CN111954630A

CN111954630A - Anti-tamper screw cap

Info

Publication number: CN111954630A
Application number: CN201980025018.8A
Authority: CN
Inventors: G·科老特科拉莫
Original assignee: Bericap Holding GmbH
Current assignee: Bericap Holding GmbH
Priority date: 2018-04-10
Filing date: 2019-04-02
Publication date: 2020-11-17
Also published as: EP3774568A1; WO2019197214A1; DE102018108491A1; BR112020017783A2; US20210024258A1

Abstract

The invention relates to a screw cap made of plastic, comprising a top plate (2) and a cylindrical cap shell (3) with an internal thread (4) extending downwards from the top plate, and comprising a safety strip (5), which is connected to the lower edge of the cap shell (3) and is provided with a retaining element (6) projecting radially inwards, the retaining elements defining a minimum inner diameter of the safety bars (5) so that they can engage on the neck (20) of the container behind a retaining ring (25) having a larger diameter, so that they can remain on the neck (20) of the container after separation from the cap shell (2), characterized in that a circumferential tear strip (7) extends between the lower edge of the cap shell (2) and the safety strip (5), which is connected to the cap shell (2) on one side and to the safety strip (5) on the other side via respective tear lines (8, 8').

Description

Anti-tamper screw cap

The present invention relates to a plastic screw closure comprising a top panel and a cylindrical cap skirt extending downwardly from the top panel and having a female thread, and having a tamper strip integrally connected to the lower edge of the cap skirt and provided with radially inwardly projecting retaining elements defining a minimum inner diameter of the tamper strip such that they can engage behind a retaining ring having a larger diameter on the container neck to be retained on the container neck after being separated from the cap skirt as required.

Plastic container closures of this type have become standard for many years. When opening the closure, the connection between the lower edge of the cap skirt and the tamper strip is torn off, since the tamper strip, by means of its radially inwardly projecting retaining elements, engages behind a retaining ring of larger diameter arranged on the container neck, and therefore, when unscrewing the screw closure, it will not follow the axial movement of the closure, which otherwise comprises the top plate and the cap skirt.

The tear line between the tamper evident band and the lower edge of the cap skirt may be of various different configurations. For example, it may relate to portions of the cap skirt and tamper evident band that are intentionally produced in the form of thin-walled portions. However, the connection between the cap skirt and the tamper evident band is typically completely separated along a larger portion of the periphery, in which case the length of these portions is limited by a narrow and frangible bridge that interrupts the circumferentially extending separation line.

In this arrangement, the connection between the cap skirt and the tamper strip, which is relatively weak along the tear line, is also relatively easy to tear, since the thread effectively provides a transmission ratio similar to a worm drive when unscrewing the screw closure, since the thread formation is relatively shallow and the torque acting in the circumferential direction is converted into a relatively high axial force between the cap skirt and the tamper strip, and in addition, shear forces occur due to the friction between the container neck and the tamper strip and the resulting relative rotation of the cap skirt with respect to the tamper strip, which makes it easy to tear the cap and the tamper strip.

However, it has been found that conventional screw closures with tamper-evident bands are still insufficient to preclude tampering operations, although many measures have also been taken on the corresponding bottle neck to prevent, for example, the tamper-evident band from being pried open without tearing the connection to the cap skirt. Especially in the case of containers with relatively expensive contents, such as in the agricultural and chemical sectors, but also in the case of expensive spirits, it appears that in many countries the contents of the container make it worthwhile to pay considerable costs and efforts to recover the closure which has been opened and to apply it to containers containing contents which are counterfeited.

In this case, for example, the torn bridge between the tamper strip and the cap skirt is restored by adhesive means, or the tamper strip is glued back along the entire periphery to imitate a perfect tear line. Experience has shown that in some cases screw closures used by counterfeiters look very similar and are produced using the simplest tools in an injection moulding process, are relatively small in number, only a few thousand, possibly manually demoulded, and are manually screwed down onto empty bottles of washed brand owners after filling with inferior contents. On the store shelf, a consumer who is not very cautious and careful cannot see the difference from the original closure.

