GB2322362A

GB2322362A - Closure with liner for chimney necked container

Info

Publication number: GB2322362A
Application number: GB9702928A
Authority: GB
Inventors: Gerry Mavin; Glenn Heighington
Original assignee: Portola Packaging Ltd
Current assignee: Portola Packaging Ltd
Priority date: 1997-02-13
Filing date: 1997-02-13
Publication date: 1998-08-26
Anticipated expiration: 2017-02-13
Also published as: GB9702928D0; GB2322123A; GB2322123B; GB9719138D0; GB2322362B

Abstract

A container neck 50 having an upwardly projecting chimney 58 which acts as a cylindrical sealing surface, has a closure 80 and a liner 92 held within the closure 80, the liner 92 sealing the container neck opening 50 when the closure 80 is initially applied to the container. Once the container has been opened by the removal of the liner 92, when the closure is fully received on the container, an annular bead 88 of the closure 80 engages the chimneyed neck 50 of the container to form a secondary seal (see figs 10, 11). The liner may be adhered to the chimneyed neck of the container by use of induction heating, and may initially be held in position between the bead 88 and the chimneyed neck of the container. The closure may have a second bead 90 which forms a tertiary seal with the chimneyed neck when the closure is fully received on the container. The closure 80 may have projections 94 to hold the liner 92 in place before application to the container neck. The closure may be of a more flexible material than the container neck so that it can be axially pushed on to the container. There may be tamper evident means for the closure.

Description

2322362 CLOSURE WITH LINER AND IMPROVED SECONDARY SEAL is The present

invention relates to closures for containers and to a method of applying a closure to a container. In particular, the present invention relates to a closure incorporating a foil or other liner for sealing to a neck surrounding a container opening and to a method of reliably sealing the foil or other liner to the neck without distorting or 10 otherwise damaging the liner.

Many closure systems include a cap and a foil liner for sealing a neck opening of a container to preserve the freshness of the product and provide visual evidence that the container has not previously been opened. The underside of the foil liner is usually provided with a substance, such as an adhesive or a polymer coating, which adheres the liner to the container neck when the substance is activated by, for example, induction heating or some other means. Preferably, the foil liner is adhered to the entire perimeter of the neck opening so that the container is completely sealed by the liner.

The foil liner may be applied to the neck before the cap with the foil liner being pressed against a rim of the neck opening by an applicator while the adhesive or other suitable substance is activated. By evenly pressing the liner against the rim during its application, an effective seal may be obtained around the entire perineter of the neck opening. After the neck opening has been sealed with the foil liner, the cap may be applied in a separate step which is well known in the art. Although this method of applying the foil liner and the cap in separate steps may be used to achieve an effective seal between the foil liner and the perimeter of the neck opening, the is method is nevertheless time consuming and inconvenient.

In order to overcome this problem it is also known to position the foil liner in the cap prior to its application and this allows the foil liner and the cap to be applied simultaneously to the container neck. The cap is seated on the neck using a known capping technique and in this position the cap is used to hold the foil liner against the perimeter of the neck opening whereupon the adhesive or other substance is activated to adhere the foil liner to the neck. The effectiveness of the seal between the foil liner and the perimeter of the neck opening depends, in part, on whether the foil liner is uniformly held against the neck by the cap when the adhesive or other substance is activated. If the cap is misaligned and is at a slight angle relative to the neck, the cap may not apply sufficient pressure to the foil liner to obtain an effective seal around the entire perimeter of the neck opening. With threaded closures of the recently introduced type which are initially applied by an axial force using minimal, if any, rotation between the closure and the neck, the final position, or height, of the cap relative to the neck may vary depending upon the initial orientation of the cap threads relative to the neck threads. At the upper end of this height range, a gap as large as the vertical spacing between adjacent turns of thread may be introduced between the underside of the topof the cap and the perimeter of the neck opening. This gap may also prevent the cap from applying sufficient force to press the foil liner against the neck. As a result the foil liner may be only partially adhered.

