CA2028225C

CA2028225C - Tamper resistant containers

Info

Publication number: CA2028225C
Application number: CA002028225A
Authority: CA
Inventors: Garry D. Flaherty; Murray G. Larche
Original assignee: GLENDEN TEK CORP.
Current assignee: GLENDEN TEK CORP
Priority date: 1990-10-22
Filing date: 1990-10-22
Publication date: 1996-08-06
Anticipated expiration: 2010-10-22
Also published as: CA2028225A1

Abstract

A tamper resistant container is provided, which comprises a complimentary lid and a base formed from resiliently deformable plastic. Together, these are releasably resealable when respective wall portions thereof are secured in frictionally internested relation. Opposed, axially spaced apart circumferential grooves and beads are thereby arranged in interfitting register to resist unauthorized axial withdrawal of the lid from the base. Such leverage as might be applied to an outermost one of these base walls in order to expose protected undersurface potions of the lid, (and apply the axial leverage needed to separate the lid from the base), biases the internested grooves and beads into securely seated relation. If further leverage is applied to the outermost wall the necessary forces exceed the resistance of an intermediately frangible zone of weakness (extending along a portion of the outermost wall and the base), to tearing. This results in visible evidence of tampering.
Authorized access, on the other hand, is facilitated by a readily frangible tab portion arranged between lines of weakness in the outermost wall.

Description

- ~028225 FIELD OF THE INVENTION
The present invention relates generally to the field of tamper resistant containers, and is particularly concerned with the provision of tamper evident containers having releasably resealable closures.

BACKGROUND OF THE lNv~ lON
Although tamper evident closure devices have been previously proposed, they have not found wide application or acceptance in the packaging industry because of their inherent complexity of design, difficulties attendant their manufacture, and high costs of production. The cost of modifying or producing new containers suitable for use in combination with these previously suggested containers has also represented a barrier to their wide spread acceptance.
Moreover, the usefulness of these earlier suggested closures is severely diminished due to their incompatibility with existing filling machines.

.~

20282~5 SUMMARY OF THE lNVk..llON
There remains a need in the art for alternatives to the previously proposed tamper resistant closures, in order to meet continuing interests of public safety and to maintain consumer confidence and convenience.
In accordance with the present invention , there is provided a tamper resistant container including a lid and a base formed from resiliently deformable plastics material.
The containers are preferably molded, as by injection molding, in one piece from a resilient, notch-sensitive material such as low density polyethylene. Medium and high density polyethylene materials are less desirable molding materials.
The term "notch-sensitive" is know in the art to mean that the material is normally difficult to tear or similarly break, but if a notch-line or line of weakness or other zone of weakness (as might occur, for example, at a juncture between one wall and another wall of a molded container) is cut or otherwise formed therein, the material can be relatively readily separated along the line of weakness.
The containers comprise a combination of a depending skirt lid wall and a pair of mutually opposed first and second base walls that are arranged in generally parallel relation with one another. Mutually opposed surfaces of the skirt wall are adapted to be received through an inter-wall opening between the pair of base walls, and to be secured in frictionally internested relation therebetween. In this arrangement, the first of the two base walls engages an 20~2~5 adjacent one of the mutually opposed surfaces of the skirt wall in resiliently biased relation to forcingly bias the other of the mutually opposed side wall surfaces against the second adjacent base wall.
In addition, respective ones of two circumferential beads are arranged on corresponding opposed surfaces of the skirt wall, and are resiliently urged into interlocking relation with complimentary grooves formed in respective adjacent ones of the base walls.
In accordance with the present combination, the depending skirt wall is embraced in continuously outwardly shielded relation by the outermost wall to thereby limit access to the lid surface against which mechanical leverage might otherwise be applied and to thereby frustrate axial removal of the lid through unaided manual means.
To facilitate authorized opening of the container, an outermost one of the base walls comprises an at least one readily frangible tab defined between lines of weakness. This tab extends over a limited and preferably minor arc of a circumferential portion of the outermost wall. The frangible tab is adapted to be broken away upon opening of the container to form a discontinuity in the otherwise continuous outermost base wall, and to thereby expose an adjacent previously shielded portion of the skirt wall. This not only signifies that the container has been opened, but also provides access to a sufficient amount of exposed adjacent skirt wall to provide a point at which leverage can be applied to manually remove the lid from the base of the container.

