Spinneret

Abstract

The present disclosure relates to a spinneret for producing hollow fiber membranes in a phase inversion process.

Description

Technical Field

[0001] The present disclosure relates to a spinneret for producing hollow fiber membranes in a phase inversion process. Background Art

[0002] Semipermeable hollow fiber membranes used in medical devices such as capillary dialyzers and capillary filters are mainly manufactured using the phase inversion process. A spinneret with a nozzle having two concentric orifices, an outer annular slit and a central hole is usually used. The polymer solution is extruded into the precipitation bath through the outer annular slit of the nozzle, while the central fluid is extruded through the inner hole of the nozzle.

[0003] The spinning train includes a plurality of spinnerets implemented in a spinning machine for producing a plurality of hollow fiber membranes which are bundled into fiber strands. Hundreds of spinnerets are arranged in the spinning train, and each spinneret is supplied with a polymer solution and a core fluid respectively.

[0004] A spinning train is a specially designed structure that includes subunits for depositing, washing, drying, crimping and collecting the fibers. A train of such machines requires a large investment. Increasing the spinning capacity requires duplication of these machines, resulting in duplication of the investment.

[0005] The object of the present disclosure is to provide an option for the capacity expansion of a spinning bank which does not require duplication of the entire equipment of the spinning bank and allows retrofitting of existing spinning banks.

[0006] DE3022313A1 discloses a spinning nozzle for producing semi-permeable hollow fibers, which has several separate hollow sections extending along the entire length of the hollow fiber, each of which has a through hole. The spinneret has a plurality of independent openings for injecting a first liquid, and a corresponding number of annular grooves around each opening. These annular grooves are connected together to form a continuous seam for extrusion of a fiber forming material.

[0007] US3081490A discloses a spinneret for the production of hollow yarns, which consists of two circular plates and is firmly held together by four bushing screws. The first plate is provided with a central spinning orifice, which has two alignment holes or positioning holes for pins and a cylindrical conduit or hole coaxial with the spinning orifice and with a larger diameter. The conduit extends from the upper surface of the first plate to the upper end of the spinning orifice. The lower side of the second plate is provided with a circular recess, which forms a supply chamber for a spinning solution or melt; and four holes terminating in the recess, through which the spinning solution or melt is supplied to the recess. A supply channel opening to the hole is drilled on the second plate for supplying a gas or liquid medium to the interior of the hollow pin via the opening. The pin terminating in the capillary is fixed to the hole of the second plate by a hollow screw and is concentrically located in a cylindrical hole having a diameter greater than the pin. A spinneret with a similar structure but with six spinning orifices is also described.

[0008] JPS5590608A discloses a spinneret with a high concentricity orifice and a water or gas outlet. The spinneret is obtained by simultaneously processing the periphery of the nozzle end and the inner surface of the polymer outlet to form the orifice, and by punching holes and blind holes for connecting water or gas. The nozzle with a water or gas blind hole and multiple polymer ports at the center is fixed in a holder with a central polymer outlet. Summary of the invention

[0009] A double spinneret is provided which can replace the spinneret (single spinneret) in a spinning machine and double its production capacity. Instead of one hollow fiber per spinneret, the double spinneret delivers two hollow fibers per spinneret. Since the installation dimensions of the double spinneret are the same as those of the single spinneret, the fiber production capacity of the spinning machine can be doubled, while the basic design of the machine remains unchanged. Since only spare parts such as the spinneret and polymer pump need to be replaced, the modification of existing spinning units requires almost no investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Book Figure 1 shows a side view and a front view of an exemplary embodiment of a spinneret of the present disclosure;

[0011] Figure 2 yes Figure 1 A top view of a spinneret;

[0012] Figure 3 is along Figure 2 The cross-sectional view of the line AA shown;

[0013] Figure 4 yes Figure 3 A detailed view of section B is shown;

[0014] Figure 5shows a side view and a front view of another exemplary embodiment of a spinneret of the present disclosure;

[0015] Figure 6 yes Figure 5 Top view of the spinneret;

[0016] Figure 7 is along Figure 6 The cross-sectional view of the line AA shown;

[0017] Figure 8 yes Figure 1-3 An exploded cross-sectional view of the parts of the spinneret is shown. DETAILED DESCRIPTION

[0018] Provide a spinneret, each of which produces two hollow fibers (double spinneret), instead of only one hollow fiber as known spinnerets (single spinneret). The double spinneret has the same installation dimensions as the single spinneret and can be used to modify existing spinning machines.

[0019] The spinneret of the present disclosure is characterized in that it has two nozzles, each of which has two concentric orifices, an outer annular slit and a central orifice. The outer annular slit of each nozzle is connected to a compartment for a polymer solution in the spinneret, and the central orifice of each nozzle is connected to a reservoir for a central fluid via a capillary.

