Abstract:
A screw closure ( 2 ) is provided on a soft packaging ( 1 ), preferably a film bag. Said screw closure consists of a first part, which consists of a spout having a fastening flange ( 4 ) for connecting to the soft packaging ( 1 ), and a second part ( 2 ) in the form of a screw cap ( 5 ). The screw cap has a top surface ( 50 ) and a lateral wall ( 51 ) having an internal thread ( 52 ) present in the lower region. Above the internal thread there is a thread-free portion ( 53 ), in the upper region of which a sliding seal ( 10 ) is arranged. The sliding seal ( 10 ) presses on a likewise thread-free region ( 7 ) of the spout above the external thread ( 6 ) disposed on the spout. A screw closure that is leak-proof even during unscrewing is thus achieved.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a screw closure for soft packagings, namely film bags, consisting of a spout, which is mounted on the film bag and has external thread and a fastening flange, and a cap which can be screwed onto the spout and has a top surface and a lateral wall. 
         [0002]    Screw closures for rigid packagings, such as glass or plastic bottles are widely used. In the case of these conventional, rigid packagings, the screw closures have to only substantially ensure a sealing function in the completely closed state. Said sealing function takes place with different forms of seals, wherein particularly seals are used which comprise sealing elements that are disposed in the corner area between the lateral wall and the inside of the top surface. Typical examples of such seals are described in the WIPO patent specification WO-A-9011944 and also in the WIPO patent specification WO-A-9011232 as well as in the WIPO patent specification WO-A-9731834. The so-called sealing olives represent another type of seals on screw closures, which are designed substantially as a ring wall running coaxially with respect to the lateral wall of the screw cap. Said sealing olives are integrally formed on the bottom side of the top surface in a vertically downward direction and seal off the container neck or the spout on the inside. The German patent publication DE-A-44 01 751 and the American patent publication U.S. Pat. No. 4,253,581 describe a typical example of such a sealing olive. Combinations of the two previously mentioned types are also known as, for example, the European Parliament patent specification EP-A-417554 demonstrates. 
         [0003]    In the case of soft packagings in the form of film bags, the spout is formed from a separate part which consists of the actual, cylindrical, tubular spout having a flange integrally formed thereon, said flange serving to fasten this part of the screw closure onto the soft packaging. Two different variants are basically known with regard to this type of screw closures. The first variant includes those closures in which a hole is punched out in the film of the soft packaging in the region of the spout, said hole being directly connected to and communicating with the spout, and wherein the flange is adhesively bonded or welded around said punched-out hole. The second variant consists of the film bag being completely closed and of an internal thread being additionally arranged on the inside wall of the spout. An annular cutting element is disposed in the internal thread so as to be transaxially movable, and said cutting element can be moved via driving elements on the top surface of the screw cap. The cutting element is operated by means of the screwing motion of the cap and has at least one cutting tooth on the lower edge thereof pointed in the direction of the film of the film bag. The cutting tooth can thus cut open the film of the film bag. Typical examples of this second variant are known from the Swiss patent specification CH-A-695019 or from the European Parliament patent specification EP-A-1795456 as well as from diverse other documents. 
         [0004]    In the case of both of these types of screw closures on film bags, the screw caps can be additionally provided with tamper-evident bands. 
         [0005]    Because the motion of unscrewing the screw cap frequently requires that a relatively high frictional force be overcome, the user has to hold the soft packaging with a relatively strong force while at the same time he or she unscrews the cap. As a result of this high holding force, the soft packaging is deformed and the internal pressure in said soft packaging is increased. As soon as the screw cap having the typical seal mounted in the corner area between the lateral wall and the top surface is now only slightly opened, this seal is now no longer effective. Whereas this does not present a problem with rigid packagings, this is extremely problematic with soft packagings because the user has to continue to exert force in order to completely open the closure. Now that the aforementioned seal is no longer effective, the contents of the packaging are pressed outwards; and even if only small quantities are involved, the result is unaesthetic, unhygienic and also often causes the closures to stick after they have been closed. 
