Abstract:
A syringe tip cap sealingly closes a distal opening of a syringe body. The syringe tip cap has a fastening ring which can be placed and fastened on the syringe body about the distal opening, and a closure cap which closes the distal opening in a sealed manner and is connected releasably to the fastening ring. The fastening ring has a locking means device that locks together with a locking device of the closure cap. The locking device of the fastening ring and the locking device of the closure cap are configured in such a way that they cannot be unlocked without sustaining damage. The syringe tip cap may be produced in a two-component injection molding process.

Description:
BACKGROUND OF THE INVENTION  
     Field of the Invention  
       [0001]     The invention relates to a syringe tip cap for closing a distal opening of a syringe body in a sealed manner, and to a method for producing such a syringe tip cap.  
         [0002]     U.S. Pat. No. 6,190,364 describes such a syringe tip cap for a syringe body. The syringe body has a distal tip and a distal opening extending through the latter, such that an injection liquid located in the syringe body can exit the syringe body via the distal opening. The syringe comprises a fastening ring, or luer collar, which is formed in one piece with the syringe or is placed on the distal tip of the syringe body and connected fixedly thereto. The fastening ring has thread elements which interact with thread elements of a two-part closure cap in order to hold the closure cap on the fastening ring. In use, the closure cap encloses the distal tip and closes and seals off the distal opening of the syringe body.  
         [0003]     To inject the injection liquid, the closure cap is unscrewed from the fastening ring and a syringe needle is secured on the fastening ring and thus on the syringe body in such a way that a needle opening extending through the syringe needle is in fluidic communication with the distal opening of the syringe body. To secure the syringe needle on the fastening ring, the syringe needle is connected to a thread element which interacts with the thread element of the fastening ring.  
         [0004]     To ensure that possible use of or tampering with the syringe content is made evident, the syringe tip cap according to U.S. Pat. No. 6,190,364 comprises a sealing strip which is connected permanently both to the fastening ring and also to the closure cap, such that the sealing strip tears when the closure cap is detached from the fastening ring.  
         [0005]     A disadvantage of this syringe tip cap is that producing three separate parts (two-part closure cap, sealing element) and joining these parts together to form a syringe tip cap is an elaborate procedure.  
       SUMMARY OF THE INVENTION  
       [0006]     It is accordingly an object of the invention to provide a syringe tip cap and a production method which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a syringe tip cap for closing a distal opening of a syringe body in a sealed manner, which syringe tip cap ensures that any use of or tampering with the syringe content is made evident, and which syringe tip cap is also of a simplified structure and is thus easier to produce.  
         [0007]     With the foregoing and other objects in view there is provided, in accordance with the invention, a syringe tip cap for sealingly closing a distal opening of a syringe body, the syringe tip cap comprising:  
         [0008]     a fastening ring to be arranged and fastened on the syringe body about the distal opening; and  
         [0009]     a closure cap releasably connected to the fastening ring and sealingly closing the distal opening;  
         [0010]     the fastening ring having a first locking device interlocked with a second locking device of the closure cap, and wherein the first locking device and the second locking device are configured not to be unlocked without sustaining damage and, after unlocking, cannot be returned to an initial locked state.  
         [0011]     In other words, the objects of the invention are achieved by a syringe tip cap for closing a distal opening of a syringe body in a sealed manner, the syringe tip cap having a fastening ring which can be arranged and fastened on the syringe body about the distal opening, and a closure cap which closes the distal opening in a sealed manner and is connected releasably to the fastening ring, said fastening ring comprising a locking means which locks together with a locking means of the closure cap, and the locking means of the fastening ring and the locking means of the closure cap being configured in such a way that they cannot be unlocked without sustaining damage, i.e. after being unlocked, they cannot be locked together again without sustaining damage.  
         [0012]     The locking means can be formed by locking tabs and by locking recesses which enclose the latter with a form fit, the locking tabs being connected either to the fastening ring or to the closure cap, and the locking recesses being connected to the other part, i.e. the fastening ring or closure cap, such that the closure cap is locked together with the fastening ring and cannot be unlocked without sustaining damage.  
         [0013]     The locking recesses can be undercut in the longitudinal direction. Moreover, the locking recesses can be undercut in the radial direction.  
         [0014]     The fastening ring preferably comprises a proximal, annular portion, and a hollow cylindrical fastening wall which extends distally from the annular portion.  
