GB2311060A - Improvements in tamper-evident container closures - Google Patents

Abstract

The invention provides container closure assemblies comprising a container neck (1,20) and a closure (2,21) secured on the container neck by screw threads. A tamper-evident ring (3,22) is severably attached to the closure and has inwardly projecting retaining tabs (15) for retaining it on the container neck after the closure has been removed for the first time. The invention is characterized by the provision of side wall elements (7,8) on the container neck defining windows (10,26) for receiving individual retaining tabs (15) of the tamper-evident ring to block rotation in both directions of the tamper-evident ring on the container neck and obstruct tampering with the flexible tabs (15).

Description

IMPROVEMENTS IN TAMPER-EVIDENT CONTAINER CLOSURES The present invention relates to improvements in tamperevident container closure assemblies. In particular, it relates to improved container closure assemblies comprising a tamper-evident ring on the closure.

It is known to provide container closure assemblies comprising: a container neck having a first screw thread and a retaining lip located below the first screw threads; a closure comprising a base portion and a skirt portion and having a second screw thread on the inside of the skirt portion, the second screw thread cooperating with the first screw thread to retain the closure on the container neck; and a tamper-evident ring severably joined to the skirt portion of the closure and retained below the retaining lip on the container neck when the closure is unscrewed from the container neck for the first time. The separation of the tamper-evident ring from the closure skirt provides a visible indication that the closure has been removed from the container neck at least once.

W094/11267 describes container closure assemblies of the above type. These assemblies are characterized by the provision of a tamper-evident ring that a comprises a collar and a plurality of flexible, inwardly projecting retaining tabs on the collar. When the closure and tamper-evident ring are secured onto the container neck for the first time, the flexible tabs flex outwardly to pass over the retaining lip on the container neck without unduly stressing the collar. The flexible tabs then snap back, to abut against the underside of the retaining lip on the container neck, thereby blocking removal of the tamper-evident ring from the container neck when the closure is unscrewed for the first time, thereby achieving reliable separation of the tamperevident ring from the closure. A longitudinal ratchet rib may be provided on the container neck below the retaining lip. The ratchet rib allows the tamper-evident ring to be screwed onto the container neck, but blocks rotation of the tamper-evident ring in an unscrewing direction by abutment against the inwardly projecting tabs, and thereby further ensures reliable separation of the tamper-evident ring from the closure skirt when the closure is unscrewed for the first-time.

It has now been found that additional, important advantages can be achieved by the provision of windows in the container neck for receiving individual tabs projecting inwardly from the tamper-evident ring.

Accordingly, the present invention provides a container closure assembly comprising a container neck having a first screw thread and a retaining lip located below the first screw thread; a closure comprising a base portion and a skirt portion and having a second screw thread on the inside of the skirt portion, said second thread cooperating with said first thread to retain the closure in a fully secured position on the container neck and to enable the closure to be removed from said fully secured position by unscrewing; and a tamper-evident ring severably joined to the skirt portion of the closure and comprising a circumferential collar and one or more retaining tabs projecting inwardly from the collar for abutment against the retaining lip to retain the tamper-evident ring on the container neck when the closure is removed from said fully secured position for the first time; characterized in that the assembly further comprises at least one pair of side wall elements extending longitudinally on said container neck below the retaining lip, said pair of side wall elements defining a window positioned and dimensioned to receive one of said tabs when the closure is fully secured on the container neck to substantially block rotation of said one of said tabs in either direction.

Preferably, one pair of the side wall elements defining one said window is provided for each of the tabs on the tamper-evident ring.

Preferably, the side wall elements each comprise longitudinal ribs projecting from the container neck, and preferably extending from the retaining lip down to a projecting shoulder located below the bottom of the tamperevident ring. Preferably, the window defined between the longitudinal ribs is just wide enough to receive one of the retaining tabs.

Here and elsewhere in the specification the term "below" applied to the container neck signifies axially more remote from the mouth of the container neck.

It will be appreciated that the projecting longitudinal ribs will also tend to obstruct rotation of the tamperevident ring by abutment against said retaining tabs when the tamper-evident ring is being screwed onto the container neck for the first time. In order to minimise this obstruction, preferably the projecting rib over which the tab of the tamper-evident ring must ride in order to snap fit into the window has a transverse cross-section that is ramped. That is to say, the surface of the projecting rib has a relatively gentle slope (near-tangential) on the side facing away from the window, and a relatively steep (nearradial) surface facing into the window, the latter surface providing an abutment surface against which the tab abuts when the closure is unscrewed for the first time.