         [0006]    In the case of simple screw closures without a cutting element running on the inside of the spout, it would basically be conceivable to maintain the seal by means of a sealing olive which projects sufficiently deep into the spout; however, as soon as the screw closure is provided with an inner cutting element, this kind of seal is then impossible. Even a seal pursuant to the German patent specification DE-A-39 38 713 is not capable of providing any help in this regard. According to this solution, two concentric ring walls are arranged on the bottom side of the top surface of the screw cap, which rest as sliding seals against the spout on both sides, that is to say on the inside and on the outside. Such a solution can however not be implemented with screw closures having a cutting element. The US patent specification U.S. Pat. No. 4,371,091 describes a somewhat exotic solution. A circumferential sealing nose is integrally formed on the lateral wall of the screw cap directly above the internal thread. When completely screwed on, said sealing nose comes to rest directly in the region of the spout&#39;s upper edge and can extend downwardly beyond said edge. Furthermore in such a solution, the seal is already no longer in engagement at a slight unscrew angle and is likewise consequently impractical for the use intended here. In the 60s of the previous century, plastic closures could still hardly be produced with a high degree of precision. The seals in screw closures, which were emerging at that time, were applied to the bottom of the cap top surface particularly as curved, annular sealing lips and required however a high degree of precision in order for them to be demoldable at all. For this reason, a solution was proposed in the English patent specification GB-1205887 in which a sliding surface was provided on the upper end of the spout, on which annular sealing beads on the inside of the screw cap above the internal thread thereof fit snugly. Because this solution applied to bottles, the seal served substantially the purpose of sealing the closure in the closed state. After a certain unscrewing motion, the seals were no longer in engagement with the spout, which however, as is generally known, is not required with bottle. 
         [0007]    In a similar fashion, however considerably more complex in the embodiment, the German patent specification DE-1935874 describes a solution. In this case, the seal is already no longer provided after practically a single rotation, which however, as previously mentioned, does not present a problem for relatively rigid bottles. 
       SUMMARY OF THE INVENTION 
       [0008]    It is therefore the aim of the present invention to provide a screw closure for soft packagings of the kind described at the beginning of the application, in which even when increased pressure is being applied to the soft packaging, the closure is capable of ensuring the required impermeability up until the unscrewing motion has been fully completed. 
         [0009]    In so doing, the solution should be applicable to conventional screw closures, the spout of which is mounted above an already present opening in the soft packaging, as well as particularly to soft packagings which are completely aseptically closed and which have a cutting element inside in the spout, which cuts open the soft packaging when the screw closure is opened. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    In the attached drawings, two exemplary embodiments of the subject matter of the invention are schematically represented and are explained in detail in the following description. In the drawings: 
           [0011]      FIG. 1  shows the manipulation of a screw closure on a soft packaging in a perspective view, 
           [0012]      FIG. 2  shows a diametric vertical section through a screw closure according to the invention without a cutting element, 
           [0013]      FIG. 3  shows a second embodiment of the screw closure according to the invention, once again in a diametric vertical section and this time having a cutting element in the completely closed position, 
           [0014]      FIG. 4  shows the same screw closure in a partially opened intermediate position, in which the threads on the spout and screw cap are still engaged, 
           [0015]      FIG. 5  shows again the same screw closure, wherein the screw cap is opened to such an extent that the aforementioned threads are no longer engaged; however, a sealing situation is still present, whereas 
           [0016]      FIG. 6  shows the screw closure according to the invention in a completely opened position. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    In  FIG. 1 , the screw position when opening a screw closure, which is provided on a soft packaging  1 , is depicted. The soft packaging can be a laminated cardboard packaging or, as is here of particular importance, a film bag as the one shown in  FIG. 1 . When opening the film bag  1 , the user holds the bag in one hand while he or she at the same time unscrews the screw closure  2  with the other hand. In so doing, said user exerts a force F on the film bag. As a result of this force, the internal pressure in the film bag is increased. If the screw closure is in this instance related to a conventional embodiment, the increased internal pressure would lead to the liquid being able to escape between spout and screw cap  5 . The solution according to the invention remedies the problem. 
