Abstract:
A method is disclosed for the sealing of hard shell capsules having coaxial body parts which overlap when telescopically joined. Also described is an apparatus to seal the capsules. The method comprises the steps of holding the capsule in a precise and upright position and injecting a quantity of sealing fluid in the overlap of the body parts. An apparatus for performing the method is also disclosed. The apparatus comprises a sealing clamp to hold the capsule in an upright position and means to inject the sealing fluid in the overlap of the body parts.

Description:
This invention relates to a method of and apparatus for sealing capsules and to the capsule formed thereby. 
     The capsules sealed by the method and apparatus according to the present invention are hard shell, telescopically joined capsules with coaxial partly overlapping body parts. The capsules may be made of gelatin or of other materials whose properties are pharmaceutically acceptable with respect to their chemical and physical properties. 
     The problem to be solved with respect to such capsules as compared to other dosage forms is the fact that the coaxial body parts must be well sealed in order to avoid leaking of any content to the outside or contamination thereof. Further, tampering with the content of the capsule or the capsule as such should be evident and externally visible for safety proposes. Any technique of sealing the capsules must be suitable for large scale bulk production to reduce manufacturing time and costs and to reduce waste due to imperfections of the product. 
     BACKGROUND OF THE INVENTION 
     EP 0 116 743 A1, EP 0 116 744 A1 and EP 0 180 543 A1 disclose methods and devices for sealing such capsules having hard shell coaxial cap and body parts which overlap when telescopically joined. The process employed comprises the steps of dipping batches of the capsules randomly oriented in mesh baskets or oriented with their cap parts upright into a sealing fluid making capillary action within the overlap of the cap and body parts or spraying the sealing fluid or steam thereof onto the seam of the overlap, removing the sealing fluid from the surface of the capsules by an air blower, and applying thermal energy to the capsules while conveying the baskets through a dryer. The documents disclose the use of a wide range of sealing fluids and specific temperatures and modes of application of thermal energy, the disclosure of which is incorporated herein by reference. 
     EP 1 072 245 A1 also discloses a method for sealing telescopically joined capsules with coaxial body parts through subsequent application of a sealing liquid by the overlapping region at the joint between a cap and a body, the removal of excess sealing liquid, and the application of thermal energy for drying purposes. This document particularly describes the steps of applying a sealing liquid including a solvent uniformly to the external edge of the gap of a capsule to be sealed to form a liquid ring around the circumference of the capsule, removing excess sealing liquid from the exterior of the capsule and drying the capsule by applying thermal energy from outside while gently tumbling and conveying the capsule on a spiral path. Spray nozzles are used for individually applying the sealing liquid. The excess solution is removed from around the capsule by vacuum suction or air jets. The disclosure of this document is incorporated herein by reference, too. 
     The prior systems for sealing capsules are partly imperfect as regards the quality of the seal and the controllability of the process parameters influencing the quality of the seal. 
     SUMMARY OF THE INVENTION 
     The present invention aims at providing an improved method and apparatus for sealing telescopically joined capsules with coaxial partly overlapping body parts, through subsequent application of a sealing fluid and an improvement of the fluid injection phase in order to reach the maximum volume available in the overlap of the body parts while the capsule remains free of residual liquid on its surface. 
     With respect to this object the present invention provides a method and an apparatus for sealing telecopically joined capsules with coaxial partly overlapping body parts as defined in the appended claims. Sealing clamps are used to seal efficiently hard capsules. Filled or empty capsules are to be oriented before the sealing operation. The sealing clamps hold each capsule in a precise and reproducible upright position. A known quantity of sealing fluid is injected in the overlap of the body parts within a well-defined volume. The excess of sealing fluid is removed from the outside of the capsule shell. Moreover the excess of sealing fluid is removed from the sealing clamp to prevent build-up of sealing fluid. Finally the capsule is released properly. 
