FIELD OF THE INVENTION

This invention relates to a closure for a container, in particular a wide-mouthed container the contents of which are pressurised, eg a carbonated beverage. It also relates to a closure in combination with a container.

BACKGROUND ART

Closures for wide-mouth containers are known such as those described in the applicants earlier applications, for example WO2006/000774 and WO2011/151630. These seek to provide a closure capable of securely closing a wide-mouth container the contents of which may be at high pressure, eg during transportation and/or when subject to elevated temperatures, whilst remaining relatively easy for a consumer to remove. Further modifications of the closures described in the patent specifications mentioned above are also disclosed in co-pending applications Nos GB1212058.0 and GB1215979.4.

A wide-mouth container can be used both to store a beverage (or other contents) and as a drinking vessel once the closure has been removed. In some cases, the closure may also be designed so it can be used to re-close and/or re-seal the container.

Whilst the closures described in the above documents are satisfactory in many cases, the present invention seeks to provide improvements which improve the

performance of the closure, in particular the ease and reliability of opening, closure and/or re-closure thereof, controlled venting of the container and/or to improve the

manufacturability of the closure. SUMMARY OF INVENTION

According to a first aspect of the present invention, there is provided a closure for a container having a circular opening defining an axis and a lip around said opening, the closure comprising: an inner component having a collar portion for locating about the exterior of the container beneath the lip of the container; and an outer component for fitting over the inner component and interacting therewith for releasably securing the collar portion under the lip, the collar portion comprising a ring and a plurality of spaced apart radially moveable parts around it circumference joined at their lower ends to the ring and a plurality of spaced apart upstands on the ring interposed between said radially moveable parts, the outer component comprising a cap having an upper part for closing the mouth of the container and a skirt part depending therefrom for fitting around said collar portion, the skirt part having spaced apart features projecting from its inner surface for interacting with the collar portion such when the cap is in a first (closed) rotational position relative to the collar portion, substantially radially inward facing surfaces of said features are aligned with said radially moveable parts so as to secure them beneath the lip of the container and, when the cap is in a second (open) rotational position relative to the collar portion, said substantially radially inward facing surfaces are no longer aligned with said radially moveable parts and said upstands on the collar engage substantially axially facing surfaces of said spaced apart features so as to limit axial movement of the collar portion into the cap.

The first aspect of the invention thus provides a cap-on-collar closure in which in which the appropriate relative axial and/or rotational positions of the inner and outer components are more reliably maintained during the opening and/or closing process so the closure can be more easily and reliably operated. In particular, it helps ensure that when the closure is removed from the container, the first and second components are maintained in appropriate axial and/or rotational positions relative to each other to facilitate easy refitting of the closure to the container.

According to a second aspect of the invention, there is provided a container having a circular opening defining an axis and a lip around said opening and a closure for closing said opening comprising: an inner component having a collar portion for locating about the exterior of the container beneath the lip of the container; and an outer component for fitting over the inner component and interacting therewith for releasably securing the collar portion under the lip, the collar portion comprising a ring and a plurality of spaced apart radially moveable parts around it circumference joined at their lower ends to the ring, the outer component comprising a cap having an upper part for closing the mouth of the container and a skirt part depending therefrom for fitting around said collar portion, the upper part including, or having attached thereto, a bore feature which, in use, extends into the mouth of the container, the bore feature being adapted to carry an o-ring for providing a seal between the bore feature and an inner surface of the container and the skirt part having spaced apart features projecting from its inner surface for interacting with the collar portion such when the cap is in a first (closed) rotational position relative to the collar portion, substantially radially inward facing surfaces of said features are aligned with said radially moveable parts so as to secure them beneath the lip of the container, the inner surface of the container having a lead-in surface adjacent said opening and a plurality of spaced apart venting grooves in said lead-in surface to facilitate venting of the container as the o-ring is withdrawn therefrom.

Thus, this second aspect of the invention enables a container and closure to be provided in which:

a) The closure comprises a cap-on-collar closure in which radially moveable parts of the collar are secured beneath the container lip by radially inward facing surfaces of the skirt portion of the cap (so the closure can be secured to the container without the need for thread features on the exterior of the container), b) The cap carries a bore feature for extending into the mouth of the container and is adapted to carry an o-ring for sealing with an inner surface of the container (so a reliable seal is provided between the cap and the container), and c) The container has venting grooves in a lead-in surface to facilitate controlled venting of the container as the cap is loosened and the o-ring seal is released (but before the cap is free to be removed from the container).