In an attempt to overcome this problem it has been proposed to provide an annular bead which depends from an undersurface of the top of the cap and which serves to press the foil liner into engagement with the perimeter of the neck opening. Once the foil liner has been removed, the annular bead also serves as a "mini-plug" which engages with the neck opening when the cap is screwed onto the neck and provides a partial, if not always very effective, secondary seal.

one problem with closure systems of this type and which is particularly prevalent in the United Kingdom stems from the different manufacturing technique that is typically used to produce the neck of the containers. Whereas in the United States the container necks are typically formed using a pull-up neck finish of the type illustrated schematically in Figure 1 and in which a blow pin 10 is pulled up through an annular shear steel 12, the necks for containers used in the United Kingdom are typically formed using a ram-down neck finish. The manufacturing process used in the United States creates a neck opening 14 having a relatively thin, but generally smooth, annular rim 16 to which a foil liner may be readily adhered without much difficulty. By contrast, the process used in the United Kingdom and which is illustrated schematically in Figure 2 in which a blow pin 18 and cutting ring 20 are rammed down through an annular shear steel 22, produces a neck opening 24 which is surrounded by a much more rigid perimeter containing far more plastics material than its US counterpart. Whilst this rigid perimeter has a number of advantages, it unfortunately results in a characteristic annular wall 26 which projects upwardly from the radially inner edge of an annular rim 28 and which is known in the trade as a chimney.

Although plastics containers are almost universally made of a relatively rigid material such as high density polyethylene (HDPE), when it comes to making closures for those containers there is a choice to be made between making the cap of a similar HDPE material or of a more flexible medium density, or even low density, polyethylene (MDPE and LDPE respectively). Here again there has been a tendency for the manufacturing process in the United Kingdom to differ from that in the United States.

If the caps are formed of HDPE, it is often not possible for a capping machine relying on the application of a simple downward force to automatically correct a misalignment of a cap with respect to a container neck since neither one of the cap or the container neck is significantly more flexible than the other. As a result, unless there is a degree of human intervention to correct the situation, which is both costly in terms of manpower and lost production time, the misaligned cap is not properly sealed permitting the contents of the container to leak out, potentially damaging not only those goods with which they come into contact but also the reputation and reliability of the entire bottling and closure process. However, the process is not significantly improved if, instead of using HDPE, the caps are made of LDPE. Under these circumstances, whilst the positioning of an initially misaligned cap may be automatically corrected by a combination of downward pressure and flexing of the cap, there is a tendency for the harder plastic of the neck to damage the softer plastic forming the sealing surface of the cap which, if the damage is bad enough, can create a path by which the contents of the container may leak out past the cap once the foil liner has been removed. It is because of considerations such as these that many plastics caps in the United Kingdom are made of HDPE and are screwed onto the container necks rather than pushed on. However, this in turn means that where the cap is fitted with a foil liner, the annular depending bead is constrained to be relatively shallow so that, upon screwing the cap down onto the container neck, the foil liner is not distorted or damaged by the shearing action that would otherwise take place between the depending annular bead and the chimney. As a result any secondary sealing action provided by the annular depending bead once the foil liner had been removed is of limited effectiveness.

Preferred embodiments of the present invention seek to address the above problems of the prior art.

According to a first aspect of the present invention there is provided a closure in combination with a container neck, the container neck defining an annular rim surrounding a neck opening and formed with a chimney projecting upwardly from said rim such that the chimney defines a cylindrical sealing surface surrounding said neck opening, the closure comprising a cap having a top and a downwardly extending skirt portion depending from said top and a liner received within said cap for attachment to the container neck to seal said neck opening, the cap being provided with an annular bead depending from said top and which is shaped such that, when the closure is fully received on the container neck and after the liner has been removed, a radially outer surface of the bead engages the cylindrical sealing surface defined by the chimney.

Advantageously, the annular bead may be shaped such that, when the closure is fully received on the container neck and after the liner has been removed, the radially outer surface of the annular bead abuts the chimney in such a way as to be in confronting - 6 relationship with a substantial portion of the cylindrical sealing surface. Preferably the radially outer surface of the annular bead may have an axial dimension greater than or equal to that of the cylindrical sealing surface.

