Abstract:
Apparatus for forming a bag assembly from a tube and a tubular flexible membrane operates in accordance with a four step process. This process includes the steps of clamping the tube within an open end of the membrane, injecting liquid adhesive into the open end of the membrane, clamping the membrane and tube where the adhesive was injected, and heating and curing the assembly.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a silicone bag assembly for use in pharmaceutical manufacturing and for holding health care related solutions and, more particularly, to apparatus for manufacturing such a bag assembly. 
     At the present time, virtually all bags used by the pharmaceutical industry and for holding health care related solutions (such as intravenous bags) are manufactured of polyvinyl chloride (PVC). PVC is a commonly used inexpensive plastic material which is naturally hard. To soften such material so that it can be used as a flexible bag and as flexible tubing, plasticizers such as phthalate esters are added to the PVC to soften it. Recently there has been concern that phthalates may leach from the PVC to which they have been added, thereby contaminating aqueous fluids held in PVC bags and traveling through PVC tubing. Since PVC bags are used to store intravenous solutions and blood for transfusions, phthalates which leach from the PVC are infused directly into a patient&#39;s bloodstream. It has therefore been proposed to form the bag and tubing from silicone, which does not react with contacting liquids or leach chemicals into contacting liquids. Accordingly, a need exists for apparatus capable of manufacturing such a bag assembly, particularly in a continuous production process. 
     SUMMARY OF THE INVENTION 
     According to the present invention, the bag assembly is formed from a tube and a tubular flexible membrane with opposed open ends. The basic inventive apparatus includes a base for supporting the membrane and the tube with the tube extending into one of the membrane open ends, a first clamp adapted to flatten and clamp the membrane to itself and to the tube along a line spaced from and substantially parallel to the open end, an injector adapted to inject liquid adhesive into the open end and around the tube between the open end and the line, and a second clamp adapted to flatten and clamp the membrane to itself and to the tube between the line and the open end. Accordingly, the first clamp is operative to prevent injected adhesive from getting into the interior of the tubular membrane. 
     Using the aforedescribed basic apparatus, a continuous production manufacturing apparatus is provided including a pair of endless belt systems arranged for movement in opposite angular directions. The first belt system includes a plurality of bases mounted thereon at a plurality of equally spaced locations. The second belt system has mounted thereon a plurality of the first and second clamps and is dimensioned to expose a leading portion of the first endless belt system. The clamps are arranged so that each first clamp is spring coupled to the second endless belt system so as to be yieldably biased away from the second endless belt system. The clamps are arranged so that the first clamp contacts a respective base before the second clamp contacts that base. A membrane placement station is arranged to place a respective flexible membrane on each base while that base is exposed, and a tube insertion station is arranged to insert a tube into such a placed membrane. An adhesive injection station is arranged to inject liquid adhesive into the open end of each membrane while on its respective base with a respective tube inserted therein while a first clamp contacts the membrane but before a second clamp contacts the membrane. After the second clamp contacts the membrane, the clamped assembly cures while travelling along the belt systems. The clamps later separate from the bag assembly, which falls off the trailing end of the first endless belt system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing will be more readily apparent upon reading the following description in conjunction with the drawings in which like elements in different figures thereof are identified by the same reference numeral and wherein: 
     FIG. 1 is a perspective view of a bag assembly which may be produced by apparatus constructed according to the present invention; 
     FIG. 2 is a perspective view of a manually operated apparatus according to the present invention; 
     FIGS. 3-5 schematically depict steps in the formation of a bag assembly using the apparatus shown in FIG. 2 according to this invention; 
     FIG. 6 is a schematic perspective view showing continuous production manufacturing apparatus according to the present invention; 
     FIG. 7 is a perspective view showing a clamp assembly for use in the apparatus shown in FIG. 6 according to the present invention; 
     FIG. 8 is an end view of the clamp assembly shown in FIG. 7 with the first clamp member contacting the base; 
     FIG. 9 is an end view of the clamp assembly shown in FIG. 7 with both clamp members contacting the base; 
     FIG. 10 is a perspective view of an illustrative adhesive injection head; and 
     FIG. 11 illustrates the path taken by the adhesive injection head shown in FIG.  10 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, FIG. 1 shows an illustrative bag assembly, designated generally by the reference numeral  20 , which includes a flexible silicone membrane  22  which is formed as a seamless thin-walled tube having opposed ends  24 ,  26 . The bag assembly  20  further includes a pair of silicone tubes  28 ,  30  inserted into the ends  24 ,  26 , respectively. Each of the tubes  28 ,  30  is terminated by a flange and has a stainless steel backup cup slidably mounted thereon, which do not form a part of the present invention. In any event, each of the ends  24 ,  26  is flattened and sealed to itself and to a respective one of the tubes  28 ,  30 , as by adhesive or the like. 
