GB2385321A

GB2385321A - Tamper evident closure

Info

Publication number: GB2385321A
Application number: GB0203572A
Authority: GB
Inventors: Dean Walding
Original assignee: Dragon Plastics Ltd
Current assignee: Dragon Plastics Ltd
Priority date: 2002-02-14
Filing date: 2002-02-14
Publication date: 2003-08-20
Also published as: GB0203572D0

Abstract

A tamper evident closure for the screw threaded neck of a container has an inner sleeve (12) comprising upper and lower portions (17,18) connected by frangible webs (19) along a line of weakness (fig 1,23). Two rows of teeth (21,22) are provided on the inside of the lower portion (18). These ensure that the cap is retained when first screwed on, and that the lower portion moves to and remains at a lower position when the cap is first screwed off. An outer sleeve (13) may also be provided. Cam means (fig 1, 20) are provided to urge the upper and lower portions (17,18) apart.

Description

Tamper Evident Closure This invention relates to a tamper evident screw closure, particularly for bottles.

Tamper evident closures are widely used to give assurance to a purchaser that the contents of a container have not been adulterated or tampered with after leaving the packing plant.

Typically such a closure for a bottle comprises a ring at the free end of a skirt of the cap, this ring having a one-way latch for engaging an annular protrusion or neck ring of the bottle. The ring automatically engages the protrusion as the cap is screwed on, and breaks or is broken as the cap is removed for the first time. The appearance of the cap is thus changed, and warns the purchaser/user that the container has been opened.

Advantageously the ring remains on the bottle, as evidence that the screw cap has previously been removed. In a typical arrangement, for example on a lemonade bottle, the ring will drop by a few millimetres in order that a gap is visually evident when the cap is next screwed on.

I The tamper evident ring can often be re-attached to the cap in an unauthorized manner.

For example the ring of a lemonade bottle may be re-attached to the cap by adhesive in such a way that the consumer may not notice.

As an alternative the cap may include a tear-off circumferential strip which, when removed, noticeably changes the appearance thereof. The strip may comprise a mid-portion of the cap so as to leave a lower ring of material below the neck protrusion.

Whilst this arrangement is more complex it does not prevent careful re-assembly by adhesive or welding.

Deliberate tampering or adulteration is most likely in the case of high value products such as perfume or alcoholic spirit. High profit can be made by illegally substituting or

diluting genuine product. Measures such as separate external seals or covers are used, but a purchaser may not know that these additional features have been removed; in other words no witness remains on the container.

What is required is a tamper evident closure which leaves a witness when the cap is first removed, yet is a substantial deterrent to tamperers. The closure should also preferably be adaptable to both conventional and child resistant caps, and be suitable for conventional containers having a neck ring below the screw-threaded portion of the outlet.

According to the invention there is provided a tamper evident closure for a screw threaded neck of a container, the container having a substantial continuous radially outwardly protruding neck ring at the base of the screw threading, the neck ring defining a continuous recess thereunder, and the closure comprising an end wall and a circular depending skirt having a circumferential line of weakness, internal screw threading being provided on the side of said line adjacent the end wall, and internal resilient teeth on the other side, said teeth being directed radially inwardly and axially towards said end wall, and comprising an upper tooth adjacent said line, and a lower tooth relatively distant from said line, and said skirt further including cam means adapted to urge axially apart annular portions of said skirt on either side of said line on relative unscrewing motion of the portion including said screw threading, wherein, in use, the lower tooth is adapted to engage the neck ring recess on first screwing on said closure to a container, and said upper tooth is adapted to engage said recess on first unscrewing of said closure.

Preferably a plurality of lower and upper teeth are provided in a circumferential array. In the preferred embodiment the upper and lower teeth alternate, and most preferably are immediately adjacent one another.

The cam means typically comprise a discontinuity extending axially of the wall of the inner sleeve. In one embodiment the discontinuity comprises one or more ramp faces, which are preferably straight.

In a preferred embodiment the circumferential line of weakness is defined by a plurality of circumferentially spaced frangible webs connecting the annular portions of the skirt.

These webs may extend along the or each discontinuity.

Preferably the screw threading is defined by a component adapted for rotational fixing with respect to a portion of said skirt. The component may comprise an insert of the skirt, and may include said end wall. Rotational fastness may be assured by means of a spline connection, by adhesive, welding or in any appropriate manner. In the preferred embodiment a screw threaded insert includes an external flange for abutment with said skirt and to limit insertion thereof. Said flange may be continuous.

In one embodiment the closure includes an external sleeve for the screw threaded portion and adapted to be rotationally fast therewith. The sleeve may be an extension of the end cap or may be fixed with respect to the end cap by welding, adhesive or in any other suitable manner.