In alternative preferred embodiments, the side wall elements are defined by the sides of a window recess formed in the container neck for receiving the tab of the tamperevident ring. In such cases, the retaining lip is preferably formed at least on part by the top of the window recess. Preferably the window recess is rectangular, and just wide enough to receive one of the retaining tabs. The window recess may also be provided with a projecting lip across its top and/or longitudinal projecting ribs along its sides.

A first advantage of the container closure assemblies according to the present invention is that the tamperevident ring is held in a substantially fixed rotational position relative to the container neck even after it has separated from the closure skirt. This prevents the tamperevident ring from rattling on the neck, and makes it more difficult to remove the separated tamper-evident ring from the container neck without cutting it. Furthermore, it ensures that any distinctive shape and/or decoration of the tamper-evident ring is always properly aligned with a corresponding shape and/or decoration on the closure when the closure is resecured on the container neck.

A further advantage of the assemblies according to the present is that the presence of side wall elements on either side of the flexible tabs on the tamper-evident ring when the tamper-evident ring is secured on the container neck makes it very much more difficult to insert a blade or similar object beneath the flexible tabs to flex them outwards and thereby remove the tamper-evident ring from the container neck without also separating it from the closure skirt.

Preferably, the tabs on the tamper-evident ring can flex outwardly into recesses or gaps provided in the collar of the tamper-evident ring. This enables the tamper-evident ring to be snap-fitted onto the container neck without unduly stressing the collar or the severable connections between the collar and the closure skirt. Details of this preferred feature are given in our International patent application W094/11267, the entire content of which is expressly incorporated herein by reference.

Preferably, the tamper-evident ring is moulded integrally in one piece with the closure.

The present invention is especially suitable for use in the container closure assemblies for carbonated beverage containers described and claimed in our International patent application W095/05322, the entire content of which is expressly incorporated herein by reference.

The present invention is also especially useful for use in snap-on, twist-off container closure assemblies for plastic milk bottles and the like.

Specific embodiments of the present invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows side elevation, partially cut away, of a container closure assembly according to the invention with the closure and tamper-evident ring attached thereto fully secured on the container neck; Figure 2 shows part of a cross-section through II-II in the container closure assembly of Figure 1; Figure 3 shows a similar view to Figure 1 for an alternative embodiment of the present invention; and Figure 4 shows a similar fragmentary cross-section as Figure 2 for the embodiment of Figure 3.

Referring to Figures 1 and 2, the container closure assembly comprises a container neck 1, a closure 2 and a tamper-evident ring 3. The closure 2 is retained on the container neck 1 by complementary threads on the container neck and the closure skirt. The threads are pressure-safety threads specially adapted for carbonated beverage containers, substantially as described and claimed in our International patent application W095/05322, the entire content of which is expressly incorporated herein by reference.

The container neck 1 is provided with a circumferential retaining lip 4 having a sloped upper surface 5 and a lower abutment surface 6 that extends substantially perpendicular to the longitudinal axis of the assembly. The container neck is also provided with pairs of longitudinal ribs 7,8 extending from the retaining lip 4 downwardly to a shoulder 9 on the container neck. A window 10 is defined between the longitudinal ribs 7,8. The longitudinal rib 7 has a ramped transverse cross section as shown most clearly in Figure 2, the cross-section being made up of a substantially tangential lead-in surface 11 and a substantially radial abutment surface 12 facing the window 10. In contrast, the rib 8 has substantially radial abutment surfaces on both sides.

The tamper-evident ring 3 is moulded integrally in one piece with the closure 2, and is joined thereto by narrow severable bridges 13. The tamper-evident ring 3 comprises a collar 14 and a plurality of integrally formed, inwardly projecting retaining tabs 15. The tabs 15 can flex outwardly into gaps in the collar 14 to enable the tamperevident ring to be snap fitted over the retaining lip 4 when the closure and tamper-evident ring are fitted onto the container neck for the first time. The operation of the flexible retaining tabs is described and claimed in detail in our International patent application W094/11267, the entire content of which is expressly incorporated herein by reference.

In this embodiment, the number of windows 10 defined by pairs of longitudinal ribs 7,8 on the container neck is equal to the number of flexible retaining tabs 15 on the tamper-evident ring. The window 10 has a radial extent (width) that it just large enough to receive one of the flexible tabs 15.

In use, the closure with the tamper-evident ring attached is screwed onto the container neck. As the fully secured position is approached, the flexible tabs 15 flex outwardly to snap over the retaining lip 4. At substantially the same time, the flexible tabs 15 flex outwardly and ride over the lead-in ramp surface 11 on the rib 7 of the container neck. The flexible tabs 15 then snap into the window recesses 10 at the exact position where the closure is fully secured on the container neck. The flexible tabs then substantially fix the rotational position of the tamper-evident ring on the container neck by abutment against the longitudinal ribs 7,8.