     The use of spray clamps instead of bushings or any other apparatus enables to limit the zone where the sealing fluid is injected to the overlap of the body parts. The design of the sealing clamp limits the location of the sealing fluid to the interior volume of the clamp. The excess of sealing fluid remaining in the clamp is recovered through suction channels. 
     Using a spray clamp also forces the capsules to be cylindrical which is an advantage when using flexible polymer material to manufacture capsule. Thus the capsule diameter is homogeneous on 360°. The penetration of the sealing liquid by the capillary effect on the whole capsule circumference is favoured. An additional benefit to use a sealing clamp is to guarantee an actual vertical positioning of the capsule with regard to the location of the sealing liquid injection hole. 
     The spray clamp can be composed of different parts. Each part will participate to the various steps of the process. As an example, the injection of the sealing liquid can happen in one part whilst the excess of sealing fluid can be collected in a second part. 
     The number of main functional parts that compose the spray clamp can vary from one to six. The number of injection ports can vary from one to eight. The number of suction ports can vary from one to ten. The number of airing can vary from one to six. The positioning of those parts can be spatially arranged to obtain the desired effect. One to three liquid recovery grooves can be added to the design of clamp. 
     In a preferred embodiment the sealing clamp consists of two parts. These two parts are joined together to open and close the sealing clamp. 
     The present invention will now be described in more detail, by way of example, with reference to the accompanying drawings in which the following figures show: 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  first embodiment of a sealing clamp in open position in perspective view, 
         FIG. 2  sealing clamp of  FIG. 1 , closed, in cross section, 
         FIG. 3  second embodiment of a sealing clamp in open position in perspective view, 
         FIG. 4  sealing clamp of  FIG. 3 , closed, in cross section, 
         FIG. 5  third embodiment of a sealing clamp in open position in perspective view, 
         FIG. 6  sealing clamp of  FIG. 5 , closed, in cross section, 
         FIG. 7  forth embodiment of a sealing clamp in open position in perspective view, 
         FIG. 8  sealing clamp of  FIG. 7 , closed, in cross section, 
         FIG. 9  fifth embodiment of a sealing clamp in open position in perspective view, 
         FIG. 10  sealing clamp of  FIG. 9 , closed, in cross section, 
         FIG. 11  sixth embodiment of a sealing clamp in open position in perspective view, 
         FIG. 12  sealing clamp of  FIG. 11 , closed, in cross section, 
         FIG. 13  seventh embodiment of a sealing clamp in open position in perspective view, 
         FIG. 14  sealing clamp of  FIG. 13 , closed, in cross section. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a first embodiment of a sealing clamp  1  consisting of a first part  2  and a second part  3 . In the closed sealing clamp the edge of the cap of a capsule, not shown in the drawings, is precisely located between 0 and 2 mm above the injection port  5 . The sealing fluid is injected via an injection port  5  located at 90° from the parting line of the first part  2 . Air or any other gas can flow through an airing  6  located at 45° from the parting line of the first part  2  and two suction ports  7  located at 90° and 60° from the parting line of the second part  3 . The injection port  5  and the airing  6  are located between 0 and 2 mm below the cap edge while the two suction ports  7  are in the liquid recovery groove  8 . 
     The difference between the first embodiment of a sealing clamp in  FIGS. 1 and 2  and the other embodiments shown in  FIG. 3 to 14  consists in the number and position of injection ports  5 , airings  6 , suction ports  7  and liquid recovery grooves  8 . The embodiments one to four of  FIGS. 1 to 8  enable sealing of 20 to 50% of the maximum surface available. With the sealing clamp of embodiment five a sealed surface of 80% is reached. Use of the sealing clamp of embodiment six gives a large sealed zone of 90 to 100%. With the sealing clamp of embodiment seven the total removal of the excess of sealing fluid from the capsule shell is possible preventing subsequent process defects. 