[0020] The compartment for the polymer solution is connected to a supply port for the polymer solution located in the side wall of the spinneret.

[0021] These capillaries are all connected to the reservoir for the central fluid in the spinneret, which is in turn connected to a feed port for the central fluid, which is located on the spinneret upper side. In a further embodiment, two reservoirs for the central fluid are connected to a single, public feed port for the central fluid. In a further embodiment, two capillaries are connected to a single, public reservoir for the central fluid.

[0022] In one embodiment, the longitudinal axes of the two nozzles of the double spinneret deviate from the vertical middle plane (parallel to the front side and the rear side) of the spinneret. In other words, the longitudinal axes of the two nozzles are located in a common plane, which is not parallel to any sidewall of the spinneret. This ensures that a larger distance is arranged between the two hollow fibers produced using a double spinneret. In another embodiment, the axes of the two nozzles are located in the vertical middle plane of the spinneret.

[0023] In one embodiment, the spinneret is composed of two separate building blocks, which are assembled to form the spinneret. The first building block is the spinneret body, which is used to define the outer wall of the compartment for the polymer solution, the outer wall of the annular seam of the feed port for the polymer solution and the nozzle. The upper side of the spinneret body has two openings, and the second building block is inserted into the two openings. The second building block defines the inner wall of the compartment for the polymer solution, the capillary, at least one reservoir for the center fluid and at least one feed port for the center fluid.

[0024] In a further embodiment, the spinneret body is made up of two subunits, and each subunit comprises a nozzle of the spinneret. The upside of each subunit has a cylindrical hole, and when the spinneret is assembled, the cylindrical hole engages with the corresponding parts of the second construction block of the spinneret. One of the subunits is characterized in that there is a feed port for polymer solution in one of the sidewalls of the subunit. The two subunits are linked transversely. The sidewalls of the two subunits comprise the matching openings on the interface of the subunit. In one embodiment, the tubular connector is positioned in the tubular conduit formed when the subunits are linked.

[0025] In a further embodiment, the second building block consists of two subunits ("nozzle inserts"), each subunit comprising a capillary, a reservoir for the core fluid and a delivery port for the core fluid. In one embodiment, the subunits are rotationally symmetric.

[0026] Therefore, the spinneret of the present disclosure comprises two, three or four subunits.The modular design of the spinneret greatly facilitates the maintenance of the spinneret and the replacement and substitution of defective or worn parts.

[0027] The spinneret of the present disclosure only includes a feed port for polymer solution. The feed port supplies polymer solution to the two nozzles of the spinneret. The feed port is connected to a compartment for polymer solution, which is defined by the inner wall of the spinneret body and the outer surface of the nozzle plug. The compartment for polymer solution includes three parts: two rotationally symmetrical shells formed around the nozzle plug, and a tubular conduit connecting the shell. The tubular conduit is aligned with the orifice of the feed port and has the same inner diameter. The diameter of each shell and the distance between the walls forming the shell are maximum at the level of the tubular conduit, and are reduced towards the nozzle of the spinneret (i.e. the bottom of the spinneret). Two shells have the same shape and volume.

[0028] It has been found that although the spinneret of the present disclosure has only one feed port for supplying polymer solution to two nozzles, rather than one feed port for each nozzle, the two nozzles have the same output characteristics. Therefore, the hollow fibers produced by the nozzles of the double spinneret (within the measurement accuracy) have the same size. This is due to the special form of the compartment for the polymer solution to produce a uniform flow of the polymer solution through the compartment.

[0029] A further advantage of the disclosed spinnerets is that each spinneret requires only one pump for the polymer solution, ie only half the pumps compared to a conventional spinning machine producing the same amount of fibers.

[0030] The disclosed spinneret significantly reduces the space requirement of the spinning machine. Alternatively, by replacing the conventional spinneret with the disclosed twin spinneret, the spinning capacity of the spinning group can be doubled without requiring further space.

[0031] The present disclosure also provides a method for producing hollow fiber membranes, comprising feeding a polymer solution into a polymer solution feed port of a spinneret of the present device, and simultaneously feeding a center solution into at least one center solution feed port of the spinneret of the present disclosure, extruding the polymer solution through the outer annular slits of the two nozzles of the spinneret of the present disclosure, and simultaneously extruding the center fluid through the central orifices of the two nozzles of the spinneret of the present disclosure.