Advantageously, the chimney may be provided at an end remote from the rim with a radially outwardly inclined surface and the annular bead may be shaped so as to press the liner into engagement with said radially outwardly inclined surface when said closure is initially applied to the container neck. Preferably the end of the annular bead remote from said top may be provided with a generally radially outwardly inclined surface with which to confront the radially outwardly inclined surface provided on the chimney when said closure is initially applied to the container neck with the liner disposed between the two. Preferably the generally radially outwardly inclined surface provided at the end of the annular bead remote from said top may be smoothly curved so as to minimise any damage to the liner as the closure is applied to the container neck. Preferably the liner may be adapted to adhere to the radially outwardly inclined surface provided on the chimney in order to seal the neck opening.

Advantageously, the radially outwardly inclined surface provided on the chimney may be shaped so as to guide the radially outer surface of the bead into engagement with the cylindrical sealing surface once the liner has been removed and upon application of the cap to the container neck.

Advantageously, the radially outer surface of the annular bead may merge with a radially outwardly inclined surface adjacent said top, the radially outwardly inclined surface engaging the radially outwardly inclined surface on the chimney to define a secondary annular seal once the liner has been removed and the closure is fully received on the container neck.

Advantageously, an end of the annular bead remote from said top may be shaped such that, once the liner has been removed and upon application of the cap to the container neck, the radially outer surface of the bead is guided into engagement with the cylindrical sealing surface.

Advantageously, the cap may be provided with a second annular bead depending from said top and spaced radially outwardly from the first such that, when the closure is fully received on the container neck and the liner has been removed, the second annular bead engages said annular rim to form a tertiary annular seal. Preferably said second annular bead may be of saw-tooth cross-section.

Advantageously, the cap and container neck may be provided with complimentary engagement means so that the cap may be repeatedly attached and detached from the container neck. Preferably the complimentary engagement means may be adapted so that the cap may, at least initially, be applied to the container neck by an axial force. Preferably the complimentary engagement means may comprise tamper evidencing means which must first be overcome before the cap can be detached from the container neck after its initial application.

Advantageously, the cap may be formed of a material which is more flexible than the material from which the container neck is formed. Preferably the container neck is formed of HDPE and the cap is formed of MDPE or LDPE.

Advantageously, the liner may be retained within - 8 the cap by the engagement of the liner with one or more radially inwardly projecting formations provided on an inner surface of the downwardly extending skirt portion. Preferably the first annular bead projects downwardly from said top such that an end of the bead remote from the top is spaced a greater distance from the top than the one or more radially inwardly projecting formations which serve to retain the liner within the cap.

According to a second aspect of the present invention there is provided a closure for use with a container neck defining a neck opening, the closure comprising a cap having a top and a downwardly extending skirt portion depending from said top, and a liner received within said cap for attachment to the container neck to seal the neck opening, the liner being retained within the cap by the engagement of the liner with one or more radially inwardly projecting formations provided on an inner surface of the downwardly extending skirt portion, the cap further comprising an annular bead depending from said top such that an end of the bead remote from the top is spaced a greater distance from said top than the one or more radially inwardly projecting formations which serve to retain the liner within the cap.

Advantageously, the annular bead may have an axial dimension in excess of 2.Omm.

said top may be chamfered on a radially outer surface.

Advantageously, a radially outer surface of the annular bead may merge with a radially outwardly inclined surface adjacent said top.

Advantageously, the cap may be provided with a second annular bead depending from said top and spaced radially outwardly from the first. Preferably said second annular bead may be of saw-tooth cross-section. Preferably said second annular bead may project downwardly from said top to a lesser extent than said first bead.

According to a third aspect of the present invention there is provided a method of applying a closure to a container neck, the container neck defining an annular rim surrounding a neck opening and formed with a chimney projecting upwardly from said rim, a neck stretch portion below said rim and engagement means provided on an exterior surface of said neck stretch portion, and the closure comprising a cap having a top, a downwardly extending skirt portion depending from said top, complimentary engagement means provided on an internal surface of said downwardly extending skirt portion, an annular bead also depending from said top and a liner received within the cap for attachment to the container neck to seal said neck opening, the method comprising the steps of presenting the closure to the container neck; applying an axial force to urge the engagement means on the neck stretch portion into engagement with the complimentary engagement means provided on the downwardly extending skirt portion and to cause the annular bead to press the liner against a surface of the chimney; and applying heat to the liner to cause the liner to adhere to the chimney.

