GB2225778A

GB2225778A - Tamper evident closure

Info

Publication number: GB2225778A
Application number: GB8827328A
Authority: GB
Inventors: Henryk Dudzik
Original assignee: Lawson Mardon USA Inc
Current assignee: Amcor Specialty Cartons Americas LLC
Priority date: 1988-11-23
Filing date: 1988-11-23
Publication date: 1990-06-13
Also published as: GB2241231B; AU4636189A; WO1990005681A1; ZA898948B; CA2002940A1; GB2241231A; GB9106466D0; GB8827328D0; KR900701617A

Abstract

A screw cap (10) comprising an internally threaded skirt (14) including a frangible indicator (22) having a projection (30) adapted to be engaged by a projection (40) on the neck (20) of the jar (12) as the cap is rotated to remove it. Pressure applied by the projection (40) causes frangible supports (26) to snap and the indicator (22) to break, thus providing an indication (both visual and tactile) that the jar has previously been opened. The cap can be made and applied to a jar by currently used systems and is a little more expensive than a conventional cap.

Description

TAMPER EVIDENT CLOSURE This invention relates to a tamper evident closure and especially to a tamper evident screw cap for a container, a package including such a screw cap, and a container adapted for use with such a screw cap.

It is desirable to provide a clear indication to a purchaser that a package has not been tampered with especially where the package is a food package eg. a coffee or jam jar. It is a current practise to provide vessels, for example glass jars, with a closure cap removably attached to the jar by means of screw threads, the cap comprising a closure portion (generally planar) with a skirt depending from a periphery thereof, the skirt having internal screw threads adapted to cooperate with external threads on a neck portion defining an opening in the jar through which access may be gained to the interior of the jar. Such screw caps are commonly moulded of a suitable plastics material, for example polypropylene.Such jars when used for certain products, for example coffee, are commonly supplied with a sheet material, for example a metal foil, covering the opening and sealed to the rim of the jar bounding the opening: intactness of the foil when the screw cap is first removed can provide some visual reassurance that the contents have not been tampered with, as well as the foil maintaining the contents of the jar in good condition.

However, the foil may sometimes be damaged when first removing the closure so that this visual reassurance is not very reliable and in any event a hypodermic syringe may be used to inject noxious material through the foil in a position which is not readily noticeable at a casual inspection. Furthermore, jars are not sealed when used for other products, for example jam, with a separate foil seal of this type.

One of the various objects of the present invention is to provide an improved screw cap for use in closing an opening in a container.

Another of the objects of the invention is to provide an improved tamper-evident package.

In one aspect the invention may be considered to provide a tamper evident screw cap for a container, comprising a closure portion with a skirt depending therefrom, interengaging means an interior of and on the exterior of a neck portion defining an opening in a container whereby to removably retain the cap on the neck portion to close the opening, the cap being removable from the by an action including rotation of the cap relative to the neck portion, the skirt further comprising at least one indicator which is frangible and which is adapted to be engaged by a projection provided on the neck portion of a jar to which the cap has been applied as the cap is rotated relative to the neck portion to remove it therefrom and to be thereby fractured thus to provide an indication that the cap has previously been removed from the neck portion, but which is not fractured during initial application of the cap to the neck portion.

In another aspect the invention may be considered to provide a tamper evident screw cap for a container comprising a closure portion with a skirt depending therefrom, the skirt haing internal screw threads adapted to cooperate with external threads on a neck portion defining an opening in a container whereby to retain the cap on the neck portion to close the opening, the skirt further comprising at least one indicator comprising a frangible portion which is visible externally of the skirt and an inwardly projecting engagement portion comprising a first surface adapted to be engaged by an external projection from the neck portion of a container to which the cap has been applied as the cap is rotated to remove it from the neck portion thereby to apply a force to the frangible portion causing it to fracture thus to provide an indication that the cap has previously been removed from the neck portion, the engagement portion further comprising a second surface adapted to engage said external projection of a container as the cap is first applied thereto and to permit the frangible portion to pass the projection as the cap is first applied to the neck portion without fracture of the frangible portion.