[0032] Suitable polymer solutions and suitable center fluids for producing semi-permeable hollow fiber membranes are well known in the art. For example, a solution comprising 1) at least one polysulfone, polyethersulfone or polyarylethersulfone, and 2) at least one polyvinylpyrrolidone dissolved in 3) a mixture of N-methyl-2-pyrrolidone (NMP) and water can be used as the polymer solution, and a mixture of water and NMP can be used as the center fluid.

[0033] The spinneret of the present disclosure will now be further explained with reference to the accompanying drawings.

[0034] Figure 1 A side view and a front view of an exemplary embodiment of a spinneret 10 of the present disclosure are shown. The spinneret body 11 is characterized by having a feed port 12 in its side wall. Two feed ports 13 for the center liquid are present on the upper side of the spinneret body 11. The spinneret body includes a first subunit 14 and a second subunit 15, which are attached to each other via the side walls of each subunit.

[0035] Figure 2 yes Figure 1 A top view of the spinneret showing two feed ports 13 for the center fluid and the first subunit 14 and the second subunit 15 attached to each other via the side walls of each subunit.

[0036] Figure 3 is along Figure 2 The cross-sectional view along line AA shown is a cross-sectional view through the central axis of the feed port 13 for the central fluid. Figure 3 As shown, the spinneret includes four subunits or components 14, 15, 23. The subunits 14 and 15 together form the spinneret body 11. Two identical nozzle inserts 23 are respectively installed in the cylindrical openings of the subunits 14 and 15 of the spinneret body. Each nozzle insert 23 is characterized in that it has a capillary 18, a reservoir 19 for the center fluid and a feed port 13 for the center fluid. At the interface of the subunits 14 and 15, there is a matching connection orifice 17, which together forms a conduit for the polymer solution between the subunits 14 and 15. The inner walls of the subunits 14 and 15 and the outer surface of the nozzle insert 23 together define a compartment 16 for the polymer solution.

[0037] Figure 4 yes Figure 3 A detailed view of section B is shown. It shows a compartment 16 for the polymer solution and a portion of a capillary 18 for the central fluid. A nozzle 24 having an outer annular slit 20 and a central orifice 26 is defined by the inner surfaces of the compartment 16 and the capillary 18.

[0038] Figure 5 A side view and a front view of another exemplary embodiment of a spinneret 10 of the present disclosure are shown. The spinneret body 11 is characterized by having a feed port 12 in its side wall. Two feed ports 13 for the center liquid are present on the upper side of the spinneret body 11. The spinneret body is composed of a single piece.

[0039] Figure 6 yes Figure 5 Top view of the spinneret showing the two feed ports 13 for the center fluid and the feed port 12 for the polymer solution.

[0040] Figure 7 is along Figure 6 The cross-sectional view along the line AA is a cross-sectional view through the central axis of the feed port 13 for the central fluid. Figure 7 The spinneret shown comprises three subunits or components 11, 23. Two identical nozzle inserts 23 are mounted in the cylindrical opening of the spinneret body 11. Each nozzle insert 23 features a capillary 18, a reservoir 19 for the center fluid and a feed port 13 for the center fluid. The inner wall of the spinneret body 11 and the outer surface of the nozzle insert 23 together define a compartment 16 for the polymer solution. Figure 7As shown, the compartment 16 for the polymer solution comprises three parts. The part formed around the nozzle insert 23 is a rotationally symmetrical shell, the diameter of which decreases towards the nozzle 24. The two parts of the compartment 16 formed around the nozzle insert 23 are connected via a tubular conduit 25. A sealing ring (O-ring) 21 is positioned around the feed conduit 12 for the polymer solution.

[0041] Figure 8 yes Figure 1-3 An exploded cross-sectional view of the components of the spinneret 10 is shown. Figure 8 A cross-section along the vertical mid-plane (between the front and back side of the spinneret) of the subunits 14 and 15 of the spinneret body 11 is shown. Figure 1-3 Compared with the spinneret, the subunits are oriented in the opposite direction. Dimensions are in mm. Since the central axis of the spinneret nozzle is not located in the vertical midplane, Figure 8 The nozzle cannot be seen.

[0042] The feed port 12 for the polymer solution is integrated into one side wall of the subunit 15, and the connection orifice 17 is located on the opposite side wall of the subunit 15. The connection orifice 17 is aligned with the opening of the feed port 12. The subunit 14 is characterized by having a connection orifice 17 aligned with the connection orifice 17 of the subunit 15 and having the same diameter.

