RESEALABLE CLOSURE FOR A CONTAINER

Abstract: A readily manually removable closure (10) for an open topped container (11) is constructed of a metal lid (18) and a platic ring (32) which are effectively permanently joined together via the engagement of a peripheral channel formation (26) of the lid (18) within a channel formed in the plastic ring (32). The plastic ring (32) includes an inwardly directed bead (34) which engages under a radially outward formation, such as a curl (16), at the rim (14) of container (11) to sealingly retain the channel formation (26) of the metal lid component (18) on rim (14). The plastic ring component (32) includes a depending skirt (42) which is manually manipulable to cause the bead (34) to disengage the curl (16) to facilitate manual removal of the closure.

Description: RESEALABLE CLOSURE FOR A CONTAINER Technical Field This invention relates to a closure for an open topped container wherein the container opening is defined by a rim, and the container includes at or adjacent its rim, a radially outward formation such as an external fold, curl, roll, bead or the like. In particular, the invention relates to a resealable closure structure for facilitating the removal and resealing of the closure onto a container. The invention will be described herein in relation to a closure for a container such as a can for containing a liquid such as paint, however it is to be understood that the closure may be used for other types of containers for containing other types of product. Background It is often highly desired by consumers that a can of product, for example of paint, after first being opened, be resealable with the container lid. This is particularly so for cans of 10 litres or larger capacities as commonly all of the product in the can is not used at the one time. Thus the can needs to be resealed to preserve the remaining contents for use at a later time. A known resealing facility involves the provision of an expandable metal locking ring. Such known locking rings include lever arrangements for clamping the ring around an assembled lid and can for ensuring the lid is sealingly retained on the can. These locking rings, however, are expensive for can manufacturers to provide and cause problems for fillers, for example paint manufacturers, who have to fill the cans with their product. The locking rings present handling difficulties, particularly in relation to automatic filling machinery. Another problem is that upon removal of such a locking ring to re-open a can, the lid is often stuck on the can, for example by the adhesive effect of product which was lodged between the sealing surfaces on the lid and the can when it was re- sealed. Such a stuck lid can be quite difficult to remove because only a relatively small amount of the lid edge is available for gaining leverage to prise the lid off the can. Furthermore, if the edge is raw, it can cut the fingers of a user. Another attempt at providing for re-sealability of a lid on a can has involved the provision of a plastic lid. However this did not gain market acceptance because the sealing and resealing was not effective in that the product, which was paint, tended to leak from the cans at the interface between the can seam and the plastic lid. Also the plastic of the lid needed to be relatively soft to facilitate its manipulation for removal from and re-application to the can, but this requisite softness proved to be too soft to withstand loads that are imposed when full cans are stacked for transportation and storage. United States Patent No. 3,930,580 discloses a "pry-off' closure cap for a container which comprises a metal cover disc held in a moulded plastic ring. The plastic ring includes a skirt portion having inwardly projecting container engaging means consisting of either spaced lugs or a continuous bead. The container engaging means are for engaging a radially outwardly projecting cap engaging bead at the rim of the container. However, in order to remove the closure cap from the container, a user must engage a pry-off hook under the skirt and must manipulate it to pry-off the closure cap. That is, the closure cap of US 3,930,580 is not manually removeable from the container. Thus there is a need for a closure for effectively sealing a container which avoids the need for a separate locking ring, is sufficiently strong to withstand normal stacking loads and is readily manually removable from and resealable onto a container. The present invention seeks to provide a closure which meets this need. The discussion herein of the background to the invention is included to explain the context of the invention. For the purposes of Australia this is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge in Australia as at the priority date of any of the claims. Disclosure of the Invention According to the invention there is provided