Process For The Manufacture Of Capillary Exchangers

Abstract

A process for the manufacture of capillary exchangers in which the capillaries are arranged side by side in spaced relationship to each other, is described and comprises the steps of A. coating the end zones of a number of capillaries produced in the above-described manner and still containing their auxiliary cores, with reinforcing mantles of a material capable of superficially dissolving the wall of the capillary during its application; B. arranging these capillaries in a bundle leaving spaces between them for the flow of a liquid or gaseous medium therethrough; C. pouring between the reinforcing mantles at one end of the bundle a layer of a hardenable material capable of adhering sealingly to the said mantles, whereby the ends of the capillaries at the level of their adjacent reinforcing mantles are embedded in a transverse wall formed by said material after hardening, and D. removing the auxiliary cores from the capillaries before or after step (c).

Parent Case Text

This application is a continuation-in-part of our pending patent application, Ser. No. 831,174, filed June 6, 1969.

Description

DESCRIPTION OF INVENTION

The invention concerns a process for the manufacture of capillary exchangers.

Capillary exchangers have many applications, e.g., as exchangers for gases or components of solutions, for heat exchange and the like, and, especially as dialyzers for the purification of blood, in so-called artificial kidneys.

The manufacture of truly unobjectionable membrane capillary exchangers for the last-named purpose has met with considerable difficulties in the past. It is necessary to avoid the formation of thrombi in the blood and leaks in the capillaries especially where they are embedded in the walls of the dialyzer, and elsewhere, which leaks occur especially in the form of so-called pinholes. Of course, it is desirable to obtain a maximum purifying effect in the smallest possible quantity of blood which is to remain the shortest time possible outside the body of the patient.

Capillary exchangers have been used as artificial kidneys which suffer, however, from a number of drawbacks. Above all, the sealing of the capillaries, especially near their open ends, where they are embedded in the necessary transverse walls of the exchanger, often leaves much to be desired. Shearing stresses exerted on the capillary at the embedded zones thereof are considerable and may lead to rupture. Leaks which are difficult to avoid may also occur at these zones.

Permeability separating apparatus have been described in U.S. Pat. No. 3,228,877 issued Jan. 11, 1966 to Henry I. Mahon, and in U.S. Pat. application, Ser. No. 57,055 filed on June 25, 1964 (which became known through the publication of Dutch Pat. application Ser. No. 269,380 on June 25, 1964), in which systems bundles of capillary fibers are sealed each in a bore in a transverse wall, each bundle containing a smaller or larger number, e.g., thousands, of such fibers. Such a bundle is inserted into a bore in the said wall and may then be cemented in the bore by pouring a suitable cement, e.g., a heat-hardenable synthetic rubber of phenolformaldehyde or acrylic resin into the bore between the wall of the latter and the bundle. The capillary openings at the end of the bundle which protrudes a short way from the transverse wall should be sealed by a substance which is not compatible with the cement, whereby the latter is prevented from penetrating into the capillaries. The ends of the capillaries can then be cut off.

This method of cementing the capillary bundles in bores of a transverse wall has, however, a number of obvious drawbacks. Thus, it is difficult to control the length of the zone along which the cement will spread over the capillaries while it is still in the liquid or molten state. Also a uniform cementing of all capillaries of the bundle in the bore cannot be guaranteed as the capillaries contact each other in the bundle in an irregular pattern. Penetration of the cement into any interstices between the individual capillaries must needs be irregular and incomplete.

In the German Auslegeschrift No. 1,226,988 of Oct. 20, 1966 by Hans-Joachim Dietzsch, a process for cementing capillaries in a transverse wall has been described, whereby the individual capillaries are provided near their ends, with coatings of a substance which becomes tacky when heated. The end-coated capillaries are then held suitably in spaced relationship with the coatings contacting each other, the coatings are then heated or softened and rendered tacky by application of a suitable solvent so that the coatings all adhere to each other and, with the optional application of pressure and/or with the aid of layers or strips of equally tacky material which are interposed between the coatings of the capillaries, the whole is combined to form a transverse wall which becomes rigid upon cooling or upon evaporation of the solvent.

However, it is quite difficult to soften the coatings in the bundle evenly and to form a uniform, equally thick layer free from air bubbled and leaks. Moreover, this method requires a horizontal positioning of the capillaries when combining the coatings to form the transverse wall in order to avoid downward flow of the re-molten material which may lead to very irregular wall-formation and closing of the capillary openings.