The frangible portion is preferably attached to the remainder of the skirt by frangible supports which extend between a body of the frangible portion and portions of the skirt at either side, axially, of the body of the frangible portion. Suitably the supports have a relatively small circumferential width (by comparison with the circumferential width of the body).

In a preferred screw cap in accordance with the invention the body has a weakened portion at a circumferentially central region of the body which extends generally axially across the body thus to divide it into two parts. The weakened portion suitably has a circumferential width which is between about 5% and 10% of the circumferential width of the frangible portion.

Preferably the opening within which the frangible portion is supported extends between about 300 and 500 of arc around the skirt, suitably about 400.

The preferred screw cap comprises two pairs of frangible supports each pair associated with one of the two parts of the frangible portion. The supports of each pair are axially opposed at opposite sides of the body and are conveniently situated at a central region of the associated part. Conveniently each of the frangible supports extends across between about 10 and 15% of the circumferential width of the associated part of the frangible portion, suitably about 12.5% and is disposed with its centre substantially at the centre of the associated part, considered circumferentially.

Preferably a screw cap according to the invention comprises two inwardly projecting portions on the frangible portion, positioned at circumferentially opposite end portions thereof. The first, engagement portion is adapted to be engaged by a projection from the neck of the container as aforesaid, whilst the second projecting portion is adapted to engage the neck portion when the frangible portion is fractured to militate against the frangible portion becoming forced between the neck portion and the remainder of the skirt as the cap is rotated to remove it. .Preferably, in addition, in the preferred screw cap, the second end portion is configured so that when the supports are fractured during removal of the cap, the second end portion is urged into engagement with part of the skirt bounding the frangible portion whereby to urge the frangible portion away from the skirt and to cause the weakened portion to fracture.

There now follows a detailed description to be read with reference to the accompanying drawings of a screw cap embodying the invention. It will be realised that this screw cap has been selected for description to illustrate the invention by way of example and not of limitation of the invention.

In the accompanying drawings; Figure 1 is a perspective view of a cap embodying the invention; Figure 2 is a perspective view showing part of a container embodying the invention; Figure 3 is a fragmentary perspective view showing part of the cap; Figure 4 is a view in section showing part of a cap and of the container showing an indicator and showing in chain dot line a frangible portion of the indicator as it is fractured during the initial opening of the container; and Figure 5 is a view in section showing an indicator and screw threads of the cap.

The illustrative screw cap 10 is intended for use with a container, namely a glass jar 12 which is especially suitable for use in storing granulated coffee or the like. The illustrative tamper evident screw cap 10 comprises a substantially flat closure portion 12 from which a skirt 14 depends. The skirt 14 has internal screw threads 16 (see figure 5) adapted to cooperate with external threads 18 on a neck portion 20 which defines an opening in the jar 20, whereby to retain the cap on the cap 10 and jar 12 are provided with four-start threads; however, any convenient number of starts may be used, e.g. a six-start thread which may simplify manufacture.

The skirt 14 comprises two indicators 22 (positioned at opposite sides of the skirt 14 which are frangible.

Each indicator 22 comprises a frangible portion including a body 24 and frangible supports 26. The frangible supports 26 extend between the body 24 and portions of the skirt 14 at either side, axially, of the body 24 (that is the portions nearer to the closure portion 12 and to the rim of the skirt 14 remote from the closure portion 12, respectively). The frangible supports 26 have a relatively small circumferential width by comparison with the circumferential width of the body 24, suitably being about 6% of the circumferential width of the whole of the body 24. The groove 28 is positioned internally of the skirt 14, as can be seen in the drawings. The body 24 has a weakened portion 29 at a circumferentially central region of the body. The weakened portion is in the form of a groove 28 which extends generally axially across the body to divide it into two parts (see figure 4).The width of the groove 28 is about 7.5% of the circumferential width of the body 24. The body 24 further comprises two inwardly projecting portions 30, 32 positioned at circumferentially opposite end portions of the body 24 one on each of the two parts of the body. The first portion 30 cam prises a first surface 34 and a second surface 36 the purpose of which will be described hereinafter. The end portion of the body 24 adjacent the second projecting portion 32 comprises a surface 38, the purpose of which will be described hereinafter.