a resealable closure for an open topped container wherein the container opening is defined by a rim and the container includes a radially outward formation at or adjacent the rim, the closure including a metal lid for closing the container opening and a plastic ring, wherein the metal lid includes a peripheral portion for sealingly engaging the container rim and the plastic ring is secured to the metal lid and engages said peripheral portion, the plastic ring including at least one element for engaging the radially outard formation of a container to retain said peripheral portion of the metal lid in sealed engagement on said rim, and the plastic ring further including a depending portion which extends exteriorly of the container when the closure is assembled thereon, wherein manual manipulation of the depending portion is operative on said at least one element to facilitate removal of the closure from the container. The term "ring" in the above paragraph and hereinafter is to be understood as encompassing non-circular forms as well as circular. Thus the invention is intended to cover closures for containers of circular, oval, hexagonal, square, rectangular or other polygonal cross-section. The radially outward formation of the container at or adjacent its rim may be an external curl, fold, roll, bead or the like, or any other radially outward formation which provides an undersurface or ledge on which the at least one element of the plastic ring component of the closure can effectively engage. The invention provides a closure which is constructed of two components which are effectively permanently joined together. The two components are the metal lid and the plastic ring. Thus to a user, the closure is effectively a single item. The plastic ring may be secured to the metal lid by press fitting (to be more fully described below), or it may be moulded onto the metal lid. The at least one element of the plastic ring for engaging the radially outward formation of the container rim is preferably a bead which includes a surface which seats under the formation and thus holds the peripheral portion of the metal lid in sealed engagement with the container rim. Preferably the bead also includes a ramp surface which cams over the radially outward formation of the container as the closure is applied to the container, thereby facilitating application of the closure onto a container to reseal the container opening. The bead may be continuous around the periphery of the closure, alternatively it may be interrupted to provide a plurality of elements (for example bead portions) for engaging the radially outward formation at or adjacent to the container rim. Preferably the depending portion of the plastic ring is a skirt which surrounds the container when the closure is assembled thereon. It may however have other forms, one of which may be depending sections spaced around the periphery of the ring. Preferably the plastic ring includes a channel and the ring is secured to the lid by pressing the ring and the lid relatively together for the peripheral portion of the lid, or at least a part of that portion, to seat within the channel. The above mentioned at least one element of the plastic ring in the form of a bead may protrude partially across said channel and provide for a "snap" fitting of the ring onto the lid. Preferably the peripheral portion of the lid for sealingly engaging the container rim includes a channel which seats over the container rim. Preferably this channel includes a gasket and the at least one element of the plastic ring, when it engages the radially outward formation of the container rim, causes the gasket to be compressed thereby ensuring the closure is sealingly retained on the container. The invention also includes a closure as described when assembled on a container. For a better understanding of the invention and to show how it may be carried into effect, embodiments thereof will now be described, by way of non- limiting example only, with reference to the accompanying drawings. Brief Description of Drawings Fig. 1 shows in cross section a closure assembled on a container, portions only of the container and closure being shown; Fig. 2 illustrates how a closure may be removed from a container; Fig. 3 shows portion of still another embodiment of a closure ready for assembly on a container; Fig. 4 shows the closure and container of Fig. 3 assembled together; Fig. 5 shows a plastic ring component having a handle; Fig. 6 shows a plastic ring component having a depending extension for assisting leverage; Figs 7A and B show a plastic ring component having notches, with Fig. 7B showing a detail of Fig. 7A; Figs. 8A and B show a plastic ring component having a feature for enhancing stackability, wherein Fig. 8B shows section AA of Fig. 8A; Fig. 9 shows a closjre having an alternative stackability feature and