[0043] A connecting pipe 22, whose inner diameter matches the inner diameter of the feed port 12 and whose outer diameter matches the inner diameter of the connecting orifices 17 of the subunits 14 and 15, is installed in the connecting orifice 17 of the subunit 15. The length of the joint pipe 22 is equal to the sum of the hole lengths of the connecting orifices 17 of the subunits 14 and 15. The protruding portion of the joint pipe 22 can be inserted into the connecting orifice 17 of the subunit 14 when assembling the spinneret body to form a conduit with the same inner diameter as the feed port 12. In one embodiment, the joint pipe 22 is fixed in the connecting orifice 17 with an adhesive.

[0044] Reference numerals list

[0045] 10 Spinneret

[0046] 11 Spinneret body

[0047] 12 Port for polymer solution feeding

[0048] 13 Inlet port for core solution

[0049] 14 First main subunit

[0050] 15 Second main subunit

[0051] 16 Chamber for polymer solution

[0052] 17 Connection port

[0053] 18 Capillary

[0054] 19 Reservoir for center solution

[0055] 20 Annular seam

[0056] 21 Sealing ring

[0057] 22 Connector Pipe

[0058] 23 Nozzle insert

[0059] 24 Nozzle

[0060] 25 Catheter

[0061] 26 Center hole

Claims

1. A spinneret (10) for producing hollow fiber membranes, comprising two nozzles (24), each nozzle (24) comprising two concentric orifices, namely an outer annular slit (20) and a central orifice (26), the outer annular slits (20) of the two nozzles (24) being in fluid communication with a compartment (16) for a polymer solution, the spinneret (10) comprising a spinneret body (11) and two nozzle inserts (23) of the same size, each nozzle insert comprising a capillary (18), a reservoir (19) for a central fluid and a second feed port (13) for the central fluid, the spinneret (10) having a single first feed port (12) for the polymer solution, the first feed port (12) being located in a side wall of the spinneret (10), characterized in that The first feed port (12) for the polymer solution is connected to a compartment (16) for the polymer solution, the compartment (16) being defined by the inner wall of the spinneret body (11) and the outer surface of the nozzle insert (23), the compartment (16) for the polymer solution comprising three parts: two rotationally symmetrical shells formed around the nozzle insert (23), and a tubular conduit (25) connecting the shells, the tubular conduit (25) being aligned with the orifice of the first feed port (12) for the polymer solution and having the same inner diameter as the first feed port (12) for the polymer solution; Each central orifice (26) is the mouth of a capillary tube (18) connected to a reservoir (19) for the central solution.

2. A spinneret (10) according to claim 1, wherein each capillary (18) is connected to a separate reservoir (19) for the core solution, which reservoir (19) is in turn connected to a separate second feed port (13) for the core solution.

3. The spinneret (10) according to any one of claims 1 to 2, wherein the longitudinal axes of the two nozzles (24) are located in a common plane which is not parallel to any side wall of the spinneret (10).

4. The spinneret (10) according to any one of claims 1 to 2, wherein the spinneret body (11) comprises a first subunit (14) and a second subunit (15), the second subunit (15) comprising a first feed port (12) for the polymer solution.

5. The spinneret (10) according to claim 3, wherein the spinneret body (11) comprises a first subunit (14) and a second subunit (15), the second subunit (15) comprising a first feed port (12) for the polymer solution.

6. Spinneret (10) according to claim 4, wherein the first subunit (14) and the second subunit (15) are connected laterally, and the first subunit (14) and the second subunit (15) have matching orifices (17) in the side walls adjacent to the interface of the connected subunits.

7. Spinneret (10) according to claim 5, wherein the first subunit (14) and the second subunit (15) are connected laterally, and the first subunit (14) and the second subunit (15) have matching orifices (17) in the side walls adjacent to the interface of the connected subunits.

8. A method for producing a hollow fiber membrane, comprising: Feeding the polymer solution into the first feed port (12) for polymer solution of the spinneret (10) described in any of the preceding claims; simultaneously feeding the center solution into the second feed port (13) for center solution of the spinneret (10) described in any of the preceding claims; extruding the polymer solution through the outer annular gap (20) of the two nozzles (24) of the spinneret (10) described in any of the preceding claims; and simultaneously extruding the center fluid through the central orifice (26) of the two nozzles (24) of the spinneret (10) described in any of the preceding claims.

9. The method of claim 8, wherein the polymer solution comprises 1) polysulfone, polyethersulfone or polyarylethersulfone; and 2) at least one polyvinylpyrrolidone.

10. The method of claim 9, wherein the polymer solution comprises 3) N-methyl-2-pyrrolidone.

11. The method of claim 9, wherein the polymer solution comprises 3) N-methyl-2-pyrrolidone, and water.

12. A method according to any one of claims 8 to 11, wherein the center fluid comprises water.

13. The method according to any one of claims 8 to 11, wherein the center fluid comprises water, and N-methyl-2-pyrrolidone.

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