         [0015]     It may be expedient if the locking tabs are connected to an outer annular bead of the closure cap and, starting from the annular bead, they extend parallel to the longitudinal axis in the proximal direction and at a distance from an outer face of the closure cap, the locking recesses being open toward a distal front end face of the fastening wall.  
         [0016]     In the fastening wall, locking recesses can be formed which enclose, with a form fit, locking tabs formed on an outer face of the closure cap. The fastening ring and the closure cap can comprise interacting thread elements which define a thread pitch.  
         [0017]     Each locking tab expediently has a stop face which extends at an angle of inclination and which, when the closure cap is unscrewed from the fastening ring as guided by the thread elements, bears against a side face of the locking recess enclosing the respective locking tab, said angle of inclination being greater than the thread pitch, such that the locking tabs and/or the locking recesses are forcibly deformed during unscrewing.  
         [0018]     The fastening ring can be placed and fixed on a distal tip of the syringe body through which the distal opening extends.  
         [0019]     In order to receive a distal tip of the syringe body, the closure cap preferably has the shape of a hollow cylinder closed at one end.  
         [0020]     In the closure cap, there is expediently a cylinder-shaped closure plug on which a central protruding portion is arranged for engaging in the distal opening of the syringe body. In a preferred embodiment of the invention, the closure cap has a central portion which is assigned to the distal opening of the syringe body and which is intended to engage in the distal opening.  
         [0021]     The closure cap can have outer longitudinal ribs and be made from thermoplastic elastomers.  
         [0022]     The fastening ring and the closure cap are expediently produced, in a two-component injection-molding operation, from different materials that do not integrally connect with one another.  
         [0023]     The object is further achieved by a method for producing a syringe tip cap according to the invention, wherein the closure cap and the fastening ring are produced together, by means of a two-component injection-molding operation, in an interlocked manner in such a way that they cannot be unlocked without sustaining damage and, after being unlocked, cannot be locked together again without sustaining damage.  
         [0024]     After production of the closure cap and of the fastening ring, a closure plug is preferably inserted into the closure cap.  
         [0025]     In an advantageous embodiment, the syringe body is sealed off by the closure cap which, for this purpose, has a portion which is assigned to the distal opening of the syringe body and which is intended to engage in the distal opening. In this way, reliable sealing is guaranteed without the aforementioned closure plug. The closure cap is made from thermoplastic elastomers.  
         [0026]     Other features which are considered as characteristic for the invention are set forth in the appended claims.  
         [0027]     Although the invention is illustrated and described herein as embodied in a syringe tip cap and method for producing a syringe tip cap, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
         [0028]     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]      FIG. 1  shows a side view of a first embodiment of a syringe tip cap according to the invention, placed on a syringe body;  
         [0030]      FIG. 2  shows a longitudinal section through the syringe tip cap from  FIG. 1 , along the line II-II in  FIG. 1 ;  
         [0031]      FIG. 3  shows a side view of a second embodiment of the syringe tip cap according to the invention, placed on a syringe body;  
         [0032]      FIG. 4  shows a longitudinal section through the syringe tip cap from  FIG. 3 , along the line IV-IV in  FIG. 3 ;  
         [0033]      FIG. 5  shows a longitudinal section through the syringe tip cap from  FIGS. 3 and 4 , along the line V-V in  FIG. 3 ;  
         [0034]      FIG. 6  shows a side view of a further embodiment of the syringe tip cap according to the invention, placed on a syringe body;  
         [0035]      FIG. 7  shows a cross-sectional view of the syringe tip cap from  FIG. 6 , along the line VII-VII in  FIG. 6 ;  
         [0036]      FIG. 8  shows a longitudinal section through the syringe tip cap from  FIGS. 6 and 7 , along the line VIII-VIII in  FIG. 6 ;  
         [0037]      FIG. 9  shows a side view of a further embodiment of the syringe tip cap according to the invention, placed on a syringe body;  
         [0038]      FIG. 10  shows a longitudinal section through the syringe tip cap from  FIG. 9 , along the line X-X in  FIG. 9 ;  
         [0039]      FIG. 11  shows a cross-sectional view of the syringe tip cap from  FIGS. 9 and 10 , along the line XI-XI in  FIG. 9 ; and  
         [0040]      FIG. 12  shows a longitudinal section through a variant embodiment of the means of sealing the syringe body. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0041]      FIGS. 1 and 2  show, in a first embodiment of the invention, an inventive syringe tip cap  101  which is placed on a syringe barrel or syringe body  103 . The syringe body  103  has a proximal end portion  105  and a distal end portion  107  which are connected by a hollow cylinder  109  which contains a syringe liquid (not shown). The distal end portion  107  is provided with a distal tip  111  wherein a distal opening  113  is formed.  