It is therefore a first object of the present invention to avoid such drawbacks and to produce a capillary exchanger apparatus in an industrially feasible process for mass production distinguished by excellent tensile strength and stability of the mounting of the capillaries in the end plates.

The process according to the invention leads to an improved capillary exchanger which, in addition to other above-mentioned advantages, make its use as an artificial kidney safe against thrombus-formation and leakage of blood from the capillaries.

The process according to the invention, which permits attainment of these objects and advantages, serves to produce a membrane capillary exchanger in which the capillaries are arranged side by side in spaced relationship to each other and are obtained by applying to an auxiliary core one or several membrane layers from a solution or solutions of substances capable of forming the membrane itself or an intermediate product convertible to the latter substance, and, in the latter case, subsequently converting the layer of intermediate product into the substance forming the membrane, the end zones of each capillary then being coated with reinforcing mantles, and in which the ends of the capillaries are maintained open, or are re-opened, during production of the exchanger, and comprises the steps of:

a. coating the end zones of a number of capillaries produced in the above-described manner and still containing their auxiliary cores, with reinforcing mantles of a material capable of superficially dissolving the wall of the capillary during its application;

b. arranging these capillaries in a bundle leaving spaces between them for the flow of a liquid or gaseous medium therethrough;

c. pouring between the reinforcing mantles at one end of the bundle a layer of a hardenable material capable of adhering sealingly to the said mantles, whereby the ends of the capillaries at the level of their adjacent reinforcing mantles are embedded in a transverse wall formed by said material after hardening, and

d. removing the auxiliary cores from the capillaries before or after step (c).

Preferably, the thickness of the poured and hardened transverse wall is limited so that the ends of the reinforcing mantles situated towards the central regions of the capillaries protrude from the transverse wall.

It is also advantageous to insert the capillaries which still contain the auxiliary core into distancing means and hold them therein, whereby the capillaries are maintained spaced from one another throughout the process, whereupon, in a preferred mode of carrying out the process in practice, one end of the bundle of capillaries thus held is introduced from above into a separating agent present in a casting mold; then a layer of the hardenable material is poured onto the surface of the separating agent, the material is hardened and the casting mold and the separating agent therein are then removed from the ends of the capillaries, while the auxiliary cores are removed from the interior of the capillaries in a manner known per se before or after application of the poured-on layer. Preferably, the poured-on layer is only so thick that it does not reach the surface of the capillaries above the reinforcing mantles, thus preventing formation of pinholes and other structural weakening of the capillary walls. It is possible to carry out the removal of the auxiliary cores from the interior of the capillaries before introduction of the capillaries into the separating agent in the mold, especially when the cores are to be removed by melting. On the other hand, the removal of the auxiliary cores from the capillaries can be carried out after the hardening of the poured-on layer, especially when such removal is brought about by dissolving the cores.

In particular, the removal of the auxiliary core can be accomplished either by dissolving out the auxiliary core with a solvent which dissolves the said core but not the membrane capillary substance nor the said intermediary substance; or, in case the auxiliary core is made of a substance with a melting point below the melting point of the membrane capillary substance or the material of the poured-on layer, it can be melted out of the interior of the capillaries.

The finished capillary exchanger possesses an exchanging surface formed by the capillaries. These capillaries with their open end faces or the adjacent zones thereof are sealingly embedded in the transverse walls described above which separate the space surrounding the capillaries from feed or collecting chambers and the exchange between the interior of the capillaries and the intercapillary space, i.e., the space surrounding the capillaries can take place in one or in both directions.

In the process according to the invention the abovementioned membrane layers are applied to the auxiliary cores by lacquering or spraying them with drying and/or curable lacquers, solutions of cellulose ester, cellulose ethers, casting resins or other resin forming liquid or pasty substances, such as, e.g., silicone rubber.

The application of one or preferably several coatings onto the auxiliary core is performed advantageously by using a solution of an intermediary substance which can be converted into the membrane substance, and the wall consisting of said intermediary substance is later converted by drying, curing or a suitable chemical treatment into the final substance forming the membrane capillary.

The dissolving or melting out of the auxiliary cores is preferably performed after the hardening of the layer or layers of casting material which form the walls of the intercapillary space extending transversely to the capillary tubes.