A number of embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a schematic diagram of the formation of a pull-up neck finish; Figure 2 is a schematic diagram of the formation of a ram-down neck finish; Figure 3 is a schematic view, partially in cross- section, of a closure in accordance with a first embodiment of the present invention; Figure 4 is a schematic view, partially in crosssection, of a container neck in accordance with a first embodiment of the present invention; Figure 5 is an enlarged view of the rim of the container neck of Figure 4; Figure 6 is a schematic view, partially in crosssection, of a closure in accordance with a second embodiment of the present invention; Figure 7 is a schematic view, partially in crosssection, of a container neck in accordance with a second embodiment of the present invention; Figure 8 is an enlarged, cross-sectional view of part of a closure in accordance with an embodiment of the present invention; Figure 9 is an enlarged cross-sectional view of a closure in combination with a container neck in accordance with an embodiment of the present invention and illustrating the manner in which a liner is held against the rim of a container neck; Figure 10 is a schematic view, partially in cross-section, of a closure in combination with a container neck in accordance with an embodiment of the present invention and illustrating how the closure engages the container neck once the liner has been removed; and Figure 11 is an enlarged cross-sectional view of the combination of Figure 10.

Figures 3 and 4 show one example of a cap and container neck embodying the present invention. The container neck 50 is formed of HDPE and projects upwardly from the body of a container 52 and includes neck opening 54 defined by an annular rim 56. Being ram-down neck finish, the annular rim 56 can been 11 - seen in the enlargement of Figure 5 to be in turn defined by an annular, upwardly projecting chimney 58 disposed radially inwardly of a generally horizontal annular flange 60. The upper radially inward surface of the chimney 58 is chamfered so as to provide an annular inclined surface 62 which extends between, and merges with, an upper, generally horizontal, annular surface of the chimney 64 and an inner cylindrical surface 66.

A neck stretch portion 68 depends from the annular rim 56 and is provided on an exterior surface with engagement means with which to engage complimentary engagement means provided on the cap.

In the example shown, the engagement means provided on the neck stretch portion 68 take the form of a helical thread configuration 70 which includes seven threads or leads 72. It will be apparent however, that the engagement means may take a number of different forms and, in particular, may, if the complimentary engagement means provided on the cap takes the form of a helical thread configuration, comprise a helical groove configuration. Likewise, it will be apparent that the thread or groove configuration 70 need not be limited to seven threads or grooves but may comprise one, two or more threads or grooves as appropriate.

Generally speaking however, it is preferable for the configuration to comprise several threads or grooves.

In the illustrated embodiment, each thread 72 extends about 1800 around the circumf erence of the neck stretch portion 68. Once again however, it will be understood that threads of a lesser or greater extent may also be employed. For example, each thread 72 may extend within a range from 900 to more than 3600. If so desired the threads or grooves may be interrupted at intervals along their length.

Preferably, the helical thread configuration 70 has a fine thread density to limit the vertical float of the cap on the neck 50. Thus, the thread density preferably lies within the range of between twelve and twenty threads per linear inch. Most preferably of all is a thread density of approximately seventeen or eighteen threads per linear inch.

In another embodiment incorporating additional tamper evidencing means shown in Figure 7 but which nevertheless shares a number of features in common, the neck stretch portion 68 terminates in a locking wall portion 74 which is formed with a plurality of ratchet teeth 76. In the example shown, the ratchet teeth 76 are arranged in two groups of between eight and fifteen teeth each, although it will be appreciated that the number and position of the teeth may be subject to considerable variation.

The cap 80 which engages the neck is formed of MDPE or LDPE and includes a top 82 having an undersurface 84 and an annular upper skirt portion 86 depending from the top. Two concentric annular beads 88 and 90 depend from the undersurface of the top 84 the inner of which engages an upper surface of a disc shaped liner 92. The liner 92 is nevertheless retained in position within the cap by a plurality of radially inwardly projecting formations 94 provided on an inner surface of the upper skirt portion 86. It will be apparent however, that the liner 92 might be retained in some other way and that, for example, the formations 94 may be replaced by a single annular bead should it be so desired.

