GB2303623A

GB2303623A - Tamper evident cap

Info

Publication number: GB2303623A
Application number: GB9514971A
Authority: GB
Inventors: Roy Anthony Caswell
Original assignee: U B PLASTICS Ltd
Current assignee: U B PLASTICS Ltd
Priority date: 1995-07-21
Filing date: 1995-07-21
Publication date: 1997-02-26
Anticipated expiration: 2015-07-21
Also published as: GB2303623B; GB9514971D0

Abstract

A tamper-evident cap for covering a flanged opening of a container, e.g. a keg, comprises a cup-shaped body 10, having a cover plate 12 and a peripheral skirt 14, and a separately formed carrier member 26 which is secured to the skirt. The carrier member has locking tabs 32 which extend in the direction of the cover plate and which engage against an undersurface of the flange in use. The skirt is joined to the cover plate via a relatively weak region 16 which can be torn to enable the cap to be removed. In a preferred embodiment, the skirt has an external tab 20 and a split line 22 to facilitate tearing. The carrier member 26 may be secured to the skirt by sonic welding, spin welding, or an adhesive. The carrier member and the body may be made from a suitable plastics material in contrasting colours.

Description

TAMPER-EVIDENT CAP This invention relates to a tamper-evident cap for covering a flanged opening to a container and is more particularly, though not exclusively, concerned with a tamper-evident cap for a keg used to contain brewery products (including cider) where a flanged opening (or keg spear) to the keg is fitted with a valve.

One type of tamper-evident keg cap is disclosed in GB 2082151 wherein a one-piece cap is moulded with a skirt having internal locking tabs which snap under a flange or shoulder of a keg spear to hold the cap on the spear. The top of the cap has a series of apertures therethrough aligned with the internal locking tabs, such apertures being defined by mould fingers used in the moulding of the tabs. The cap is also moulded with an external tab joined to a region of the skirt lying between a pair of slots and lines of weakness. The cap can be snapengaged with the keg spear and is designed to be removed by grasping of the external tab and pulling in a direction to tear the skirt along the lines of weakness. The cap is moulded from a material which, although resilient, is sufficiently brittle to prevent removal of the cap without damage.Thus, the locking tabs are also relatively brittle and, if broken off, can result in impairing the function of the valve and obstructing beer flow by entering the beer pipe. Additionally, the provision of the moulding apertures in the top of the cap permits unwanted entry of liquids, dirt and foreign bodies, which is obviously undesirable.

Similar disadvantages are possessed by the tamper-evident closure cap disclosed in EP-B-0161565 where the locking tabs are designed in such a way that they can be damaged or torn off during the opening operation and where viewing windows are provided in the cap for checking the locking tabs for signs of tampering.

A further disadvantage of providing viewing windows or moulding apertures in the cap is that it is possible to insert a tool or tools into the aperture or window so as to deflect the locking tabs sufficiently to enable the cap to be removed, the contents of the keg to be tampered with, and for the cap to be snap-fitted back into position without any evidence of tampering having taken place.

It is an object of the present invention to obviate or mitigate the above disadvantages.

According to the present invention, there is provided a tamper-evident cap comprising (a) a cup-shaped body having a cover plate adapted to overlie a flanged opening of a container and a peripheral skirt which is arranged to surround the flange in use, the skirt being joined to the cover plate via a relatively weak region to enable the skirt and the cap to be sufficiently separated to enable removal of the cap upon tearing of the relatively weak region; and (b) a carrier member which is formed separately from the body and secured to the skirt, said carrier member having locking tabs thereon which extend in the direction of the cover plate and which are arranged to engage against an undersurface of the flange in use to retain the cap in position until tearing takes place along the relatively weak region.

Such an arrangement does not rely on breaking of the locking tabs to enable removal of the cap, nor does it require the locking tabs to be formed of a relatively brittle material such as may be used for forming the cup-shaped body. The body of the cap according to the present invention need have no windows, holes or apertures therein whereby the risk of entry of liquid, dirt or other foreign bodies is reduced and unobtrusive insertion of tools to release the locking tabs is prevented.

Furthermore, the use of a cup-shaped body having no windows, holes or apertures therein makes it difficult to see how the cap is locked in position, thus making unobtrusive tampering difficult.

Most preferably, the locking tabs are disposed wholly within the cupshaped body.

Conveniently, the carrier member and the body are of contrasting colour so that any splitting of the cup-shaped body or separation of the two parts will become even more evident.

Most preferably, the relatively weak region extends completely or substantially completely around the skirt to enable complete removal of the cap during authorised access to the opening protected by the cap.

In a particularly preferred embodiment, the cup-shaped body is moulded with an external tab at a lower region of the skirt separated from the cover plate by the weakened region so that the external tab can be used to facilitate tearing of the skirt along the weakened region. In such an arrangement, it is particularly preferred for the carrier member with the locking tabs to comprise a ring which is split in a region corresponding to the location of the external tab so as to facilitate tearing of the skirt and complete removal of the carrier member from the flanged opening during authorised removal of the cap.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Fig 1 is a side elevation, partly in section, of a cup-shaped body forming one part of a tamper-evident cap according to one example of the present invention, Fig 2 is an underneath plan view of a carrier member with locking tabs forming a second part of the tamper-evident cap according to said one example of the present invention, Fig 3 is a section on the line 3-3 of Fig 2, and Fig 4 is a side elevation, partly in section, of the complete tamperevident cap according to said one example of the present invention.