a tamper evidencing facility. Detailed Description of Preferred Embodiments Fig. 1 shows a resealable closure 10 assembled on an open topped container 11. Container 11 is typically a can made of metal such as tin plate and is for containing a liquid such as paint. Can 11 , which may have a capacity for example of 10 litres, has a circumferential wall 12 and a relatively large opening having a rim 14 with a radially outward formation in the form of an external curl 16 at the rim 14. The resealable closure 10 comprises a metal lid 18 having a peripheral portion for sealing with the rim 14. The peripheral portion includes an upwardly open channel 20 having an outer wall 22 which is smoothly curved over (see references 24) to define a downwardly open channel 26 the outermost wall of which ends at an edge 28. The downwardly open channel 26 includes a gasket material 30. The outer facing surface of wall 22 resiliently engages against the inner surface of wall 12 of can 11 and channel 26 seats over rim 14 for the closure 10 to seal the opening of the can 11. The contacting surfaces of walls 22 and 12 may provide a friction seal area and a further sealing area is established between the peripheral channel 26 of metal lid 18 and the rim 14 as will be described below. The closure 10 also includes a plastic ring 32 which is secured to the metal lid 18. The plastic ring is formed to provide a channel within which the curved portion 24 of the lid providing the peripheral channel 26 is engaged to attach the plastic ring 32 to the metal lid 18. The plastic ring 32 includes an element in the form of a bead 34 for engaging the curl 16 of the container rim to retain the curved portion 24 of the metal lid 18 in sealed engagement on the container rim 14. Bead 34 protrudes partially across the channel of ring 32 and may be continuous. It is defined by an upper surface 36 which slopes downwardly from a short step surface 38 which extends substantially at right angles from an interior surface of the channel of ring 32, and a sloping ramp surface 40 which joins a depending portion 42 of the ring in the form of a skirt. The plastic ring 32 is attached to the metal lid 18 by a press fitting of the peripheral curved portion 24 of the lid into the channel of the ring past the bead 34 such that the edge 28 of the metal lid seats on the step surface 38. Thus the plastic ring 32 engages the peripheral portion 24 of the lid. The securement of the ring 32 onto the lid 18 is effectively permanent to provide the closure 10, that is, it is not intended that the plastic ring 32 and the metal lid 18 be separable in normal usage. In alternative embodiments, the step 38 may be provided by a formation which is separated from the bead 34, in which case the bead 34 commences at a lower position as appropriate for engaging a curl 16 of a can 11. As the closure 10 is assembled onto the can 11 , the curl 16 of rim 14 bears on the lower ramp surface 40 of the bead 34 and cams the depending skirt 42 and bead 34 outwardly until surface 40 passes the radially outermost extremity of the curl 16. The upper surface 36 of the bead 34 then lodges underneath the curl 16. The seating engagement of surface 36 with curl 16 (see reference 44) compresses gasket material 30 to thereby ensure a seal between peripheral portion 24 of metal lid 18 and curl 16 of rim 14. Thus the seating of bead 34 under curl 16 retains the peripheral portion 22-24 of metal lid 18 in sealed engagement on the rim 14 of can 11. Closure 10 is readily removable by manually manipulating skirt 42 outwardly to dislodge bead 34 from under curl 16 and lifting the closure off the rim 14 (see Fig. 2). In this respect, the thumb 46 of an operator may bear on the upper surface of the closure 10 whilst the operator's fingers 48 lever the skirt 42 outwardly. The ease with which the closure may be assembled on and removed from the can 11 depends on the rigidity of the plastic material of the ring 32. The harder or more rigid the plastic, the less is its flexibility and the more difficult it is to apply and remove the closure. Generally, the plastic ring 32 need not be very rigid, that is, relatively soft plastics materials can be used to ensure the closure 10 is easily resealable on a can 11 and that it is easily removable. The only requirements are that there be sufficient rigidity for the bead 34 to retain the lid in position on rim 14 whilst ensuring there is sufficient compression of gasket 30 to establish and maintain the seal. A suitable plastics material for ring 32 is polyethylene. This can have a low density to provide a relatively soft ring to thereby render it easy to apply and remove the closure from a container. The ring may be formed separately from the metal lid by, for example, injection moulding and the two components then assembled, for example by press fitting as described above. Alternatively