In a preferred embodiment the external sleeve includes an inwardly directed lower flange for covering the end of the closure distant from the screw threading. The lower flange is preferably continuous. In this embodiment the external sleeve includes circumferential weakening to permit separation into two annular portions on first removal of the closure. Preferably this circumferential weakening coincides in use with the line of weakness of said skirt.

In an alternative embodiment the external sleeve may comprise two generally annular portions connected about said closure in a manner to define a circumferential weakening.

The external sleeve may comprise a deep drawn metal shell incorporating an end wall, or may comprise a generally annular plastic moulding. In a preferred embodiment the external sleeve is of polystyrene. Such a material shatters easily and provides a witness in case of attempted tampering.

Other features of the invention will be apparent from the following description of several preferred embodiments shown by way of example in the accompanying drawings in which :- Fig. 1 is a schematic exploded drawing of typical components of a screw cap according to the present invention; Fig. 2 is an axial section through the cap of Fig. 1 assembled on a container; Fig. 3 is an axial section corresponding to Fig. 2 and showing an alternative embodiment.

With reference to Figs. 1 and 2 a tamper evident closure comprises an end cap 11, an inner sleeve 12 and an outer sleeve 13. As will become apparent various other configurations are possible, whilst achieving the object of the invention.

The end cap 11 comprises an internally threaded annular portion 14, and an end plate 15 which defines a circumferentially extending flange 16. The threaded portion is not shown, but can be of any suitable kind to suit the screw threaded neck of a container such as a bottle. The end cap is typically a one piece plastics moulding, and of itself provides the means of closing the container outlet. A suitable wad may be incorporated within the end cap to ensure a fluid tight seal.

The inner sleeve 12 comprises a plain cylindrical upper portion 17, and a cylindrical lower portion 18 having a plain outer surface and having two axially spaced circumferential rows of teeth 21,22. The upper and lower portions are intended to be separated in use, and in this embodiment are connected by a circumferential array of frangible webs 19, in a known manner.

The rows of teeth 21,22 face inwardly and toward the end cap 12, for reasons which will be explained.

A series of ramp faces 20 are formed on the upper and lower portions 17,18 as illustrated. Whilst the upper and lower portions remain attached by the webs 19, these ramp faces are inactive. However, as will become apparent relative rotation of the portions in one direction will cause the respective ramp faces to engage and axially urge the upper and lower portions apart.

The outer sleeve 13 is cylindrical and has a circumferential line of weakening 23 to define an upper part 24 and lower part 25. A circumferential inwardly directed flange 26 is provided at the lower end.

In this embodiment the closure comprises three components for ease of moulding. In use the end cap 11 is inserted into the upper portion 17, and fixed in place by e. g. friction, adhesive or welding. Inter-engaging axial splines may be provided to ensure that adequate rotational force can be transmitted between these two parts.

The outer sleeve 13 is inserted from the other end over the inner sleeve, and attached to the flange 16 of the end cap by e. g. adhesive or welding. In this way the inner sleeve is encapsulated. The line of weakening 23 and array of frangible webs 19 substantially coincide.

As will be apparent the rows of teeth 21,22 alternate, and each tooth is capable of independently flexing radially outwardly against the inner wall of the inner sleeve.

In use, as illustrated in Fig. 2 the closure is screwed onto the neck 30 of a container in conventional manner. The lower array of teeth 21 are bent radially outwardly by the usual neck ring 31 as the closure moves relatively down. As the cap becomes fully screwed on these teeth 21 spring into the recess 32 under the neck ring, close to the underside thereof. A small clearance is of course necessary to ensure free engagement of these teeth 21 into the recess 32 as the cap closes against the mouth of the container.

In the fully screwed on condition, as shown in Fig. 2, the upper array of teeth 22 remain in an outwardly flexed condition against the neck ring 31.

If an attempt to unscrew the closure is made, the teeth 21 will engage the underside of neck ring 31 after a slight rotational movement, and further unscrewing of the closure will be resisted. On application of greater torque the webs 19 and line of weakness 23 will break, thus permitting the end cap 11, upper portion 17 and upper part 24 to separate as a unit. At the same time, the respective ramp faces 20 will engage, thus urging the lower portion 18 relatively downwardly until the upper array of teeth 22 enter the recess 32 under the neck ring. Meanwhile the screw threaded component can be removed, and the contents of the container dispensed. The lift of the ramp faces 20 should of course be sufficient to ensure that the teeth 22 enter the recess 32.

If this screw threaded component is now reapplied to the bottle, and screwed fully on, an inevitable gap will be present between the two visible parts of the outer sleeve 13, thus indicating positively that the container has been opened. The upper array of teeth 22 ensure that upward movement of the lower portion is impossible, and thus reattachment of the tamper evident ring is prevented.

