NZ221030A - Plastics closure: seal retention means has flexible attachment to skirt - Google Patents

Description

\ t J ._ 221030 Priority Date(s): .. k\' Complete Specification Filed:lQ;7];1$77 Class: A/.lS; Publication Date: .,. .........27. MM P.O. Journal, No: ... , 90 O No.: Date: NEW ZEALAND PATENTS ACT, J 953 COMPLETE SPECIFICATION °2n //•v N i t0 JUL 1987 7 IMPROVEMENTS IN OR RELATING TO CLOSURES" XpfyWe, ACI AUSTRALIA LIMITED, a company incorporated in the State of Victoria, Australia, of Level 32, 200 Queen Street, Melbourne, Victoria, Australia, hereby declare the invention for which i / we pray that a patent may be granted to x»*/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 2 /•"> This invention relates to an improved closure for containers, and to an improved container-closure combination.

One common form of glass container known as Hartford glass has a cylindrical or tapered body, with an opening defined by a peripheral rim of the body. That rim is finished by heat so as to be rounded and to provide a smooth curve merging with inner and outer surfaces of a wall defining the body, Typically, the rim defines a slight radially outwardly extending bead by which it merges with the outer surface. 10 Hartford glass containers are well suited for packaging a variety of foodstuffs such as spreads and jam. They have the benefit of being re-usable, as drinking glasses for example, once their initial contents have been consumed. Similar containers can be made of plastics material. The present invention is applicable to containers^ of Hartford glass, as well as to the similar containers of plastics material; although the invention additionally extends to containers other than those having a Hartford finish.

Closures for containers having a Hartford finish 20 generally are required to be able to be reapplied to protect the contents of the container until consumed. One form of closure in use is a pressed metal lid having a top panel and a narrow peripheral skirt, such closures normally are initially retained under a partial vacuum resulting from retorting, with sealing between the closure and container rim being provided O by resilient gasket material provided around the junction of the top panel and skirt. Such. closures can be difficult to remove due to such partial vacuum, users typically finding it necessary to insert a sharp implement under the skirt and to 30 lever the latter outwardly to break the gasket seal locally. ^ However, such removal can result in deforming the closure so that it is difficult to reapply or does not provide an adequate seal when reapplied. Also, there is a risk ot injury to the user when attempting to force the implement under the closure skirt.

Such metal closures additionally are not suitable for containers for which the contents are not subjected to retorting, in this case, some similar, snap-fit plastics 39 closures can be used, but they generally are characterised by FY O . • V- .. ■ i 221030 an inadequate seal when initially applied or when reapplied. -- .. ...

The present invention is directed to providing an improved closure and an improved container/closure combination.

According to the invention there is provided a closure for a container having a container opening defined by a finish characterised by an external peripheral bead at the opening; the closure comprising a top panel, for 10 covering the container opening so as to extend above said bead, a peripheral skirt depending from the top panel/ and seal retention means extending around the inner surface of the skirt; the closure being integrally formed, from a resilient plastics material, to provide said top panel, skirt and seal retention means; the seal retention means being connected to the skirt by a resilient hinge-like junction therebetween enabling the seal retention means to flex relative to the skirt, with the seal retention means extending within said skirt from said junction towards, 20 but being spaced from, the top panel; the closure thereby being adapted to be applied and, after removal, to be re-applied, to a said container, by non-threaded engagement therewith, so as to seal the container opening, with the spacing between said seal retention means and top panel being such that the seal retention means is locatable below said peripheral bead so as to resiliently grip the container when the closure is applied or re—applied to the container.

The seal retention means (hereinafter referred to as 30 sealing means or flange) preferably comprises an annular ■ flange which projects radially inwardly from the skirt at a location spaced from the top panel. Alternatively, the sealing means may comprise an annular array of radially inwardly projecting fingers similarly located on the skirt. For ease of reference, -each of these forms of sealing means will be referred to as a sealing flange.