the plastic ring may be formed in situ on the metal lid by moulding. The metal lid, like the can 11 , may be made from tin plate. In another embodiment the bead 34 may not be continuous, thus there may be provided a number of bead lengths around the inner surface of the skirt 42. Also the bead lengths need not include a step surface 38 on which the edge 28 of lid 18 is lodged (this difference may also be made to the Fig. 1 embodiment). Also the plastic ring 32 may have slightly different cross- sectional shapes. Another difference is that the seal may be established only at the curl 16 by gasket material 30, that is, there may be no friction seal between walls 22 and 12. Figs. 3 and 4 illustrate another embodiment in which corresponding features to those of the Fig. 1 embodiment have been accorded the same reference numerals. In this embodiment the curved outer peripheral portion 24 of the metal part 18 of the closure 10 closely conforms with the channel of the plastic ring part 32 of the closure 10 within which it is engaged. A further difference is that the sealing compound or gasket material 30 extends downwardly along the outer surface of wall 22 such that when closure 10 is assembled on container 11 it provides a seal that extends along and between the outer surface of wall 22 of closure 10 and the inner surface of wall 12 of container 11. Bead 34 of this embodiment is illustrated as being continuous, however it may be broken as described hereinbefore. Gasket material 30 may be a puff compound. This embodiment provides a very good seal for products of very low viscosity (eg. very thin water or oil based liquids) within container 11. However the ease of removal of a closure 10 having such a seal may not be as easy as one having a seal as illustrated by the Fig. 1 embodiment. Its production and manufacturing costs may also be higher. Nevertheless the embodiment of Figs. 3 and 4 offers a useful alternative in accordance with the objects of the invention for the packaging of some liquid products. A container which is sealable by a closure according to the invention may have various rim profiles. Thus, for example, for a metal can the radially outward formation may be an external curl, roll or fold at the rim. Alternatively it may be a bead which is formed in the container wall below and adjacent to the rim. Such a curl, roll, fold or bead may extend continuously around the container, or alternatively it may be interrupted to thereby provide lengths of the curl, roll, fold or bead, as the case may be, around the container periphery. For a plastic container with which a closure according to the invention is useable, the radially outward formation would normally be an external bead at the container rim. Such a bead may have various cross-sectional shapes, provided that the shape includes an undersurface with which the at least one element of the plastic ring of the closure is engageable. For example, the bead of the container may have a cross-sectional shape to match the shape of a bead of the ring component of the closure to facilitate their engagement. As for a metal container, the bead of a plastic container may be located adjacent to rather than at the rim, and may be continuous or discontinuous (i.e. interrupted). A container of either metal or plastic construction may be generally straight walled, or include a shoulder or step in its side wall to provide a smaller area opening. The plastic ring component of a closure according to the invention may include other features, such as a handle or one or more extensions depending from the skirt 42 to assist in levering a closure 10 off a container 11. Thus the skirt 42 of a plastic ring component 32 may include a handle 50 (see Fig. 5) or one or more extensions 52 (see Fig. 6) for this purpose. Other features which may be included, also for assisting leverage or ease of removal of a closure 10 from a container 11 , are a scalloped shaped bottom edge (not shown) for the depending skirt of a plastic ring component, or relief grooves 56 formed through the skirt 42 and extending upwardly through the bead 34 (thus providing a non- continuous bead) (see Fig. 7), or similar relief grooves (not shown) which do not extend through the skirt - preferably such grooves are concealed, that is, they are formed in the inner facing surface of skirt 42. In effect, such relief grooves provide zones of weakness in the skirt 42 rendering it easier to lever a closure 10 off a rim 14 of a container 11. It is to be understood, however, that the provision of such grooves or other techniques for providing similar zones of weakness must not be such as to compromise the sealing retention of a closure 10 on a container 11. Other techniques for providing such zones of weakness include a circumferential variation in the degree or strength of engagement of the bead 34 with the curl 16 