of coating material 9 while keeping the volume constant, the effective hydrostatic pressure can be influenced.

[0093] After the exit of the end bolus 5b from the chamber area 2b, it may be provided that the chamber area 2b is purged with air or a solvent, e.g. with n-heptane as the solvent if the coating material comprises silicone, which is preferred.

[0094] Figure 4A illustrates a further development of the invention in which, in this case, a liquid accelerant 10 is arranged as an additional accelerating mass downstream of the bolus 5 of coating material 9 in the direction of flow. Here, it is preferably provided that the mass of the accelerant 10 is increased with increasing volume loss / mass loss in the bolus 5 of the coating material 9.

[0095] The accelerant 10 can be, for example, a solvent, e.g., n-heptane, if a silicone is used as a coating agent.

[0096] The increase in mass of the accelerant 10 is preferably carried out such that the total mass, consisting of the decreasing mass of the coating material 9 and the increasing mass of the accelerant 10, remains at least substantially constant. This ensures that the accelerating force acting on the accelerant remains constant as the bolus 5 of the coating material 9 passes through the chamber.

[0097] Figure 4B, in contrast, shows a modification in which the mass of the accelerator 10 is increased beyond the mass decrease of the coating agent 9 or the bolus 5, in particular such that the total fill height Ho of coating agent 9 and accelerator 10 remains at least substantially constant. This can, for example, additionally compensate for the fact that the viscosity of the coating agent 9 increases due to solvent filtration, which can cause a slowing of the flow velocity of the bolus 5. This can be countered by the additional mass increase of the accelerator 10.

[0098] Figure 5 shows the coating according to the invention using a centrifuge, which generates the acceleration to drive the bolus of the coating material. A simplified top view of the centrifuge plate 11 is shown.

[0099] For improved balancing, several mass transfer devices 1 are arranged on the centrifuge plate 11. A reservoir ? containing coating medium 9 is arranged at each chamber area of ​​the mass transfer device 1 to be coated. The inflow area 8a is formed by the transition from the reservoir 7 into the hollow fibers 3, for example, during the coating of the second chamber area 2b as described here. In the upper illustration of Figure 5, all reservoirs 7 are filled.

[0100] The lower illustration shows the situation after coating by centrifugation, i.e., after rotation of the centrifuge plate 11. The coating agent 9 has been driven as a bolus, as shown in Figure 2, through all the hollow fibers 3. The reservoir 7 is empty, and a residual bolus has entered the collection container 13 via the outlet port 12. The outlet port 12 or the collection container 13 may have a cross-sectional reduction or a one-way valve, particularly to prevent backflow of the coating agent 9. Figure 6 shows an embodiment in which the coating agent 9 is first mixed from two liquid components K1 and K2 in the centrifuge or on the centrifuge plate 11 before the coating agent 9, as a mixed bolus, is driven through the mass transfer device 1 by the acceleration generated by the centrifuge.

[0101] For this purpose, a piston 14 is arranged in the reservoir as an accelerating mass. Under the influence of the centrifuge's acceleration, the piston acts on the two components K1 and K2, pushing them through the mixing arrangement 15. A distributor 16 is preferably arranged downstream of the mixing arrangement to distribute the coating agent 9 evenly onto the hollow fibers 3 of the mass transfer device 1. The piston 14 acts only on the unmixed components K1 and K2. After passing through the mixer 15, the coating agent 9 is only subjected to acceleration due to the mass of the coating agent bolus. After passing through the chamber area, the final bolus, along with its remaining volume, enters the collection container 13.

[0102] Figure 7 shows an embodiment of the coating with a centrifuge, in which the bolus 5 of coating agent 9 is arranged here as one of several components K1, K2,... Kj in a sequence of several components layered in the direction of acceleration. Preferably, a component, e.g. K1, for conditioning the hollow fibers 3, e.g., consisting of a solvent, e.g. n-heptane, is provided leading the coating agent bolus, e.g., component K2, in the direction of acceleration.