It is particularly important that at least one of the two zones adjacent the ends of each of the capillaries is coated on the outer circumference thereof with a reinforcing mantle, before the above-mentioned introduction into the distancing and holding means, thus improving the stability of the mounting of the capillaries in the layer of casting material forming the transverse wall.

Such reinforcing mantles are applied to the end zones of the capillaries as coatings, consisting, e.g., of lacquer, of casting resins capable of being hardened after application, of of deposits of metal, preferably to be produced by galvanic methods.

According to the invention, such reinforcing mantles substantially improve the adherence of the end zones of the capillaries to the hardened layer of casting material forming the transverse wall. This is, for example, the case when the reinforcing mantles consist of silicone resins or metal. On the other hand these reinforcing mantles substantially strengthen the capillary end zones in the vicinity of the hardened cast layer which surrounds them. Preferably, the auxiliary mantles consist of lacquer components such as acetyl cellulose, of hardened layers of casting resins such as epoxide resins, or of metal.

According to a further mode of carrying out the process according to the invention, when the layer of casting material is poured onto the holding means to engage the capillary end, a preferably prefabricated frame surrounding the entire bundle of capillaries is also placed on the holding means about the ends of the membrane capillaries or intermediary capillaries of the bundle so that the frame is also embedded in the cast layer forming the transverse wall. This frame can be provided with appropriate projecting rims or indentations which form-lock with the final hardened cast layer so that the frame and the cast layer are very firmly joined together.

In the process according to the invention, the capillaries are bundled either in a two-dimensional arrangement so that, e.g., a single row of capillaries arranged parallel to each other is obtained, or preferably in a three-dimensional arrangement composed of a plurality of such rows. The individual capillaries are first inserted into spacing tubes and then optionally conducted from these into spacers which remain in the bundle and hold the capillaries at least until the layer or layers of casting material have been poured onto the holding means, or still better, until the layer or layers of cast material have been hardened.

The bundle of the capillaries which are in the distancing and holding means or spacers can be treated at both end thereof as described above for casting the layer or layers of material at the end zones of the capillaries.

The capillary ends at one end of the capillary bundle are preferably inserted vertically into the separating agent in a casting mold. This separating agent consists of an easily deformable substance which is always or temporarily in a liquid state, or a paste or gelatinous mass preferably having a smooth surface; this agent must be inert to the capillaries and also to the casting material used for the cast layer and must not become bonded to the latter upon cooling. The capillary ends of the bundle are, e.g., pressed or inserted without pressure into the separating agent, depending on the consistency of the latter.

After the drying or hardening of the cast layer, the separating agent is removed by simple measures such as by heating, or by dissolving in suitable solvents.

In the initial stages of the process, according to the invention, the capillaries are arranged into a bundle by first arranging the capillaries in a preferably single layer, which can be compared with the warp of a fabric as used in the textile industry, then cutting off segments of such a single-layered arrangement of capillaries, and combining a plurality of such segments to a bundle consisting of a plurality of layers.

The operations described below, which primarily concern the end zones of capillaries are preferably performed on a single row of capillaries. They can, however, also be performed on a multilayered bundle of capillaries.

Many of these operations, such as, e.g., lacquering, hardening of hardenable coating substances, metallizing, etc. are more readily performed on single layers than on multi-layered bundles.

According to the invention, spacers can be used to arrange the capillaries in bundles, which spacers remain in the bundle when the end zones of the capillaries are embedded in the poured-on material forming the transverse wall; the spacers can then be removed from the bundle or left in the same as desired.

A specific embodiment of the invention comprises embedding the spacers together with the capillary end zones in a layer of casting material in which, preferably, a prefabricated frame is fixed at the same time.

The accompanying drawings illustrate several embodiments of the invention more in detail.

For the sake of clarity, the drawings are in places distorted and out of proportion, they also contain fewer elements than in practice. Thus the number of capillaries in the single "warp beam" row of capillaries can be several thousand, the number of capillaries per exchanger bundle several hundred thousand.

