DE10054591A1 - Device for producing a polymer membrane - Google Patents

Abstract

The invention relates to a device (10) for producing a polymer membrane (11), comprising an extrusion nozzle (12) for exiting the device (10) via feed channels (13, 14) inside the device, which can be used to form polymer solutions (15) that form the membrane (11) , 16) from the outlet opening of the extrusion nozzle (12). To produce a multi-layer, layer-integrated polymer membrane (11), the feed channels (13, 14) are brought together at a distance (17) in front of the outlet opening (122) of the extrusion nozzle (12).

Description

The invention relates to a device for production a polymer membrane comprising an extrusion die for the exit from the device via the device interior Feed channels can be fed, which form the membrane Polymer solutions from the extrusion nozzle.

There are various types of prior art directions for the production of multilayer polymer membranes branches, whether as flat membranes or as so-called Hollow thread membranes, known. The one that occurs The problem is explained below using hollow fiber memes industries that are involved in producing the more layered polymer membranes problems but also apply equally to flat membranes. In this respect, the following is intended equally also apply to flat membranes.  

So-called hollow core nozzles (tube-in-orifice spinnerets) have previously been used to produce polymer membranes designed as hollow fiber membranes, such hollow core nozzles being described by P Aptel et al., J. Membr. Sci. 22: 199-215 ( 1985 ). In this known device, a hollow mandrel is provided, via which a so-called lumen filler, ie a gaseous or liquid medium, is guided to an outlet opening of the device. The hollow mandrel is positioned centrally in a bore so that an annular gap of constant width is created through which the polymer solution is extruded. The device is constructed in such a way that both liquid flows, namely the polymer solution and the lumen filler, are guided in the device in a liquid-tight and separate manner and are brought into contact with one another only at the exit of the extrusion nozzle. The medium which is conveyed as a lumen filler through the hollow mandrel in the production of hollow fiber membranes is necessary in order to stabilize the shape of the extruded polymer solution until the polymer material forming the membrane is solidified by phase inversion. The effect of the medium (lumen filler) on the polymer solution to be structured can be inert, structure-forming and / or solidifying / coagulating.

Multi-layer membranes, the membrane wall of which is little at least two separate layers of the same and / or different polymers exist with such In principle, hollow core nozzles cannot be produced, since only one Polymer solution supply is present. They are just so-called blend membranes can be produced, the ge mixed polymer solutions can be formed. such However, membranes do not have separate layers of the membrane-building polymers.  

A further development of the one described above Hollow core nozzle is disclosed in EP-A-0 483 143, with who manufacture hollow fiber membranes under Ver described using a so-called coextrusion die in addition to a membrane-forming polymer solution at the same time an inner liquid medium (lumen filler) and an the outer surface of the extruded polymer solution contacting external liquid medium separately guided in the device and at the exit of the extru sion nozzle are brought together. Such multi-channel Triple-nozzles (double-tube-in-orifice) are also used spinnerettes) called. On the aforementioned principle of Triple nozzles are indeed in the relevant specialist literature It has been said several times that by means of this more layered hollow fiber membranes should be able to be produced, such hollow fiber membranes have no entrance found in commercial use and are in the market also not available. It must be doubted that with hollow filament manufactured by this known device industries actually meet the expectations placed on them can do justice, d. H. on the one hand, a very safe one Operation of the device, which is highly reproductive ability to decorate the polymer membranes thus produced ensures, and on the other hand ensures that effective Lich multi-layer polymer membranes are produced can, in which the individual polymer layers a show high integrity with each other.

It is therefore an object of the present invention to To create a device with which it is possible to do more Layered polymer membranes with a very large structure integrity of the individual polymer layers manufacture each other, the device with high Reproductive ability should be able to do such  To be able to continuously manufacture membranes safely and the device being simple and inexpensive should be adjustable.