202~225 In accordance with a tamper evident container according to the present invention, the container includes a zone of intermediate weakness which is located between the outermost one of the base walls and the other base wall. This defines an at least one intermediately frangible portion of the outermost wall adjacent the readily frangible tab. The resistance of this intermediately frangible portion to tearing is less than the resistance of the intermediately frangible portion to being pulled back over the second bead sufficiently to provide unauthorized access to axially leveragable surfaces of the depending skirt wall. The result is that the required access cannot be had, (except as otherwise provided by the readily frangible tab) without normally occasioning visible tearing along the zone of weakness.
In a preferred form, the beads are arranged in axially spaced relation along respective ones of the side walls, and are advantageously arranged such that the groove on the outermost base wall is positioned in greater axially spaced apart relation from the inter-wall opening, than is the groove on the opposed base wall.
The mutually opposed base walls preferably extend from a common continuous lateral base wall arranged opposite the inter-wall opening. It is further preferred that the mutually opposed base walls are not axially co-extensive, and that the groove in the outermost wall is arranged adjacent the lateral base wall. More particularly, it is preferred that the outermost base wall has an axial height that is less than ~02~2~5 the axial height of the opposed base wall, and angularly offset from the opposed base wall at the free end thereof.
In accordance with the preceding aspects of the present invention, the arrangement of the respective beads, grooves and the internesting of the walls, affords the container tamper resistant characteristics.
Tamper evident characteristics can be imputed to the present container through the provision of a zone of intermediate weakness located intermediate between the outermost one of the base walls, and the other base wall.
This defines an at least one intermediately frangible portion of the outermost one wall, adjacent the readily frangible tab.
This intermediately frangible portion has a resistance to tearing that is less than the resistance of the intermediately frangible portion to being pulled back over the second bead whereby access to axially leveragable surfaces of the depending skirt wall cannot be had without normally occasioning visible tearing along the zone of weakness.
The interrelated operability of the various elements set forth hereinabove will become more apparent on reference to the detailed description of a preferred embodiment which follows below.

202~225 -Introduction to the Drawings Figure 1 is an elevated side view in cross-section through an internested lid and base of a container according to the present invention;
Figure 2 is a perspective view including the cross-sectional surface illustrated in Figure 1, and including a portion of the circumference of the container;
Figures 3a and 3b are, respectively, cross-sectional and elevated side views depicting details of the readily frangible tab; and, Figures 4, 5 and 6 illustrate the removal of the readily frangible tab, to gain access to the container, and at the same time leave clear visible evidence of such access.

DETATT~T~n DESCRIPTION OF THE INVENTION
Referring now to Figures 1 and 2 of the drawings, there is illustrated a tamper resistant container 1 including a lid 2 and a base 3 all formed from resiliently deformable plastic materials.
The lid 2 comprises a crown 4 having a surface 5 terminating at a peripheral edge 6 which is contiguous with an adjacent edge 7 of the depending skirt wall 8. The skirt wall 8 has an inwardly facing circumferential bead 9 which extends in generally parallel relation to the adjacent edge 7, and along the skirt wall 8, at a first axial location thereon.
Skirt wall 8 also includes an outwardly facing circumferential bead 10 which also extends along the skirt wall 8 in generally - 202822~
parallel relation to the adjacent edge~7, at a second axial location thereon. The inwardly facing bead 9 is located intermediately between the outwardly facing bead 10 and the adjacent edge 7.
The base 3 comprises a side wall 11 having an edge wall 12 defining a container opening indicated generally by reference numeral 13. Opening 13 is adapted to be releasably resealably closed in secured relation by lid 2, when depending skirt wall 8 is engaged in surrounding frictional relation about edge wall 12. In this arrangement, the first circumferential groove 14 on edge wall 12 is arranged in interfitting axial register with inwardly facing bead 9. A lateral outwardly extending ledge 15 is contiguously formed from side wall 11 and supports a continuously resiliently deformable locking wall 16. A
circumferential bead 16a disposed on locking wall 16, and ledge 15, define a second circumferential groove 17 which is adapted to be arranged in interfitting axial register with the outwardly facing bead 10.
Depending skirt wall 8 is resiliently biased towards edge wall 12 by locking wall 16, and is arranged in frictionally internested relation between walls 12 and 16 with respective grooves 14, 17 and beads 9 and 10, engaged in said interfitting axial register with one another.
Locking wall 16 comprises an at least one readily frangible tab 18 which is defined between lines of weakness l9a and l9b. Frangible tab 18 extends over a limited arcuate extent 20 of a circumferential portion of the locking wall 16.