In the drawings:

FIG. 1 represents in a partial view and in perspective an apparatus for bundling the capillaries;

FIG. 2 shows the same apparatus schematically in a lateral view;

FIGS. 3 to 7 illustrate schematically successive stages of introducing the capillary bundle into distancing and holding means;

FIGS. 8 to 10 illustrate schematically several embodiments and modes of application of the distances and holding means;

FIGS. 11 and 12 illustrate successive stages of the process in order to apply reinforcing coatings to the capillary end zones;

FIGS. 13 to 16 illustrate successive stages of applying a cast layer forming a transverse wall in which the capillaries are embedded;

FIGS. 17 and 18 show other modes of carrying out in practice the steps illustrated in FIGS. 16 and 15, respectively;

FIGS. 19 and 20 illustrate the same process stages as FIGS. 15 and 16, but with simultaneous introduction of a frame into the casting mold;

FIG. 21 shows in a longitudinal sectional view a first embodiment of a membrane capillary exchanger manufactured by the process according to the invention, in which inlet and outlet chambers are shown schematically;

FIG. 22 shows a top view of the exchanger of FIG. 21;

FIG. 23 illustrates a further embodiment of a capillary exchanger in longitudinal section, in which the inlet and outlet chambers are not shown;

FIG. 24 is a top view of the exchanger shown in FIG. 23; and

FIG. 25 shows schematically and in longitudinal section a further preferred embodiment of a membrane capillary exchanger manufactured by the process according to the invention.

FIG. 1 shows such a "warp beam"-type of single-layer, side-by-side arrangement of capillaries 1 on a roller 2. This single layer arrangement of the capillaries is unrolled from the roller 2 in the direction of the arrow 3, conveyed to a storage holder 4 and inserted into it. The storage holder 4 consists of a plurality of rows of bores or channels 5, which can be provided by rows of tubes 6. Advantageously, each bore 5 is destined for receiving a single capillary 1.

The introduction of the capillaries 1 into the storage holder 4 is preferably accomplished by filling one row at a time of the bores 5 with a layer of the capillaries 1. For this purpose the capillaries are led through a guide plate 7 provided with holes 5', which plate can be moved parallel to itself upwardly or downwardly as indicated by the double arrow 8.

After one layer of capillaries has been inserted into the storage holder, the knife 9 (not shown in FIG. 1, see FIG. 2) cuts off this layer of capillaries at position 10.

After moving the guide plate 7 the distance of one row of bores, the process described for introducing the capillaries can be repeated. The layer of capillaries can be conveyed for introduction into the storage holder 4, by means of the pair of rollers 11 (also only shown in FIG. 2), which is accordingly driven intermittently in the direction of rotation of arrow 12.

FIG. 2 shows schematically a side view of the same apparatus as is shown in FIG. 1. In FIG. 1 only the front portion of the storage holder 4 is shown in perspective view, FIG. 2 shows its whole length. In both figures the lower row of the bores 5 is already filled with capillaries 1. The capillaries 1 are shown in lateral unsectioned view in all of the figures of the drawings.

Preferably the bores 5 are open at both ends of the storage holder 4 and the length of the storage holder is less than the length of the capillary segments, so that these, as shown in FIG. 3, can protrude a short distance from both ends of the storage holder.

Furthermore, it is suggested that the rear ends 13 of the bores 5 or the tubes 6 are tapered or bent inwardly so that their rear orifices are narrower than their front orifices.

After the storage holder 4 has been completely filled with capillary segments 1, as shown in FIG. 3, spacers 14, consisting, for instance, of one or more woven pieces, the apertures of which are of the same size or larger than the diameter of the capillaries 1, while the distance between the apertures corresponds to the spacing of the bores of the storage holder, which spacers are located at one end of the storage holder, are appropriately brought into position (FIG. 4), advantageously at the end at which the tapered ends 13 of the bores are to be found.

These spacers will hold the capillaries 1, which in practice are never exactly parallel, by friction at the walls of the openings in the spacers, so that the capillaries will not slide out of the spacers even when the bundle is brought to the vertical position shown in FIG. 11 to 20.

In FIG. 4 the following process step is illustrated: the capillaries 1 are inserted by the pusher 15 through the storage holder and the front ends thereof are pushed into the spacers 14 to be in frictional engagement with the latter. Then all of the capillaries are drawn with the aid of the spacers 14 to the left in FIG. 6, i.e., out of the storage holder; at the same time or subsequently the spacers are distributed over the entire length of the bundle of capillaries until the latter are finally borne only by the spacers 14, namely, after the capillaries have been completely withdrawn from the storage holder (FIG. 7). These operations can be performed by hand or these movements can also be carried out automatically by known mechanical means (not shown). It is also possible to place the capillaries directly into the spacers without the intermediary use of a storage holder.