As formed, the sealing flange may extend radially inwardly from the skirt and axially away from the top 39 - 3 - •WEKT Office ll HWEPIWO RECEIVED 221030 panel. In such case, the flange preferably is turned before application of the closure to a container so as to extend axially toward the top panel; or the flange may be so turned on initial application of the closure to a container. Alternatively, the sealing flange as formed may extend substantially parallel with the top panel. In that alternative, the flange may be turned before or during its application to a container so as to extend axially toward the top panel. In a still further alternative, the sealing flange as formed may extend axially toward the top panel. However, in each of these arrangements, the sealing flange is adapted to engage against the outer surface of the container body on application of the closure to the container; with the resilience of the flange urging it toward that surface. Preferably the sealing flange, on application of the closure to a container, is forced by that surface to move to a position in which it more closely is parallel to the inner surface of the closure skirt. Such movement may be permitted 221030 by a small radial clearance between the sealing flange and the skirt and/or by resilient deformation of the sealing flange and/or skirt* The sealing flange may increase in thickness away from its junction with the skirt. On. full application of the closure to a container the flange may engage the outer surface ^ at a peripheral bead defined at the rim of the container opening. However, on full application of the closure, the flange preferably engages the container outer surface below 10 such bead and, particularly in such case, the inner surface of the closure skirt has a diameter or is configured to allow the , flange to more closely approach a parallel relationship with the skirt in riding over the bead; the resilience of the flange then allowing it to recover radially inwardly to grip the outer surface of the container below the bead\ The sealing flange is adapted to hold the closure in a sealing relationship with the container opening. The flange may provide the initial seal obtained when the closure is first applied and, thereafter, when reapplied; with the top 20 panel also engaging the peripheral rim of the container when the closure is fully applied or reapplied. However, it is preferred that a positive seal is achieved between the top panel and that edge when the closure is first applied to the container.

In one arrangement? a resilient sealing gasket material is provided within the closure, around the junction of the top panel and skirt. . Such gasket is adapted to resiliently engage and provide a seal with the peripheral rim of the container opening. Subject to the suitability of the 30 plastics material of which the closure is made, such seal can be enhanced by a partial vacuum produced during processing or retorting. Alternatively, an adhesive may be provided around that junction and provide a sealing bond between the closure and container rim on initial application of the closure.

In a preferred arrangement, a sealing member preferably is secured within the closure, such as by being dimensioned to achieve an interference fit therein, by being mechanically retained or by being bonded to the underside of 39 the top panel. Most preferably, the closure skirt defines FY -4- 221030 m * locating means spaced from the top panel, and between the latter and the sealing flange; with the sealing member being snap-fitted between the locating means and the top panel• The locating means may be an annular rib or bead defined by the closure skirt, Alternatively, it -,may be plurality of angularly spaced lugs defined by the skirt. In a still further alternative, the sealing flange extending around the inner surface of the closure skirt may define the locating means. On full application of the closure to a container, the locating means preferably is located around, and closely adjacent or in contact with, the or a bead defined by the container rim.

Where a sealing member of annular or disc form is provided, it may comprise a backing layer and, over a surface of the backing layer remote from the closure 'top panel, a barrier layer. The backing layer may comprise or include a paper-board, such as a relatively thick layer of paper-board, or a thin layer of paper-board bonded on a surface thereof remote from barrier layer to a layer of corrugated paper-board. Alternatively, the backing layer may comprise a foamed plastics layer, such as foamed polyethylene or polystyrene.

The barrier layer may comprise a metal foil, such as aluminium foil. Alternatively, it may comprise a glassine paper. The barrier layer may be firmly bonded to the surface of the backing layer remote from the closure top panel. However, it preferably is weakly, bonded to the backing layer, such as by means of a wax, to enable separation of the barrier and backing layers when the closure is first removed from the container. In the latter case, the barrier layer is able to be retained as a membrane covering the container opening, on first removal of the closure, due to an adhesive bond provided between the barrier layer and the container rim; the membrane protecting the contents of the container until perforated and removed.