The object is achieved according to the invention in that for the production of a multilayered, layered ink grated polymer membrane the feed channels in one Distance in front of the outlet opening of the extrusion nozzle are merged.

The main advantage of the invention is that, as required by the task, with this device the production of multilayer membranes of high integri activity is possible, d. H. by means of the device safe production of multilayer polymer membranes by extrusion of the deformed and to the solution composite combined polymer solution from the extrusion nozzle becomes. This outstanding feature of the device is achieved in that the the polymer layers of Polymer streams forming polymer membrane even before Exiting from the opening of the nozzle inside the nozzle already be contacted in layers and this polymer solution composite together in the formed Form is extruded from the device. Another The advantage of the solution according to the invention is that a device is also available according to the task that is, except for the special inventive Solution, the remaining basic principles of constructive Does not leave the construction of such devices, d. H. a simple and a continuous and continuous rend reproducible manufacturing process for polymer Ensure membranes safely.

The number of feed channels determines the number of Layers of the polymer membrane that can be produced with the device.  So, following this principle, they are arbitrary Layered polymer membranes can be produced.

According to an advantageous embodiment of the device the device is in particular not only for Suitable for the production of multilayer flat membranes, but especially for the production of a Hollow thread membrane trained polymer membrane, wherein in in this case the extrusion nozzle is essentially circular is annular.

Preferably in the design of the device for the production of hollow fiber membranes Polymer membranes in the axial center of the extrusion nozzle an outlet for a medium that is liquid or can be gaseous, provided, this medium as so-called lumen filler serves with the, as already initially in connection with the description of the stand the technology mentioned, the multi-layered, highly structured rell integrated, from the opening of the extrusion nozzle escaping polymer solutions stabilized as long until the polymer forming the polymer membrane Material is solidified by phase inversion, whereby the medium onto the polymer solution to be structured inert, structure-forming and / or solidifying or can have a coagulating effect.

For certain polymer solutions of each polymer layers of the membrane, for example when used a so-called wet spinning process, it makes sense the extrusion nozzle preferably in the exit direction of the Polymer membrane downstream of an aftertreatment to provide the structure of the structure by means of the Device produced multilayer polymer membrane to influence branches in an advantageous manner.  

For example, the aftertreatment section advantageously be a precipitation bath. By providing the Post-treatment route, for example through the vorbe Written precipitation bath, can specifically solidify the emerging from the outlet opening of the extrusion nozzle multilayer polymer membrane can be achieved, d. H. the Phase inversion can be influenced in a targeted manner. The Nachbe action line can be directly the exit opening be provided downstream of the extrusion die or in predetermined distance, so as to have a targeted influence the exiting the exit opening of the extrusion nozzle multilayer polymer membrane.

Experiments have shown that polymer membranes emerge gender characteristics can be produced if preferably the distance, d. H. the length between the Outlet opening of the extrusion die and the assembly guidance of the feed channels for the polymer solutions within the device, in a range between 0.001 mm and 2 mm, preferably 0.005 mm and 1 mm, is in particular 0.1 mm to 0.5 mm. The distance will possibly depending on the number of layers established. The distance also goes into the dimensioning Transport kinetics of the polymer solutions supplied.

Taking into account the foregoing, it is equally advantageous, the clear opening width of the Extrusion nozzle in a range between 0.1 mm and 5 mm, preferably 0.15 mm and 1 mm, in particular 0.15 mm and 0.3 mm.

Taking into account the foregoing, it is furthermore advantageous, the clear opening width of the Feed channels at the point where they are brought together <0.002 mm, preferably <0.04 mm in size.  

Taking into account the foregoing, it is finally also advantageous that the ratio the clear opening width with two intended feeders channels for each one to be fed over it Polymer solution <250, preferably <50, in particular < 10 is.