Spacers can be, for instance, perforated sheets or woven material, as shown in section in FIG. 8, or combs the teeth of which have been laid across each other, as shown in FIGS. 9a and 9b (separated position) and FIG. 9 (crossed position, in which the capillaries 1 have been inserted). In some of the apertures of the spacers according to FIGS. 8 and 9, capillaries 1 of the capillary bundle have been inserted in a manner corresponding to FIG. 7.

FIG. 10 shows an embodiment of the spacers 14 constructed as an inset unit; these spacers are formed by flat walls 114 and corrugated walls 115, which are joined together in such a way that channels 116 are formed between them in which the capillaries 101 are placed.

FIG. 25 contains further modifications of spacers 214 serving as inset unit.

FIGS. 11 to 16 show the subsequent operations to which the capillary bundle is then subjected.

The capillary ends are strengthened by auxiliary, reinforcing mantles 20 before the formation of the hardened layer of casting material 18. These reinforcing mantles can be formed, for example, by dipping the entire multilayered arrangement of capillary ends according to FIG. 11 into a lacquer or a casting resin and subsequently drying and/or curing the coatings, at the dipped-in capillary ends, or also by deposition of metal with or without the aid of electrolytic processes, the latter, for example, by silver reduction after the capillary ends have been made conductive. In FIG. 13 this bundle is placed with the capillaries in vertical position above a layer of a separating agent 17 having an even and smooth surface, which has been poured into a trough 16. The lower ends of the capillaries are dipped or inserted into this layer of holding agent (FIG. 14). Then, as shown in FIG. 15, a layer 18 of casting material is poured onto the surface of the holding layer 17 and between the capillaries, and the cast layer is then hardened in the mold constituted by the surface of the holding agent 17 and the walls of trough 16. After this hardening process, or also during it, the capillary bundle together with the said poured-on and hardened layer 18 of cast material is withdrawn from the holding means 17 (FIG. 16).

The reinforcing mantles 20 are preferably so short, that, as shown in FIG. 16 they protrude beyond the hardened layer of casting material 18, or, as shown in FIG. 17 they do not protrude beyond the layer of casting material 18 but are covered by the latter.

FIG. 17 illustrates a further modification of the treatment of the end face zones on the capillaries. The underside of the hardened layer of casting material together with the protruding ends of the capillaries can be finished by machining operations (e.g., by milling or smoothing), so that the capillaries terminate flush with the hardened layer of casting material forming the transverse wall.

This could also be done in the case of the embodiment shown in FIG. 16.

After these operations have been completed, the other end of the capillary bundle can also be provided with a layer of hardened casting material in the same manner as described above and illustrated in FIGS. 11 to 16, by rotating the bundle by 180.degree. and repeating these steps.

FIG. 18 shows a modification of this process whereby an exchanger is produced in which the capillaries are closer to each other in their end face zone than in the adjacent zone of the exchanger. The reinforcing mantles are not shown in this figure. If, on the other hand, it is desirable to have capillaries spaced wider apart, in the zone in which they are embedded in the terminal face walls as well as in any other zones of the exchanger, the process steps shown in FIGS. 13 to 17 will afford this result. An embodiment of a capillary exchanger according to the invention in which the capillaries are arranged to meet this requirement illustrates a preferred feature of the invention.

The spacers 14 can, for example, remain or be removed after the production of the layers of hardened cast material 18. This can be done by pulling out the spacers or by dissolving them in a solvent.

FIGS. 19 and 20 illustrate a further modification of the process stages illustrated in FIGS. 15 and 16. Here, a prefabricated frame 21 is simultaneously embedded into the layer of casting material 18 at the time of the production of this layer. Preferably the frame 21 is provided with a projecting rim 22, so that the layer of casting material 18 is fastened onto the inward side of the frame by form-locking serration. The frame can be joined with the opposite frame and spaced from it by distancing bolts or posts 23 as can be seen in FIGS. 21 and 22 which represent side view and top view of a complete exchanger.

Analogously, FIGS. 23 and 24 show an exchanger having a non-rectangular frame.