It will be appreciated that in this arrangement, the bore feature (and o-ring carried thereby) is part of (or is secured to) the outer component, ie the cap. This second aspect of the invention preferably also has the plurality of spaced apart upstands on the collar ring interposed between said radially moveable parts as described above in the first aspect of the invention. However, in other embodiments of the second aspect of the invention, these upstands on the ring may be omitted (so the collar portion is more similar to the collar portion of other cap-on-collar closures such as those described in the prior art referred to above).

A preferred embodiment of the container has an outwardly projecting lip and a plurality of spaced apart cam features beneath the lip which comprise a first side face for limiting rotation of the inner component in the tightening direction relative to the container and a second side face for driving the radially moveable parts radially outwards when the inner component is rotated in the loosening direction relative to the container. The lip is preferably shaped such that its external diameter decreases towards the open end of the container and the cam features each have an outwardly facing surface between said side surfaces which blends with the contour of the lip and which lie at a diameter corresponding to or marginally greater than the maximum external diameter of the lip. The outwardly facing surface preferably has a width (in the circumferential direction) of 2mm or less, and preferably 1mm or less, so as to be sufficiently small so that it is not felt or noticed by the mouth of a user drinking from the container.

The inner surface of the container preferably comprises a frusto-conical lead-in surface adjacent the circular opening, the surface of which is inclined to the axis of the container. The lead-in surface preferably leads to a substantially parallel-sided cylindrical surface, the surface of which lies substantially parallel to said axis. The diameter of the cylindrical surface is substantially the same as the smaller (lowermost) end of the frusto- conical surface. As will be described further below, a plurality of spaced apart venting grooves are provided in the lead-in surface to assist venting of the container, the grooves extending from the interior of the container towards the mouth of the container.

According to a third aspect of the invention there is provided a closure for a container having a circular opening defining an axis and a lip around said opening, the closure comprising: an inner component having a collar portion for locating about the exterior of the container beneath the lip of the container; and an outer component for fitting over the inner component and interacting therewith for releasably securing the collar portion under the lip wherein the outer component is formed of a plastics material comprising polyoxymethylene (POM). The inner component of such a closure is preferably formed of a plastics material comprising polyethylene terephthalate (PET).

The third aspect of the invention enables a closure to be provided with improved stiffness and which is better able to retain its strength at elevated temperatures. POM is also self-lubricating and has good moulding properties in that it can be 'sprung' out of a mould whilst retaining its moulded shape well. The third aspect of the invention can also be used in conjunction with features of the first and/or second aspects of the invention, in particular:

a) a plurality of spaced apart upstands on the collar portion ring interposed

between radially moveable parts thereon to enable appropriate relative axial positioning of the inner and outer components to be more reliably maintained during the opening and/or closing process;

b) a bore feature carried by the outer component for extending into the mouth of the container and adapted to carry an o-ring for sealing with an inner surface of the container (so a reliable seal is provided between the cap and the container), and/or;

c) venting grooves in a lead-in surface of the container to facilitate controlled venting of the container as the cap is loosened and the o-ring seal is released (but before the cap is free to be removed from the container).

According to a further aspect of the invention, there is provided a closure for a container having a circular opening defining an axis and a lip around said opening, the closure comprising: an inner component having a collar portion for locating about the exterior of the container beneath the lip of the container; and an outer component for fitting over the inner component and interacting therewith for releasably securing the collar portion under the lip, the collar portion comprising a ring and a plurality of spaced apart radially moveable parts around it circumference joined at their lower ends to the ring, the radially moveable parts being arranged to snap-fit beneath the lip of the container when the inner component is fitted onto the container, the outer component comprising a cap having an upper part for closing the mouth of the container and a skirt part depending therefrom for fitting around said collar portion, the inner component being a snap-fit within the outer component such that the skirt part covers the ring, the upper part including, or having attached thereto, a bore feature which, in use, extends into the mouth of the container, the bore feature being adapted to carry an o-ring for providing a seal between the bore feature and an inner surface of the container, the skirt portion having spaced apart projecting features on its inner surface for interacting with the collar portion such when the cap is rotated relative to the collar to a closed position, said projecting features secure said radially moveable parts beneath the lip of the container and when the cap is rotated to an open position relative to the collar, said radially moveable parts can be driven outwards by features on the container to disengage from the container lip.