     Apparatus for manually forming a bag assembly  20  is shown in FIG.  2 . As shown, the apparatus includes a base  32  adapted to support the membrane  22  and the tubes  28 ,  30 . Accordingly, the base  32  is formed with a groove  34  sized to accommodate the tubes  28 ,  30  therein. Mounted to the base  32  are a pair of first clamps  36  which are pivotally mounted at one end and are held down by holders  38 . Each first clamp  36  has a groove  40  which is aligned with the groove  34  when the first clamp  36  is in contact with the base  32 . A pair of second clamps  42  are also provided. The second clamps  42  are provided with bores (not shown) into which the posts  44  are inserted to provide an appropriate alignment for the clamps  42 . The clamps  42  are each formed with a groove  46  which is aligned with the groove  34  when the clamps  42  are lowered on the posts  44 . 
     FIGS. 3-5 schematically depict the steps for forming a bag assembly using the apparatus shown in FIG.  2 . Thus, as shown in FIG. 3, initially a tubular membrane  22  is placed on the base  32  and the tubes  28 ,  30  are inserted into the open ends  24 ,  26 , respectively, of the membrane  22 . Next, the clamps  36  are pressed down over the membrane  22  and the tubes  28 ,  30  so as to flatten and clamp the membrane  22  to itself and to the tubes  28 ,  30  along lines spaced from and substantially parallel to the open ends  24 ,  26 . Adhesive injectors  48  have their heads inserted into the open ends  24 ,  26  to inject liquid adhesive, preferably liquid silicone when the membrane  22  and the tubes  28 ,  30  are formed of silicone, into the open ends  24 ,  26  and around the tubes  28 ,  30  between the open ends and the aforedescribed clamp lines. Thus, the clamps  36  prevent adhesive from entering the interior of the tubular membrane  22 . Next, as shown in FIG. 5, the clamps  42  are put in place and the entire assembly is heated to cure the adhesive. When the clamps  36 ,  42  are removed, the bag assembly including the membrane  22  and the tubes  28 ,  30  may be removed from the base  32 . 
     FIGS. 6-11 illustrate different aspects of a continuous production manufacturing apparatus, designated generally by the reference numeral  50 , for manufacturing the bag assembly shown in FIG.  1 . The apparatus  50  includes a first endless belt system  52  and a second endless belt system  54 . As shown, the first endless belt system  52  is longer than the second endless belt system  54  so as to leave exposed a leading portion of the first endless belt system  52  which immediately precedes that portion of the first endless belt system  52  which is overlain by the second endless belt system  54 . Thus, the first endless belt system  52  includes a belt  56  formed into a continuous loop around drive rollers  58 . It is understood that there are other support rollers intermediate the drive rollers  58 , but for purposes of clarity the intermediate support rollers are not shown. Secured to the belt  56 , at a plurality of equally spaced locations, are a plurality of base members  60 . Each of the base members  60  is substantially the same as the base  32  (FIG.  2 ), but without the clamps  36 , the holders  38  and the posts  44 . In addition, each of the base members is provided with one or more heater cartridges  62 . The base members  60  are formed of a heat conducting material so that the heater cartridges  62  maintain the surface temperature of the base members  60  at a temperature in the range from about 150° F. to about 400° F., preferably about 300° F. 
     The second endless belt system  54  includes a belt  64  formed into an endless loop around drive rollers  66 . Again, for purposes of clarity, intermediate support rollers have not been shown. The drive rollers  66  are arranged to rotate oppositely to the drive rollers  58  so that the belts  56 ,  64  move in opposite angular directions, as shown by the directional arrows. Mounted to the belt  64  at a plurality of equally spaced locations, with the same spacing as the base members  60 , are a plurality of clamp fixtures  68 . Preferably, there is a plurality of clamp fixtures  68  along each longitudinal edge of the belt  64 , so that bag assemblies with tubes at opposite ends can be fabricated. As best shown in FIG. 7, each clamp fixture  68  includes a first clamp block  70  and a second clamp block  72 . The second clamp block  72  is secured to the belt  64  and is generally rectilinear with an L-shaped cross section when viewed orthogonally to its direction of travel along the second endless belt system  54 , as best seen in FIGS. 8 and 9. The first clamp block  70  is generally rectilinear and is sized to fit within the opening of the L-shape of the second clamp block  72 . The first clamp block  70  is spring coupled to the second clamp block  72 , as by posts  74  within the interior of compression springs  76 . Thus, the first clamp blocks  70  are yieldably biased out of the L-shape openings of the second clamp blocks  72  in a direction away from the belt  64 . Further, the clamp blocks  70 ,  72  are formed of a heat conducting material and have heater cartridges  78 ,  80 , respectively, which maintain the surface temperature of the blocks  70 ,  72  the same as that of the base members  60 . 