Referring now to Fig 1 of the drawing, there is illustrated a cup-shaped body 10 which is injection moulded out of a suitable plastics material, eg polystyrene, so as to define a circular cover plate 12 which is adapted to overlie an outwardly extending flange of a keg spear, and a depending peripheral skirt 14. The skirt 14 is joined to the cover plate 12 via a weakened region 1 6 provided by a thin wall region extending completely around the body 10 adjacent the cover plate 12.

Alternatively or additionally, weakening may be effected by a ring of minute perforations around the wall.

The lower edge or rim of the skirt 14 is moulded with an external peripheral flange 18 and with an external tab 20 disposed on the opposite side of the weakened region 16 to the cover plate 12. The external tab 20 is connected to the skirt 14 adjacent a tear line 22 extending upwardly from the lower edge of the skirt 14 to the weakened region 16. The tear line 22 may be defined by a line of minute perforations through the skirt 14 and/or by a thin region of the skirt 14.

The cup-shaped body 10 has no apertures, windows or openings therein apart from the possible presence of a line of minute perforations to define the tear line 22 and/or the weakened portion 16.

Referring now to Figs 2 and 3, there is illustrated a carrier member 24 which is moulded from a suitable plastics material, eg polystyrene, in a separate moulding procedure to that used for producing the cup-shaped body 10 and in a contrasting colour to the latter. The carrier member comprises a ring 26 which is split at 28 and which has an outward annular flange 30 around its lower edge. The ring 26 is moulded with a series of upwardly projecting and inwardly directed locking tabs 32. In this example, eleven locking tabs 32 are provided.

Referring now to Fig 4, the carrier member 24 is inserted into the cupshaped body 10 so that the locking tabs 32 are located completely within the body 10, and so that the split 28 lies opposite the split line 22 in the skirt 14. The upper surface of the flange 30 of the Mg26 engages against the lower surface of the flange 18 of the skirt 14 and is secured thereto by any suitable procedure such as by sonic welding, spin welding or an adhesive. In such condition, it will be seen that the locking tabs 32 extend towards the cover plate 12 and terminate at a location spaced below the under surface of the cover plate 12 by an amount which corresponds to the thickness of the flange of the keg spear.The locking tabs 32 are sufficiently flexible so that they can be deformed outwardly to enable the cap to be snap-fitted to the keg spear and sufficiently resilient to spring back under the flange so as to retain the cap in position.

When the cap is in position on the keg spear, it will be appreciated that the only part of the carrier member 24 which is externally viewable is the outer peripheral surface of the flange 30 and that it is impossible to see the locking tabs 32, thereby making it difficult to deduce how the cap has been retained in position on the keg spear. The body 10 can be moulded out of a suitably brittle plastics material such that it will be broken if attempts are made to unscrew the keg spear with the cap in position.

When it is desired to remove the cap, the external tab 20 is manually grasped and pulled so as to tear the skirt 14 along the line 22 and thereafter tearing takes place completely around the weakened portion 16 so as to enable the skirt 14 to be completely detached from the cover plate 12. Tearing of the ring 24 is not necessary because the split 28 therein is aligned with the split line 22. The provision of the split 28 also permits the carrier member 24 to be completely removed from the keg spear when the skirt 14 has been removed.

Claims

1. A tamper-evident cap comprising (a) a cup-shaped body having a cover plate adapted to overlie a flanged opening of a container and a peripheral skirt which is arranged to surround the flange in use, the skirt being joined to the cover plate via a relatively weak region to enable the skirt and the cap to be sufficiently separated to enable removal of the cap upon tearing of the relatively weak region; and (b) a carrier member which is formed separately from the body and secured to the skirt, said carrier member having locking tabs thereon which extend in the direction of the cover plate and which are arranged to engage against an undersurface of the flange in use to retain the cap in position until tearing takes place along the relatively weak region.

2. A cap as claimed in Claim 1, wherein the locking tabs are disposed wholly within the cup-shaped body.

3. A cap as claimed in any one of the preceding claims, wherein the carrier member and the body are of contrasting colour.

4. A cap as claimed in any one of the preceding claims, wherein the relatively weak region extends completely or substantially completely around the skirt to enable complete removal of the cap during authorised access to the opening protected by the cap.

5. A cap as claimed in any one of the preceding claims, wherein the cup-shaped body is moulded with an external tab at a lower region of the skirt separated from the cover plate by the weakened region.

6. A cap as claimed in Claim 5, wherein the carrier member with the locking tabs comprises a ring which is split in a region corresponding to the location of the external tab so as to facilitate tearing of the skirt and complete removal of the carrier member from the flanged opening during authorised removal of the cap.

7. A tamper-evident cap substantially as hereinbefore described with reference to the accompanying drawings.