In addition to the distance between the clear opening width of the extru nozzle, the clear opening width of the feed channels and the ratio of the clear opening widths, here on Example of two feed channels shown goes in the formation of the device for manufacturing be the multilayered polymer membranes Direction of the feed channels with respect to each other Exit axis or exit plane of the extrusion nozzle on. So it is advantageous, for example, the feed channels relative to the exit plane or exit axis the extrusion nozzle at an angle of α <90 °, preferred wise <45 ° to form inclined to each other, it is also advantageous, the feed channels relative to each other at an angle of β <90 °, preferably < 45 °, based on the location of their merging as Peak of the angle β, inclined to each other form.

The invention will now be described with reference to the following schematic drawings using an off management example and with reference to by means of Device producible multilayer, as hollow thread Membranes formed polymer membranes described. In it show:

Fig. 1 in section a device for producing a two-layer polymer hollow fiber membrane as has been used in the prior art,

Fig. 2 is a plan view of the embodiment shown in FIG. 1 device,

Fig. 3 is a section through an inventive apparatus for producing a two-layer strength polymer hollow fiber membrane,

Fig. 4 is a plan view of the embodiment shown in Fig. 3 device,

Fig. 5 is a section along line CD of FIG. 3,

Fig. 6 shows a section along line AB of Fig. 3,

Fig. 7 is a scanning electron micrograph of the cross section of a two layer polymer hollow fiber membrane illustrated in FIG. 1 using the prior art depicting lumbar device when using polymer solutions of the same composition which have been supplied via the two feed channels,

Fig. 8 shows an enlarged detail from the Dar position of FIG. 7,

Fig. 9 is a scanning electron micrograph of the cross section of a produced by the two-layer polymer membrane erfindungsge MAESSEN device when using polymer solutions of the same composition which have been supplied via the two feed channels,

Fig. 10 shows an enlarged detail from the lung depicting of Fig. 9,

Fig. 11-18 scanning electron microscope images of the cross section of a two-layer polymer membrane produced by means of the device according to the invention, each in section and in each case in an enlarged section, the individual test specimens of the scanning electron microscope image from a hollow fiber length of 1000 m of a two-layer poly the hollow fiber membrane has been removed,

Fig. 19 is a scanning electron microscope image of the cross section of a two-layer polymer hollow fiber membrane, which was produced by means of the device according to the invention under the same conditions as the two-layer polymer hollow fiber membranes shown in FIGS . 9 and 10 with the difference that two different polymer solutions have the same basic polymer and a water / solvent mixture was used as the lumen filler,

Fig. 20 shows an enlarged detail from the lung depicting of Fig. 19,

Hollow fiber membrane Fig. 21 is a scanning electron micrograph of the cross section of a two-layer multi-layer, which was made with the inventive apparatus and were prepared under the same conditions as those shown in Fig. 19 and two-layered hollow polymer represented 20-filament membranes, the polymer solutions of different polymers passed and

Fig. 22 is an enlarged view of Fig. 21.

First of all, reference is made to FIGS. 1 and 2, which represent a device 10 as it has been used in the prior art for the production of two-layer polymer membranes 11 designed as hollow fiber membranes. The device 10 comprises a body which can be cylindrical. The body of the device 10 has a through hole 26 which is axial to the through axis 18 and through which a gaseous or liquid medium (a so-called lumen filler) can flow axially in the exit direction 21 . In addition, the device 10 has a plurality of feed channels 13 and 14 , which are arranged here essentially rotationally symmetrically about the axis 18 , it being possible for a predetermined number of respective feed channels 13 and 14 to be provided. Both the feed channels 13 , 14 and the axially through the device 10 through feed channel 26 for the lumen filler (liquid or gaseous medium) 27 open with their openings (extrusion nozzle 12 , extrusion nozzle 21 , outlet opening 20 ) in one plane, that is, based on the Representation of FIG. 1, in the upper surface of the device 10 , also compare the top view according to FIG. 2.