     As shown in FIG. 6, as a clamp fixture  68  comes down around the right side of the second endless belt system  54 , the first clamp block  70  initially contacts a respective base member  60 , also shown in FIG.  8 . As the clamp fixture  68  moves to the left, the second clamp block  70  approaches the base member  60  and the first clamp block  70  is moved into the L-shape opening of the second clamp block  72  against the force of the spring  76 . When the second clamp block  72  contacts the base  60 , as shown in FIG. 9, both the first and second clamp blocks  70 ,  72  are in contact with the base member  60 . 
     The apparatus  50  also includes a membrane placement station  78  adjacent the exposed portion of the first endless belt system  52 . The membrane placement station  78  is arranged to take a length of tubular flexible membrane  80 , illustratively cut from a supply  82  of tubular flexible silicone membrane, and place that length  80  on an adjacent base member  60 . At a downstream location along the first endless belt system  52  is a tube insertion station  84  arranged to insert a length of tube  86  into an open end of a membrane  80  on a base member  60  while that base member  60  is still within the exposed portion of the first endless belt system  52 . Illustratively, there is a tube insertion station  84  on each side of the belt system  52  and the tube  86  is illustratively Sani-Tech® 45 or Tygon® tubing manufactured by Norton Performance Plastics Corporation of Sparta, N.J. 
     Downstream from the tube insertion station is an adhesive injection station  88 . The adhesive injection station  88  is arranged to inject liquid adhesive into the open end of the membrane  80  after a first clamp block  70  engages the membrane  80  but before the second clamp block  72  engages the membrane  80 . Exemplary adhesive is Sani-Tech® 45 or 70 LIM silicone adhesive, manufactured by Norton Performance Plastics Corporation of Sparta, N.J. Illustratively, there is an adhesive injection station  88  on each side of the belt system  52 . The adhesive injection station  88  includes an injection head which illustratively is of the form shown in FIG.  10  and designated generally by the reference numeral  92 . The head  92  is bifurcated with a gap  94  for receiving a tube  86 . Illustratively, the injection station  88  is arranged to cause the head  92  to move along the closed path shown in FIG.  11 . Thus, from the initial location  96 , the head  92  is caused to move downwardly as shown by the arrow  98  and then inwardly to extend into an open end of a membrane  80 , as shown by the arrow  100 , with the tube  86  being received within the gap  94 . Next, the head  92  moves laterally as indicated by the arrow  102 , following the movement of the membrane  80 . During this travel, liquid adhesive is injected into the open end of the membrane  80  through the slots  104  of the head  92 . The clamp block  70  prevents the adhesive from reaching the interior of the tubular membrane  80 . Next, the head  92  is moved outwardly from the open end of the membrane  80 , as indicated by the arrow  106 , then upwardly, as indicated by the arrow  108 , and finally laterally in the direction opposite to the direction of travel of the membrane  80 , as indicated by the arrow  110 , back to the initial location  96 . 
     After liquid adhesive is injected into the open end of the membrane  80 , the second clamp block  72  contacts the membrane  80 . It will be recalled that the base members  60  and the clamp blocks  70 ,  72  are all heated. Thus, as the membrane  80  with the tube  86  and the liquid adhesive travels along the apparatus  50 , the heat applied by the base member  60  and the clamp blocks  70 ,  72  cures the adhesive. When the membrane and tube assembly reaches the leftmost end of the belt system  52 , the clamp blocks  70 ,  72  disengage therefrom and the membrane and tube assembly falls off the end of the belt system  52  into a receptacle (not shown) provided therefor. 
     The assembly  20  can be constructed to have any desired capacity. As presently contemplated, the capacity will probably be in the range from about 750 ml up to about 5 liters, but larger capacity assemblies, even up to one thousand liters, are within the scope of this invention. Further, the assembly  20  is not limited to any specific use, although it is presently contemplated that it will be used for storage (and cryogenic shipment) of intermediate or concentrated drug products during manufacture in an industrial setting. 
     The aforedescribed inventive apparatus results in a number of manufacturing advantages. Thus, stock items of tubing and tubular membranes can be utilized. Also, it is economically advantageous to only adhesive weld the two ends of the bag, instead of having to perform a full perimeter adhesive weld. Further, the clamp design leaves the diameter of the tubing intact while insuring a good seal between the tubing and the membrane. Additionally, an all silicone (including adhesive) product is produced. 
     Accordingly, there has been disclosed improved apparatus for forming a bag assembly. While illustrative embodiments of the present invention have been disclosed herein, it will be understood that various adaptations and modifications to the disclosed embodiments are possible, and it is intended that this invention be limited only by the scope of the appended claims.