Abstract:
An apparatus and method for cleaning polymer film are provided and include a support assembly for supporting the polymer film to be cleaned, the support assembly being constructed and arranged to move the polymer film for cleaning, and at least one nozzle disposed adjacent the polymer film for providing CO 2  to the polymer film for dislodging particulate matter from the polymer film and the at least one aperture, and for cleaning thereof.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to polymer film cleaning. 
         [0002]    Polymer films and webs have to date been cleaned with dionized (DIO) water, air megasonics, ultraviolet (UV) light, and combinations thereof to remove particles and debris from the polymer. However, such cleaning applications are not sufficient for purposes of medical devices using polymer films. This is especially so where polymer films have been provided with holes or apertures, and the area of the film surrounding such holes and apertures becomes clogged and contaminated with particles and remnants of the film when the holes are formed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    For a more complete understanding of the present invention, reference may be had to the following drawings taking in conjunction with the detailed description of the invention, of which: 
           [0004]      FIGS. 1A and 1B  are side and top views, respectively, of a polymer film having apertures therethrough at which debris and contaminates are at said apertures. 
           [0005]      FIG. 1C  shows the impact of debris laden and contaminated apertures upon fluid transfer through the apertures. 
           [0006]      FIG. 2  shows a portion of an apparatus according to the invention for cleaning the polymer film. 
           [0007]      FIG. 3  shows a portion of the apparatus of  FIG. 2 . 
           [0008]      FIG. 4  is a view of a portion of the CO 2  cleaning apparatus of  FIG. 2 . 
           [0009]      FIGS. 5A and 5B  are side and top views, respectively, of the apertures having been cleaned by the system of  FIGS. 2 and 6 . 
           [0010]      FIG. 5C  shows the result of such cleaning upon fluid transfer through the apertures. 
           [0011]      FIG. 6  shows another apparatus according to the invention for cleaning the polymer film. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    Referring to  FIGS. 1A-1C , there is shown a polymer or polyimide film  10  or web which may be used in different processing and manufacturing applications. In particular, but only by way of example, the polymer film  10  may be used in the medical and health care industries. The film  10  may be used in medical devices, such as for example an insulin inhaler device. Accordingly, the film  10  is usually required to be of a clean and sterile construction. 
         [0013]    As shown in  FIGS. 1A and 1B , when the film  10  is formed or manufactured with one or a plurality of holes  12  or apertures therethrough, particulate matter and/or veils  14  may be formed or accumulate at edges  16  or a perimeter of the holes  12 , thereby substantially reducing if not impeding a flow  18  of a fluid through the holes  12 , as shown in  FIG. 1C . Veils are the remnants of polymer disposed at the holes  12  when the holes are formed. Flow  19  is as a result of no veils or matter to impede fluid flow through the hole  12 . 
         [0014]    The holes shown in  FIGS. 1A-1C  usually range in size from microns to sub-microns. However, holes of different sizes in the polymer film may certainly be formed, depending upon the application of the polymer film  10 . 
         [0015]      FIGS. 2 and 3  show a portion of an apparatus  20  according to the invention for transporting the polymer film  10  and cleaning thereof with CO 2 .  FIG. 2  shows the apparatus  20  having a plurality of reels, one of which is designated generally as a source reel  22 ; while another reel is designated generally as a take up reel  24  for the film  10 . The film  10  already has the holes  12  formed therein and the source reel  22  of such film  10  is mounted to the apparatus  20 , with the film  10  being fed over idler reels  26 ,  28 , under a select tension for cleaning. Guide reels  30 ,  32  position the film  10  for movement with the idler reels  26 ,  28  to align the film for cleaning as discussed below. 
         [0016]    As shown in  FIGS. 2 and 3 , at least one or perhaps a plurality of CO 2  cleaning assemblies  34 ,  36  are disposed on the apparatus. The CO 2  cleaning assemblies  34 ,  36  each consist of moveable mounting members and nozzle assemblies for positioning nozzles with respect to the polymer film  10  for cleaning of same. As shown more particularly in  FIGS. 2 and 3 , mounting brackets  38  support CO 2  nozzles  40 , which brackets  38  can be moved to a plurality of positions with respect to each other in order to move and adjust the nozzles  40  to a select position with respect to the polymer film  10  passing thereby for cleaning. Movement of the nozzles  40 , as shown in  FIG. 4  by arrows  42 ,  44  provide for the nozzles to be trained in a plurality of positions for effective cleaning by both nozzles  40  of opposed surfaces  10   a ,  10   b  of the polymer film  10 . The opposed surfaces  10   a ,  10   b  may be cleaned either concurrently or sequentially. The arrow  42  shows the nozzle  40  being moved with respect to a longitudinal axis of the film  10 . The arrow  44  shows the nozzle  40  being moved to track across a width of the film  10  for cleaning of the film. 