of the rim 14 of container 11 - this may be achieved by relieving the bead to some extent at some portions. Another possibility is to provide depending tear away tabs which may be torn upwardly to relieve the engagement force of the bead at portions around the container periphery. With this feature, a highly secure seal can be provided for the initial packaging of a product in a container 11 and, although the re-sealability of the closure 10 is weakened, it can still be made adequately re-sealable to suit some applications. A further feature which may be included is for the plastic ring component 32 to include a tamper evidencing facility. For example, a tear-off strip may be provided in place of or as a depending extension on the skirt 42. Such a tear- off strip (not shown) is preferably tapered downwardly such that its lower edge does not extend to any significant degree outwardly from the outer surface of side wall 12 of a container 11. This is to eliminate or minimise the size of the downwardly facing ledge provided by such edge and thereby limit its accessibility for tampering. For a similar reason, a container 11 may include a bead, or a shoulder, which is sized and positioned such as to reduce access to the bottom edge of the skirt 42. The plastic ring component 32 of a closure 10 according to any of the embodiments of the invention may also be formed so as to improve the stackability of closures 10 for disposal in association with automatic filling machinery and of containers 11 which are sealed by the closures 10. For example, the ring 32 may be formed to provide an upwardly facing ledge 62 around its periphery (see Fig. 8). Alternatively, the plastic ring component 32 of the closure 10 may include a number of upright ribs 64 around its outer surface (see Fig. 9) having upper surfaces 66 which provide for stackability of the closures 10. Fig. 10 also illustrates a tamper evidencing facility in the form of a portion 60 of the skirt 42 of plastic ring component 32 being a tear-off strip. Tear-off strip portion 60 includes a finger grippable tag 61. In use of the closure 10 of Fig. 10, the container (not shown) would include a peripheral bead which is located immediately below the bottom edge of skirt 42 thereby limiting finger access to that edge thus rendering it very difficult to remove the closure. Removal of tear-off strip portion 60 leaves a portion of the periphery of skirt 42 readily accessible to the fingers of an operator thereby enabling manual removal of the closure. It is to be understood that some of the features of the invention may take forms other than those which are specifically described and illustrated above. For example, many cross sectional shapes for the plastic ring component 32 are possible and the metal lid component 18 may also be of any suitable form, as will be known by persons who are skilled in the art. Another variation is that an O ring seal or the like may be used instead of a gasket material 30. A closure according to the invention is suitable for use with machinery for automatically filling the container. It also provides sufficient stackability strength, that is it can withstand the loads imposed when a number of filled containers are stacked one on another. 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: CLAIMS 1. A resealable closure for an open topped container wherein the container opening is defined by a rim and the container includes a radially outward formation at or adjacent to the rim, the closure including a metal lid for closing the container opening and a plastic ring, wherein the metal lid includes a peripheral portion for sealingly engaging the container rim and the plastic ring is secured to the metal lid and engages said peripheral portion, the plastic ring including at least one element for engaging the radially outward formation of a container to retain said peripheral portion of the metal lid in sealed engagement on said rim, and the plastic ring further including a depending portion which extends exteriorly of the container when the closure is assembled thereon, wherein manual manipulation of the depending portion is operative on said at least one element to facilitate removal of the closure from the container. 2. A resealable closure as claimed in claim 1 wherein the at least one element of the plastic ring is a bead which includes a surface which seats under the radially outward formation of the container. 3. A resealable closure as claimed in claim 2 wherein the bead also includes a ramp surface which cams over the radially outward formation of the container as the closure is applied to the container. 4. A resealable closure as claimed in claim 2 or 3 wherein the bead is continuous around the periphery of the closure. 5. A resealable closure as claimed in claim 2 or 3 wherein the bead is interrupted to provide a plurality of bead lengths around the periphery of the closure. 