Abstract:
Screw caps with guarantee strips are known. Usually, such guarantee strips are torn off by means of a tab or the guarantee strip encompasses an edge on the container and all of the predetermined breaking point links are torn in their longitudinal direction when the cap is unscrewed. According to the invention, radially projecting parts are provided on the container or its pouring opening ( 2 ) in the form of positive closing means ( 11, 12 ) which engage in corresponding recesses ( 13, 15 ) of the guarantee strip on the screw cap and prevent mutual twisting. Twisting on the screw cap results in a shearing movement being exerted on the predetermined breaking links ( 6 ), which have little resistance against these forces.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a screw cap of plastic and to a container of plastic or soft material with a pour-out, wherein the screw cap has a guarantee strip at the lower circumferential edge, which via break-off webs is connected to the lower edge of the casing wall of the screw cap.  
           [0003]    2. Discussion of Related Art  
           [0004]    Screw caps of the above mentioned type have been known for many years, and their design shape is not least dependent on the material from which the container on which the closure is placed is manufactured. With glass bottles the pour-out is usually standardized and the rotary closures must accordingly correspond to the standard. With containers of plastic one may vary the pour-out much more freely. With containers of so-called soft material, pour-outs of plastic are fastened thereon, which may be manufactured with a large degree of freedom with regard to design. This invention relates to screw caps which cooperate with containers of plastic or soft material, having a pour-out manufactured of plastic and wherein the screw cap and pour-out are matched to one another.  
           [0005]    It will be discussed what is understood by containers of soft material. Containers of soft material may be flexible tubing containers of plastic films or containers of coated cardboard or in particular also containers which are manufactured of multi-layer laminated film materials. Such multi-layer laminated films can have a paper or cardboard layer which is designed multi-layered with plastic films or an aluminum foil layer.  
           [0006]    In the present case, only screw caps with a guarantee strip are of interest, which may only be opened by rotating the screw cap, wherein simultaneously the guarantee strip is separated from the screw cap. Design forms of such closures are taught by German Patent Reference DE-A-31 11 692, from European Patent Reference EP-B-0&#39;149&#39;496, from European Patent Reference EP-B-0&#39;460&#39;557, from European Patent Reference EP-B-0&#39;593&#39;396 or from European Patent Reference EP-B0&#39;625&#39;950. The manufacture of such screw caps is problematic. On manufacture, the core must be torn out of the screw cap. Although the rear-engagements in the region of the thread are not a problem, the rear-engagements in the region of the break-off webs represent a large problem. These relatively fragile locations are often destroyed on manufacture. This leads to interruption of production and to the rejection of the manufactured closures. In order to reduce the danger of destruction one must provide relatively many break-off webs. The result of this is a difficult opening of the screw cap. As is known, on screwing open, all break-off webs are loaded uniformly in tension so that their forces sum and their result is directly related to the number of the required break-off webs. Break-off webs are very thinly designed material bridges in whose region there arises an alignment of molecule chains during the injection procedure. These molecule chains then run in the direction of the break-off webs and have their greatest force of resistance precisely in their running course. In other words the forces occurring on screwing-open run practically axially to the pour-out direction and thus exactly in the running direction of the break-off webs. Added to this is that on screwing-off the tension forces are increased relatively slowly, wherein a material stretching occurs which leads to a further alignment of the molecule chains and effects an increased tear strength.  
           [0007]    In order to reduce the danger of destruction of the guarantee ring or of the guarantee strip on removal from the mold, one also applies injection tools with sliders. This however leads to extraordinarily expensive tools.  
           [0008]    In order to avoid these problems, according to German Patent Reference DE-A-31 00 629 one has put forward a screw cap with a guarantee strip with which the guarantee strip initially is integrally formed on the screw cap over the entire wall and the break-off line is produced only retrospectively way of a suitable cutting while leaving the break-off webs. Such closures are considerably easier to open and may be produced almost without rejections. The manufacture however is enormously expensive, alone on account of the two-step manufacture. Accordingly such closures are scarcely on the market.  
           [0009]    Snap hinge closures are also known in the most varied of design forms, which are placed onto specially shaped plastic containers, in particular are also screwed on the containers. With this, on the lower part of the snap hinge closure there are guarantee strips with several tear tabs which may be placed into a suitably designed container neck in a rotationally secure manner. Thus, the removal of the rotary closure from the container is prevented without opening the snap hinge closure, and may be placed on afterwards. All these closures however have one guarantee strip with a tear-open tab, and the guarantee strip must first be removed by hand, and subsequently the snap hinge closure may be brought into its position of use. U.S. Pat. No. 4,722,449 shows an example of such a closure.  