Beneath the radially inwardly projecting formations 94, the inner surface of the upper skirt portion is provided with engagement means which are complimentary to those provided on the outer surface of the neck stretch portion 68. As before, these engagement means may take many forms but, in the example shown, comprise a multi lead helical thread configuration 96 having seven threads or leads 98 and a thread density of roughly seventeen or eighteen threads per linear inch. once again, it will be appreciated that, if the engagement means provided on the neck stretch portion 68 comprises a helical thread configuration, then the engagement means provided on the inner surface of the upper skirt portion may comprise a helical groove configuration. Each thread 98 extends between 1500 to 1900 around the inner surface of the upper skirt portion 86. However, it is to be understood that this thread length may be increased or decreased if desired. For example, each thread may extend in a range from 900 to more than 3600 and likewise the thread density is not limited to being about seventeen or eighteen threads per linear inch but nevertheless preferably lies in the range from about twelve to twenty threads per linear inch. Preferably, the thread configuration 70 on the neck stretch portion 68 and the thread configuration 96 on the upper skirt portion 86 each have at least two threads and a thread density of at least twelve threads per linear inch. If so desired the threads or grooves may be interrupted at intervals along their length.

The two thread configurations 70 and 96 are shaped so as to slip past one another and engage when a direct, axially downward force is applied to the cap 80 urging the cap into engagement with the neck 50. In other words, when the cap 80 is pushed onto the neck 50, the threads on the cap 98 snap over and engage the threads on the neck 72. This is made possible not only by virtue of the shape of the thread configurations 70 and 96 but also by virtue of the increased flexibility of the cap compared to the neck being made of MDPE or MPE as opposed to the HDPE of the neck.

In the illustrated embodiment, the two thread configurations 70 and 96 each have multiple turns of thread so that a vertical line drawn across each thread configuration intersects four or five turns of thread depending upon the location of the line around the circumference of the neck stretch portion 68 or upper skirt portion 86. This ensures that when the cap 80 is applied to the neck 50 there will be multiple turns of thread engagement. Of course, the total cumulative thread engagement is subject to variation and, depending upon the linear thread density, may be as little as one turn of thread engagement or more than five turns of thread engagement.

Although optional, the cap shown in Figure 6 includes additional tamper evidencing means to alert the consumer to possible tampering with the contents of the container. A removable lower skirt portion 100 is frangibly attached to a lower edge of the upper skirt portion 86 by frangible means such as bridges 102. In an alternative arrangement, the bridges 102 may be replaced by a circumferentially extending line of weakness or tear line or a combination of bridges and tear lines. The lower skirt portion 100 is provided on an inner surface with a plurality of ratchet teeth 104 which are complimentary to, and shaped to engage with, the ratchet teeth 76 provided on the locking wall portion 74 of the neck 50. As shown in Figure 6, the ratchet teeth 104 may be joined directly to the upper skirt portion 86 thereby forming the frangible bridges 102. However, it will be apparent that other configurations may also be used and that, for example, the lower skirt portion 100 may include a radially inwardly extending shoulder which is joined to the upper skirt portion 86 by frangible bridges 102 in preference to the ratchet teeth 104.

During the application of the cap 80 to the container neck 50, the ratchet teeth 104 slip between, and interengage with, the ratchet teeth 76 at the same time as the threads on the cap 98 snap over and engage the threads on the neck 72. once in position, the mutual engagement of the ratchet teeth 76 and 104 prevent the cap 80 from being unscrewed from the container neck 50 so long as the lower skirt portion remains attached to the upper skirt portion 86.

In order to remove the cap therefore, the lower skirt portion 100 must first be at least partially separated from the upper skirt portion 86 and this may be accomplished by twisting the cap 80 relative to the container neck 50 and breaking the frangible bridges 102. Alternatively, the lower skirt portion 100 may be removed before the cap is unscrewed by gripping a tear tab 106 provided on the lower skirt portion and pulling the lower skirt portion away from the upper skirt portion 86. A vertically extending line of weakness 108 adjacent the tear tab 106 facilitates the removal of the lower skirt portion 100.