Preferably the outer sleeve has continuous printing over the surface thereof so that separation of the two parts causes a visual discontinuity.

In an alternative construction, illustrated in Fig. 3, the outer sleeve comprises a metal sheath 43 which fully encloses the end cap 41 and inner sleeve 42. The lower edge 44 of the sheath is rolled over after insertion of the assembly of inner sleeve and end cap therein.

It will be appreciated that there are various possibilities for constructing and assembling the closure of the invention.

The embodiment illustrated in Figs. 1 and 2 has certain advantages. In particular the inner sleeve may be moulded of a relatively soft flexible material such as a polyolefin whereas the end cap and outer sleeve may be of a relatively hard and dimensionally stable material such as polystyrene. By this means the resilience of the teeth 21,22 is

assured whereas the outer surface of the closure is rigid and highly suitable for printing and the like so as to give a high quality appearance.

After assembly and fixing of the end cap and outer sleeve, the inner sleeve is fully retained; accordingly drive from the end cap to the inner sleeve, and vice versa, by splined connection is sufficient.

In the alternative the end cap 11 and upper part 24 may be moulded as a single component, and the lower part 25 attached by welding or the like on assembly of the closure.

If made of a brittle material such as polystyrene, the lower part will discourage any attempt to free the upper array of teeth 22 from the recess 32. Access from below can be restricted by the flange 26, and the lower part can be made breakable if an attempt is made to insert a tooth release tool from below.

A continuous array of teeth 21,22 is desirable in order to increase the difficulty of tooth release, but is not essential. Nor need the two arrays of teeth alternate.

Any suitable cam means may be provided. For example the ramp faces illustrated in the drawings may be substituted by a circumferential generally serpentine gap, the peaks thereof coinciding to force the portions apart on slight relative rotation.

Although not illustrated, the closure is suitable for use with many kinds of conventional child resistant closure (CRC). Such closures usually comprise a two part cap, in which one part must be moved relative to the other part in order to engage unscrewing dogs.

Typically the outer cap of a CRC must be urged downwards against a resilient return force. Such a cap can be incorporated in the closure according to the invention, for example in substitution of the end cap 41 of Fig. 3. For unscrewing motion, the entire outer cap is urged downwardly, the arrangement being that such travel is less than that required to permit engagement of the upper row of teeth 22 in the recess 32.

Claims

1. A tamper evident closure for a screw threaded neck of a container, the container having a substantial continuous radially outwardly protruding neck ring at the base of the screw threading, the neck ring defining a continuous recess thereunder, and the closure comprising an end wall and a circular depending skirt having a circumferential line of weakness, internal screw threading being provided on the side of said line adjacent the end wall, and internal resilient teeth on the other side, said teeth being directed radially inwardly and axially towards said end wall, and comprising an upper tooth adjacent said line, and a lower tooth relatively distant from said line, and said skirt further including cam means adapted to urge axially apart annular portions of said skirt on either side of said line on relative unscrewing motion of the portion including said screw threading, wherein, in use, the lower tooth is adapted to engage the neck ring recess on first screwing on said closure to a container, and said upper tooth is adapted to engage said recess on first unscrewing of said closure.

2. A closure according to claim 1 wherein a plurality of lower and upper teeth are provided in a circumferential array.

3. A closure according to claim 2 wherein said upper and lower teeth alternate.

4. A closure according to claim 3 wherein said upper and lower teeth are immediately adjacent one another.

5. A closure according to any preceding claim wherein said cam means comprises a discontinuity extending axially of the wall of the inner sleeve.

6. A closure according to claim 5 wherein said discontinuity comprises one or more ramp faces.

7. A closure according to claim 6 wherein said one or more ramp faces are straight.

8. A closure according to any preceding claim wherein said circumferential line of weakness is defined by a plurality of circumferentially spaced frangible webs connecting the annular portions of the skirt.

9. A closure according to any preceding claim wherein the screw threading is defined by an insert adapted for rotational fixing with respect to a portion of said skirt.

10. A closure according to claim 9 wherein said insert includes an external flange for abutment with said skirt and to limit insertion thereof.

11. A closure according to claim 10 wherein said flange is continuous.

12. A closure according to any preceding claim and further including an external sleeve for the screw threaded portion and adapted to be rotationally fast therewith.

13. A closure according to claim 12 wherein said external sleeve includes an inwardly directed lower flange for covering the end of the closure distant from the screw threading.

14. A closure according to claim 13 wherein said external sleeve includes circumferential weakening to permit separation into two annular parts on first removal of the closure.

15. A closure substantially as described herein with reference to the accompanying drawings.