During operation of the known device 10 , the polymer solution 15 is fed via the feed channels 13 and polymer solution 16 via the feed channels 14 of the device 10 and a lumen filler (liquid or gaseous medium) 27 via the central feed channel 26 . After the polymer solutions 15 , 16 and possibly the medium (lumen filler) 27 have emerged, a two-layer hollow fiber polymer membrane 11 is formed , in which, however, there is no connection of the individual polymer solutions 15 , 16 with high structural integrity, see also FIGS. 7 and 8, represent the cross sections of two-layer polymer hollow fiber membranes produced with the known device 10 . It is clearly visible in FIGS. 7 and 8 that no real integral connection between the outer and the inner polymer layer is achieved.

The device 10 according to the invention shown in FIGS. 3 to 6 differs from that shown in FIGS. 1 and 2 in that the two feed channels 13 , 14 before the actual exit plane of the polymer membrane 11 from the device, ie according to the illustration of FIG. 1 are below the upper boundary surface at a predetermined distance 17 merged therewith. This makes it possible for the different or the same polymer solutions 15 , 16 supplied via the feed channels 13 , 14 to be brought together directly at the location 25 of the merging of the two feed channels 13 , 14 in the extrusion nozzle 12 itself, and thereby to provide a high structural integrity for both Polymer solutions 15 , 16 is reached.

The part of the device 10 in which the extrusion nozzle 12 is formed can be formed by a separately designed, possibly plate-shaped extrusion nozzle element 121 , which can be connected in a pressure-tight manner to the rest of the device 10 by means of bolts (not shown here). The extrusion nozzle element 121 may have a thickness corresponding to the distance 17 , see FIG. 3. This enables a quick interchangeability of different extrusion nozzle elements 120 and a quick exchange for maintenance and cleaning purposes.

The essential difference of the device according to the invention according to FIGS. 3 to 6 compared to the known device according to FIGS. 1 and 2 is also that only one outlet opening of the extrusion nozzle 12 is present in the device 10 according to the invention. The extrusion nozzle 12 is essentially circular in shape, see FIG. 4, so that the device 10 can be used to produce multilayer polymer membranes designed as hollow fiber membranes. However, it should also be pointed out that the device 10 according to FIG. 3 is in principle also suitable for the production of multilayer polymer flat membranes, in which case the extrusion nozzle 12 is designed as a linear or flat flat nozzle.

FIGS. 5 and 6 show sections CD and AB along the indicated lines CD and AB according to FIG. 3. These representations also refer to complete training of the apparatus 10 for preparing multilayered polymer hollow fiber membranes.

The aforementioned distance 17 is determined as a function of the polymer solutions 15 , 16 used or the clear opening width 22 of the extrusion nozzle 12 . The distance 17 is, for example, in a range between 0.001 mm and 2 mm, preferably 0.05 mm and 1 mm, in particular 0.1 mm to 0.5 mm. The clear opening width 22 of the extrusion nozzle is in a range between 0.1 mm and 5 mm, preferably 0.15 mm and 1 mm, in particular 0.15 mm and 0.3 mm.

The clear opening width 23 , 24 of the feed channels 13 , 14 at the location 25 of their merging is to be observed in the construction or implementation of the device 10 and is also included as a parameter in the dimensioning of the device 10 . For example, the clear opening width 23 , 24 of the feed channels 13 , 14 at the point 25 of their merging is <0.02 mm, preferably <0.04 mm.

The ratio of the clear opening widths 23 , 24 in two provided feed channels 13 , 14 , which are considered here by way of example, is also used for a polymer solution 15 , 16 to be fed in above, the ratio being <250, preferably <50, in particular <10. Also the supply passages 13, 14 relative to the exit plane or exit axis 18 of the extrusion nozzle 12 at an angle of α <90 °, preferably <45 °, inclined to each other, wherein the supply channels 13, 14 relative to each other at an angle of β <90 °, preferably <45 °, based on the location 25 of their merging as the apex of the angle β, are inclined to one another. In the illustration of the device 10 of FIG. 3 is a reference side of the two angles α, β in the same plane, ie in a plane parallel to the tread plane and exit from axle 18. However, this is not absolutely necessary, that is, in order to stay in the example of the illustration in FIG. 3, it could be, for example, the feed channel 13 up to the location 25 of the merging of the two channels 13 , 14 with its angle relative to the exit axis 13 or Exit plane are in the angular range listed above.