Where the barrier layer is weakly bonded to the backing layer, the surface of the backing layer to which the barrier layer is so bonded may be defined by an intermediate, metal foil or glassine paper layer firmly bonded to the 221030 backing layer. Such intermediate layer can be omitted where the backing layer is of paper-hoard providing a smooth surface to which the barrier layer can be weakly bonded. However# an intermediate layer is highly desirable where the backing layer is o£ foamed plastics, so as to provide such smooth surface and facilitate application thereto of'an adhesive or glue by .'""n which the barrier layer is to be weakly bonded to the backing layer.

In an alternative form of the preferred arrangement, 10 the sealing member, of annular or disc form, may be provided by a gasket member of a plastics material which is more resilient than the plastics material comprising the closure top panel, skirt and annular sealing flange, Such gasket member may be provided in a moulded closure by providing a quantity of a sealing compound within the closure, spinning the latter to uniformly distribute the compound around the top panel of the closure adjacent the skirt, and then curing the compound to form the gasket member. However/ the gasket member can be provided by moulding the closure against that 20 member, or by moulding the gasket member against the closure. In the first of these moulding arrangements, a quantity of plastics material to form the gasket member can be placed in a mould and compression moulded therein; with the closure then being injection moulded against the gasket member in such mould. In the second moulding arrangement, the closure member is injection moulded in a suitable mould, after which a male member of the mould is retracted slightly to define a cavity into which the material to form the gasket member is injection moulded» It is indicated above that, subject to the suitability of the plastics material of which the closure is made, a seal obtained with the closure of the invention can be enhanced by a partial vacuum produced by retorting. Subject to such suitability of the material, the closure in fact is well suited to packing or filling under vacuum, that is, under a retorting procedure. Also, the closure is found to perform well under vacuum, a vacuum seal being maintained for substantial periods and ensuring a good shelf-life with 39 suitable contents. o c FY 22103 41 Reference now is directed to the drawings in which: Figures 1 and 2 show a closure In side elevation and plan view; Figure 3 is a partial sectional view on an enlarged scale and showing the closure as applied to a container; and Figure 4 corresponds to Figure 3, but shows a modified form of closure.

In Figures 1 to 3, the closure 10 has a top panel 12 and a peripheral skirt 14. On its inner surface, skirt 14 has 10 an integral sealing flange 16 spaced from panel 12. Flange 16 merges with skirt 14 at a resilient hinge-like junction 18 enabling it to flex relative to skirt 14.

Closure 10 is of integral construction, and formed by injection moulding of a suitable plastics material such as polypropylene. In the as formed condition of closure 10, its flange 16 projects radially inwardly from junction 18, and away from panel 12. However, flange 16 is turned, preferably by use of a suitable tool prior to application of closure 10 to a container, so as to extend towards panel 12. The 20 thickness of flange 16 increases radially from a minimum at junction 18, and this thickness increase retains flange 16 in its turned position.

The form of container 20 with which closure 10 most preferably is intended to be used is shown in Figure 3, This has a slightly tapered peripheral wall 22, terminating at an opening defining rim 24. The latter has been heat finished so that it is smoothly curved and defines an outer peripheral bead 26.

On application of closure 10 to container 20, it is 30 presented axially to the container under pressure. During application, flange 16 engages and rides over bead 26 under w the pressure, and therafter recovers radially inwardly to grip and seal against outer surface 26 of wall 22, below bead 26. Within the possible axial extent of flange 16, skirt 14 has a minimum diameter at 30 and is increased in diameter at 32 to enable the required flexing of flange 16 in riding over bead 26. The outer surface of skirt 14 is stepped at 34 to provide a required wall thickness and strength adjacent flange 16. 39 Within closure 10, there is fitted a liner wad 36 of FY -7- I 22103 ^ disc form which covers the underside of panel 12. Spaced from panel 12, an annular rib 38 is defined on the inner surface of skirt 14. Wad 36 is retained in closure 10 by being snap-fitted over rib 38. The thickness of wad 36 is such that it is retained adjacent panel 12 by rib 38.

Wad 36 has a backing layer comprising a foamed plastics material 40 and aluminium foil 42 securely bonded to material. Wad 36 also has a barrier layer 44, of aluminium foil or glassine paper, weakly bonded to foil 42 by a wax 10 layer therebetween. A heat or pressure sealable adhesive around the periphery of layer 44 bonds the latter to rim 24 of container 20 when closure 10 is first applied. On first removal of closure 10, layer 44 separates from wad 36 to remain as a membrane which continues to seal container 20 until perforated.