DE 102006001323 discloses a snap-on closure which is not threaded but is latched onto the container neck only by axial pressure and which essentially comprises a retaining ring and a closure cap with a snap-on edge which are pivotably connected together by means of a hinge portion. The relatively smaller diameter retaining ring engages behind the relatively larger diameter annular enlargement on the container neck to permanently secure the closure on the container neck. The closure is selectively moved into either a closed position or an open position by pivotally moving the closure cap relative to the retaining ring.

A connection between the retaining ring and the closure cap, similar to the tear line between the cap skirt and the tamper strip in the case of screw closures, is not suitable in this case, since the ordinary consumer will not be able to tear the connection easily by lifting the closure cap. For this reason, on the snap-on closure according to DE 102006001323, a tear-off strip is provided between the closure cap and the retaining ring, which tear-off strip is connected on the one hand to the closure cap and on the other hand to the retaining ring by means of two parallel tear lines and which tear off radially outwards by means of a gripping tab and then open the closure cap and thus separate the connection between the retaining ring and the closure cap outside the hinge section.

Thus, in snap-on closures, the provision of a tear line by means of a tear strip to be pulled off radially is mainly employed for the following reasons, since the tear line can be more easily separated by a shear force transverse to the axial direction of the closure than by lifting the cap alone. For screw closures of the kind which, by rotation of the screw cap, shear the connection along the tear line and/or tear axially to an increased extent by means of the thread transmission ratio, such a tear strip arranged between the cap skirt and the retaining ring and providing an indirect connection between the cap skirt and the retaining strip seems unnecessarily complex.

Such tear-off strips therefore form a connection between the cap skirt and the retaining strip indirectly, but were not previously known for screw closures, since in the case of screw closures there is no corresponding necessity to reduce the force required for separating the tamper-evident strip from the cap skirt by the provision of the tear-off strip.

The most relevant prior art is considered to be a conventional plastic screw closure with a tamper evident band.

In contrast to this prior art, the object of the present invention is to provide a screw closure having the features set forth in the opening part of the present description, which as far as possible precludes the above-mentioned tampering action and which is capable of ensuring greater security of the container contents.

This object is achieved in that a circumferentially extending tear strip extends between a lower end portion of the screw closure in the form of a retaining and tamper evident strip and an upper portion in the form of a screw cap, which tear strip is connected on the one hand to the cap skirt and on the other hand to the tamper evident strip/retaining strip by means of respective tear lines, wherein the tear strip is designed and connected to the cap skirt and/or the tamper evident strip such that it is irreversibly deformed as much as possible when torn.

Thus, the closure according to the present invention comprises three integrally connected together and generally cylindrical or annular elements, namely a screw cap, which in turn comprises a top panel and a cap skirt having an internal thread, a tear strip and a tamper strip.

The screw closure according to the invention therefore has a completely circumferentially extending tear strip between the cap skirt and the tamper strip, which establishes a connection between the cap skirt and the tamper strip by means of only two tear lines, and which can therefore be completely separated from at least the tamper strip or the cap skirt, or from both, and which therefore leaves a clearly visible and unclonable gap between the tamper strip and the cap skirt after being torn open.

The tear strip therefore plays a key role in the tamper-evident function of the screw cap, as long as its presence or absence between the lower portion of the screw cap, known as the "tamper strip", and the lower edge of the cap skirt is very clearly perceptible, in particular even more clearly perceptible than the gap between the tamper strip and the cap skirt, which gap is produced in the case of conventional screw caps after the tamper strip directly connected to the lower edge of the cap skirt has been torn, but which gap can be closed again by displacing the tamper strip that has been separated from the screw cap.

Contrary to what was just mentioned in the prior art, in the closure according to the invention the gap between the cap skirt and the tamper strip can no longer be easily closed by displacing and gluing the tamper strip to the lower edge of the cap skirt, since the retaining ring for the tamper strip on the container neck retains the tamper strip at a certain spacing relative to the cap skirt by means of the usual and mutually cooperating dimensions of the screw closure and the container neck.

The tear strip is thus connected to the lower edge of the cap skirt and to the upper edge of the tamper strip by means of respective tear lines, wherein the tear strip has at a suitable circumferential position (at one end of the tear strip) a grip tab by means of which it can be torn completely or partially along the two tear lines by a radially outwardly acting pulling force and, if desired, can be separated from the closure cap skirt. In this case, too much force is not required, since the tear strip is not closed in the circumferential direction but has a free end which is connected to the grip tab. When the tear strip is pulled radially away from the cap, a shear force can be applied on the tear line by means of the tab, more particularly always only at the point of transition between the portion of the tear strip that has been detached and the portion that is still connected, so as to cause the material to tear progressively along the tear line until finally the entire tear strip can be removed, or else one of the portions that remains connected to the tamper strip or the screw cap by means of the residual section of the peripheral edge. In this case, the force to be applied is relatively small and significantly less than the force required to axially stretch and tear the tear line simultaneously along the entire circumference.

The tear strip, which in most cases is no longer needed after tearing and is discarded by the consumer as waste, also makes it more difficult for a counterfeiter to restore the closure to the apparently original state again after complete removal of the tear strip.

In contrast, in the case of conventional screw closures, all parts of the closure remain on the bottle neck even after opening.

Considering only itself, this measure of separating the tear strip and disposing it separately from the rest of the closure may still not prevent a counterfeiter from having collected and fitted together all three parts of the closure again at a point of sale, for example at a filling station. In this case, in a similar manner to the case involving the above-described tampering operation, the two intact tear lines, i.e., the tear line between the tear strip and the cap skirt and the tear line between the tear strip and the tamper strip, can be restored by gluing together to a state simulating the original conditions for a consumer who makes only a gross inspection.

However, according to the present invention, this can be prevented, since the tear strip is configured and connected to the cap skirt and/or the tamper strip, such that upon tearing, the tear strip is irreversibly deformed. The irreversible deformation can then no longer be reversed, so that even if an attempt is made to restore the connection between the tear-off strip and the cap skirt and the tamper strip, the deformation of the tear-off strip gives a clear indication: i.e. the closure has been opened once and is no longer in its original state.

Thus, for example, to avoid waste, the tear strip may not be completely separated from one of the portions of the closure and can, for example, still remain connected to a portion of the tamper strip. However, the original one-piece screw closure is nonetheless deformed by the disassembly, and in particular the tearing of the strip, so that it is not possible to reassemble the parts without them being easily visible.

The irreversible deformation of the tear-off strip can be achieved in particular by making the tear-off strip comprise along its periphery alternating portions of relatively more stretchable and relatively less stretchable. During the tearing operation, the less stretchable part will then resist the forces occurring when tearing the strip, while the more stretchable part will be stretched more. The stretchability of at least the more stretchable part is self-evidently matched to the tear strength of the tear line, so that the force required to tear the tear line in any case also results in stretching of the more stretchable part.

In particular, irreversible deformation can also be promoted if one or both tear lines are slightly more resistant in the region of the non-stretch portion than in the region of the stretch portion, which further increases the difference in stretch. This is achieved, for example, by different cross sections for the respective connection points between the tear-open strip and the easily tearable bridges between the cover skirt and the tamper strip, respectively, or by an undulation of the wall thickness of the circumferentially extending weakening line.

A further feature of an embodiment of the closure according to the present invention is that the tear strip and/or the tamper strip has a tooth arrangement on its inner side which, when engaged with a corresponding tooth arrangement on the container neck, prevents the tear strip or the tamper strip from rotating together with the screw cap of the closure in the opening direction. This arrangement of teeth makes it difficult to open the closure by simply rotating the screw cap, since a plurality of teeth engage simultaneously and rotation of the screw cap will require tearing of the tear line simultaneously along its entire circumference. Thus, the arrangement of teeth between the tear strip and the container neck forces the consumer to first tear the tear strip and remove it.

The individual teeth in the region of the tear-open strip and the tamper strip, in particular the teeth on the inner side of the tamper strip and the tear-open strip, may relate to the same or different circumferential angular spacings. Preferably, to open the screw cap, the consumer is more or less forced to remove the tear strip first to enable the screw cap to rotate in the opening direction. Preferably, the tear strip is interrupted in its circumferential direction in the circumferential direction, so that after the closure has been completely opened, the tear strip is completely released from the container neck and furthermore the tear strip has been irreversibly deformed during separation along the tear line.

The tear line may be provided in different ways, for example by shaping the tear line during injection moulding or by a circumferentially extending interruption with axial branches, or alternatively by cutting into the connection region between the tear strip and the cap skirt and the tamper strip after the closure has been injection moulded as a unit with the tear strip and the tamper strip, wherein the connection between the tear strip and the adjacent element may also be completely separated along each circumferential portion, leaving only a single frangible branch. The cuts formed circumferentially along the tear line may also be implemented at different circumferential locations to different depths to provide more and less tearable portions that promote irreversible deformation of the tear strip.

As already mentioned, the tear strip itself, viewed in the circumferential direction, may also comprise alternating relatively more stretchable and less stretchable portions. The alternating relatively more stretchable portions and less stretchable portions may in particular comprise alternating radially thinner and radially thicker regions of the tear strip.

The alternating relatively more stretchable and less stretchable portions may also have different widths, i.e. varying from one portion to another as measured in the circumferential direction.

The stretchability of the tear strip may also vary in the axial direction, and such variations in stretchability, in particular due to different wall thicknesses of the tear strip, may also be limited to one or more circumferential portions, which in turn may involve different stretching in the circumferential direction. For example, regions of different wall thickness of the tear strip may extend along the serrated line between the tear lines towards the tamper strip and along the peripheral edge of the tear strip between the tear lines towards the cap skirt.

One of the free ends of the tear strip may also have a tear tab that can be grasped from the outside to pull the tear strip apart along the entire circumference before turning the screw cap to open the closure, allowing the closure to be opened and which can be achieved with much less force than would be required if the tear line had to be separated only by a rotational movement of the screw cap.

The tear-line may also preferably have a robust construction, so that opening the closure will not be possible, or will need to be overcome with great difficulty, without first loosening the tear-off strip along the entire circumference, i.e. merely by turning the screw cap, but is relatively easily possible, due to the shearing action caused by the transverse force, when gripping the tear-off tab and moving it radially apart to separate the tear-line, because the force for separating the tear-line is substantially smaller than that which would be required, for example, when unscrewing the cap to separate the tear-line almost simultaneously along the entire circumference, if it were applied gradually in the form of points along the entire circumference, respectively, only in the region of the part of the tear-off strip that has already been detached. In any case, however, the tear strip is completely separated from the cap skirt or from the tamper strip or from both, by rotating the screw cap or preferably by pre-tearing the tear strip.

One embodiment provides that the tear strip extends along the entire circumference of the closure, except for interruptions limited to circumferential angles of less than 5 °. The tear strip thus has two directly opposite free ends. In this case, one of the ends may be provided with a gripping tab that overlies the other end radially outwardly.

For example, the tear strip may be first produced by injection molding together with the screw cap and the tamper strip in the form of a completely circumferentially closed tear strip, wherein the tear strip is axially cut through shortly before attachment of the grip tab after removal from the mold.

An additional safety measure consists in the printed portion on the tamper-evident closure cap, in particular the printed image, which extends on the outside of the closure cap above one or both tear lines and thus above the cap skirt, tear-off strip and/or tamper strip.

Such printed images are preferably produced by a laser printer or another similar expensive and complex printer capable of printing curved surfaces of 3-dimensional bodies in a manner that is very difficult to counterfeit.

In order to make it easy to unscrew the closure cap, the cap skirt may also have an external knurling.

Other features and possible uses of the invention will become apparent from the following description of the preferred embodiments and the accompanying drawings, in which:

FIG. 1 shows a side view of a closure according to the present invention;

FIG. 2 shows a cross-sectional view containing the axis of the closure;

FIG. 3 shows a cross-sectional view of the closure from below along the line V-V in FIG. 2;

FIG. 4 shows a side view of the closure fitted on an associated container neck;

figure 5 shows a cross-sectional view containing the axis of the closure fitted on the container neck;

FIG. 6 shows a cross-sectional view along line VI-VI in FIG. 4;

FIG. 7 shows a side view of an associated container neck;

figures 8a, 8b show two cross-sectional views of the tear-away strip and the abutment in a cut plane containing the axis of the closure at different angular positions; and

fig. 9a, 9b show side and perspective views of the closure without a tear strip on the container neck.

The external view shown in fig. 1 shows a screw cap 10 with a screw cap 1, comprising a top panel 2 and a cap skirt 3, the cap skirt 3 in turn being connected to a tear strip 7 by means of a tear line 8, the tear strip 7 being connected to a tamper strip 5 by means of a further tear line 8'. The screw closure comprises a single plastic part, i.e. the screw cap 1 (the cap skirt 3 and the top panel 2) is produced in one piece with the tear strip 7 and the tamper strip 5 in an injection moulding process, wherein material that may remain in the region of the tear lines 8, 8' after further processing will create a connection between all three parts.

It is also possible to see the grip tab fitted at the free end of the tear-off strip 7 at a circumferential position of the tear-off strip, which grip tab is interrupted at this position in the circumferential direction. The grip tab 13 may also have a frangible connection to the other end of the tear strip 7 directly opposite the end provided with the grip tab. The references 7' and 7 "in fig. 1 indicate different parts of the tear strip which have different wall thicknesses or are partly formed as projections and recesses, thus providing deformation of the tear strip 7 when the strip is torn.

The tear strip 7 has two diametrically opposed free ends. For example, it can be produced first as a completely circumferentially closed tear-off strip with the screw cap 1 and the tamper strip 5, and then severed by axial cutting shortly before the grip tab 13 is attached.

As can be seen from the sectional view in fig. 2, the cap skirt 3 of the screw cap 1 has a thread 4 on its inner side, which thread 4 can be interrupted by ventilation slots 4'. In this case, the tear line 8 is formed by a circumferentially extending separation line which is interrupted only by easily breakable bridges 12 which hold the tear strip 7 and the cap skirt 3 together. The tear line 8 ' is also formed by a circumferentially extending separation line, which tear line 8 ' is interrupted by a breakable bridge 12 ' between the tear strip 7 and the holding strip 5. As the grip tab 13 is lifted and moved radially away from the closure, each bridge 12' progressively tears and the tear strip 7 separates from the cap skirt 3 and the tamper strip 5 in this way and can be removed along the periphery of the screw closure 10, so that thereafter the wider gap between the cap skirt 3 and the tamper strip separates the cap skirt 3 from the tamper strip 5 and there is no longer any connection between the cap skirt and the tamper strip. The tamper strip furthermore has on its inner side a so-called folded flexible strip 6 which prevents the tamper strip 5 from being displaced or removed upwards in the direction of the cap skirt 3.

Unscrewing of the cap without separating the tear strip is prevented by a tooth 9 on the inside of the tear strip 7, which tooth 9 engages with a corresponding mating tooth arrangement 19 on the container neck 20 and prevents rotation of the tear strip. The connection between the tear-off strip 7 and the cap skirt 3 by means of a plurality of breakable bridges then prevents the closure cap from loosening. Otherwise, in order to break all the bridges 12 simultaneously, it would be necessary to apply a force that cannot be applied by the average consumer. The consumer is thus more or less forced to remove the tear strip 7 to open the closure. The breakable connection along the tear lines 8 and 8 'can therefore also be relatively stronger than the connection between the tamper strip and the cap skirt in conventional screw closures, since the bridges 12, 12' break one by one, respectively, when the tear strip is pulled radially apart.

In contrast, in order to open the closure without removing the tear-off strip, all breakable bridges must be torn off almost simultaneously, which would require a correspondingly large force.

Fig. 4 shows the screw cap 10 fitted on the container neck 20, and fig. 5 and 6 show a cross-sectional view of the screw cap 10 fitted on the container neck 20 including the axis of the cap and a cross-sectional view perpendicular to the axis, respectively. It can be seen from fig. 5 that the spacing between the tamper strip and the lower cap edge is initially bridged by the tear strip, but this spacing cannot be reduced significantly after removal of the tear strip 7 either, since the retaining ring 25 at the periphery of the container neck only allows a slight axial play of the tamper strip 5.

Fig. 7 shows the container neck 20 without the screw closure 10. The particularity of this container neck 20 is that there is provided a mating tooth arrangement 19 adapted to the tooth arrangement 9 at the inner side of the tear strip 7, which prevents the tear strip 7 from rotating together with the screw cap 1 in the opening direction. A retaining ring 25 is provided below the counter-toothing arrangement 19 at a distance from the upper opening edge of the container neck, which is usually slightly smaller than the inner distance between the inner side of the top plate and the top side of the retaining element of the tamper strip, which engages with the underside of the retaining ring, so that the tamper strip 5 of the screw closure 10 has only a slight axial mobility. This is also necessary in the case of conventional closures to prevent easy access to the tamper evident strip from the outside, which would allow tampering with the screw closure.

Fig. 8a and 8b show two cross-sectional views through the region of the tear strip 7 in a cross-sectional plane containing the axes respectively but at different circumferential positions 7', 7 "of the tear strip 7. The sectional view shows in each case a tear-off strip 7 and two tear lines 8 and 8', respectively, which form a transition on the one hand to the cap skirt 3 and on the other hand to the tamper strip 5. As will be seen, the cross-sections of the tear strip 7 differ significantly from one another at different circumferential positions, and the cap skirt 3 as well as the directly adjoining portions of the tamper strip 5 are adapted in terms of their thickness and position to the respective configuration of the cross-section of the tear strip 7. As a result, upon tearing from the closure cap, the tear-off strip 7 is deformed more or less depending on the respective local cross-section, to which extent the adjoining portions of the cap skirt and the tamper strip 5 are at least partially affected. As a result, it is almost impossible to subsequently reinsert the tear strip 7 into the gap between the tamper strip and the cap skirt and to join it thereto by gluing or welding to the cap skirt and the tamper strip without such tampering being visibly observable.

By suitable design of the tear-off strip in terms of its shape and wall thickness, which can vary in many ways, in particular also by a stepped axial profile, the arrangement of teeth 9, its repetition pitch, and the length and varying repetition pitch relative to the different circumferential portions 7', 7 ", different wall thicknesses in the circumferential and/or in the axial direction, different distribution of the teeth 9, etc., and finally also by the design configuration of the tear-off line or the adjustment of its tear strength, the tear-off strip 7 can be designed such that it is significantly visible and irreversibly deformed by the forces generated when it is torn off. Thus, once the tear strip has been torn, it is almost impossible to relocate it to the closure and connect it to the cap skirt 3 and the tamper evident strip 5 without such tampering being readily identifiable.

Fig. 9 shows a side view (fig. 9a) or a perspective view (fig. 9b) of the closure 10 fitted on the container neck 20 after removal of the tear strip 7. As can be seen, a clear gap is provided between the lower edge of the cap skirt 3 of the screw cap 1 and the upper edge of the tamper strip 5, and this gap makes it easy to identify that the tear strip has been removed, and thus the closure has apparently been opened.

Indeed, the tamper strip 5 has a certain axial play on the container neck 20, but even when the screw cap is screwed firmly and the tamper strip 5 is pushed axially upwards as far as possible, there is always a gap between the lower edge of the cap skirt 3 and the upper edge of the tamper strip 5, which gap corresponds approximately to the axial width of the tear strip in the region previously provided.

Claims

1. Plastic screw closure comprising a top panel (2) and a cylindrical cap skirt (3) extending downwardly therefrom and having an internal thread (4), and a tamper evident band (5) which is connected to the lower edge of the cap skirt (3) and is provided with retaining elements (6) projecting radially inwardly, the retaining elements (6) defining a minimum inner diameter of the tamper evident band (5) such that they can engage behind a retaining ring (25) of larger diameter on a container neck (20) in order to retain the container neck (20) after separation from the cap skirt (2), characterized in that a circumferentially extending tear strip (7) extends between the lower edge of the cap skirt (2) and the tamper evident band (5), the tear strip being connected on the one hand to the cap skirt (2) by means of respective tear lines (8, 8'), and on the other hand to said tamper strip (5).

2. Screw closure according to claim 1, wherein the tear strip has an internal tooth arrangement (9) which, when engaged with oppositely directed teeth (19) on the container neck (20), prevents rotational movement of the tear strip (9) about a closure axis at least in an opening direction of the closure (10).

3. Screw closure according to claim 1 or 2, wherein the tamper strip (6) has an internal arrangement of teeth (11) which, when engaged with oppositely directed teeth (19') on the container neck (20), prevent rotational movement of the tamper strip (6) about a closure axis in the opening direction of the closure (10).

4. Screw closure according to any one of the preceding claims, wherein the tear line (8, 8') between the tear strip (7) and the cap skirt (2) and/or the tamper strip (6) is produced by cutting in a plastic material which is initially thicker in configuration along the tear line after production by means of injection moulding.

5. Screw closure according to any one of the preceding claims, wherein the tear strip (7) is connected to the cap skirt (2) and/or to the tamper strip (6) only by breakable bridges distributed along a circumferentially extending tear line (8, 8').

6. Screw closure according to any one of the preceding claims, wherein the tear strip (7) comprises alternating relatively more stretchable portions (7 ") and less stretchable portions (7') seen in the circumferential direction.

7. The screw closure according to claim 6, wherein the alternating relatively more stretchable portions (7 ") and less stretchable portions (7') comprise alternating radially thinner and thicker regions of the tear strip (7).

8. Screw closure according to claim 6 or 7, wherein the width of the alternating relatively more stretchable portions (7 ") and less stretchable portions (7') varies circumferentially measured in circumferential direction.

9. Screw cap according to any of the preceding claims 6-8, characterized in that the more stretchable part (7 ") and the less stretchable part (7') are distributed differently in axially different regions of the tear strip (7) seen in the circumferential direction.

10. Screw cap according to any one of the preceding claims, characterized in that the cross section of the tear strip (7) varies along the circumferential direction, measured perpendicular to the circumferential direction.

11. Screw closure according to any one of the preceding claims, wherein the tear strip (7) comprises various axial portions having different outer diameters, which are connected together by a tapered transition portion.

12. Screw cap according to any of the preceding claims, characterized in that the tear strip (7) has two ends, at least one of which has a grip tab (13).

13. Screw closure according to any one of the preceding claims, wherein the tear strip (7) extends along the entire circumference of the closure except for an interruption limited to a circumferential angle of less than 5 °.

14. Screw closure according to one of the preceding claims, wherein a grip tab (13) provided at a free end of the tear strip (7) is arranged radially outside and outwardly covers two mutually oppositely provided free ends of the tear strip (7).

15. Screw closure according to any one of the preceding claims, wherein the cap skirt (3) has an outer gripping knurl.

16. Screw closure according to any one of the preceding claims, characterized in that there is an external printing, in particular a printed image, which extends on the outside of the closure (1) on one or both tear lines (8, 8') and preferably on the cap skirt (3), the tear strip (7) and/or the tamper strip (5).

17. Screw closure according to claim 14, wherein the printed image on the cylindrical outer surface of the screw closure (1) is designed such that it can only be produced by a complex printing process such as laser printing.