Looking more closely at the cap 80, it can be seen from Figure 8 that the top 82 comprises a generally circular disc having a thickness of approximately 0.75mm. The two annular beads 88 and 90 depend from the undersurface of the top 84 close to where the top merges with the upper skirt portion 86 but, as shown, the two beads are of quite different cross-sectional shape. The inner bead 88 is defined, on its radially inner edge, by a downwardly extending wall 110 which forms an angle with the undersurface 84 of between 900 and 1000 but preferably of between 910 and 920. The downwardly extending wall 110 extends to a point between 2mm and 3mm from the undersurface 84, and preferably to a point 2.4mm from the undersurface, whereupon it merges with an upwardly extending arcuate wall 112 which has a radius of curvature of between 0.6mm and I.Omm but preferably a radius of curvature of 0.8mm. The arcuate wall 112 extends to a point between 1.3mm and 1.9mm from the undersurface 84, and preferably to a point 1.6mm. from the undersurface, whereupon it merges with a substantially vertical wall 114. At a distance between 0.5mm and 0.9mm from the undersurface 84, and preferably at a distance of 0.7mm from the undersurface, the substantially vertical wall 114 merges with a radially outwardly and upwardly inclined surface 116 which subtends an angle at the under surface 84 of approximately 450. At a hight substantially level with the undersurface 84, the radially outwardly and upwardly inclined surface 116 merges with a radially outwardly and downwardly inclined surface 118 which once again subtends an angle at the undersurface 84 of approximately 450 but which this time defines a radially inner edge of the outer annular bead 90. At a distance between 1.0mm and 1.4mm from the undersurface 84, and preferably 1.2mm from the undersurface, the radially outwardly and downwardly inclined surface 118 comes to a point where it merges with a second radially outwardly and upwardly inclined surface 122 to provide the annular bead 90 with a substantially saw tooth cross section. This cross-section however, is slightly asymmetric in that the second radially outwardly and upwardly inclined surface 122 does not subtend an angle at the undersurface 84 of approximately 45 but 17 - instead subtends an angle of approximately 300.

The liner 92 seals the neck opening 54, preserving the freshness of the product stored in the container and providing a further tamper evidencing feature. In the illustrated embodiments, the liner 92 comprises a foil sealing disc of a commercially available type and includes an adhesive layer 130 for adhering the disc to the annular rim 56 and a tab 132 for use in removing the disc from the container neck 50. The adhesive layer 130 is provided by suitable means such as a heat sensitive compound which bonds with the annular rim 56 upon the application of heat by an inductionmeans or other suitable source. As has been previously stated, the liner 92 is inserted into the cap 80 before the cap is applied to the container neck 50 and is loosely retained in this position by the engagement of the liner with the radially inwardly projecting formations 94.

Because the cap 80 is formed of a material which is more flexible than the material from which the container neck 50 is formed (ie because MDPE or LDPE is more flexible than HDPE) and because of the shape of the respective thread configurations 70 and 96, the cap 80, complete with liner 92, may be applied to the container neck 50 in an axial direction. This greatly facilitates the capping process and makes it possible to closely control the extent to which the cap 80 is pushed onto the neck 50. This is in marked contrast to capping techniques which involve the relative rotation of the cap with respect to the container neck in which it is far more difficult to prevent over or under tightening. The axial application of the cap 80 also enables the capping process to correct any caps which might initially be misaligned with respect to the container neck 52.

once the cap 80 and liner 92 have been snapped onto the container neck 50, the liner is held against the annular inclined surface 62 of the chimney 58 by means of the arcuate wall 112 of the annular bead 88.

Before the axial closing force is removed and with the liner 92 held in this position, the cap 80 and container neck 50 are exposed to a quantity of heat sufficient to activate the adhesive layer 130. This has the effect of adhering the liner 92 to the inclined annular surface 62 of the chimney 58 thereby sealing the neck opening 54. only once the neck opening has been sealed is the heat source removed and the axial closing force released.

