NZ250040A - Tamper evident resealable container closure: frangible membrane joins cap to container rim - Google Patents

Description

0 0 4 0 Priority Date(s): .

Complate ST: scification Filed: l?J',c31^ Class: Publication Date: .. 2.5. JUL. 1395 P.O. Journal, No: —_ ' •;''V C"-\ j.* i'\ 2 2 OCT 1993 r ,- ' f .. ! PATENTS FORM 5 Number PATENTS ACT 1953 Dated COMPLETE SPECIFICATION A TAMPER EVIDENT CLOSURE We, IMPACT INTERNATIONAL PTY LTD, an Australian company of Corner Victoria and O'Connell Streets, Smithfield, New South Wales 2164, Australia do hereby declare the invention for which I/we pray that a Patent may be granted to me/us, and the method by which it is to be performed, to be particularly described in and by the following statement. 250040 The present invention relates to closures for containers, and in particular to a tamper evident closure.

A wide variety of closures are known for sealing various types of containers. Common closures include screw caps, snap fit caps, removable plugs and tabs, frangible membranes, and the like. The present invention is concerned more particularly with closures which permit the container to be temporarily re-sealed after use.

A major problem with such closures is that because the contents can be readily accessed, unauthorised tampering is not obvious to the end user. It is also difficult to provide such containers with an effective hermetic seal to prevent inadvertent contamination of the contents before use. This is particularly important in food packaging and medical applications, where the contents must often be kept sterile for relatively long periods before use.

In order to ameliorate these problems, various tamper evident seals have been devised. One known form of seal consists essentially of a membrane which is heat sealed around a dispensing orifice of the container and adapted to be peeled off at the required time of use. However, unauthorised tampering is nevertheless possible, because the membranes can be readily removed without damage by the application of hot air or contact with a heated surface, for example. The membrane can be subsequently re-attached to the orifice, again with the application of heat, rendering the tampering very 0 04 0 difficult to detect. This problem has become particularly pertinent in view of several recent instances of deliberate poisoning of consumable products marketed for human use.

Another form of tamper evident closure which is often applied to screw caps takes the form of a plastic ring extending around the neck of the container. The ring is joined to the screw cap by a series of circumferentially spaced frangible tabs. Removal of the 10 screw cap separates the cap from the ring by rupturing the tabs so as to render the tampering evident to the user. However, this form of closure has two major disadvantages. Firstly, the closure itself is not normally able to provide an effective hermetic seal. 15 Additionally, the tamper evident ring can be completely removed once the tabs are ruptured, thereby removing the tamper evident component of the closure.

It is an object of the present invention to provide a tamper evident closure which overcomes, or 20 substantially ameliorates, at least some of the deficiencies of the prior art.

Accordingly, the invention provides a container having a tamper evident closure, said container including a dispensing aperture, a rim surrounding the aperture, a 25 cap adapted to close the aperture, and a frangible membrane sealingly joining the cap to the rim, the cap being movable upon rupture of the membrane between a closed position in releasable snap fitting engagement 250040 with the rim to temporarily seal the container and a raised position wherein the cap rests loosely above the rim, such that rupture of said membrane is evidenced by the cap being in either the closed or the raised position, and wherein the frangible membrane is adapted to be ruptured by manual depression of the cap toward the closed position.

Preferably, the cap includes a tubular neck portion and a peripheral channel recessed into the neck, the channel being adapted for snap fitting engagement with the rim.

Preferably also, the neck portion of the cap incorporates an outwardly diverging generally frusto-conical surface nestingly engageable with the rim to define the raised position in which the cap rests loosely over the aperture. Preferably, the recessed channel is disposed immediately adjacent the frusto-conical surface and an intermediate outwardly protruding lip cooperates with the rim to define a relatively sharp tactile transition between the closed and raised positions of the cap. In this way, the channel, conical surface, lip and rim cooperate to urge the cap into either the closed or raised position and resist intermediate positions.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which Figure 1 is a cross sectional side elevation ; o i1-1 > :"<f ^ \\ IS9S $ 250040 showing a container incorporating a tamper evident closure in the raised position with the membrane intact; and Figure 2 is an enlarged cross sectional view showing the closure of the container of Figure 1 in the closed position with the membrane ruptured.

Referring to the drawings, the invention provides a container 1 having a dispensing aperture 2 defined by a peripheral rim 3. The rim depends inwardly from a generally annular shoulder 4 forming the top of the container. A cap 6 is provided to close the aperture. As best seen in Figure l, the container is formed with a frangible membrane 8 sealingly joining the cap 6 to the rim 3 to seal the contents in the container. The membrane is essentially the line of contact between the cap and the rim of the container.

