EP0763475A1

EP0763475A1 - Tamper evident closure and neck

Info

Publication number: EP0763475A1
Application number: EP96304865A
Authority: EP
Inventors: Janos Terkely
Original assignee: ACI Operations Pty Ltd
Current assignee: Visy Glass Operations Australia Pty Ltd
Priority date: 1995-08-28
Filing date: 1996-07-01
Publication date: 1997-03-19
Also published as: AUPN506695A0

Abstract

A tamper evident closure (1) of resilient plastics material includes a lower band (3) frangibly connected to a cap portion (2). The closure is assemblable on a container neck structure (10) that includes an annular groove (15) within which a bead (7) on the band (3) locates. The groove (15) and bead (7) are shaped such that the bead (7) is gripped within the groove (15) to prevent any possibility of the band (3) being removed intact with the cap portion (2) upon unsealing a container.

Description

This invention relates to a tamper evident closure of the type that is made of a resilient plastics material and includes a lower band frangibly connected to a cap portion and which, in use of the closure to seal a container, is retained on a neck of the container upon removal of the cap portion. The invention particularly relates to a neck structure for a container for such a closure.
In closures of the type with which the invention is concerned, it is known for the tamper evident band to include an annular bead on its inner surface. The neck of a container for receiving the closure usually includes a shoulder formation and upon assembly of the closure on the neck, the annular bead of the tamper evident band rides over the shoulder formation to seat below it. Usually the cap portion of the closure and neck include complementary thread forms such that the cap portion is removable axially of the neck by "unscrewing" it therefrom. When an unscrewing force is applied to the cap portion, the bead on the tamper evident band contacts the shoulder formation to prevent further axial movement of the band and thus create a force between the cap portion and the band. Continued unscrewing force applied to the cap breaks the frangible connection of the band to the cap portion, thus freeing the cap for removal from the neck of the container and leaving the tamper evident band on the neck.
A problem with this known type of structure, particularly in respect of closures of small size, for example of about 24 mm diameter or less, is that sometimes the bead on the tamper evident band is not retained by the shoulder formation on the neck of a container. That is, it may flex over that shoulder with the result that the band is not broken free of the closure and is, instead, removed intact with the cap portion.
The present invention seeks to overcome this problem.
According to the invention there is provided a neck structure for a container for use with a tamper evident closure, the neck structure including means for gripping a bead or the like on the circumferential inner surface of a tamper evident band of a closure. In use, the gripping means acts to retain a tamper evident band in an axial position on the neck structure with sufficient force such that upon an attempt to remove the cap portion of a closure (which would tend to cause the cap to move in an axial direction), the frangible connection of the cap portion and the band is broken and the cap separates from the band.
The bead on the circumferential inner surface of the band need not be continuous, that is, the invention includes like structures, such as ribs or other functionally equivalent structures in place of a continuous bead.
Preferably the gripping means includes an annular groove within which a bead or the like of a tamper evident band may locate. Preferably the groove is structured such that the bead or the like tends to wedge within the groove. In an example structure, the groove may be defined in part by a lower annular flange or bead which may include a ramp surface for contacting a complementary ramp surface of a said bead or the like on a closure.
The invention also includes a tamper evident closure having a tamper evident band frangibly connected to a cap portion, wherein the band includes a bead or the like on its circumferential inner surface, the bead or the like being adapted for gripping by the gripping means of a neck structure.
The invention furthermore includes a neck structure and a closure as described hereinabove in an assembled relationship.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings. The specific form and arrangement of the features of the invention as shown in the drawings is not to be understood as limiting on the invention, the scope of which is to be interpreted according to the generality of the preceding description.

Figure 1 shows one embodiment of a neck structure according to the invention;
Figure 2 is a sectional view of the neck structure of Figure 1;
Figure 3 is a sectional view of a tamper evident closure for assembly with a neck structure as shown in Figure 2; and
Figure 4 is a sectional view of the closure of Figure 3 assembled with the neck of Figure 2.