In order to gain access to the contents of the container 52 the cap 80 must first be removed from the container neck 52 and, if the cap and container neck are provided with tamper evidencing means such as those shown in Figures 6 and 7, this will mean that the tamper evidencing means will also have to be overcome. Once the cap has been removed from the container neck it is then a simple matter for the liner 92 to be pulled away from its adherence to the chimney 58 by grasping and pulling at the tab 132 provided for this purpose.

Upon re-sealing the container once the liner 92 has been removed, the action of applying the cap 80 to the container neck 50 brings the arcuate wall 112 of the annular bead 88 into engagement with the inclined annular surface 62 of the chimney 58. This engagement serves to guide the annular bead 88 into the neck opening 54 and causes the substantially vertical wall 114 to be brought into confronting relationship with the cylindrical surface 66. The mutual abutment of these two surfaces 114 and 66 defines a primary seal which serves to prevent the contents of the container 52 leaking out past the cap 80. The fact that this seal provides an improved performance over the "mini plugs" of the prior art is due to the f act that, because of the increased length of the annular bead

88, the substantially vertical wall 114 is able to abut the chimney 58 in such a way as to be in confronting relationship with a substantial portion if not all of the cylindrical surface 66. While the fact that the annular bead 88 is able to be formed having an increased length is due to those features which enable the cap 80 to be applied to the container neck 50 in an axial movement which can be closely controlled rather than one which requires the cap to be rotated relative to the container neck and which is far more difficult to control.

At the same time as the substantially vertical wall 114 is brought into engagement with the cylindrical surface 66, the radially outwardly and upwardly inclined surface 116 is brought into engagement with the inclined annular surface 62. This engagement forms a secondary annular seal which once again serves to prevent the contents of the container 52 leaking out past the cap 80.

In addition to these primary and secondary seals, the application of the cap 80 to the container neck 50 also brings the second annular bead 90 into engagement with the annular flange 60 to define a tertiary seal. This tertiary seal also serves to prevent the contents of the container 52 leaking out past the cap So.

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Claims

CLAIMS:

1. A closure in combination with a container neck, the container neck defining an annular rim surrounding a neck opening and formed with a chimney projecting upwardly from said rim such that the chimney defines a cylindrical sealing surface surrounding the neck opening, the closure comprising a cap having a top and a downwardly extending skirt portion depending from said top and a liner received within said cap for attachment to the container neck to seal said neck opening, the cap being provided with an annular bead depending from said top and which is shaped such that, when the closure is fully received on the container neck and after the liner has been removed, a radially outer surface of the bead engages the cylindrical sealing surface defined by the chimney.

2. The combination of claim 1, wherein the annular bead is shaped such that, when the closure is fully received on the container neck and after the liner has been removed, the radially outer surface of the annular bead abuts the chimney in such a way as to be in confronting relationship with a substantial portion of the cylindrical sealing surface.

3. The combination of claim 1 or claim 2, wherein the radially outer surface of the annular bead has an axial dimension greater than or equal to that of the cylindrical sealing surface.

4. The combination of any preceding claim, wherein the chimney is provided at an end remote from the rim with a radially outwardly inclined surface and the annular bead is shaped so as to press the liner into engagement with said radially outwardly inclined surface when said closure is initially applied to the container neck.

5. The combination of claim 4, wherein an end of the annular bead remote from said top is provided with a generally radially outwardly inclined surface with which to confront the radially outwardly inclined surface provided on the chimney when said closure is initially applied to the container with the liner disposed between the two.

6. The combination of claim 5, wherein the generally radially outwardly inclined surface provided at the end of the annular bead remote from said top is smoothly curved so as to minimise any damage to the liner as the closure is applied to the container neck.

7. The combination of any of claims 4 to 6, wherein the liner is adapted to adhere to the radially outwardly inclined surface provided on the chimney in order to seal the neck opening.

8. The combination of any of claims 4 to 7, wherein the radially outwardly inclined surface provided on the chimney is shaped so as to guide the radially outer surface of the bead into engagement with the cylindrical sealing surface once the liner has been removed and upon application of the cap to the container neck.

9. The combination of any of claims 4 to 8, wherein the radially outer surface of the annular bead merges with a radially outwardly inclined surface adjacent said top, the radially outwardly inclined surface engaging the radially outwardly inclined surface on the chimney to define a secondary annular seal once the liner has been removed and the closure is fully received on the container neck.