         [0042]     The syringe tip cap  101  first comprises a fastening ring  115 , customarily referred to as a luer lock ring or luer lock adapter, and a closure cap  117  which is connected to the fastening ring  115  in such a way that it cannot be released from the latter without being destroyed, as will be explained in detail below. The fastening ring  115  comprises a proximal, annular portion  119  which, when placed on the distal tip  111  of the syringe body  103 , is held securely on the tip by frictional forces. For this purpose, an outer annular portion can have radially inwardly projecting contact portions which permit optimal fixing of the fastening ring on the tip. Moreover, the syringe body can have, in the area of the distal tip, an outer annular bead (not shown) which the fastening ring can engage around with a form fit, thus leading to further improved fixing. This is known per se, and so the securing of the fastening ring on the syringe body will not be described in detail here.  
         [0043]     The annular portion  119  of the fastening ring  115  is adjoined distally by a hollow cylindrical fastening wall  123  whose inner face  125  has thread elements  127 .  
         [0044]     The closure cap  117  has the shape of a hollow cylinder closed at one end, and, in the assembled state, the distal tip  111  of the syringe body  103  is arranged inside the hollow cylinder. The closure cap  117  has a proximal portion  129  and a distal portion  131 . A closure plug  135 , which is let into the closure cap  117 , has, at a proximal end face  137 , a central protruding portion  141  which, when fitted, engages in the distal opening  113  of the distal tip  111  in order to reliably seal the syringe body  103 . The closure plug can be formed in one piece with the closure cap.  
         [0045]     As complements to the thread elements  127  of the fastening ring  115 , the proximal portion  129  of the closure cap  117  has thread elements  149  for holding the closure cap  117  in the fastening ring  115 . As an alternative to thread elements, the proximal portion  129  of the closure cap  117  can have outwardly protruding engagement portions which engage in thread elements of the fastening ring  115  in order to hold the closure cap  117  in the fastening ring  115 , or, conversely, the fastening ring could have engagement portions which protrude inwardly from its fastening wall and interact with thread elements of the closure cap.  
         [0046]     Formed on the outside of the distal portion  131  of the closure cap  117 , there are longitudinal ribs  143  which improve handling when unscrewing the closure cap  117  from the fastening ring  115 .  
         [0047]     The closure cap  117  has a circumferential, flange-like annular bead  153  from which four locking tab  155  (alternatively, more or fewer locking tabs may also be provided) issue in the proximal direction parallel to a longitudinal axis  157  and at a radial distance from an outer face  116  of the closure cap  117 . The locking tabs  155  are triangular in radial view ( FIG. 1 ) and thus have a cross section increasing in size as the axial distance from the annular bead  153  increases, adjacent locking tabs  155  each being at an identical angle distance from one another.  
         [0048]     In the fastening wall  123  of the fastening ring  115  there are locking recesses  159  which enclose the locking tabs  155  with a form fit (i.e., form lock, positive lock). The locking recesses are open toward a distal front end face  161 , and the cross section of the locking recesses  159  increases in size as the axial distance from the end face  161  increases, i.e. the locking recesses are undercut in the longitudinal direction. By virtue of the described configuration, the locking tabs  155  are as it were interlocked with the locking recesses  159 . The locking recesses  159  are additionally open toward the outer face of the fastening wall  123 , such that the locking tabs  155  and in particular their connection to the annular bead  153  are visible to the user from the outside. Outer surfaces of the locking tabs  155  visible from the outside are also flush with the outer face of the fastening wall  123 .  
         [0049]     The above-described shape of the locking tabs  155  and locking recesses  159  has the effect that the closure cap  117  cannot be unscrewed from the fastening ring  115  without the locking tabs  155  and/or locking recesses  159  being damaged. Either the locking tabs  155  tear when being unscrewed from the closure cap  117 , or the locking tabs  155  and/or the locking recesses  159  are irreversibly deformed when being unscrewed. Such damage shows the user that the syringe body  103  has already been opened once, and it makes any use of or tampering with the syringe content evident.  