When the closure is unscrewed from the container neck for the first time, the flexible tabs 15 abut against the radial abutment surface 12 of the ribs 7, and also against the abutment surface 6 of the retaining lip 4 to block rotational and axial movement of the tamper-evident ring, and thereby achieve reliable separation of the tamperevident ring from the closure 2. Once separated, the tamper-evident ring drops down to rest on the shoulder 9 of the container neck, thereby giving a clear visual indication that the container closure assembly has been opened at least once.

Referring to Figure 3, the alternative embodiment shown in the drawing also comprises a container neck 20, a closure 21 for the container neck 20, and a tamper-evident ring 22.

The closure 21 and tamper-evident ring 22 are substantially identical to those in the embodiment of Figures 1 and 2.

The container neck 20 has substantially identical threads to those described for the embodiments of Figures 1 and 2.

However, on the container neck 20 the retaining lip 4 and longitudinal ribs 7,8 of the embodiments of Figures 1 and 2 have been replaced by a cylindrical shoulder 24 having a ramped top edge 25 and extending for at least the height of the tamper-evident ring below the threads.

A plurality of window recesses 26 are radially spaced around the shoulder 24. Each recess 26 is just wide enough to receive one of the flexible tabs 15 on the tamper-evident ring, and extends for a sufficient height to allow the tamper-evident to drop down visibly after separation of the tamper-evident ring from the closure. The window recesses are substantially rectangular.

In use, the window recesses operate substantially as described above for the windows 10 in the embodiment of Figures 1 and 2. Once the flexible tabs 15 have snapped into the window recesses, the tamper-evident ring is substantially immobilised against rotational or upward movement, but can drop down once it has separated from the closure when the closure is removed from the container neck for the first time. The provision of window recesses makes it particularly difficult to access the flexible tabs 15 in order to attempt to remove the closure without separation of the tamper-evident ring.

The above embodiments are preferably formed from thermoplastic materials by conventional moulding methods.

Preferably, the container necks are formed by blow moulding polyethylene terephthalate or similar materials.

Preferably, the closures and tamper-evident rings are formed integrally in one piece by injection moulding polyethylene or similar materials.

The above embodiments have been described by way of example only. Many other embodiments falling within the scope of the accompanying claims will be apparent to the skilled reader.

Claims (10)

1. A container closure assembly comprising: a container neck having a first screw thread and a retaining lip located below the first screw thread; a closure comprising a base portion and a skirt portion and having a second screw thread on the inside of the skirt portion, said second screw thread cooperating with said first screw thread to retain the closure in a fully secured position on the container neck and to enable the closure to be removed from said fully secured position by unscrewing; and a tamper-evident ring severably joined to the skirt portion of the closure and comprising a circumferential collar and one or more retaining tabs projecting inwardly from the collar for abutment against the retaining lip to retain the tamper-evident ring on the container neck when the closure is removed from said fully secured position for the first time; characterized in'that the assembly further comprises at least one pair of side wall elements extending longitudinally on said container neck below the retaining lip, said pair of side wall elements defining a window positioned and dimensioned to receive one of said tabs when the closure is fully secured on the container neck to substantially block rotation of said one of said tabs in either direction.

2. A container closure assembly according to claim 1, comprising one pair of said side wall elements defining one said window for each of the said tabs.

3. A container closure assembly according to claim 1 or 2, wherein said side wall elements comprise a pair of longitudinal ribs projecting from the container neck.

4. A container closure assembly according to claim 3, wherein one of said pair of ribs has a ramped transverse cross-section to assist fitting the tamper-evident ring onto the container neck.

5. A container closure assembly according to claim 1 or 2, wherein said side wall elements comprise the sides of a window recess formed in the container neck.

6. A container closure assembly according to claim 5, wherein the retaining lip comprises the top of said window recess.

7. A container closure assembly according to any preceding claim, wherein the tamper-evident ring is shaped or decorated in a pattern that aligns with a matching shape or decoration on the closure skirt when the closure is fully secured on the container neck.

8. A container closure assembly according to any preceding claim, wherein the tabs on the tamper-evident ring can flex outwardly into recesses or gaps provided in the collar to enable the tamper-evident ring to be snap-fitted onto the container neck.

9. A container closure assembly according to any preceding claim, wherein the tamper-evident ring is moulded integrally in one piece with the closure.

10. A container closure assembly substantially as hereinbefore described with reference to the accompanying drawings.