On application of closure 10 to container 20, wad 36 engages the rim 24 of the container. The diameter of wad 36 and of the inner surface of skirt 14 therearound preferably slightly exceeds that of rim 24 so that any deformation of the 20 underside of wad 36 is within its peripheral edge. .Also, rib 38 preferably has an inner diameter which, at most, only slightly exceeds the outer diameter of bead 26. Rib 38 thus encircles bead 26 and provides a centering action on bead 26 which assists in correct application of closure 10.

After initial removal, closure 10 can readily be reapplied, with a seal with the container being provided by flange 16 resiliently engaging .around container surface 28. Where an adhesive bond initially provides a seal between wad 36 and edge 24, the adhesive to provide this can be selected 30 to provide a required bond strength.

, " As an alternative to the form of seal described with reference to wad 36, the latter may comprise a metal foil layer 44 having an outer, plastics film layer which engages rim 24. In such alternative, the outer layer of such laminate may be induction welded to the rim; the resultant seal therebetween preferably achieving a predetermined bond strength enabling the seal to be broken when required.

In a further alternative, top panel 12 may have an 39 integral annular sealing fin which depends from the underside FY 221030 thereof, substantially concentrically within skirt 14♦ In such case, a liner wad either is not provided or is of annular form and located between the fin and skirt 14. In such alternative, a seal between the closure and the container may at least in part be provided by the fin locating in and resiliently engaging around the inner surface of the container peripher wall. However, where such annular form of wad is used, an adhesive, or induction weld, bond may be provided to provide a seal around the container rim.

In the alternative form of Figure 4, corresponding parts have the same reference numeral plus 100, In this instance, a bead corresponding to bead 38 o£ Figure 3 is omitted; wad 136 being more loosely retained, prior to application of closure 110, between panel 112 and flange 116. Also, wad 136 is of an alternative construction, having a backing layer comprising corrugated paper-board 141 bonded to flat paper-board layer 143, and aluminium foil 142 firmly bonded to layer 143. Also, an aluminium foil or glassine paper barrier layer 144 is weakly bonded to foil 142 while, at its face remote from foil 142, layer 144 is bonded to rim 124.

In the foregoing, closures according to the invention are illustrated with reference to containers of the Hartford glass type. However, it is to be understood that the closures can be used with other types of container, whether of glass, plastics or other materials. Thus, for example, the closure can be used with containers having a cylindrical or tapered body but not having a Hartford rim finish.

Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the constructions and arrangements o£ parts previously described without departing from the spirit or ambit of the invention.

Claims (29)

221030 "WHAT WE CLAIM IS:

1. A closure'for a container having a container opening defined by a finish characterised by an external peripheral bead at the opening; the closure comprising a top panel, for covering the container opening so as to extend above said bead, a peripheral skirt depending from the top panel, and seal retention means extending around the inner surface of the skirt; the closure being integrally formed, from a resilient plastics material, to provide said top panel, skirt and seal retention means; the seal retention means being connected to the skirt by a resilient hinge-like junction therebetween enabling tbe seal retention means to flex relative to the skirt, with the seal retention means extending within the skirt from said junction towards, but being spaced from, the top panel; the closure thereby being adapted to be applied and, after removal, to be re-appliea, to a said container, by non-threaded engagement therewith, so as to seal the container opening, with the spacing between said seal retention means and top panel being such that the seal retention means is locatable below said peripheral bead so as to resiliently grip the container when the closure is applied or re-applied to the container.

2. A closure according to claim 1, wherein the seal retention means comprises an annular flange which projects radially inwardly from said junction.

3. A closure according to claim 1, wherein the seal retention means comprises a discontinuous flange defining an annular array of radially inwardly projecting fingers which project radially inwardly from said junction.

4. A closure according to claim 2 or claim 3, wherein the flange, as formed, extends radially inwardly from the skirt and axially away from the top panel, and is turned so as to extend axially toward the top panel.