         [0050]     The closure cap  101  according to the invention cannot be produced by first producing the fastening ring  115  and the closure cap  117  separately from each other, for example in a known injection-molding operation, and then joining them together, because the locking tabs  115  cannot be engaged in the locking recesses  159  without sustaining damage. Therefore, the closure cap  117  and the fastening ring  115  are produced at the same time in a known two-component injection-molding operation to form the complete syringe tip cap  101 . In doing this, materials for the closure cap  117  and the fastening ring  115  have to be used which do not join integrally to one another during the two-component injection-molding operation, so as to permit unscrewing of the closure cap  117  from the fastening ring  115  in later use. The closure cap  117  can therefore be made, for example, from a thermoplastic elastomer and the fastening ring  115  can be made from polycarbonate. After the fastening ring  115  and the closure cap  117 , locked together in one another, have been produced simultaneously in a two-component injection-molding operation, the closure plug  135  is inserted into the closure cap  117 .  
         [0051]     To perform an injection procedure, the closure cap  117  is unscrewed from the fastening ring  115 , and a needle, provided with a thread element, is screwed into the fastening ring  115  so that the syringe body  103  communicates with the needle via the distal opening  113 . The liquid to be injected can then be injected using a syringe plunger.  
         [0052]     FIGS.  3  to  5  show another embodiment of a syringe tip cap  201  with a fastening ring  215 , a closure cap  217  and a closure plug  235 . This syringe tip cap  201  differs from the syringe tip cap  101  shown in  FIGS. 1 and 2  in that it has differently configured locking tabs  255  and differently configured locking recesses  259 . The other features of the syringe tip cap  201  are substantially identical to the corresponding features of the syringe tip cap  101 , so that in these respects reference is made to the above description.  
         [0053]     The locking tabs  255  of the closure cap  217  are arranged in an area of the outer face  216  of the closure cap  217  completely enclosed by the fastening wall  223 . Starting from the outer face  216  of the closure cap  217 , they extend in a radial direction in respect of the hollow cylinder shape of the closure cap  217 . It is additionally provided that a cross-sectional surface of the respective locking tab  255 , oriented perpendicular to the radial direction, becomes larger the further it is from the outer face of the closure cap  217  (undercut in radial direction).  
         [0054]     The locking tabs  255  are enclosed with a form fit by locking recesses  259  which are formed in the fastening wall  223  of the fastening ring  215 . The cross-sectional surface of the locking recess  259  oriented perpendicular to the radial direction also becomes larger as the distance from the outer face of the closure cap  217  increases. The locking recesses  259  extend through the fastening wall  223  of the fastening ring  215  completely, so that the locking tabs  255  are visible from outside. The locking tabs  255  end flush with the outer face of the fastening wall  223 .  
         [0055]     The closure cap  217  has a circumferential annular bead  253  arranged between the thread elements  249  and the longitudinal ribs  243  of the closure cap  217 . The annular bead  253  bears on a front end face  261  of the fastening wall  223 .  
         [0056]     FIGS.  6  to  8  show a further embodiment of a syringe tip cap  301  with a fastening ring  315 , a closure cap  317  and a closure plug  335 . This syringe tip cap  301  differs from the previously explained syringe tip caps  101  and  201  in that it has differently configured locking tabs  355  and differently configured locking recesses  359 . The other features of the syringe tip cap  301  are substantially identical to the corresponding features of the syringe tip caps  101  and  201 , so that in these respects reference is made to the above descriptions.  
         [0057]     The closure cap  317  has a circumferential annular bead  353  arranged between the thread elements  349  and the longitudinal ribs  343  of the closure cap  317 . Starting from this annular bead  353 , four locking tabs  355  extend in the proximal direction, parallel to the longitudinal axis  357  and spaced apart from the outer face  316  of the closure cap  317 , the locking tabs  355  having a decreasing cross section as the distance from the annular bead  353  increases, and adjacent locking tabs  155  each being at an identical angle spacing from one another. Alternatively, more or fewer than four locking tabs  355  could also be formed.  