[0103] In the direction of acceleration behind the bolus of the coating material, at least one further component Kj is provided, which acts as an accelerating mass, since it acts on the bolus of the coating material and which preferably also has a functional effect, e.g. is a component for rinsing out residual coating material, e.g. also from solvent, preferably n-heptane.

[0104] Here it can be seen that a piston with its mass also acts on the bolus of coating agent and the liquid accelerant. Preferably, to ensure its free movement, it is vented or pressure-relieved upstream in the reservoir, which contains all components. Figure 8 shows an embodiment in which several mass transfer devices 1 are coated simultaneously with the coating agent 9 in a common reservoir 7. The acceleration a, acting in the direction of the arrow, forces the coating agent 9 from the reservoir 7 into the respective chamber areas to be coated, e.g., chamber areas 2b, of the mass transfer devices 1.The total volume of the coating agent 9 in the reservoir is preferably divided equally between the respective mass transfer devices and forms a bolus according to the invention in each chamber area, the volume of which in the chamber area is less than the total filling volume of the chamber area. For this purpose, the coating agent can be guided through a distributor 16 arranged between the reservoir and the mass transfer devices 1. It is not shown that the respective residual bolus can be collected in a common collection container after the mass transfer devices 1. It is irrelevant whether the acceleration is generated by gravity or artificially, e.g., in a centrifuge.

[0105] Figure 9 shows an exemplary coating with acting gravity in the first chamber area 2a of a mass transfer device 1, i.e. the chamber area that borders the hollow fibers 3 on the outside.

[0106] On the left side of Figure 9, a reservoir 7 comprises several components, at least one of which forms the coating agent 9. Further components can be functional, e.g., for pre- or post-conditioning the hollow fibers 3 or acting as an accelerator mass or liquid accelerator. The reservoir 7 is connected via a supply line to the inlet port 8a of the chamber area 2a to be coated. The coating agent is fed from the inlet port 8a to the outside of the hollow fibers 3, makes contact with them, and flows as a bolus along the hollow fibers 3 to the outlet port 8b. The inlet port 8a and outlet port 8b can, for example, pass through a core onto which the hollow fibers 3 are wound.

[0107] The flow velocity can be reduced by means of the preferably provided clamp 17 in the line between reservoir 7 and mass transfer device 1. In the left part of Figure 9, the coating material and any other components are each subjected to only one force, which is determined by the acceleration and mass of the components.

[0108] In contrast, Figure 9 shows an otherwise identical arrangement on the right-hand side, in which the coating material 9 and, if applicable, further components K, which are layered with the coating material 9 in the reservoir ?, are driven by the acceleration mass m of a piston 14. For this purpose, the piston 14 can be, for example, sealed with at least one O-ring 17 and be displaceable in the cylindrical reservoir 7. The piston 14 has a valve 18 so that, after its stop in the reservoir ?, the components K can continue to move.

[0109] It may be provided here and generally that the at least one liquid component driving the bolus 5 of the coating agent 9, which forms an accelerator, has such a large volume, in particular which is larger than the total filling volume of the chamber area to be coated, so that it is ensured that with this component the bolus of the coating agent can be driven completely through the chamber area.

[0110] Figure 10 illustrates a variant of the process in which the coating takes place in one chamber area and the coating is then transferred through the membrane into the pores on the side of the other chamber area.

[0111] As previously shown in Figure 2, a single hollow fiber 3 is depicted, which has pores 3a symbolized in its wall. This fiber is initially coated in the chamber area 2b, for which the partial bolus 5'a with an initial volume is driven through the hollow fiber as bolus 5' and finally exits as the final bolus 5'b with the remaining volume. This situation can be seen at the end of the fourth line of the diagram in the process flow.

[0112] The lower row shows on the left that the pores 3a of the hollow fiber 3 are subsequently coated internally with the coating agent 9. Then, pressure is applied from the inside to the still liquid coating agent 9 using a fluid, preferably a solvent 20 (e.g., n-heptane when silicone is used as the coating agent), causing it to be transferred through the membrane wall into the pores 3a on the side of the other chamber area 2a. The fluid 20 is then removed. This is preferably carried out when the pores 3a on one side, the future target side where the coating is to be applied, are larger than the pores on the other side, from which the coating process is initiated. The different pore sizes are not shown in Figure 10.