In FIG. 21, in addition, there is shown a pair of supply or collecting chambers 24, one connected to each side of the exchanger, which supply chambers assure the collective supply and removal of the intracapillary substance to and from all of the capillaries through the feed pipes 25.

Finally, FIG. 25 shows in longitudinal sectional view a multiple counter-current exchanger produced according to a preferred mode of the process according to the invention, which exchanger consists of an outer casing 221 having end walls 200 and 200a and containing an arrangement of several single-layered rows 210a to 210f mounted therein, which rows are made up of capillaries which are arranged in parallel and from the center row outward, and of diminishing length, each of said rows consisting of one layer of capillaries 201 which at their ends 201a and 201b are sealingly embedded with broadened foot portions 234 of their reinforcing mantles 220 in transverse walls 239, 240 which are disposed spaced from the end walls 200 and 200a of the casing 221.

The capillaries 201 extend each through a duct 206, and the ducts are joined at their open ends to form transverse walls 237 and 238, the whole constituting and inset unit 236. Transverse wall 237 of unit 236 is plane and the other transverse wall, 238, is convex and, preferably, more strongly curved than the adjacent transverse wall 240 formed by the poured-on layer 218 and foot portions 234 of reinforcing mantles 220. The reinforcing mantles 220 extend along the capillaries into the end regions of tubular ducts 206 of inset unit 236.

Transverse wall 239 and end wall 200 as well as the portion of the adjacent side wall of casing 221 enclose a space 247 serving as an inlet chamber having a central inlet opening 248 for a first fluid F.sub.1 which is to be passed through the capillaries 201.

Transverse wall 240 and the adjacent end wall 200a and side wall of casing 221 enclose a second space 249 serving as a collecting basin at the bottom of the exchanger and being provided with a discharge pipe 250, preferably provided with a discharge valve, through which treated fluid F.sub.1 ' from the capillaries can be discharged from the exchanger.

Between convex transverse wall 240 and inner transverse wall 238, a chamber 242 is provided in the casing 221, which chamber owing to the stronger curvature of wall 238, has a smaller cross-section in its central zone than at its outer zones. When feeding fluid F.sub.2 into the chamber 242 through the inlets 243, 244, the fluid is thus caused to circulate about the central zone within the chamber, which fact substantially contributes to an even, radially symmetric entry of the fluid into the tubular ducts 206.

The tubular channels 206 are narrowed in the vicinity of their open ends at 206a and 206b, which contributes to an even distribution of the fluid F.sub.2 and by obstruction causes a slowing down of the flow rate of the fluid F.sub.2 through the tubular channels 206.

Fluid F.sub.2 ' resulting from fluid F.sub.2 by the exchange taking place through the walls of capillaries 201, gathers in a chamber 245 provided between transverse walls 237 and 239 in casing 221 and is discharged from the latter through outlet openings 246.

The walls of the capillaries of the exchanger produced according to the invention can be formed of one or several layers. The membrane coatings forming the walls of the capillaries can consist of inorganic, organic or metallic materials. Organic membranes, can, for example, consist of cellulose hydrate. They can be produced, e.g., by the process described in French Pat. No. 1,539,221, issued on Aug. 31, 1967.

The capillaries can thus be produced as coated layers on auxiliary cores, these auxiliary cores being prefabricated solid threads and wires, or threads and wires which are themselves capillaries, said cores being composed of substances which are relatively easily soluble and/or relatively easily fusible compared with the membrane coatings or intermediary substances, and said cores are then removed by dissolving and/or melting them out of the coatings forming the capillaries proper. The coating layer on the auxiliary core can, for example, be produced by lacquering or spraying the auxiliary core with drying and/or hardening lacquers, casting resins or other cross-linking, fluid or pasty substances such as silicone rubber. The auxiliary cores can, for example, consist of polystyrene polyvinyl acetate or wax; the specific solvent therefor can, e.g., be trichloroethane, benzine or the like.

The dissolving out and/or melting out of the core can, according to the invention, be performed simultaneously on all of the capillaries, preferably after the formation of the hardened layer of casting material 18 or 218.

The diameter of the capillaries is preferably in the range of from 0.1 to 5 mm; the distances between them in the capillary bundle of the exchanger have similar dimensions.