2o28~25 -Lid 2 also includes a recessed central surface 21 which lies in a plane generally below the peripheral edge 6.
A plurality of mutually spaced apart ribs 22 extend upwardly from the recessed central surface 21, adjacent the peripheral edge 6, and is adapted to engage superposed lids in supporting relation, when a plurality of said lids are arranged in mutually stacked relation. Ribs 22 facilitate individual de-nesting of the stacked lids.
Locking wall 16 includes a free edge 23 that is angularly offset in spaced relation from the depending lid skirt wall 8. Leverage can be manually exerted against the free edge 23, in an attempt to gain access to the contents of the container, but such leverage biases the beads 9 and 10 into securely seated relation in respective ones of the corresponding grooves 14 and 17, and thereby reactively increases the resistance against axial removal of the lid 2 from the base 3. Accordingly, axial withdrawal of the lid 2 from base 3 typically requires that axial forces be applied against undersurfaces 26. Access to such undersurfaces can be facilitated by way of the readily frangible tab 18 in the manner more explicitly reviewed in reference to Figures 4 through 6, hereinbelow.
The interrelationship of the parts hereinbefore described thereby resist attempts at tampering, by frustrating attempts to covertly withdrawal lid 2 from base 3. Moreover, this arrangement includes tamper evident features, and more specifically a zone of intermediate weakness 24 which is located intermediate between the locking wall 16 and the side wall 11. This zone of intermediate weakness 24 defines an at least one intermediate frangible portion 25 of locking wall 16, adjacent the readily frangible tab 18. The zone of intermediate weakness 24 has a resistance to tearing that is less than the resistance of the intermediately frangible portions 25 of locking wall 16, to being pulled back over the outwardly facing bead 10. Accordingly, access to axially leveragable surfaces 26 of the depending skirt wall 8 cannot normally be had without resulting in visible tearing along the zone of intermediate weakness 24.
The container according to the present invention is useful in conjunction with existing filling and packaging apparatus, and provides a releasable but tightly resealable container which is particularly advantageous in domestic storage of food stuffs. The tamper resistent, and especially tamper evident, features of the present invention serve a duel purpose in advantageously facilitating the secure resealing of the packaging.
Referring now in particular to Figures 3a and 3b of the drawings, there is illustrated certain details associated with the readily frangible tab 18. Lines of weakness l9a and l9b are arranged in mutually circumferential spaced apart relation on either side of at least one readily frangible tab 18. Lines of weakness l9a and l9b, in cooperation with zone of weakness 24 (not shown in either of these two figures), permit tab 18 to be readily broken away when legitimate access to the contents of the container 1 is sought. The container, being preferably moulded from low density polyethylene, is -"notch sensitive" along the respective lines and zone of weakness, to thereby readily facilitate consumer access to the contents of container 1. Figure 3a is a cross-section view through line A-A of Figure 3b, and illustrates the notched character of line of weakness l9a. Accordingly, leverage applied to free edge 23 results in readily frangible tab 18 breaking away from adjacent circumferential portions of locking wall 16. Continued leverage results in readily frangible tab 18 breaking away along zone of weakness 24 in order to expose undersurface 26 of the pending lid skirt.
In operation, (and referring now in particular to Figures 4, 5 and 6 of the drawings), readily frangible tab 18 is grasped by a consumer desiring legitimate access to the contents of the packaging. As shown more particularly in Figure 5, an outward and downward leveraging action in the direction indicated generally by reference arrow "A", results in frangible tab 18 breaking away in the manner hereinbefore described in relation to Figures 3a and 3b. With readily frangible tab 18 removed, the relationship between lid 2 and base 3 of the still sealed container 1 is substantially as illustrated in Figure 6 of the drawings. Leveraging forces applied in the direction indicated by reference arrow b to undersurface 26 and generally opposed leverage applied in the manner suggested by reference arrow c to free edge 23 result in beads 9 and 10 being deformably released from respective ones of grooves 14 ad 17, such that the lid 2 is axially removed from base 3. Note that minimal displacement of free end 23 results in bead 10 being released from local engagement -from groove 17, without exceeding the resistance of zone of weakness 24 to tearing, once frangible tab 18 has been removed. Similarly, resealing of container 1 with lid 2 is accomplished in part by bead 10 exerting a radial outward force against the angular offset of free end 23 as lid 2 is forced into axial register with base 3. Here again, minimal outward displacement of free end 23 results in bead 10 being reseated in groove 17 to in part provide for releasably resealable engagement of lid 2 with base 3. The co-acting biases of the respective parts of the containers according to the present invention provide an excellent seal for preserving the contents of the container in respect of such things as, for example, humidity, and odors.