5." A closure according to any one of claims 2 to 4, wherein the flange increases in thickness away from said junction.

6. A closure according to any one of claims 1 to 5, wherein a resilient sealing gasket material is provided NtW ZEALAND . PATENT office ~10" , flfSEPWO ACCENTED '■ ' • " ! 221030 within the closure, around the junction of the top panel and skirt, said gasket material being adapted to resiliently engage and provide a seal with a peripheral rim of the container opening.

7. A closure according to any one of claims 1 to 5, wherein a sealing member is secured within the closure.

8. A closure according to claim 7, wherein the closure skirt defines locating means spaced from the top panel, and between the latter and the seal retention means; with 10 a sealing member being snap-fitted between the locating means and the top panel.

9. A closure according to claim 8, wherein the locating means is an annular rib or bead defined by the closure skirt.

10. A closure according to claim 8, wherein the locating means comprises a plurality of angularly spaced lugs defined by the skirt.

11. A closure according to claim 8, wherein the locating means comprises an annular rib extending around the inner 20 surface of the closure skirt,

12. A closure according to any one of claims 7 to 11, wherein the sealing member is of annular or disc form, and comprises a backing layer and, over -a surface of the backing layer remote from the closure top panel, a barrier layer.

13. A closure according to claim 12, wherein the backing layer comprises paper-board.

14. A closure according to claim 12, wherein the backing layer includes a thin layer of paper-board bonded to the 30 barrier layer and a layer of corrugated paper-board bonded to the thin layer of paper-board over a surface of the latter remote from the barrier layer.

15. A closure according to claim 12, wherein the backing layer comprises a foamed plastics layer.

16. A closure according to claim 15, wherein the foamed plastics layer is formed of foamed polyethylene or polystyrene.

17. A closure according to any one of claims 12 to 16, 39 wherein the barrier layer comprises a metal foil. f new Zealand i patent office -11" itWEPIW 221030

18. A closure according to any one of claims 12 to .17, wherein the barrier layer comprises an aluminium foil. .

19. A closure according to any one of claims 12 to 16 wherein the barrier layer comprises glassine paper.

20. A closure according to any one of claims 12 to 19, wherein the barrier layer is weakly bonded to the backing layer to enable separation of the barrier and backing layers when the closure is first removed from the container. 10

21. A closure according to claim 20/ wherein the barrier layer is weakly bonded to the backing layer by means of wax.

22. A closure according to claim 20 or claim 21, wherein the barrier layer Is weakly bonded to the backing layer such that, if the barrier layer is more strongly bonded to a rim of the opening of a said container on first application of the closure to said container, the barrier layer is able to be retained in sealing engagement over said opening, by separation from said backing layer, on first removal of 20 the closure from said container.

23. A closure according to any one of claims 12 to 22, wherein the diameter of the sealing member is such that, on application of the closure to said container, any deformation of the underside of the sealing member is within its peripheral edge.

24. A combination comprising a closure according to any one of claims 1 to 23 and a said container, the seal retention means of the closure resiliently engaging an external surface of said container below said peripheral 30 bead.

25. A combination according to claim 24, wherein said bead is slightly radially outwardly extending and is formed by heat finishing of the container around its opening.

26. A combination according to claim 24, wherein said seal retention means is adapted to resiliently ride over said bead during application or re-application of the closure to the container by provision of a slight spacing 8688L 39 between the seal retention means and the -12- 221030 and/or by resilient deformation of the seal retention means and said skirt.

27. A combination according to claim 24 in which the closure is that according to claim 21, wherein said harrier layer is bonded to a rim of tbe container opening such that, on first removal of the closure from the container, the barrier layer is retained in sealing relation over said opening by separation of the barrier layer from said backing layer.

28. A closure according to claim 1, substantially as herein described with reference to Figures 1 and 2 or Figure 4 of the accompanying drawings.

29. A combination according to claim 24, substantially as herein described with reference to Figures 1 to 3 or to Figure 4 of the accompanying drawings.' AosIvpsiJUcx By Htetttef/Their Authorised Agents, A. J. PARK & SON Per