The cap is movable upon rupture of the membrane between a closed position (Figure 2) in releasable snap fitting engagement with the container rim 3 to temporarily re-seal the container, and a raised position (Figure l) wherein the cap rests loosely over the aperture above the rim.

More specifically, in the closed position, the rim 3 snaps into a complementary peripheral channel 10 recessed into the outer surface of a neck 11 formed in the cap. In this configuration, the upper surface of the rim is urged into abutting engagement with the corresponding downwardly depending surface 13 on the 250040 underside of the cap to provide an air tight seal. The neck 11 also incorporates an outwardly diverging generally frusto-conical surface 15 forming a peripheral ramp engageable with the rim 3 of the container to define the raised position in which the cap simply rests loosely over the aperture. This position corresponds to the configuration of the cap as shown in Figure 1, and is approximately the same as the initial configuration before the membrane is ruptured. However, with the membrane intact the cap will feel secured to the container but once the membrane is ruptured the cap in the raised position will feel loose and un-secured.

It will be appreciated that the recessed channel 10 is disposed immediately above the frusto-conical surface 15 to define an intermediate outwardly protruding lip 18. The outer diameter of the lip 18 is marginally greater than the inner diameter of the rim, requiring a degree of resilient deformation of these components to accommodate movement of the cap between the closed and raised positions. In this way, the lip 18 co-operates with the rim 3 to provide the snap fitting and define a relatively sharp and unstable transition between the closed and raised positions which tends to prevent the cap from resting in an intermediate position.

It is preferred that the shoulder and rim of the container, the cap, and the intermediate membrane 8, are initially formed as a unitary component from a suitable plastics material in a single moulding operation to 2 5 0 0 4 0 facilitate high rate production.

Turning now to describe the mode of use, the container is initially purchased by the intending user with the cap in the configuration shown in Figure 1, joined to the container by the intermediate membrane 8 which is essentially the line of contact between the two components. In this configuration, the container is sealed.

When the contents are required for use, the cap is simply manually depressed into the container whereupon the membrane is ruptured, and the cap snapped into the closed position. To access the contents of the container, the cap is simply manually withdrawn by the application of sufficient force to overcome the retaining force of the snap fitting. Once the snap fitting is released, the cap simply rests loosely over the aperture above the rim, in the raised position. In this position, the outwardly diverging ramp formed by the frusto-conical surface 15 prevents the cap from dropping further into the aperture. In this way, it will be appreciated that rupture of the membrane is evidenced by the cap being either in the closed position, or resting loosely in the raised position, thereby indicating possible tampering.

Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

£OUl

Claims (7)

WHAT WE CLAIM IS:

1. A container having a tamper evident closure, said container including a dispensing aperture, a rim surrounding the aperture, a cap adapted to close the aperture, and a frangible membrane sealingly joining the cap to the rim, the cap being movable upon rupture of the membrane between a closed position in releasable snap fitting engagement with the rim to temporarily seal the container and a raised position wherein the cap rests loosely above the rim, such that rupture of said membrane is evidenced by the cap being in either the closed or the raised position, and wherein the frangible membrane is adapted to be ruptured by manual depression of the cap toward the closed position.

2. A container according to claim 1, wherein the cap includes a tubular neck portion and a peripheral channel recessed into the neck portion, the channel being adapted for snap fitting engagement with the rim.

3. A container according to claim 2, wherein the neck portion of the cap incorporates an outwardly diverging generally frusto-conical surface nestingly engageable with the rim to define the raised position in which the cap rests loosely over the aperture.

4. A container according to claim 3, wherein the frangible membrane is disposed intermediate the frusto-conical surface of the cap and the container rim to position the cap in a fixed raised position prior to rupture of the membrane.

5. A container according to any one of claims 2 to 4, wherein the recessed channel is disposed immediately adjacent the frusto-conical surface and an intermediate outwardly protruding 9 2500*0 lip cooperates with the rim to define a relatively sharp tactile transition between the closed and raised positions of the cap.

6. A container according to any one of the preceding claims wherein the shoulder and rim of the container, the cap, and the intermediate membrane, are initially formed as a unitary component from a suitable plastics material in a single moulding operation.

7. A container substantially as herein described with reference to the accompanying drawings. WEST-WALKER McCABE per j ATTORNEYS FOR THE APPLICANT