           [0010]    U.S. Pat. No. 3,650,428 teaches a screw cap of the above mentioned type with which ratchet-like projections are attached on the pour-out which cooperate with ratchet-like positive-fit means on the guarantee strip. This solution requires a guarantee strip which is not closed per se, with a tear-open tab, wherein the guarantee strip must be removed before screwing off the closure. Furthermore, the assembly is a further problem of this embodiment. The ratchet-like design is necessary because the screw cap is screwed on. This is possible because the guarantee strip, as already mentioned, is not closed per se, but comprises an opening by which the required elasticity is provided. These closures are not regarded as particularly secure. On screwing-on, the edges of the ratchet-like parts are slightly deformed, and thus such closures may often be also unscrewed without damage to the guarantee strip.  
         SUMMARY OF THE INVENTION  
         [0011]    It is one object of this invention to provide a screw cap of the above mentioned type which may be screwed off with a considerably lower force, without disadvantages of the known screw caps. The various embodiment forms of this invention are discussed in the claims, and their effect and significance are explained by way of the drawings and the following description.  
           [0012]    It is another object of this invention to specify a method for assembly of the screw caps according to this invention, which permits a particularly rational and inexpensive assembly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    In the accompanying drawings there are embodiment examples of the subject matter of this invention and these are subsequently described in detail, wherein:  
         [0014]    [0014]FIG. 1 is a vertical diametrical section taken through a first embodiment form of a screw cap according to this invention, with a pour-out placed on a container of soft material;  
         [0015]    [0015]FIG. 2 is a similar view but with a screwed-off cap;  
         [0016]    [0016]FIG. 3 is a similar view but shows a vertical diametrical section taken through a slightly modified pour-out;  
         [0017]    [0017]FIG. 4 shows a perspective view of the screw cap with a pour out according to FIG. 1;  
         [0018]    [0018]FIG. 5 shows a perspective view of a smaller variant of the closure;  
         [0019]    [0019]FIG. 6 shows a lateral view of the pour-out according to FIG. 2;  
         [0020]    [0020]FIG. 7 shows one variant of a pour-out in a top view; and  
         [0021]    [0021]FIG. 8 shows a screw closure in a vertical diametrical section which is designed fitting with the pour-out according to FIG. 7. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0022]    The screw cap  1  may basically be formed conventionally. The screw cap  1  comprises a circumferentially cylindrical casing wall  7  which is closed off to the top by a cover surface  50 . On the lower side of the cover surface  50  there can be an annular sealing bead  51 . The casing wall  7  has an inner thread which is preferably formed as a fine thread  17 . The fine thread  17  only needs to be provided in the lower region of the casing wall  7 . A guarantee strip  5  is integrally formed on the lower edge of the casing wall  7  via break-off webs  6 . The guarantee strip  5  may be designed conically widening to the bottom as in the embodiments according to the FIGS. 1, 2 and  4 - 6 . Such a design is aesthetically satisfactory and also has the advantage of an easy removal from the mold. In contrast to guarantee strips which are arranged aligned directly below the casing wall of the screw cap, with a guarantee strip of the shape shown, no rear-engagement is present. Accordingly, the core of the injection-molding tool may be withdrawn without at the same time loading the guarantee strip or in particular the break-off webs which represent the connection between the casing wall  7  and the guarantee strip  5 . The guarantee strip  5  may however also be arranged running parallel to the axial direction of the rotary closure, as shown in FIG. 8 for example. With this arrangement, the guarantee strip  5  must be arranged displaced to the outside by at least the wall thickness of the screw cap.  
         [0023]    In the embodiments shown, the pour-out is always drawn as a separate part. This however is not necessary. The pour-out may be manufactured as one piece with a plastic container. The form of the pour-out shown here includes an annular wall  9  on whose lower end a flange  8  is integrally formed. The flange  8  is arranged running perpendicular to the annular wall  9 . With a one-piece design of the pour-out with the container, the flange  8  would practically represent the container itself, and the pour-out  2  would accordingly form a bottle neck. An outer thread  10  is integrally formed on the outside on the annular wall  9 , which likewise is preferably designed as a fine thread. The thread  10  does not extend over the complete length of the annular wall  9 . On the pour-out  2  a positive-fit  11  is integrally formed between the outer thread  10  and the flange  8  arranged at the very bottom. This positive-fit  11  in FIG. 2 has the shape of radial outwardly projecting cams  12 . As roughly shown in FIG. 4, for example four cams  12  are uniformly distributed over the circumference. This means that accordingly the guarantee strip  5  also comprises roughly equally large recesses  13 . With this design form the cams  12  engage through the recesses  13  which here are designed as openings  15 . With this design form the cams  12  engage through the same rear-engaging part  19  of the guarantee strip  5 , such as shown in FIG. 2 and in FIG. 6. This has the advantage that also after separation of the guarantee strip  5  and the screw cap  1 , the guarantee strip  5  remains held on the pour-out  2 . However the manufacture of such a pour-out requires sliders because the manufacture mold or the injection mold engages behind the cams  12 .  