         [0058]     When being unscrewed in direction of rotation  375  (in the counterclockwise direction as seen from above in  FIG. 6 ), a beveled stop face  373  of each locking tab  355  exerts a pressure against an opposite, correspondingly beveled side face  377  of a locking recess  359  of the fastening ring  315 . The pressure face has an angle of inclination a which is greater than a thread pitch defined by the thread elements  349 , such that the locking tabs  355  and/or the locking recesses  359  are forcibly deformed when the closure cap  317  is unscrewed from the fastening ring  315 , and use of or tampering with the syringe content is made evident. These locking tabs  355  and locking recesses  359  also engage in one another, or are as it were interlocked, so that they can be produced only in a two-component injection-molding operation.  
         [0059]     The locking recesses  359  are formed in the fastening wall  323  of the fastening ring  315  and enclose the locking tabs  355  with a form fit. The locking recesses  359  are open toward a front distal end face  361 , and their cross section decreases as the distance from the end face  361  increases. The locking recesses  359  extend through the fastening wall  323  such that the locking tabs  355  are visible from the outside to a user. Outer surfaces of the locking tabs  355  visible from the outside are flush with the outer face of the fastening wall  323 .  
         [0060]     FIGS.  9  to  11  show a further embodiment of a syringe tip cap  401  with a fastening ring  415 , a closure cap  417  and a closure plug  435 . This syringe tip cap  401  differs from the syringe tip caps  101 ,  201  and  301  shown in FIGS.  1  to  8  in that it again has differently configured locking tabs  455  and locking recesses  459 . The other features of the syringe tip cap  401  correspond substantially to those of the syringe tip caps  101 ,  201  and  301 , so that in these respects reference is made to the above descriptions.  
         [0061]     The locking tabs  455  of the closure cap  417 , which have a wedge-shaped cross section or a rounded triangular cross section ( FIG. 11 ), are arranged protruding radially from the outer face  416  of the closure cap  417  and are completely enclosed by the fastening wall  423  of the fastening ring  415 .  
         [0062]     A pressure face  473  of each locking tab  455  extends in a radial tangential ascent, and a side face  481  of each locking tab  455 , lying opposite the pressure face  473 , runs in a plane parallel to or containing the longitudinal axis  157 . When the closure cap  417  is unscrewed from the fastening ring  415  in direction of rotation  475  (counterclockwise as seen from above in  FIG. 9 ), the locking tabs  455  are pressed against corresponding side faces  477  of the locking recesses  459  of the fastening ring  415  and, if appropriate, are deformed or destroyed together with the locking recesses  459 .  
         [0063]     The locking recesses  459  enclose the locking tabs  455  with a form fit and are arranged, with a complementary configuration to these, in the fastening wall  423  of the fastening ring  415 . The locking recesses  459  are only depressions in the inner face of the fastening wall  423  and do not pass completely through the latter.  
         [0064]     The closure cap  417  comprises a circumferential annular bead  453  which is arranged between the thread elements  449  and the longitudinal ribs  443  of the closure cap  417 . The annular bead  453  bears on a front end face  461  of the fastening wall  423 .  
         [0065]     The term “interlocked” and similar expressions relate, in the context of the invention, to formations (locking means) which engage spatially in one another and behind one another and are undercut in the longitudinal direction, in particular locking tabs and locking recesses which engage in one another, in such a way that the locking means cannot be released from one another without sustaining damage. Conversely, the syringe tip cap according to the invention cannot be produced by separately producing the fastening ring and closure cap and then joining and locking them together, since the locking means would also be identifiably damaged or destroyed here. As has already been mentioned, production is feasible only in a two-component injection-molding operation.  
         [0066]      FIG. 12  shows a variant of the means of sealing the syringe body  103 . The sealing is effected by the closure cap  117  which, for this purpose, has a portion  141 ′ which is assigned to the distal opening  113  of the syringe body  103  and is intended to engage in the distal opening  113 . Even without the closure plug  135 , a reliable seal is ensured. The clearance  114  can be configured as an annular groove or also as a plurality of individual grooves to increase the elasticity.  
         [0067]     This application claims the priority, under 35 U.S.C. §119, of European patent application No. 04 012 833.2, filed May 29, 2004, and European patent application No. 05 010 397.7, filed May 12, 2005; the disclosures of the prior applications are herewith incorporated by reference in their entirety.