Abstract:
A hollow fiber spinning nozzle in which supply bores and a nozzle structure connected to these and having a mass discharge opening and a needle with a coagulation agent bore are formed in a base body. At least two plate-shaped bodies structured by means of micro-structure technology are joined together to form the base body.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of copending application Ser. No. 10/504,854, filed Aug. 27, 2004, which is a nationalization of PCT/EP03/01447, filed Feb. 13, 2003 and published in German, and hereby claims the priority thereof to which it is entitled. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a hollow fiber spinning nozzle in which coagulation agent/support agent passages and mass supply passages and a nozzle structure connected to these and having a mass discharge opening and a needle with a coagulation agent/support agent bore are formed in a base body. 
         [0004]    2. Description of the Related Art 
         [0005]    Hollow fiber spinning nozzles are already known which serve the manufacture of polymeric hollow fiber membranes. As shown in  FIG. 1  in accordance with the enclosed drawing, such hollow fiber spinning nozzles  10  consist of a base body  12  made of metal into which a plurality of bores  14 ,  16 ,  18 ,  22  have been introduced. A tube  20  has been fitted into the bore  14  and a coagulation agent passage or a support agent passage  22  has been formed therein for the introduction of the coagulation agent or support agent. The bores  16  and  18  form mass supply passages for a polymer which is discharged via a ring passage  22  which likewise consists of a corresponding bore. Methods of customary metal working are used in the manufacture of the known hollow fiber spinning nozzles  10 . It is here therefore that the nozzle structure arises by the assembly of both nozzle parts, with any irregularity, for example in the geometry of the ring space  22  totalizing from the production errors on the production of the base body  12  and the tube  20 . Furthermore, possible assembly errors also occur which can likewise result in an irregularity of the geometry. Finally, the hollow fiber spinning nozzles known from the prior art cannot be reduced to any desired size. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore the object of the invention to provide hollow fiber spinning nozzles with which fine capillary membranes can also be manufactured, with the production tolerances being minimized and the manufacturing process for these hollow fiber spinning nozzles being made much cheaper. 
         [0007]    This object is solved in accordance with the present invention which is directed to a hollow fiber spinning nozzle in which coagulation agent/support agent passages and mass supply passages and a nozzle structure connected to these and having a mass discharge opening and a needle with a coagulation agent/support agent bore are formed in a base body which is constructed by the joining together of at least two plate-shaped bodies structured by means of microstructure technology. A completely innovative manner of construction is thus provided for hollow fiber spinning nozzles, since the invention moves away from conventional metal working and uses methods of microstructure technology. In accordance with the invention, at least two plate-shaped bodies structured by means of microstructure technology are namely assembled to form the hollow fiber spinning nozzle. A second non-structured plate is preferably joined onto a first plate formed by means of microstructure technology in this process, with the second plate only being structured after attachment to the first plate. The plates are really connected to one another. A plurality of advantages are opened up by the new production method. First, a substantially smaller dimensioning of the nozzle structure can be realized by means of microstructure technology. Moreover, a substantially higher precision can be realized with respect to the nozzle structure. This precision comes about in that the nozzle structure arises in one step. It is only restricted by the precision of the underlying lithography mask which is used in microstructure technology. Such lithography masks can, however, be produced extremely precisely with tolerances of 100 nm. A further advantage of the method in accordance with the invention lies in the substantially lower production costs of the spinning nozzles. 
         [0008]    Special aspects of the invention are summarized in the following paragraphs. 
         [0009]    Generally, all materials of microstructure technology can naturally be used for the realization of the hollow fiber spinning nozzles in accordance with the invention, provided they can be anisotropically etched and bonded. However, mono-crystalline silicon, gallium arsenide (GaAs) or germanium can particularly advantageously be used. 
         [0010]    In accordance with a particular embodiment of the invention, a hollow fiber spinning nozzle consists of two plates, with the mass supply passages, a mass flow homogenization zone, a coagulation agent/support agent supply bore and a needle stub being cut out in the first plate, while a nozzle structure having a mass annular gap and a needle with a coagulation agent/support agent bore being cut out in the second plate. 
         [0011]    Alternatively, a design is also feasible in which the second plate additionally contains the mass supply passages and the mass flow homogenization zone. These elements and the needle stub are omitted on the first plate there. A particular feature of this design is that the needle of the spinning nozzle is only connected to the first plate at an end face. 
         [0012]    These preferred aspects for a hollow fiber spinning nozzle, with which a simple capillary hollow fiber membrane can be manufactured, advantageously have the following dimensions: 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Thickness of the first plate: 
                 0.250-1.500 
                 mm 
               
               
                   
                 Thickness of the second plate: 
                 0.050-1.500 
                 mm 
               
               
                   