6. A resealable closure as claimed in any one of claims 1 to 5, wherein the depending portion of the plastic ring is a skirt which surrounds the container when the closure is assembled thereon. 7. A resealable closure as claimed in any one of claims 1 to 5 wherein the depending portion of the plastic ring is an extension which depends from only a portion of the periphery of the ring for levering the closure off the container. 8. A resealable closure as claimed in claim 7 wherein the depending portion is in the form of a handle. 9. A resealable closure as claimed in claim 7 including a plurality of extensions which depend from spaced portions of the periphery of the ring. 10. A resealable closure as claimed in claim 6 wherein the skirt includes zones of weakness around its periphery for facilitating removal of the closure from a container. 11. A resealable closure as claimed in claim 10 wherein the zones of weakness are provided by grooves within the skirt which extend substantially in a direction along the container when the closure and container are assembled. 12. A resealable closure as claimed in claim 11 wherein the grooves extend upwardly through said element for engaging the radially outward formation of a container. 13. A resealable closure as claimed in claim 11 or 12 wherein the grooves extend through the thickness of the skirt. 14. A resealable closure as claimed in any one of claims 1 to 13 wherein the peripheral portion of the metal lid for sealingly engaging the container rim includes a channel which seats over the container rim. 15. A resealable closure as claimed in claim 14 wherein the channel includes a gasket material which is compressed when the at least one element of the plastic ring engages the radially outward formation of the container. 16. A resealable closure as claimed in any one of claims 1 to 15 wherein the plastic ring includes a chεnnel within which at least a part of the peripheral portion of the metal lid is fitted to secure together the plastic ring and the metal lid. 17. A resealable closure as claimed in claim 16 wherein the peripheral portion of the metal lid is press-fitted into the channel of the plastic ring. 18. A resealable closure as claimed in claim 16 wherein the at least one element of the plastic ring in the form of a bead protrudes partially across the channel of the plastic ring to provide for a snap fitting of the plastic ring onto the metal lid. 19. A resealable closure as claimed in any one of claims 1 to 18 wherein the plastic ring is moulded onto the metal lid. 20. A resealable closure as claimed in any one of claims 1 to 19 wherein the peripheral portion of the metal lid terminates in an outermost edge which faces generally downwardly and which engages the at least one element of the plastic ring. 21. A resealable closure as claimed in any one of claims 1 to 20 wherein the plastic ring of the closure includes a tamper evidencing facility for an initial sealed assembly of the closure on a container. 22. A resealable closure as claimed in claim 21 wherein the tamper evidencing facility is a tear off strip of at least a peripheral portion of the depending portion of the plastic ring. 23. A resealable closure as claimed in claim 22 wherein the tear off strip tapers in cross section downwardly such that its lower most edge does not extend substantially outwardly of the container exterior wall. 24. A resealable closure as claimed in any one of claims 1 to 23 wherein the depending portion of the plastic ring includes a shoulder which defines an upwardly facing surface adjacent an uppermost surface of the ring for stacking a container onto the closure or for stacking a plurality of closures. 25. A resealable container as claimed in any one of claims 1 to 23 wherein the plastic ring includes spaced ribs around the exterior surface of the plastic ring which extend generally vertically and terminate below the uppermost surface of the plastic ring, thereby providing upwardly facing surfaces for stacking a plurality of closures or for stacking a container onto the closure. 26. A resealable closure as claimed in any one of claims 1 to 25 and an open topped container, the container opening being defined by a rim and the container including a radially outward formation at or adjacent to the rim, wherein the closure is in sealed engagement with the container. 27. A resealable closure for a container substantially as hereinbefore described with reference to any one of the embodiments as illustrated in the accompanying drawings.

Inventors: NULTY TREVOR BERNARD, STEFANO JOSEPH, NULTY, TREVOR, BERNARD, STEFANO, JOSEPH
Applicants: NAT CAN COMPANY PTY LTD, NULTY TREVOR BERNARD, STEFANO JOSEPH, NATIONAL CAN COMPANY PTY. LTD., NULTY, TREVOR, BERNARD, STEFANO, JOSEPH
Application year: 2000
Main classification: B65D45
IPC codes: B44D3, B65D43