     A second embodiment of a sealing clamp  11  shown in  FIGS. 3 and 4  consists of a first part  12  and a second part  13 . In the closed sealing clamp the edge of the cap of a capsule, not shown in the drawings, is precisely located between 0 and 2 mm above the injection port  15 . The sealing fluid is injected via an injection port  15  located at 90° from the parting line of the first part  12 . Air or any other gas can flow through an airing  16  located at 75° from the parting line of the first part  12  and two suction ports  17  located at 90° and 60° from the parting line of the second part  13 . The injection port  15  is located between 0 and 2 mm below the edge of the cap of a capsule while the airing  16  and the two suction ports  17  are in the liquid recovery groove  18 . 
     A third embodiment of a sealing clamp  21  shown in  FIGS. 5 and 6  consists of a first part  22  and a second part  23 . In the closed sealing clamp the edge of the cap of a capsule, not shown in the drawings, is at the bottom  29  of the liquid recovery groove  28 . The sealing fluid is injected via an injection port  25  located at 90° from the parting line of the first part  22  in the liquid recovery groove  28 . Air or any other gas can flow through an airing  26  located at 45° from the parting Is line of the first part  22  and two suction ports  27  located at 90° and 60° from the parting line of the second part  23 . The airing  26  and the two suction ports  27  are located in the liquid recovery groove  28 . 
     A forth embodiment of a sealing clamp  31  shown in  FIGS. 7 and 8  consists of a first part  32  and a second part  33 . In the closed sealing clamp the edge of the cap of a capsule, not shown in the drawings, is at the bottom  34  of the liquid recovery groove  38 . The sealing fluid is injected via an injection port  35  located at 90° from the parting line of the first part  32  in the liquid recovery groove  38 . Air or any other gas can flow through an airing  36  located at 45° from the parting line of the first part  32  and two suction ports  37  located at 90° and 60° from the parting line of the second part  33 . The airing  36  and the two suction ports  37  are located in the liquid recovery groove  38 . Additional features are an absorbent layer  39  and a vertical rubber coating  40  at the bottom of the sealing clamp  31 . 
     A fifth embodiment of a sealing clamp  41  shown in  FIGS. 9 and 10  consists of a first part  42  and a second part  43 . In the closed sealing clamp the edge of the cap of a capsule, not shown in the drawings, is at the bottom  50  of a liquid injection groove  49  of the sealing clamp  41 . The sealing fluid is injected via two injection ports  45  located at 60° from the parting line of the first part  42  and at 60° from the parting line of the second part  43 . Both injection ports  45  enter into a liquid injection groove  49 . Air or any other gas can flow through two airings  46  located at 30° from the parting line of the first part  42  and of the second part  43  and through four suction ports  47  located at 90° and 120° from the parting line of the first part  42  and of the second part  43 . The airings  46  and the suction ports  47  are located in the liquid recovery groove  48 . 
     A sixth embodiment of a sealing clamp  51  shown in  FIGS. 11 and 12  consists of a first part  52  and a second part  53 . In the closed sealing clamp the edge of the cap of a capsule, not shown in the drawings, is precisely located between 0 and 2 mm above the injection port  55 . The sealing fluid is injected via an injection port  55  located at 60° from the parting line of the first part  52 . Air or any other gas can flow through an airing  56  located at 90° from the parting line of the first part  52  and a suction port  57  located at 120° from the parting line of the second part  53 . The airing  56  and the suction port  57  are in the liquid recovery groove  58 . 
     A seventh embodiment of a sealing clamp  61  shown in  FIGS. 13 and 14  consists of a first part  62  and a second part  63 . In the closed sealing clamp the edge of the cap of a capsule, not shown in the drawings, is at the bottom  70  of a liquid injection groove  69  of the sealing clamp  61 . The sealing fluid is injected via two injection ports  65  located at 135° from the parting line of the first part  62  and at 135° 0  from the parting line of the second part  63 . Both injection ports  65  enter into a liquid injection groove  69 . Air or any other gas can flow through two airings  66  located at 150° from the parting line of the first part  62  and of the second part  63  and through four suction ports  67  located at 30° and 60° from the parting line of the first part  62  and of the second part  63 . The airings  66  and the suction ports  67  are located in the liquid recovery groove  68 .