                 Outer diameter of the needle: 
                 0.020-1.500 
                 mm 
               
               
                   
                 Length of the needle, incl. needle stub: 
                 0.100-2.000 
                 mm 
               
               
                   
                 Diameter of the coagulation agent bore: 
                 0.010-1.000 
                 mm 
               
               
                   
                 Length of the coagulation agent bore: 
                 0.150-2.500 
                 mm 
               
               
                   
                 Outer diameter of the annular gap: 
                 0.040-3.000 
                 mm 
               
               
                   
                 Length of the annular gap: 
                 0.050-1.500 
                 mm 
               
               
                   
                 Height of the spinning nozzle: 
                 0.300-3.000 
                 mm 
               
               
                   
                 Edge length of the spinning nozzle: 
                 1.000-25.00 
                 mm. 
               
               
                   
                   
               
             
          
         
       
     
         [0013]    A further preferred aspect of the invention consists of three plates, with the first plate including supply passages, a homogenization zone and a needle stub with a central supply bore, a second plate which adjoins the first plate has supply passages, a homogenization zone and a further needle stub with a concentric ring passage and a needle extension, and wherein a third plate which in turn adjoins the second plate has a nozzle structure consisting of a central bore and two concentric annular gaps. Capillary membranes with co-extruded double layers can be manufactured by means of this hollow fiber spinning nozzle in accordance with the invention. 
         [0014]    An alternative embodiment results in that the hollow fiber spinning nozzle is made up of three single plates, with the first plate having a central supply bore, a second plate adjoining the first plate having parallel supply passages and homogenization zones arranged with respect to these as well as a needle stub with a concentric ring passage and a central bore and with the third plate adjoining the second plate having a nozzle structure consisting of a central bore and two concentric annular gaps. 
         [0015]    The outer diameter of the multi-passage hollow fiber spinning nozzle is advantageously smaller than 1 mm. The outer diameter of the multi-passage hollow fiber spinning nozzle is particularly advantageously smaller than or equal to 0.45 mm. A dialysis membrane with an inner diameter of 200-300 μm can be manufactured with this. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Further details and advantages of the invention result from the embodiments shown in the drawings. 
           [0017]      FIG. 1  is a schematic section through a hollow fiber spinning nozzle in accordance with an embodiment in accordance with the prior art. 
           [0018]      FIG. 2  is a schematic section through a hollow fiber spinning nozzle in accordance with a first aspect of the invention. 
           [0019]      FIG. 3   a  is a schematic sectional representation of a hollow fiber spinning nozzle in accordance with a second embodiment of the invention, showing a first of three variants of the arrangement of the mass supply passages. 
           [0020]      FIG. 3   b  is another schematic sectional representation of a hollow fiber spinning nozzle in accordance with the second embodiment of the invention, showing a second of three variants of the arrangement o the mass supply passages. 
           [0021]      FIG. 3   c  is a further schematic sectional representation of a hollow fiber spinning nozzle in accordance with the second embodiment of the invention, showing the third of three variants of the arrangement of the mass supply passages. 
           [0022]      FIG. 4  is a partly sectioned three-dimensional representation of a hollow fiber spinning nozzle in accordance with  FIG. 2 . 
           [0023]      FIG. 5  is a partly sectioned three-dimensional representation of a hollow fiber spinning nozzle in accordance with the embodiment of  FIG. 3   a.    
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
         [0025]    In  FIG. 2 , a hollow fiber spinning nozzle  10  in accordance with a first aspect of the invention is shown. Here, the total base body  26  is put together from two single plates  30  and  32 . In the first plate  30 , mass supply passages  34 , a mass flow homogenization zone  36 , a coagulation agent supply bore  38  and a needle stub  40  are formed by a corresponding etching process which will be described in detail later. The three-dimensional design of the hollow fiber spinning nozzle shown here in  FIG. 2  results from  FIG. 4 . It can be seen there that the mass supply passages, i.e. the passages for the supply of the polymeric mass to be precipitated, are arranged in cross shape in the embodiment shown here. The mass flow homogenization zone  36  results as a ring space around the needle stub  40 . The coagulation agent supply bore  38  is broadened in its region pointing toward the upper side, as can in particular be seen from  FIG. 2 . 