         [0017]    Referring to  FIG. 4 , there is shown the polymer film  10  disposed for movement adjacent to at least one and perhaps a plurality of CO 2  nozzles  40 . The film may be moved as between the source reel  22  and the take-up reel  24  as shown in  FIG. 2 . The film  10  may be moved under a high rate of speed and the nozzles  40  positioned at opposed surfaces  46 ,  48  of the film  10  for providing carbon dioxide (CO 2 ) in either pure or ultra-pure CO 2  snow form. Each one of the nozzles  40  is adapted for rotational movement as shown by the arrow  44  with respect to a surface of the film that passes the nozzle, and is adapted for angular movement as represented by the arrow  42  as well. The nozzles  10  may be of the single point or broad spray nozzle variety, such as those distributed by Eco-Snow Systems LLC of Livermore, Calif. 
         [0018]    The apparatus  20  may be mounted in a hermetically sealed housing (a “clean box”) having a controlled atmosphere in a chamber of the box, such that dew point and temperature of the atmosphere are controlled for purposes of optimizing the cleaning, humidity control, sterilizing the environment and filtration of any particulars removed or sloughed-off from the film  10 . The system of the present invention is adapted for use, for example, by pharmaceutical companies who use polymer film to make medical devices, which devices are used to control dosage of medicines. 
         [0019]    Referring now to  FIGS. 5A-5C , it can be seen that the particulate matter, debris and veils have been removed by this CO 2  system of the present invention, thereby resulting in clean, clear apertures through which medicines or other fluid compositions may readily pass in an unimpeded flow  19  for subsequent use. 
         [0020]    Use of purified CO 2  gas or liquid or a combination thereof does not contain any bacteria and particulate matter. No side effects to the patient or the film  10  should occur by use of such CO 2  on the polymer film. The high pressure of the CO 2  snow from the spray nozzle  40  will dislodge veils and particulate matter at the apertures without any detrimental effect or damage to the polymer film. 
         [0021]    A filtration element can be employed in order to capture the particulate matter and veils that are dislodged during the cleaning process. The clean box process chamber temperature may be kept at about 60° C., by way of example only. Different types of film may require different cleaning temperatures and process conditions. 
         [0022]    By way of example only, the nozzles  40  may be located one half inch (½″) from the film  10  surface (such as for example above the film surface  46 ), while the scan rate of the film is, for example, 100 mm/second. Different film types may require different scan rates for optimal cleaning of the film. 
         [0023]      FIG. 6  shows an apparatus  50  according to the present invention for cleaning the polymer film  10 . The apparatus  50  includes a housing  52  in which a chamber  54  is disposed therein. The chamber  54  includes sufficient amount of space for an air filter  56  and air blower  58  disposed in the chamber  54 . A hinged glass door  60  provides access to the chamber  54 . 
         [0024]    Arranged within the chamber  54  is a plurality of drums; one of which is a supply drum  62 , while the other of which is a motorized take-up reel  64 . The supply drum  62  holds a supply of the polymer film  10  to be cleaned with the CO 2  spray. The supply drum  62  has a magnetic brake so as to tension the web or film  10  as it is drawn up by the motorized take-up reel  64 . The tension applied to the polymer web or film  10  facilitates cleaning of the film. Idler wheels  66 ,  68  are disposed between the supply drum  62  and the take-up reel  64  to facilitate maintaining tension on the polymer film  10  and for the cleaning operation. 
         [0025]    CO 2  nozzles  70 ,  72  are disposed to apply the CO 2  spray to the surface of the polymer film  10  to dislodge any contaminant material on the film and in particular which may be lodged in the apertures  12  formed in the film. 
         [0026]    A conduit or passage  74  is provided in communication with the chamber  54  for the introduction of an inerting gas, such as clean dry air (CDA) or nitrogen (N 2 ), to be introduced into the chamber as shown by arrows  76 . A passageway or conduit inlet  78  for the CO 2  is also in communication with the chamber  54  and through which CO 2  is provided from a CO 2  source (not shown) to the nozzles  40 ,  70 ,  72 . 
         [0027]    Power for the take-up reel  64  is provided from a power connector  80 . An emergency off (EMO) switch  82  is also provided at an exterior of the housing  52 . Indicators are provided for dew point  84  in the chamber  54 , temperature  86  in the chamber, scan or rate  88  of speed of web, and distance  90  of the nozzle opening to the web in film  10  (in millimeters) are also provided in a faceplate of the housing  22 . 
         [0028]    The inerting gas introduced into the chamber  54  is to assist with reducing humidity in the chamber and for displacing a contaminant environment which may be proximate to the film  10  web to be cleaned. Air circulation within the chamber  54  is provided by the air blower  58 . The air filter  56  is also disposed in the chamber  54 , the air filter being removably mountable in order to change or clean same. 
         [0029]    It will be understood that the embodiments described above are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the present invention as described and claimed herein.