[0113] Figure 11 shows scanning electron microscope images (top and bottom) of two different hollow fiber membranes as examples of membranes to which the aforementioned method of transferring the coating material between the membrane sides can be applied. Both images show that the pores of the membrane are smaller on the inner side compared to the outer side.

[0114] Figure 12 visualizes the result of a determination of the skin thickness inside the membrane of a hollow fiber, i.e. the thickness of the coating material deposited on the inner membrane surface as a result of the measurement at different flow rates with oxygen gas.

[0115] On average, all measurements show that the coating reduces the inner diameter of the hollow fiber membrane by the thickness of the coating layer, which here averages 0.62 micrometers. A total mass of 0.32 grams of coating material was deposited, of which 0.212 grams were deposited on the skin and 0.108 grams on the pores.

[0116] Figure 13 shows the result of a coating according to the prior art cited above of the same applicant, wherein coating material was pumped in a cycle through a mass exchange device.

[0117] This results in an average residence time (r). m ), which is expressed as a ratio of the module's filling volume (Vp) r ) to flow rate of the coating agent (adhesive / adhesive mixture) Q BM can be calculated. Shorter residence times could only be achieved at higher flow rates. This leads to higher pressure losses on the coating side and significantly different transmembrane pressures in the flow direction.

[0118] Here, according to the scanning electron microscope image of Figure 13, a total coating thickness of greater than 10 micrometers was achieved with a wall thickness of the hollow fiber, in particular the previously uncoated hollow fiber, of 30 micrometers.

[0119] In the coating process according to the invention, carried out by gravitational or centrifugal acceleration, the amount of coating agent is smaller (for example, half to one-third of the priming volume of the mass transfer device), so that, under the same pressure conditions, the movement of the coating agent can be faster (in particular, two or three times faster). This reduces the residence time of the coating agent on the membrane surface. Furthermore, the local pressure in the radial direction can be regulated, for example, in the centrifuge, via the rotational speed / radius of the centrifuge.

[0120] According to the invention, a coating thickness of less than 2 micrometers was achieved, as shown in Figure 14 for the same originally uncoated hollow fiber membrane that was also used in the coating according to Figure 13.

[0121] The advantages of the method according to the invention are thus clearly demonstrated.

Claims

Patent claims 1. Method for coating at least one mass transfer device (1), comprising an exchange chamber (2) in which at least one material-permeable, in particular porous, membrane (3) is arranged, in particular in which a plurality of material-permeable, in particular porous, hollow fibers (3) are arranged, wherein the exchange chamber (2) is divided by the at least one membrane (3) into a first chamber area (2a) in which the at least one membrane (3) can be contacted with a first exchange medium on a first membrane side and into a second chamber area (2b) in which the at least one membrane (3) can be contacted with a second exchange medium on a second membrane side, wherein a liquid coating agent (9), in particular a coating agent (9) comprising silicone, is filled into one of the two chamber areas (2a, 2b) and thereby the coating agent (9) is applied to the chamber area (2a, 2b).2b) assigned side of the at least one membrane (3) is deposited onto the membrane surface and / or into the pores (3a) of the at least one membrane (3), after which excess coating agent (9) is removed from the chamber area (2a, 2b), characterized in that a reservoir (7) containing the coating agent (9) is connected to an inlet port (8a) of one of the two chamber areas (2a, 2b), preferably to an inlet port (8a) of the second chamber area (2b) of the at least one mass transfer device (1), wherein the volume of the coating agent (9) entering the chamber area (2a, 2b) of the at least one mass transfer device (1) to be coated is smaller than the total fillable volume of the chamber area (2b) of the at least one mass transfer device (1) to which the reservoir (7) is connected,and by means of an acceleration force exerted on the coating material (9) the coating material (9) as a bolus (5) from the inlet connection (8a) to an outlet connection (8b) of the chamber area, (2a, 2b) is driven along the at least one membrane (3) through the chamber area (2a, 2b), wherein the volume of the bolus (5) of coating material (9) decreases as it passes through the chamber area (2a, 2b) due to the deposition of coating material (9) on the membrane surface and / or the incorporation of coating material (9) into the pores (3a) of the at least one membrane (3), and at the outlet connection (8b) the bolus (5) of coating material (9) with a residual volume exits the chamber area (2a, 2b), in particular being collected in a collection container (13).