         [0026]    The design of the second plate  32  can also be seen from  FIGS. 2 and 4  which has a mass discharge opening  42  which directly adjoins the mass flow homogenization zone  36 . This mass discharge opening or the mass annular gap  42  results, with the needle  44  with coagulation agent bore  46 , in the high-precision nozzle structure  48 . The embodiment shown in  FIGS. 2 and 4  of mono-crystalline silicon has, for example, a thickness of the first plate of 0.4 mm, a thickness of the second plate of 0.1 mm, an outer diameter of the needle of 0.05 mm, a length of the needle including the needle stub of 0.15 mm, a diameter of the coagulation agent bore  38  in the expanded region of 0.1 mm, an outer diameter of the annular gap  42  of 0.1 mm and a length of the annular gap  42  of 0.1 mm. The height of the base body  26 , i.e. the height of the total spinning nozzle  10 , accordingly amounts to 0.5 mm, while an edge length of the base body  26  of the spinning nozzle  10  amounts to 2 mm. 
         [0027]    In the manufacture of hollow fiber spinning nozzles by means of microstructure technology, 2 round wafer disks with diameters of 100 to 300 mm are the starting point. A plurality of spinning nozzle structures are simultaneously made from these wafers. The individual hollow fiber spinning nozzles  10  are then obtained by dividing the wafers already processed. The individual split spinning nozzles can each be given a single nozzle structure, as shown here, or also a plurality of nozzle structures in one nozzle structure compound. This is achieved in that not all nozzle structures formed on the wafer are separated from one another, but that a plurality of nozzle structures together form one multi-nozzle unit which are cut out from the wafer along their outer contour. 
         [0028]    The manufacture of the spinning nozzles  10  starts with the two-side structuring of a first wafer which accommodates the elements  34 ,  36 ,  38 ,  40  of the plate  30  of the spinning nozzle  10 . The structures are produced with a sequence of standard lithography processes, i.e. masks of photoresist, SiO, Si—N or similar, and standard etching processes. In the standard etching processes, in particular reactive ion etching (RIE), deep reactive ion etching (DRIE) and cryo-etching should be named. Specific deep etching processes such as DRIE and cryo-etching are particularly suitable. The lithography masks for the front side and for the rear side must be optically aligned to one another. Subsequently, the second wafer, from which the second plate should be manufactured, is bonded to the correspondingly structured first wafer. In this process, all bonding methods can be used, anodic bonding, direct bonding or similar. 
         [0029]    However, direct bonding is particularly suitable since the highest strengths are reached and thus a good hold of the needle on the first plate is ensured. In the next step, the nozzle structure  48  with the annular gap  42  and the coagulation agent bore  46  are manufactured in a two-stage etching process. In the first step, only the deeper coagulation agent bore is driven forward. In the second step, both structures are then etch finished. Said lithography processes and etching processes are again used, with the use of the deep etching process being more advisable here than in the working of the first wafer. In the final step, the individual spinning nozzles are, as already previously described, cut out of the wafer by suitable separation processes such as wafer sawing or laser working. 
         [0030]    Further alternative aspects of the invention will be explained with reference to  FIGS. 3 and 5 . Here, a hollow fiber spinning nozzle  10  is shown for the manufacture of a hollow fiber co-extruded from two layers. Here, a hollow fiber spinning nozzle  10  is shown with a base body  100  consisting of three single plates  102 ,  104  and  106 . The single plates in turn consist of mono-crystalline silicon. A supply passage  108  for the coagulation agent is cut out in the first plate. In addition, supply passages  110 ,  112  for a first polymer are provided which open into an associated homogenization zone  114 . The homogenization zone  114  surrounds a corresponding needle stub  116 . 
         [0031]    A coagulation agent bore  118  is likewise cut out in the second plate  104  and is surrounded by a further needle stub  120  and by a ring space  122 . Furthermore, further supply passages  124  are cut out in the second plate  104  with a subsequent homogenization zone  126 . Finally, the third plate  106  has two annular gaps  128  and  130  for the respective polymeric materials which should be co-extruded as well as a needle  132  with a coagulation agent bore  134 . In the variants of  FIG. 3   a ,  FIG. 3   b  and  FIG. 3   c , the supply passages  124  are each designed differently. While the supply passage  124  for the second polymer is only provided in the second plate  104  in the embodiment in accordance with  FIG. 3   a , it extends in the variant in accordance with  FIG. 3   b  both through the second plate  104  and through the third plate  106 . In the embodiment in accordance with  FIG. 3   c , the supply passage  124  for the second polymer extends through the second plate  104  and the first plate  102 , as shown here in  FIG. 3   c . The representation in accordance with  FIG. 5  corresponds to the section in accordance with  FIG. 3   a , with it becoming clear here that 8 supply passages  112  are arranged in star shape, while only 4 supply passages  124  are arranged in cross shape. 
         [0032]    The three plates  102 ,  104  and  106  are in turn connected to one another to form the base body  100  by a suitable bonding process, advantageously by direct bonding. Otherwise, the manufacturing method for the hollow fiber spinning nozzle  10  in accordance with  FIGS. 3 and 5  corresponds analogously to that as was already explained in detail with reference to  FIGS. 2 and 4 . 
         [0033]    The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims.