TAMPER-PROOF SCREW CAP

Abstract

A screw closure of plastic comprising a head plate (2) and a cylindrical cap skirt (3) which extends downwardly from the head plate and has a female thread (4), and a tamper-evident band (5) connected to the lower edge of the cap skirt (3) and provided with radially inwardly projecting retaining elements (6) which define a smallest inside diameter of the tamper-evident band (5) in such a way that they can engage behind a retaining ring (25) of larger diameter on a container neck (20) in order to remain on the container neck (20) after separation from the cap skirt (2), characterised in that extending between the lower edge of the cap skirt (2) and the tamper-evident band (5) is a peripherally extending tear-off band (7) which is connected by way of a respective tear line (8, 8) on the one hand to the cap skirt (2) and on the other hand to the tamper-evident band (5).

Claims

1. A screw closure of plastic comprising a head plate (2) and a cylindrical cap skirt (3) which extends downwardly from the head plate and has a female thread (4), and a tamper-evident band (5) connected to the lower edge of the cap skirt (3) and provided with radially inwardly projecting retaining elements (6) which define a smallest inside diameter of the tamper-evident band (5) in such a way that they can engage behind a retaining ring (25) of larger diameter on a container neck (20) in order to remain on the container neck (20) after separation from the cap skirt (2), characterised in that extending between the lower edge of the cap skirt (2) and the tamper-evident band (5) is a peripherally extending tear-off band (7) which is connected by way of a respective tear line (8, 8) on the one hand to the cap skirt (2) and on the other hand to the tamper-evident band (5).

2. A screw closure according to claim 1 characterised in that the tear-off band (7) has an internal tooth arrangement (9) which upon engagement with oppositely directed teeth (19) on a container neck (20) prevents a rotary movement of the tear-off band (7) about the closure axis at least in the opening direction of the closure (10).

3. A screw closure according to claim 1 characterised in that the tamper-evident band (6) has an internal tooth arrangement (11) which upon engagement with oppositely directed teeth (19) on a container neck (20) prevents a rotary movement of the tamper-evident band (6) about the closure axis in an opening direction of the closure (10).

4. A screw closure according to claim 1 characterised in that the tear line (8, 8) between the tear-off band (7) and the cap skirt (2) and/or the tamper-evident band (6) is produced by an incision in the plastic material which is initially thicker after production by means of injection moulding along the configuration of the tear line.

5. A screw closure according to claim 1 characterised in that the tear-off band (7) is connected to the cap skirt (2) and/or to the tamper-evident band (6) exclusively by easily breakable bridges distributed along the peripherally extending tear line (8, 8).

6. A screw closure according to claim 1 characterised in that viewed in the peripheral direction, the tear-off band (7) comprises alternately relatively more easily (7) and less easily stretchable portions (7).

7. A screw closure according to claim 6 characterised in that the alternately relatively more easily and less easily stretchable portions (7, 7) comprise alternately radially thinner and thicker regions of the tear-off band (7).

8. A screw closure according to claim 6 characterised in that the alternately relatively more easily and less easily stretchable portions (7, 7) are of a width varying along the periphery as measured in the peripheral direction.

9. A screw closure according to claim 6 characterised in that the more easily and less easily stretchable portions (7, 7) as viewed in the peripheral direction are distributed differently in axially different regions of the tear-off band (7).

10. A screw closure according to claim 1 characterised in that the cross-section of the tear-off band (7), as measured perpendicularly to the peripheral direction, varies along the peripheral direction.

11. A screw closure according to claim 1 characterised in that the tear-off band (7) comprises various axial portions of differing outside diameter, which are connected together by a conical transitional portion.

12. A screw closure according to claim 1 characterised in that the tear-off band (7) has two ends, of which at least one end has a gripping tab (13).

13. A screw closure according to claim 1 characterised in that the tear-off band (7) extends along the entire periphery of the closure with the exception of an interruption limited to less than 5 peripheral angle.

14. A screw closure according to claim 1 characterised in that the gripping tab (13) disposed at a free end of the tear-off band (7) is arranged radially outside the two mutually oppositely disposed free ends of the tear-off band (7) and covers said ends outwardly.

15. A screw closure according to claim 1 characterised in that the cap skirt (3) has an outer gripping knurling.

16. A screw closure according to claim 1 with external printing, which extends on the outside of the closure cap (1) over one or both tear lines (8, 8).

17. A screw closure according to claim 19 characterised in that the print image on the cylindrical outside surface of the screw closure (1) is so designed that it is to be produced only with a complex printing process.

18. A screw closure according to claim 16 with external printing which extends on the outside of the closure cap (1) over one or both tear lines (8, 8) and over the cap skirt (3), the tear-off band (7) and/or the tamper-evident band (5).

19. A screw closure according to claim 16 wherein the external printing is a print image.

20. A screw closure according to claim 17 where the complex printing process is laser printing.

Description

[0039] Further advantages, features and possible uses of the present invention will be clearly apparent from the description hereinafter of a preferred embodiment and the accompanying Figures in which:

[0040] FIG. 1 shows a side view of a closure according to the invention,

[0041] FIG. 2 shows a sectional view containing the axis of the closure,

[0042] FIG. 3 shows a sectional view of the closure from below along line V-V in FIG. 2,

[0043] FIG. 4 shows a side view of a closure fitted on an associated container neck,

[0044] FIG. 5 shows a sectional view containing the axis of a closure fitted on to a container neck,

[0045] FIG. 6 shows a sectional view along line VI-VI in FIG. 4,

[0046] FIG. 7 shows the side view of an associated container neck,

[0047] FIGS. 8a, b show two sectional views of the tear-off band and the adjoining parts in the sectional planes containing the closure axis at different angular positions, and

[0048] FIGS. 9a, b show a side view and a perspective view of a closure without tear-off band on a container neck.

[0049] The external view shown in FIG. 1 illustrates a screw closure 10 having a screw cap 1 comprising a head plate 2 and a cap skirt 3, which in turn is connected by way of a tear line 8 to a tear-off band 7 connected to a tamper-evident band 5 by way of a further tear line 8. The screw closure comprises a single plastic part, that is to say the screw cap 1 (consisting of cap skirt 3 and head plate 2) is produced in one piece together with the tear-off band 7 and the tamper-evident band 5 in an injection moulding process, wherein the material which has remainedpossibly after further processingin the region of the tear lines 8, 8 produces the connection between all three parts.

[0050] It is also possible to see at a peripheral position of the tear-off band a gripping tab fitted at a free end of the tear-off band 7 which is interrupted at that location in the peripheral direction. The gripping tab 13 can possibly also have an easily tearable connection to the other end of the tear-off band, that is directly opposite the end provided with the gripping tab. References 7 and 7 in FIG. 1 indicate different portions of the tear-off band which are of differing wall thickness or which in part form projections and recesses and thereby when the band is torn off provide that the tear-off band 7 is deformed.

[0051] The tear-off band has two directly opposite free ends. It can firstly be produced for example in the form of a completely peripherally closed tear-off band with the screw cap 1 and the tamper-evident band 5 and can then be severed by an axial cut shortly before the attachment of the gripping tab 13.

[0052] It can be seen from the sectional view in FIG. 2 that the cap skirt 3 of the screw cap 1 on its inside has a thread 4 which can be interrupted by venting grooves 4. In this case the tear line 8 is formed by a peripherally extending separation line which is interrupted only by easily breakable bridges 12 which hold the tear-off band 7 and the cap skirt 3 together. The tear line 8 is also formed by a peripherally extending separation line which is also interrupted by easily breakable bridges 12 between the tear-off band 7 and the holding band 5. When the gripping tab 13 is lifted and moved radially away from the closure the individual bridges 12 are gradually torn away and the tear-off band 7 is separated from the cap skirt 3 and the tamper-evident band 5 in that way and can be removed along the periphery of the screw closure 10 so that thereafter between the cap skirt 3 and the tamper-evident band a wide gap separates the cap skirt 3 from the tamper-evident band 5 and there is no longer any connection between the cap skirt and the tamper-evident band. The tamper-evident band in turn on its inside also has a so-called folded-over flexband 6 which prevents displacement or removal of the tamper-evident band 5 upwardly in the direction of the cap skirt 3.

[0053] Unscrewing of the cap without separation of the tear-off band is prevented by teeth 9 on the inside of the tear-off band 7, that come into engagement with a corresponding counterpart tooth arrangement 19 on a container neck 20 and prevent rotation of the tear-off band. The connection between the tear-off band 7 and the cap skirt 3 by a plurality of easily breakable bridges then prevents the closure cap from being released. Otherwise for simultaneously breaking all bridge 12 it would be necessary to apply a force such as a normal consumer would not apply. The consumer is therefore more or less compelled to remove the tear-off band 7 to be able to open the closure. The easily breakable connection along the tear lines 8 and 8 could therefore also be comparatively stronger than the connection between the tamper-evident band and the cap skirt in conventional screw closures as, when the tear-off band is radially pulled off, the bridges 12, 12 are individually successively broken.

[0054] In order to open the closure without removal of the tear-off band in contrast all of the easily breakable bridges would have to be practically simultaneously torn, which would require a correspondingly high force.

[0055] FIG. 4 shows the screw closure 10 fitted on a container neck 20 while FIGS. 5 and 6 show the screw closure 10 fitted on the container neck 20 in a section containing the axis of the closure and in a section perpendicularly to that axis respectively. It will be seen from FIG. 5 that the spacing between the tamper-evident band and the lower cap edge is initially bridged over by the tear-off band but that spacing is also not noticeably reduced after removal of the tear-off band 7 because the retaining ring 25 at the periphery of the container neck only permits slight axial play of the tamper-evident band 5.

[0056] FIG. 7 shows the container neck 20 without the screw closure 10. A particularity of this container neck 20 lies in the provision of a suitable counterpart tooth arrangement 19 to the tooth arrangement 9 at the inside of the tear-off band 7, that prevents rotation of the tear-off band 7 in the opening direction together with the screw cap 1. The retaining ring 25 is disposed beneath the counterpart tooth arrangement 19 at a spacing from the upper opening edge of the container neck, which as usual is slightly less than the internal spacing between the inside of the head plate and the top side of retaining elements on the tamper-evident band, that come into engagement with the underside of the retaining ring, so that the tamper-evident band 5 of the screw closure 10 has only a slight axial mobility. That is also necessary in the case of conventional closures to prevent easy access from the exterior to the tamper-evident band that would permit manipulation of the screw closure.

[0057] FIG. 8 shows two sectional views through the region of a tear-off band 7 in section planes respectively containing the axis, but at different peripheral positions 7, 7 of the tear-off band 7. The section in each case shows the tear-off band 7 and the two tear lines 8 and 8 respectively, forming the transition on the one hand to the cap skirt 3 and on the other hand to the tamper-evident band 5. As will be seen the cross-sections of the tear-off band differ markedly from each other at the different peripheral positions and also the directly adjoining portions of the cap skirt 3 and also the tamper-evident band 5 are adapted in respect of their thickness and position to the respective configuration of the cross-section of the tear-off band 7. The result of this is that, on being torn off the closure cap, the tear-off band 7 is more or less deformed depending on the respective local cross-section, in which respect the adjoining portions of the cap skirt and the tamper-evident band 5 are at least partially affected thereby. The result of this is that it is practically impossible for the tear-off band 7 to be subsequently re-inserted into the gap between the tamper-evident band and the cap skirt and there to join it by adhesive or welding to the cap skirt and the tamper-evident band without that manipulation being nonetheless clearly visible.

[0058] By virtue of a suitable design in respect of the shape and wall thickness of the tear-off band, that can be varied in many respects, inter alia also by a stepped axial contour, the tooth arrangements 9, the repetition spacing of which, also in relation to the length and the varying repetition spacing of the different peripheral portions 7, 7, different wall thicknesses along the periphery and/or in the axial direction, different distribution of the teeth 9 and so forth, and finally also by virtue of the design configuration of the tear lines or the adjustment of their tearing strength, the tear-off band 7 can be such that it is markedly visibly and irreversibly deformed by the forces occurring when tearing off the tear-off band. It is then practically not possible to re-position a tear-off band again once it has been torn off on a closure and to connect it to the cap skirt 3 and the tamper-evident band 5 without that manipulation being clearly recognizable.

[0059] FIG. 9 shows a side view (FIG. 9a) and a perspective view (FIG. 9b) of the closure 10 fitted on a container neck 20 after removal of the tear-off band 7. As will be seen a clear gap opens up between the lower edge of the cap skirt 3 of the screw cap 1 and the upper edge of the tamper-evident band 5, and that gap makes it clearly discernible that the tear-off band was removed and thus the closure has evidently already been opened.

[0060] Admittedly the tamper-evident band 5 has a certain axial play on the container neck 20 but even when the screw cap is firmly screwed on and even when the tamper-evident band 5 is axially pushed up 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-evident band 5, that approximately corresponds to the axial width of the tear-off band previously disposed in that region.