The neck portion 20 of the jar 12 as well as having screw threads 18 is provided with four projections 40 spaced equiangularly around the neck portion 20 but at the same position axially of the neck portion, there may, however, be provided more, or fewer, projections, e.g.

six, likewise equangularly disposed. Each of the projections comprises a stop face 42 which is substantially radial of the neck portion and meets a sloping cam face 44 at an apex, the cam face 44 smoothly merging at the end opposite the stop face 42 with the remainder of the nec portion 20.

When the cap 10 is applied to the neck portion 20 the threads 16 on the cap engage with the threads 18 of the neck portion 20 and the cap 10 is rotated to thighten the closure portion 12 into sealing engagement with the rim of the neck portion 20. The indicators 22 are then positioned relative to the projections 40 in the relationship shown in figure 4 in full line, namely with the first surface 34 of the first projecting portion 30 of the body 24 adjacent the stop face 42. As the cap 10 is applied to the neck portion 20 it will be rotated in the direction indicated by the arrow A relative to the neck portion.As the indicator 22 approaches the position in which it is shown in full line in figure 4, the second surface 36 of the projecting portion 30 will engage the cam face 44 of the projection 40 from the jar and permit the frangible portion to pass the projection 40 as the cap is first applied to the neck portion 20, without fracture of the frangible portion, the surface 36 riding over the cam surface 44 and easing the projecting portion 30 past the projection 40. Likewise if the second projection 32 from the body 24 should engage the projection 40 during application, the protecting portion 32 is so shaped as to likewise engage the cam surface 44 and ride over the projection 40 without fracturing the frangible body 24 or the frangible supports 26.

When the illustrative cap 10 is first to be removed from the portion 20, it is rotated in the direction indicated by the arrow B (figures 3 and 4). As can be seen viewing figure 4, the second surface 34 of the projecting portion 30 is moved firmly into engagement with the stop face 42. Continuing attempts to rotate the cap 10 to unscrew it from the neck portion 20 force the body 24 towards the position in which it is shown in line in figure 4 (and in which it is shown in figure 3). The body 24 pivots about the frangible supports 26 and the weakened portion 29 of the body at the bottom of the groove 28 acts as a hinge so tha the body 24 begins to bend at the weakened portion 29.Continued rotation of the cap 10 breaks the frangible supports 26 and forces the surface 38 of the body 24 into engagement with a part 39 of the skirt defining the opening within which the frangible body 24 is positioned. When the surfaces 38, 39 come into engagement, the stop face 42 still continues to push against the first surface 34 of the projection 30 and continues to cause the body to bend at the weakened portion 29 until the force exerted on the weakened portion 29 is sufficient to cause it to fracture (as shown in chain dot line in figure 4). The groove 28 is made as narrow as conveniently possible so that, when pressure is exerted as aforesaid during opening, the innermost edge portions contact each other as soon as possible. Continued pressure tnen causes these edge portions to act as a pivot and thus applies increasing tension to the weakened portion 29, finally causing it to break. As can be seen from figure i, the second projecting portion 32 from the body 24 engages the surface of the neck portion 20 when the body 24 is fractured and is configured to prevent the body 24 becoming forced between the neck portion 20 and the remainder of the skirt 1 as the cap is rotated to remove it.

The broken parts of the indicator 22 have thus become completely separated from the remainder of the skirt 14 and fall away leaving an opening in the skirt.

Any rotation of the cap sufficient to permit access to the contents of the jar 12 causes the frangible portion 24 of the indicator to fracture. This provides a clear visual indication that the cap 10 has previously been removed from the jar 20 and the fracturing of the indicator is also detectable by touch so that it also provides a warning to a blind person.

The illustrative cap 10 can readily be moulded from plastics material by the techniques commonly used in moulding caps and can be applied to the neck of an appropriate 3ar or other container including the necessary projections 40 by the techniques commonly used without there being any need to modify the operation of existing equipment. It is, of course, necessary to select an appropriate plastics material which will fracture when suitable pressure is applied in opening the container and to select the dimensions of the frangible supports 26, the weakened portion 29 and the width of the groove 28 so that the indicator 22 functions correctly.