         [0018]    A first embodiment of the subject matter of the invention is now depicted in  FIG. 2 . The screw closure is denoted in its entirety with the reference numeral  1 . With said reference numeral  1 , a screw cap  5  is on the one hand understood and on the other hand a lower part, which consists of a tubular, cylindrical spout  3 , on the lower edge of which a radially protruding flange  4  is integrally formed. An exterior thread is integrally formed to the outside of the tubular spout  3 . Above the exterior thread  6 , a thread-free section on the spout  3  can be seen. The thread-free section  7  is preferably at least the same length as the section  8  which runs in the axial direction and in which the external thread  6  is provided. 
         [0019]    The cap  5  has substantially the general design of screw caps. Said cap has a top surface  50  which is adjoined by a lateral wall  51  in a downward descending manner. The lateral wall  51  is substantially of cylindrical design. The only unusual aspect is that said lateral wall  51  is provided with an internal thread  52  in the lower region, which fits to the aforementioned external thread  6  of the spout  3 . Above the internal thread  52 , an internal thread-free region now ensues, which is approximately the same size as the thread-free section  7  of the spout  3 . 
         [0020]    In the corner region between the top surface  50  and the lateral wall  51 , circumferential sealing beads  54  are present. These sealing beads  54  form a static seal in the closed position of the closure, said seal being also able to withstand high internal pressure loads. 
         [0021]    A sliding seal  10  is integrally formed on the inner surface of the lateral wall  51  of the cap  5 . This sliding seal  10  bears with a specified contact pressure on the outside of the spout  3 . 
         [0022]    In the example of  FIG. 2  depicted here, the screw cap  5  is already unscrewed somewhat. If the screw cap  5  were shown in the completely screwed-in position, the sealing beads  54  would then rest against the upper edge of the spout  3  and the sliding seal  10  would be in contact with the spout  3  slightly above the region  8  of the external thread  6 . With this arrangement, the cap can now be unscrewed to such an extent that the external thread  6  of the spout  3  just no longer engages with the internal thread  52  of the cap  5  and the sliding seal  10  still barely rests on the outer surface of the spout  3 . 
         [0023]    The shape of the sliding seal  10  selected here is one possible embodiment among many. It is only essential that the sliding seal is subjected to a certain deformation force. The spout  3  must have for the purpose of demolding a certain amount of taper so that the inside diameter on the upper edge is slightly smaller than the inside diameter in the region of the flange  4 . In addition, the wall thickness of the spout  3  too decreases slightly from the region of the flange to the upper edge so that overall the spout  3  in the thread-free section  7  runs slightly conically and the sliding seal  10  must be able to follow this conicity and be in contact in the uppermost region with a certain amount of pressing force. 
         [0024]    Because the fitting of the screw cap is problematic if the sliding seal projects too sharply toward the inside, it can also be useful, instead of the embodiment depicted here, in which the sliding seal takes the shape of a circumferential apron that is directed downwardly, ie. with the flexible tip thereof, toward the flange . . . (parts of sentence missing in the original between lines 14 and 15 on page 10). The sliding seal can also alternatively be designed more precisely as a so-called sealing lip, which is able per se to receive less force. In this case, a plurality of such circumferential sealing lips is then preferably provided. Said sealing lip can, for example, in effect protrude vertically from the inside of the lateral wall, and they are automatically arched upwards when the screw cap is fitted. This has the major advantage that the internal pressure, which acts on the sealing lips, presses the sealing lip tighter against the spout. In addition, the plurality of sealing lips work in effect like a labyrinth seal. One such solution, which is not depicted here, is thus capable of withstanding high internal pressures despite the fineness of said sealing lips. In principle, the ejection of such a screw cap from the injection mold is problematic. Nevertheless, the technology has been known for a long time that the cap is first removed in its entirety from the mold and then the core projecting into the interior is pulled out, wherein the lateral wall  51  can now deflect towards the outside so that the interior thread  52  as well as the sliding seal  10  do not sustain any damage when the core of the cap is extracted. 