2. Method according to claim 1, characterized in that the reservoir (7) a. is connected to a single mass transfer device (1) and the volume of the coating agent (9) in the reservoir (7) is smaller than the total volume to be filled of the chamber area (2a, 2b) to be coated, or b. is connected to several mass transfer devices (1), in particular several identical mass transfer devices (1), and the volume of the coating agent (9) in the reservoir (7) is smaller than the sum of all volumes to be filled of the chamber areas (2a, 2b) to be coated of all mass transfer devices (1).

3. A method according to one of the preceding claims, characterized in that the acceleration force acting on the bolus (5) of coating material (9) is formed by: a. exclusively only the mass of the bolus (5) of coating material (9) subject to acceleration, or b. by the sum of the mass of the coating material (9) and the mass of an accelerating mass (10, 14) following the coating material (9) in the flow direction and acting on it, in particular wherein the accelerating mass (10, 14) is formed by a piston (14) or a liquid accelerating medium (10). which propels the coating material (9) in the direction of the acting acceleration.

4. Method according to one of the preceding claims, characterized in that during the passage of the bolus (5) through the mass transfer device (1) the mass of the accelerating mass (10, 14), in particular the mass of the liquid accelerating agent (10) which follows the bolus (5) of coating agent (9) in the direction of flow, is increased, in particular to at least partially compensate for a mass loss and / or a change in viscosity of the coating agent (9) caused by the coating in the bolus (5) of the coating agent (9).

5. Method according to one of the preceding claims, characterized in that the acceleration, in particular with regard to its magnitude, is changed during the passage of the bolus (5) through the mass transfer device (1).

6. Method according to one of the preceding claims, characterized in that the acceleration force is generated a. exclusively by the acceleration due to gravity, which is exerted in the chamber area (2a, 2b) on the bolus (5) of the coating material (9), in particular also on the acceleration mass (10, 14), or b. in a centrifuge (11) by the centrifugal acceleration, which is exerted in the chamber area (2a, 2b) on the bolus (5) of the coating material (9), in particular also on the acceleration mass (10, 14).

7. Method according to one of the preceding claims, characterized in that, in the case of coating under the exclusive influence of gravity, a. in an initial position the mass transfer device (1) is positioned such that the direction of the spacing between inlet connection (8a) and outlet connection (8b) is parallel to the effect of the a. the coating agent (9) is oriented to the acceleration due to gravity, wherein the inlet connection (8a) is arranged below the outlet connection (8b), in particular wherein the extent of the at least one membrane (3), preferably the axial extent of the hollow fibers (3), is oriented parallel to the effect of the acceleration due to gravity, and b. the coating agent (9) is injected in the initial position against the effect of the acceleration due to gravity through the inlet connection up to the height range of the lower potting area (4c), in particular up to the upper edge of the lower potting area (4c), c. the mass transfer device (1) is rotated from the initial position by 180 degrees to an end position in which the inlet connection (8a) is arranged above the outlet connection (8b) and the bolus (5) is driven through the mass transfer device (1) arranged in the end position only by the acceleration due to gravity.

8. Method according to one of the preceding claims, characterized in that the entry of the coating agent (9) from the reservoir (7) into the at least one mass transfer device (1) is controlled, in particular by controlling a valve arranged between the reservoir (7) and the at least one mass transfer device (1).

9. Method according to one of the preceding claims, characterized in that the bolus (5) of coating material (9) with its residual volume enters a collection container (13) connected to the drain connection (8b) through a cross-sectionally reduced area or a one-way valve.

10. Method according to one of the preceding claims, characterized in that during the coating process the other chamber area (2a) is sealed off from the external environment, in particular by means of a fluid with a differential pressure, preferably an overpressure, relative to the chamber area (2b) in which the coating takes place.