Downstream of the device 10 , ie essentially the extrusion nozzle 12 in the exit direction 21 , an aftertreatment section in the form of a precipitation bath or in another suitable manner can be provided (not shown).

Example 1 (comparative example)

In accordance with the general working steps known to those skilled in the art for producing multilayer hollow fiber membranes, a polymer solution 1 (medium 1 ) consisting of 18 parts of polysulfone-PSu (Amoco, Udel 3500 ), 12 parts of polyvenylpyrrolidone-PVP (Fluka, type K 25) and 70 Share N, N-Dinethylacetamide-DMAc (Merck). Polymer solution 2 (medium 2 ) consists of an identical composition. Water, room temperature is used as the lumen filler. The precipitation bath (medium 4 ) also consists of water. Medium 1 , 2 and 3 are formed using the known double hollow core nozzle schematically shown in FIGS . 1 and 2 at the exit of the shaping device to form a stabilized polymer solution composite and extruded directly into the precipitation bath, after solidification of the membrane former removed from the precipitation bath, washed and dried at room temperature. The device used as Verformungsvorrich device has the following dimensions: 190 microns / 360 microns / 600 microns / 860 microns / 1060 microns = hollow mandrel diameter / inner diameter of the inner ring gap / outer diameter of the inner ring gap / inner diameter of the outer ring gap / outer diameter of outer annular gap.

It has been found that the spinning process cannot be carried out safely and that a shaped body could only be produced for about 5 to 10 minutes. The "multilayer hollow fiber membrane" was characterized on the basis of SEM images ( FIGS. 7 and 8). The figures show that both polymer layers forming the membrane wall, although these consist / have been formed from one and the same polymer / polymer solution, do not form a layer composite. The integrity of the composite is therefore not given even under the conditions of the same polymer solution compositions and thus optimal conditions for a composite.

Example 2

Under the conditions of Example 1, the manufacture of the multilayer hollow fiber membrane was repeated with the difference that, instead of the known deformation device, the inventive double hollow nozzle shown and characterized in FIG. 3 was used.

The spinning process could be maintained for a long period of time, but was stopped after 1 hour. The cross section and the enlarged cross section of the multilayer hollow fiber membrane produced in this way are shown in FIGS. 9 and 10 in the form of SEM images. These recordings demonstrate complete integrity of the polymer layers that build up the membrane wall.

Example 3

4 samples were randomly selected from the hollow fiber material (approx. 1000 m) from experiment Example 2 and examined by SEM. The results of the recordings are shown in FIGS. 11 to 18. In no case was a structural inhomogeneity found. The hollow fiber membranes produced using the device according to the invention consequently have an unbeatable integrity of the membrane wall layers, as is also the case when using polymer solutions of the same composition and when using a suitable shaping device.

Example 4

In accordance with the description of Example 2 and using the shaping device according to the invention described there, a multilayer hollow fiber membrane was produced with the following differences:

• a) Polymer solution 1 , consisting of 15 parts PSu, 5 parts PVP and 80 parts DMAc
• b) Polymer solution 2 consisting of 20 parts of PSu, 20 parts of PVP and 60 parts of N-methylpyrollidone
• c) Lumen filler, consisting of 80 parts DMAc and 20 Share water

The spinning process could be maintained for a long period of time, but was stopped after 1 hour. The cross section and the enlarged cross section of the multilayer hollow fiber membrane thus produced are shown in FIGS . 19 and 20 in the form of SEM images. These recordings demonstrate complete integrity of the polymer layers that build up the membrane wall.