The material of the hardened layer of casting material 18, 218 consists of substances which have been hardened or cross-linked by thermal, drying and/or chemical processes, which substances were capable of being cast or were in the form of pastes before these processes were effected; such substances are, for example, acetyl cellulose, epoxy resins, polyester resins, polymethacrylates, single and multiple-component silicone rubbers, pastes of metal/synthetic materials, etc.

As holding agent 17, for example, gelatin/water mixtures, waxes and silicone resins can be employed. Examples of solvents which are inert towards the casting material and the capillaries, and which can be employed to dissolve the holding agent are, e.g., water, alcohol, benzine and the like. The material of the frame 21 and the distancing bolts 23 can consist of metal or synthetic material (such as polypropylene).

The material of the spacers 14 can consist of synthetic material, metal and the like; when these spacers are to be subsequently removed from the capillary bundle by dissolving operations, the spacers (in particular woven material) can be made of monofilament polyalcohol threads, which dissolve in water.

The exchangers of the invention serve, e.g., as dialysers e.g., for the separation of materials such as the separation of lower molecular portions from protein solutions, or for blood dialysis), for water extraction according to the principles of reversed osmosis, for refrigeration, or for sterilization, e.g., for substances such as milk which are conducted through the intracapillary space and can be heated there in an exact does for a short time and optionally cooled, by introducing into the intercapillary space the appropriate heating and cooling agents.

It is also possible to use such exchangers for distillation processes, e.g., for the vacuum-multiflash process for the desalting of sea water, the sea water being introduced through the capillaries and the condensation of the steam taking place in the intercapillary vacuum.

Claims

We claim:

1. A process for producing a membrane capillary exchanger in which the capillaries are arranged side by side in spaced relationship to each other and are obtained by applying to an auxiliary core one or several membrane layers from a solution or solutions of substances capable of forming the membrane itself or an intermediate product convertible to the latter substance, and, in the latter case, subsequently converting the layer of intermediate product into the substance forming the membrane, the end zones of each capillary then being coated with reinforcing mantles, and in which the ends of the capillaries are maintained open, or are re-opened, during production of the exchanger, said process comprising the steps of

a. coating the end zones of a number of capillaries produced in the above-described manner and still containing their auxiliary cores, with reinforcing mantles of a material capable of superficially dissolving the wall of the capillary during its application;

b. arranging these capillaries in a bundle leaving spaces between them for the flow of a liquid or gaseous medium therethrough;

c. pouring between the reinforcing mantles at one end of the bundle a layer of a hardenable material capable of adhering sealingly to the said mantles, whereby the ends of the capillaries at the level of their adjacent reinforcing mantles are embedded in a transverse wall formed by said material after hardening, and

d. removing the auxiliary cores from the capillaries before or after step (c).

2. A process as described in claim 1, wherein the capillaries which still contain the auxiliary core are inserted and held in distancing means, thereby maintaining the capillaries spaced from one another throughout the process, whereupon one end of a bundle of capillaries thus held is introduced from above into a separating agent present in a casting mold, then pouring onto the surface of the separating agent a layer of said hardenable material, hardening the same, removing the casting and the separating agent therein from the ends of the capillaries and removing the auxiliary cores from the interior of the capillaries, by dissolving or melting, before or after application of said poured-on layer.

3. A process as described in claim 2, wherein the thickness of the poured and hardened transverse wall is limited so that the ends of the reinforcing mantles situated towards the central regions of the capillaries protrude from the transverse wall.

4. A process as described in claim 2, wherein the removal of the auxiliary cores from the interior of the capillaries is carried out before introduction of the capillaries into the separating agent.

5. A process as described in claim 2, wherein the removal of the auxiliary cores from the capillaries is carried out after the hardening of the poured layer.

6. A process as described in claim 5, wherein the auxiliary cores are melted and thereby removed from the interior of the capillaries.

7. A process as described in claim 3, wherein, at the time of introducing said capillaries into said separating agent in said casting mold, a frame is also placed in said mold about said bundle of capillaries, which frame is subsequently embedded in said layer of poured-on hardenable material, together with said capillary reinforcing mantles.

8. A process as described in claim 3, wherein spacers are disposed between the capillaries of the bundle at least until the said layer of hardenable material has been poured onto said separating agent.

9. A process as described in claim 3, wherein spacers are disposed between the capillaries of the bundle and remain in position even after said layer of hardenable material has been poured on, said spacers being permanently connected with said layer by the hardening of the latter.