Referring initially to Figure 3, a tamper evident closure 1 is illustrated which comprises a cap portion 2 and a tamper evident band 3. Closure 1 may be formed by moulding from a resilient plastics material such as polypropylene. Band 3 is frangibly connected to cap portion 2 as indicated by reference 4. This frangible connection may include weakened bridge portions (as illustrated) or any other suitable type of frangible connection. Such connections are well known in the art and will thus not be described in detail herein. Cap portion 2 includes an internal thread form 5 and may include a non-insert type of sealing arrangement 6, both of which are also known in the art.
Band 3 on its inner circumferential surface includes a bead 7, which includes an upper surface 8 that slopes downwardly towards the central axis of the closure, and a lower surface 9 that slopes upwardly towards the central axis of the closure. The bead 7 may be interrupted such that a series of aligned ribs is formed.
Referring now to Figures 1 and 2, a neck structure 10 for receiving a closure 1 is shown. The illustrated structure is a spigot that includes a flange 11 for attachment, for example by welding, to a polymer or similar material bag, such as a bulk milk container. It is to be understood that a neck structure according to the invention may be a spigot or the like for attachment to a container (as in Figures 1 and 2) or the neck of an integrally formed container made of, for example, a plastics material or glass. The illustrated neck structure 11 may be formed by moulding from a resilient plastics material, such as for example low density polyethylene.
Neck 11 includes an external thread form 12 for engagement with thread form 5 of closure 1. It also includes, below thread form 12 an upper and a lower flange, 13 and 14, defining an annular groove 15 therebetween. Upper flange 13, which has an outwardly directed upper surface 16 that slopes downwardly, has a relatively large cross section, axially of the neck, compared to lower flange 14. Also, lower flange 14 is of slightly greater diameter than upper flange 13 and includes a downwardly sloping surface 17 which surface provides a widened entrance for groove 15. Reference 18 shows longitudinal strengthening ribs for the neck.
Closure 1 is fitted onto neck 10 by forcibly screwing the cap portion 2 onto threads 12 until band 3 flexes sufficiently relative to neck 10 for bead 7 to slide over flange 13 and locate within groove 15. This is assisted by the presence of sloping surfaces 9 (of bead 7) and 16 (of flange 13), that is, surface 16 provides a ramp surface which contacts surface 9 and cams resilient band 3 outwardly. When bead 7 is located within groove 15, its upper surface 8 is lodged under upper flange 13 and its sloping lower surface 9 bears on sloping surface 17 of lower flange 14. The contacting surfaces 17 and 9 provide complementary ramp surfaces on the flange 14 and bead 7, respectively, for bead 7 to tend to wedge within groove 15. This tendency for bead 7 to wedge within groove 15 is assisted by the resilience of the closure material in that when bead 7 is located in groove 15 (as shown in Figure 4), band 3 is slightly flexed outwardly such that there is a reaction force in band 3 that acts to urge bead 7 inwardly. This reaction force does not need to be high. Thus, the flanges 13 and 14 defining groove 15 provide a means on neck structure 10 for gripping a bead 7 on tamper evident band 3 of closure 1. Effectively, flanges 13 and 14 create reaction forces in band 3 and thus bead 7 due to the relative sizing of the interengaging parts and the resilience of the cap material.
After closure 1 has been assembled on neck 10, any unscrewing movement of cap portion 2 will tend to separate cap portion 2 from band 3 and cause frangible connection 4 to fracture. In this respect, band 3 cannot move axially of the neck or tilt relatively thereto because bead 7 is being resiliently held, that is, gripped in groove 15. This gripping of bead 7 is sufficient to resist any tendency of the bead to "ride-over" upper flange 13 without causing breakage of the frangible connection 4.
It is to be understood that the invention may include known means other than thread forms 5 and 12 for interconnection of the cap portion to a neck structure which will result in separation of band 3 upon removal of the cap. Also, although the above described embodiment includes a lower flange 14 to define a groove 15, it is within the scope of the invention to modify upper flange 13 such that it, either alone or together with the base or foot region 19 of the neck, defines a suitable groove for locating a bead or the like of a closure.
The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the scope of the following claims.

Claims

A neck structure for a container, wherein the neck structure is for receiving a tamper evident closure formed of a resilient plastics material and which includes a lower band frangibly connected to a cap portion that is retained on the neck structure upon removal of the cap portion to unseal a container, wherein the lower band includes an interrupted or continuous bead on its inner circumferential surface, characterised in that the neck structure includes means for gripping the bead.
A neck structure as defined in claim 1 wherein the gripping means includes an annular groove for receiving and locating the bead.
A neck structure as defined in claim 2 wherein the groove is structured such that the bead tends to wedge therein.
A neck structure as defined in claim 2 or claim 3 wherein the groove is formed within a circumferential flange on the neck structure.
A neck structure as defined in claim 2 or claim 3 wherein the gripping means is defined by two axially spaced circumferential flanges on the neck structure, the groove being formed by the spacing of the flanges.
A neck structure as defined in claim 4 wherein the flange, or as defined in claim 5 wherein at least one of the two spaced flanges, includes a ramp surface to provide a widened entrance for the groove for entry of the bead of a closure.
A neck structure as defined in claim 6 wherein the ramp surface is part of the lower defining surface of the groove.
A neck structure as defined in claim 4 wherein the flange, or as defined in claim 5 wherein the upper one of the two spaced flanges, includes an upper surface that slopes downwardly for camming the band of a closure outwardly to assist in assembling a closure onto the neck structure.
A neck structure as defined in any one of claims 1 to 8 wherein the neck structure is integrally formed as part of a container.
A neck structure as defined in any one of claims 1 to 8 wherein the neck structure is separately formed and includes means for attaching it to a container.
A tamper evident closure for a neck structure as claimed in any one of claims 1 to 10, wherein the closure is formed of a resilient plastics material and includes a lower band frangibly connected to a cap portion and the lower band includes an interrupted or continuous bead on its inner circumferential surface, characterised in that the bead has a wedge-like cross-sectional shape for gripping by the gripping means of a neck structure.
A closure as defined in claim 11 wherein the bead includes a sloping ramp surface for contacting a complementary ramp surface associated with a groove of a neck structure as defined in claim 6.
A closure as defined in claim 12 wherein the sloping ramp surface of the bead is its lower surface and is for contacting the ramp surface of a groove of a neck structure as defined in claim 7.
A neck structure as defined in any one of claims 1 to 10 and a closure as defined in any one of claims 11 to 13, wherein the closure is assembled on the neck.