A suitable plastics material from which to manufacture the illustrative cap 10 is polypropylene. although other sufficiently brittle polymers, for example, polystyrene or styrene acrylonitrile copolymer may be used.

Claims

1. A tamper evident screw cap for a container, comprising a closure portion with a skirt depending therefrom, interengaging means an interior of and on the exterior of a neck portion defining an opening in a container whereby to removably retain the cap on the neck portion to close the opening, the cap being removable from the by an action including rotation of the cap relative to the neck portion, the skirt further comprising at lest one indicator which is frangible and which is adapted to be engaged by a projection provided on the neck portion of a jar to which the cap has been applied as the cap is rotated relative to the neck portion to remove it therefrom and to be thereby fractured thus to provide an indication that the cap has previously been removed from the neck portion, but which is not fractured during initial application of the cap to the neck portion.

2. A tamper evident screw cap for a container comprising a closure portion with a skirt depending therefrom, the skirt having internal screw threads adapted to cooperate with external threads on a neck portion defining an opening in a container whereby to retain the cap on the neck portion to close the opening, the skirt further comprising at least one indicator comprising a frangible portion which is visible externally of the skirt and an inwardly projecting engagement portion comprising a first surface adapted to be engaged by an external projection from the neck portion of a container to which the cap has been applied as the cap is rotated to remove it from the neck portion thereby to apply a force to the frangible portion causing it to fracture thus to provide an indication that the cap has previously been removed from the neck portion, the engagement portion further comprising a second surface adapted to engage said external projection of a container as the cap is first applied thereto and to permit the frangible portion to pass the projection as the cap is first applied to the neck portion without fracture of the frangible portion.

3. A screw cap according to either one of claims 1 and 2 wherein the frangible portion is attached to the remainder of the skirt by frangible supports.

4. A screw cap according to claim 3 wherein the supports extend between a body of the frangible portion and portions of the skirt at either side, axially, of the body of the frangible portion.

5. A screw cap according to claim 4 wherein the supports have a small circumferential width relative to the body.

6. A screw cap according to claim 5 wherein the body has a weakened portion at a circumferentially central region and extending generally axially across the body thus to divide it into two parts.

7. A screw cap according to claim 6 comprising two pairs of frangible supports, each associated with one of the two parts the supports of each pair being axially opposed at opposite sides of the body.

8. A screw cap according to claim 7 wherein each pair of supports is positioned at a central region of the associated part.

9. A screw cap according to any one of the preceding claims comprising two inwardly projecting portions on the frangible portion positioned at circumferentially opposite end portions thereof the first, engagement, portion being adapted to be engaged by a projection from a neck portion of a container as aforesaid, and the second projecting portion being adapted to engage the neck portion when the frangible portion is fractured to militate against the frangible portion becoming forced between the neck portion and the remainder of the skirt as the cap is rotated to remove it.

10. A screw cap according to either one of claims 6 and 7 wherein said engagement portion projects inwardly from one end portion of the frangible portion and wherein the circumferentially opposite end portion is configured so that when the supports are fractured during removal of the cap said opposite end portion is urged into engagement with part of the skirt bounding the frangible portion whereby to urge the frangible portion outwardly of the skirt and to cause the weakened portion to fracture.

11. A screw cap according to claim 10 wherein said opposite end portion comprises an inwardly projecting portion adapted to engage the neck portion as the frangible portion is fractured to militate against the frangible portion becoming forced between the neck portion and the remainder of the skirt as the cap is rotated to remove it.

12. A tamper-evident screw cap for a container substantially as hereinbefore described with reference to the accompanying drawings.

13. A package comprising a container having an externally screw-threaded neck portion defining an opening through which access to the interior of the container may be gained, the neck portion comprising at least one external projection, and the package further comprising a screw cap according to any one of claims 1 to 12.

14. A container having an externally screw-threaded neck portion defining an opening through which access to the interior of the container may be gained, the neck portion comprising at least one external projection, adapted to cooperate with an indicator of a screw cap according to any one claims 1 to 12.