         [0024]    In order to avoid such a rear-engagement, the positive-fit  11  may also be designed rib-like as shown in FIG. 3. Preferably the ribs  16  run directed radially to the outside and parallel to the center axis of the pour-out  2 . The ribs  16  which are accordingly considerably narrower than the cams  12  which were described and shown, are also in a positive-fit connection with the guarantee strip  5  of the screw cap  1  in the closed condition of the closure.  
         [0025]    The positive fit  11  on the pour-out  2  in both embodiments is designed so that the lower edge of the screw cap  1  stands directly on the cap  12  or on the ribs  16  in the assembled condition. Thus, the recesses  13  with their upper edge run in the separating plane T between the guarantee strip  5  and the lower edge of the casing wall  7 . This is shown in FIGS. 5 and 6. This design form serves directly as an abutment on assembly which will be discussed later.  
         [0026]    Another embodiment is shown in the FIGS. 7 and 8. The pour-out  2  is also formed as a separate part. The flange  8  is clearly recognizable since the pour-out is shown as a top view. The annular wall  9  is designed with its outer thread  10  at the very inside, which can be a fine thread with several flights. The term fine thread is common in plastic technology and a person skilled in the art knows what this means, even though there is no direct definition. A fine thread has a relatively low thread pitch which is smaller than a normal thread, as for example is generally known in the case of glass bottles. Opposite the annular wall  9  with the fine thread  10  there is a concentric rim of a circumferential fine toothing  20 . The fine toothing  20  corresponds to the positive-fit  11 , for example in the form of cams  12  or ribs  16  as previously described.  
         [0027]    The screw cap  1  which fits with this is designed accordingly. Its design form is shown in FIG. 8. Here, the screw cap  1  is designed with a casing wall  7  which is closed to the top by a cover surface  50 . The closed, tab-free guarantee strip  5  via break-off webs  6  is integrally formed on the lower edge of the casing wall  7  displaced to the outside by the thickness of this casing wall  7 . The guarantee strip  5  has a fine toothing  18  which in its notching corresponds to the fine toothing  20  on the pour-out  2 . The inner thread formed as a fine thread  17  is arranged on the casing wall  7 .  
         [0028]    Various assembly methods are useful according to the various design forms. The assembly is simple with an embodiment form according to the FIGS. 7 and 8. For this the two-part pour-out  2  and screw cap  1  must only be aligned axially flush to one another while the relative angular position of the two parts to one another is completely without significance. The preferred fine threads  10  and  17 , as already mentioned, permit a ratchet-like sliding-over of the thread without problem and with relatively little force. The fine toothing  20  on the pour-out  2  and the fine toothing  18  on the guarantee strip  5  are designed so that even with an alignment of the two toothings which is not exact, on meeting, the two parts are automatically aligned to one another. According to the selection of notching of the fine toothings, the correction angle is only 3-6°. The fine toothing which is practically equal to fluting, may be provided at the lower edge of the guarantee strip with a type of run-in ramp  21  in order to simplify the running into one another. Such an assembly is extraordinarily quick and the assembly device is accordingly simple and inexpensive. Because the screw cap closures are particularly used for containers of soft material, the batch numbers are extremely large.  
         [0029]    With the embodiments according to the FIGS.  1 - 3  the positive-fit  11  and  12 ,  16  respectively are only distributed on the circumference at very few locations. On assembly this demands an axial alignment to one another in a first step, and afterwards a relative angular positioning of the two parts to one another before the two parts may be pressed onto one another again by way of a simple translatory movement. Because fine threads are provided, the assembly may be simplified if the screw cap  1  is placed on the closure  2  and is subsequently rotated until an abutment element, not shown, practically sets the correct angular position of the two parts to one another, so that the end position is achieved by an axial translation. Because one operates with a fine thread, it is of no importance whether the threads are already engaged with the angular alignment of the parts to one another. This is in contrast to normal threads which usually have a greater pitch and with which the parts initially must be moved to one another in an angular position which is axially flush and matched to one another. For example, with the closures of FIGS.  4 - 6  each relative position rotated by 90° effects a completely correct closure, this is not the case with a normal thread. The coarseness of the threads renders necessary an exact angular alignment of the two parts.  
         [0030]    On opening such a screw closure for the first time the screw cap  1  may only be rotated because immediately a shear force acts on the break-off webs  6 . This shear force occurs immediately without there previously having been effected a stretching of these break-off webs in their longitudinal direction. The molecules running aligned in the break-off webs may be opened with relatively low force effort by way of the practically hundred percent occurring shear force. Older persons or children who do not have such strong hands can thus easily open the screw cap closures.