10. The combination of any preceding claim, wherein an end of the annular bead remote from said top is shaped such thatt once the liner has been removed and upon application of the cap to the container neck, the radially outer surface of the bead is guided into engagement with the cylindrical sealing surface.

11. The combination of any preceding claim, wherein the cap is provided with a second annular bead depending from said top and spaced radially outwardly from the first such that, when the closure is fully received on the container neck and the liner has been removed, the second annular bead engages said annular rim to form a tertiary annular seal.

12. The combination of claim 11, wherein said second annular bead is of saw-tooth cross-section.

13. The combination of any preceding claim, wherein the cap and container neck are provided with complimentary engagement means so that the cap may be repeatedly attached and detached from the container neck.

14. The combination of claim 13, wherein the complimentary engagement means are adapted so that the cap may, at least initially, be applied to the container neck by an axial force.

15.The combination of claim 13 or claim 14, wherein the complimentary engagement means comprise tamper evidencing means which must first be overcome before the cap can be detached from the container neck after its initial application.

16. The combination of any preceding claim, wherein the cap is formed of a material which is more flexible than the material from which the container neck is formed.

17. The combination of any preceding claim, wherein the container neck is formed of HDPE and the cap is formed of MDPE or LDPE.

18. The combination of any preceding claim, wherein the liner is retained within the cap by the engagement of the liner with one or more radially inwardly projecting formations provided on an inner surface of the downwardly extending skirt portion.

19. The combination of claim 18, wherein the first annular bead projects downwardly from said top such that an end of the bead remote from the top is spaced a greater distance from the top than the one or more radially inwardly projecting formations which serve to retain the liner within the cap.

20. A closure for use with a container neck defining a neck opening, the closure comprising a cap having a top and a downwardly extending skirt portion depending from said top, and a liner received within said cap for attachment to the container neck to seal the neck opening, the liner being retained within the cap by the engagement of the liner with one or more radially inwardly projecting formations provided on an inner surface of the downwardly extending skirt portion, the cap further comprising an annular bead depending from said top such that an end of the bead remote from the top is spaced a greater distance from said top than the one or more radially inwardly projecting formations which serve to retain the liner within the cap.

21. The closure of claim 20, wherein the annular bead has an axial dimension in excess of 2.Omm.

22. The closure of claim 20 or claim 21, wherein the end of the bead remote from said top is chamfered on a radially outer surface.

23. The closure of any of claims 20 to 22, wherein a radially outer surface of the annular bead merges with a radially outwardly inclined surface adjacent said top.

24. The closure of any of claims 20 to 23, wherein the cap is provided with a second annular bead depending from said top and spaced radially outwardly from the first.

25. The closure of claim 24, wherein said second annular bead is of sawtooth cross-section.

26. The closure of claim 24 or claim 25, wherein said second annular bead projects downwardly from said top to a lesser extent than said first annular bead.

27. A method of applying a closure to a container neck, the container neck defining an annular rim surrounding a neck opening and-formed with a chimney projecting upwardly from said rim, a neck stretch portion below said rim and engagement means provided on an external surface of said neck stretch portion, and the closure comprising a cap having a top, a downwardly extending skirt portion depending from said top, complimentary engagement means provided on an interior surface of said downwardly extending skirt portion, an annular bead also depending from said top and a liner received within the cap for attachment to the container neck to seal said neck opening, the method comprising the steps of presenting the closure to the container neck; applying an axial force to urge the engagement means on the neck stretch portion into engagement with the complimentary engagement means provided on the downwardly extending skirt portion and to cause the annular bead to press the liner against a surface of the chimney; and applying heat to the liner to cause the liner to adhere to the chimney.

28. A closure in combination with a container neck, the combination being substantially as herein described with reference to any of Figures 2-11 of the accompanying drawings.

29. A closure for use with a container neck, the closure being substantially as herein described with reference to any of Figures 3, 6 or 8-11 of the accompanying drawings.

30. A method of applying a closure to a container, the method being substantially as herein described with reference to any of Figures 2-11 of the accompanying drawings.