Example 5

According to the description of Example 6 and using the shaping device according to the invention described there, a multilayer hollow fiber membrane was produced with the difference that a solution consisting of 15 parts of polyacrylonitrile and 85 dimethylformamide was used as polymer solution 2 .

The spinning process could be maintained for a long period of time, but was stopped after 1 hour. The cross section and the enlarged cross section of the multilayer hollow fiber membrane produced in this way are shown in FIGS. 21 to 22 in the form of SEM images. These recordings demonstrate sufficient integrity of the polymer layers building up the membrane wall.

LIST OF REFERENCE NUMBERS

10

contraption

11

polymer membrane

12

extrusion

120

extrusion

121

Extrudierdüsenelement

122

outlet opening

13

feed

14

feed

15

polymer solution

16

polymer solution

17

distance

18

Axis (extrusion nozzle)

19

Center (extrusion nozzle)

20

outlet opening

21

exit direction

22

clear opening width (extrusion nozzle)

23

clear opening width (feed channel

13

)

24

clear opening width (feed channel

14

)

25

Location (of the merge)

26

Feed channel (medium) / through hole

27

Medium (lumen filler)

Claims (11)

1. Device for the production of a polymer membrane, comprising an extrusion nozzle for the exit from the device via supply channels inside the device, the membrane-forming polymer solutions from the extrusion nozzle, characterized in that for the production of a multilayer, layer-integrated polymer membrane ( 11 ), the supply channels ( 13 , 14 ) are brought together at a distance ( 17 ) in front of the outlet opening ( 122 ) of the extrusion nozzle ( 12 ). 2. Apparatus according to claim 1, characterized in that for the production of a polymer membrane formed as a hollow fiber membrane ( 11 ), the extrusion nozzle ( 12 ) is substantially annular. 3. Apparatus according to claim 2, characterized in that an outlet opening ( 20 ) for a medium is provided in the axial ( 18 ) center ( 19 ) of the extrusion nozzle ( 12 ). 4. The device according to one or more of claims 1 to 3, characterized in that the extrusion nozzle ( 12 ) in the exit direction ( 21 ) of the polymer membrane 811 ) is provided with a post-treatment section. 5. The device according to claim 4, characterized in that the aftertreatment line is a precipitation bath. 6. The device according to one or more of claims 1 to 5, characterized in that the distance ( 17 ) is in a range between 0.001 mm and 2 mm, preferably 0.005 mm and 1 mm, in particular 0.1 mm to 0.5 mm. 7. The device according to one or more of claims 1 to 6, characterized in that the clear opening width ( 22 ) of the extrusion nozzle ( 12 ) in a range between 0.1 mm and 5 mm, preferably 0.15 mm and 1 mm, in particular 0.15 mm and 0.3 mm. 8. The device according to one or more of claims 1 to 7, characterized in that the clear opening width ( 23 ; 24 ) of the feed channels ( 13 ; 14 ) at the location ( 25 ) of their bringing together <0.02 mm, preferably <0, Is 04 mm in size. 9. The device according to claim 8, characterized in that the ratio of the clear opening widths ( 23 ; 24 ) in two provided feed channels ( 13 , 14 ) for each one polymer solution to be fed ( 15 ; 16 ) <250, preferably <50, in particular < 10, is. 10. The device according to one or more of claims 2 to 9, characterized in that the feed channels ( 13 ; 14 ) relative to the exit plane or exit axis ( 18 ) of the extrusion nozzle ( 12 ) at an angle of α <90 °, preferably <45 °, are inclined towards each other. 11. The device according to one or more of claims 2 to 9, characterized in that the feed channels ( 13 , 14 ) relative to each other at an angle of 225 β <90 °, preferably <45 °, based on the location ( 25 ) of their merging as the apex of the angle β, are inclined to each other.