Claims

1) A tamper resistant container including a lid and a base formed from resiliently deformable plastics material, comprising:
a lid having a depending skirt wall with a first circumferential bead inwardly projecting from said skirt wall and an axially displaced second circumferential bead outwardly projecting from said skirt wall;
a base having a base wall and a locking wall held in generally parallel spaced apart relation by means of a lateral ledge, said base wall having a first circumferential groove disposed in the outer face thereof;
a circumferential locking wall bead disposed on the inner face of said locking wall, said lateral ledge and said locking wall bead cooperatively forming a second circumferential groove in the inner face of the locking wall, along the junction of said ledge and said locking wall;
said skirt wall being adapted to engage said base wall, said locking wall, and said ledge, said first circumferential bead engaging said first circumferential groove and said second circumferential bead engaging said second circumferential groove, thereby effecting substantially continuous frictional engagement of said skirt wall extending at least from said first bead to said second bead;
whereby said skirt wall is embraced in continuously outwardly shielded relation by said locking wall to thereby limit the lid surface against which mechanical leverage might be applied;
wherein a limited arc portion of said locking wall defined between two spaced lines of weakness comprises a readily frangible tab; and whereby said frangible tab is adapted to be broken away upon opening of said container to form a discontinuity in said locking wall and expose an adjacent previously shielded portion of said skirt wall, to signify that the container has been opened and to provide access to a sufficient amount of exposed adjacent skirt wall in order to provide a point at which leverage can be applied to manually remove the lid from the base of the container.

2. The container according to claim 1 wherein said beads are arranged in axially spaced relation along respective said skirt and base walls.

3. The container according to claim 2 wherein said first groove is positioned in greater axially spaced apart relation from said ledge, than is said locking wall bead.

4. The container according to claim 3 wherein said ledge projects from said first base wall, and said locking wall depends substantially upwardly and outwardly therefrom.

5. The container according to claim 4 wherein said base wall and said locking wall are not axially coextensive.

6. The container according to claim 5 wherein said locking wall has an axial height which is less than the axial height of said base wall.

7. The container according to claim 1 wherein said locking wall includes a free edge that is angularly offset in spaced relation from said skirt wall, whereby leverage manually exerted against said free edge biases said first and second beads into securely seated relation in said respective grooves.

8. A tamper evident container according to claim 1 wherein a first zone of intermediate frangibility is located intermediate said base wall and said ledge and a second frangible portion of said locking wall located adjacent either side of said readily frangible tab; said second frangible portion having a resistance to tearing less than that of the first frangible portion of said locking wall to being deformed over outwardly facing said second bead whereby access to axially leveragable surface of said depending skirt wall cannot be had without visible tearing along the first zone of intermediate frangibility.

9. A tamper resistant container including a lid and a base formed from resiliently deformable plastics material;
said lid comprising a crown having a surface terminating at a peripheral edge which is contiguous with an adjacent edge of a depending skirt wall, said skirt wall having an inwardly facing circumferential bead extending in generally concentric uniformly spaced relation to said adjacent edge and along said skirt wall at a first axial location thereon; and, an outwardly facing circumferential bead also extending along said skirt wall in generally concentric uniformly spaced relation to said adjacent edge, at a second axial location thereon, with said inwardly facing bead located intermediately between said outwardly facing bead and said adjacent edge;
said base comprising a side wall having an edge wall defining a container opening adapted to be releasably and resealably closed in secured relation by said lid with said depending skirt wall engaged in surrounding frictional relation about said edge wall, said edge wall including a first circumferential groove arranged in interfitting axial register with said inwardly facing bead; and, a laterally outwardly extending ledge contiguously extending from said side wall and supporting a continuous resiliently deformable locking wall having an inwardly facing bead, which in conjunction with said ledge, defines a second circumferential groove arranged in interfitting axial register with said outwardly facing bead;
wherein said depending skirt wall is resiliently biased towards said edge wall by said locking wall, in frictionally internested relation therebetween, with respective grooves and beads engaged in said interfitting axial register with one another, and said locking wall comprises an at least one readily frangible tab defined between lines of weakness and extending over a limited arcuate extent of a circumferential portion of said locking wall.

10. The container according to claim 9 wherein said dependent skirt wall extends in generally normal relation to said peripheral edge.

11. The container according to claim 9 wherein said crown includes a recessed central surface lying in a plane generally below said peripheral edge.

12. The container according to claim 11 wherein said lid further includes a plurality of mutually spaced apart ribs extending upwardly from said recessed central surface, adjacent said peripheral edge, in supporting relation of superposed lids when a plurality of said lids are arranged in mutually stacked relation, whereby said ribs facilitate individual de-nesting of said stacked lids.

13. The container according to claim 9 wherein said locking wall includes a free edge that is angularly offset in spaced relation from said depending lid skirt, whereby leverage manually exerted against said free edge biases said beads into securely seated relation in said respective ones of corresponding grooves.

14. A tamper evident container according to claim 9 wherein a first zone of intermediate frangibility is located intermediate said locking wall and said side wall and a second frangible portion of said locking wall located adjacent either side of said readily frangible tab; said second frangible portion having a resistance to tearing less than that of the first frangible portion of said locking wall to being deformed over the outwardly facing bead whereby access to axially leveragable surfaces of said depending skirt wall cannot be had without visible tearing along the zone of intermediate frangibility.