         [0025]    In  FIGS. 3-6 , a screw cap  2  is again shown on a soft packaging  1 . The spout  3  and the flange  4  thereof are unchanged with the exception of an internal thread  22 . The aforementioned cutting element  20  is mounted in the spout  3  so as to be movable in a screw-like fashion. A driving element  23 , on the inner surface of the cutting element, serves as a stop for a second driving element  24  which projects vertically downwards from the top surface  50  of the cap. When the screw cap  5  is unscrewed, the cutting element  20 , having an external thread  25  which runs in the internal thread  22  of the spout  3 , is moved downwards and thereby cuts open the film F by means of the at least one cutting tooth  21 . A sliding seal  10 , which can be seen clearly in  FIG. 6 , is also again present in this version just as was previously described with the aid of  FIG. 2 . Particularly in this embodiment, it is very evident that it is not possible in this case to have a seal on the inside of the spout. Also in this version, the inventive solution that was already described allows, in a practically unchanged manner, for a screw closure to be used. 
         [0026]    Exactly as in the version pursuant to  FIG. 2 , the screw cap can be additionally provided with a tamper-evident band  40 , which can be attached in a positive-locking manner behind a circumferential collar  30  on the spout  3  below the external thread. When unscrewing the screw cap, the tamper-evident band  40 , which is integrally formed on the lower edge  55  of the screw cap  5  by means of predetermined breaking point bridges  4 , is torn away and remains hanging below the aforementioned collar  10 . This situation is depicted on the right side of  FIG. 2 , whereas on the left side a tamper-evident band  40 , which likewise engages behind the collar  30 , is depicted. Said tamper-evident band  40  however is removed, for example, by a tear-off tab, wherein in turn the predetermined breaking point bridges, which connect the tamper-evident band to the screw cap, are destroyed. In the drawing, the predetermined breaking point bridges are denoted with the reference numeral  41 . Said predetermined breaking point bridges can, however, only be seen in the severed condition, on the one hand as remains on the tamper-evident band  40  and on the other hand on the lower edge  54  of the screw cap  5 . 
         [0027]    In principle, the solution according to the invention can also be implemented by the sliding seal being mounted to the outside of the spout instead of to the lateral wall  51  of the cap  5 . In this case, two variants are worth considering, namely either to mount the sliding seal directly above the thread or in the region of the upper edge of the spout  3 . In the first variant, the sliding seal has to be designed relatively long in order to be able to seal up the thread across the uneven spots thereof. In the second variant, the sliding ring seal can be shorter in the radial extension and as a result a plurality of sealing rings are also worth considering in this case; whereas in the first variant, apron-like sliding ring seals are more likely to be useful. 
       REFERENCE NUMERAL LIST 
       [0000]    
       
           1 . Soft packaging, respectively film bag 
           2 . Screw closure 
           3 . Spout 
           4 . Flange 
           5 . Cap/Screw cap 
           6 . External thread 
           7 . Section having thread 
           8 . Thread-free wall region 
           10 . Sliding seal 
           20 . Cutting element 
           21 . Cutting tooth 
           22 . Internal thread 
           23 . Driving element 
           24 . Second driving element 
           25 . External thread on the cutting element 
           30 . Collar 
           20 . Tamper-evident band 
           41 . Predetermined breaking point bridges 
           50 . Top surface 
           51 . Lateral wall 
           52 . Internal thread 
           54 . Sealing bead 
           55 . Lower edge of the screw cap 
         P. Force