11. Method according to one of the preceding claims, characterized in that after a coating in one of the chamber areas (2b), in particular in the chamber area (2b) in which the smaller pore cross-section is present of the two chamber areas (2a, 2b), this chamber area (2b) is pressurized by means of a fluid (20), in particular a gas or a liquid, preferably a solvent, whereby the coating agent (9) located on the at least one membrane (3) and / or in the pores (3a) of the at least one membrane (3) is driven through the at least one membrane into the pores (3a) on the membrane side in the other chamber area (2a).

12. Method according to one of the preceding claims, characterized in that at least one further bolus of a liquid component (K), in particular a bolus of at least two components (K) layered in the direction of acceleration, is accelerated through the chamber area (2a, 2b) before and / or after the bolus (5) of coating material (9), preferably as an accelerating mass (10) acting on the bolus of coating material (9).

13. Method according to one of the preceding claims, characterized in that before the entry of the bolus (5) of coating material (9) into the chamber area (2a, 2b) the bolus (5) of coating material (9) is formed by mixing at least two liquid components (K1 , K2) in a mixing arrangement (15) arranged upstream of the inlet connection, through which the components (K1 , K2) are driven, in particular by means of the same acceleration that also drives the bolus (5) of coating material (9).

14. Method according to one of the preceding claims, characterized in that at least one of the following features is present: a. an amount of coating material, in particular silicone material, is deposited in / on the membrane, in particular on one side of the membrane, which is less than 2 grams per square meter of membrane surface, preferably less than 1 gram per square meter of membrane surface, preferably less than 0.5 grams per square meter of membrane surface, and / or b. The coating produced with the coating agent has a thickness on the surface of the at least one membrane and / or in the pores of the at least one membrane that is less than 4 micrometers, preferably less than 3 micrometers, more preferably less than 2 micrometers, preferably wherein a layer of coating agent deposited on the membrane surface is thinner than 1 micrometer and a layer deposited in the pores of the membrane is thinner than 1 micrometer, and / or c. a solvent-free coating agent is deposited in / on at least one side of the at least one membrane, and / or d. the acceleration acting on the bolus is greater than 10 times the acceleration due to gravity, preferably greater than 100 times the acceleration due to gravity, more preferably greater than 200 times the acceleration due to gravity, more preferably greater than 300 times the acceleration due to gravity.

15. Mass transfer device (1) comprising an exchange chamber (2) in which at least one material-permeable, in particular porous, membrane (3) is arranged, in particular in which a plurality of material-permeable, in particular porous, hollow fibers (3) are arranged, wherein the exchange chamber (2) is divided by the at least one membrane (3) into a first chamber region (2a) in which the at least one membrane (3) can be contacted with a first exchange medium on a first membrane side and into a second chamber region (2b) in which the at least one membrane (3) can be contacted with a second exchange medium on a second membrane side, wherein a coating agent (9), in particular a coating agent (9) comprising a silicone, is applied to the membrane surface and / or into the pores (3a) of the at least one membrane (3) on at least one side of the at least one membrane (3) that is associated with one of the chamber regions (2a, 2b).is separated, in particular by a method according to one of the preceding claims, characterized in that the substance deposited on the membrane, in particular on one side of the membrane, The amount of coating material, in particular silicone material, is less than 2 grams per square meter of membrane surface, preferably less than 1 gram per square meter of membrane surface, preferably less than 0.5 grams per square meter.

16. Mass transfer device (1) according to claim 15, characterized in that the thickness of the coating produced with the coating agent on the surface of the at least one membrane and / or in the pores of the at least one membrane is less than 4 micrometers, preferably less than 3 micrometers, more preferably less than 2 micrometers, preferably wherein a layer of coating agent deposited on the membrane surface is thinner than 1 micrometer and a layer deposited in the pores of the membrane is thinner than 1 micrometer.

17. Mass transfer device (1 ) according to claim 16, characterized in that a solvent-free coating material, in particular solvent-free at the time of coating, is deposited in / on at least one side of the at least one membrane.

Images