Thus this further aspect of the invention enables a closure to be provided in which: a) the collar portion being a snap-fit within the cap;

b) the cap having a bore feature adapted to carry an o-ring; c) the radially moveable arms being biased inwards so the collar portion is a snap- fit over the container lip;

d) the provision of cam features under the container lip for driving the radially moveable arms outwards when the cap is rotated in the loosening direction. Preferably, this further aspect of the invention also has means for retaining the inner and outer components in a desired axial and/or rotational position relative to each other upon removal of the closure so as to facilitate re-fitting of the closure to the container by the user.

Directional terms, such as upwards, downwards, upper and lower, as used herein are to be understood to refer to refer to directions relative to a container standing on a horizontal surface with the axis passing through its opening being substantially vertical (unless the context clearly requires otherwise).

The invention also relates to a closure according to the first aspect of the invention in combination with a container and to such a closure mounted on a container so as to close the container. Other preferred and optional features of the invention will be apparent from the following description and from the subsidiary claims of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, merely by way of example, with reference to the accompanying figures, in which:

Figures 1 A and IB are perspective views from beneath and above of an outer component of an embodiment of a closure according to the first aspect of the invention;

Figures 2A and 2B are perspective views from beneath and above of an inner component of an embodiment of a closure according to the first aspect of the invention;

Figure 3 is a cross-sectional view of the outer component shown in Figure 1;

Figure 4 is a cross-sectional view of the inner component shown in Figure 2;

Figures 5 A and 5B are sectional and part-perspective views of the inner and outer components of Figures 1 and 2 assembled together in a first (fully closed) rotational position relative to each other;

Figures 6 A and 6B correspond to Figures 5 A and 5B but show the inner and outer components as they are beginning to be rotated from the first (closed) position towards a second (open) position; Figures 7A and 7B correspond to Figures 6A and 6B but show the inner and outer components as they are rotated further from the first (closed) position towards the second (open) position;

Figure 8 is an underside sectional view of the closure shown in Figs 5 to 6 when almost in the second (open) position with part thereof shown in detail A;

Figures 9A and 9B correspond to Figures 7A and 7B but show the inner and outer components when they have reached the second (open) position;

Figure 10 is a underside sectional view of the closure corresponding to Figure 8 when the inner and outer components are in the second (open) rotational position shown in Fig 9 with part thereof shown in detail B;

Figures 11 A and 1 IB are a perspective views from above and below of the mouth of a first wide mouth container to which the closure is designed to be fitted and Fig 11C is a cross-sectional view thereof;

Figure 12 is a perspective view of the open end of a second, modified form of the container shown in Fig 11 to which a closure such as that shown in Figs 1 to 10 may be fitted according to the second aspect of the invention;

Figure 13A, 13B and 13C are enlarged views showing detailed features of the lip of the container of Fig 12, Fig 13 A being a vertical section through the lip, Fig 13B being a horizontal section through the lip and Fig 13C being a side view of the lip; and

Figure 14A is a side view of the container of Fig 13 and Fig 14B a cross-sectional view thereof.

DETAILED DESCRIPTION OF THE EMB ODEVIENT S

Figures 1 and 2 shows perspective views from above and below of an outer and an inner component of a closure according to a preferred embodiment of the first aspect of the invention. Such a closure may also be used in the second aspect of the invention described further below.

Figures 11 A-l 1C illustrate a container 30 to which the closure can be fitted. The container has a circular opening 31 defining an axis A and has a lip 32 around the opening 31. A number of small cam features 33 are provided under the lip 32. One side 33 A of each cam feature comprises an inclined surface in the form of a ramp and the other side 33B a surface which is substantially perpendicular to the wall of the container 30. These features 33 are similar to those described in some of the prior art mentioned above and described in more detail in GB1212058.0. A lead in surface 34A adjacent the opening 31 leads to the internal surface 34 of the container.

The container 30 has an opening 31 the periphery of which defines a plane perpendicular to the axis A of the container. The diameter of the opening of a wide-mouth container is typically in the range 55 - 65 mm.

The container 30 is typically formed of a plastics material, eg polyethylene terephthalate (PET), and formed by injection moulding followed by blow moulding, or may be formed of glass or a wide range of other materials, eg metal formed by pressing and drawing operations. The use of such materials and such fabrication techniques are well known.

A further modification of the container is shown in Figs 12 to 14 (which are described further below).

The outer component is in the form of a cap and comprises an upper part 10 which, in use, extends across and closes the opening of a container (not shown) and a skirt part 11 depending from the periphery of the upper part 10. As shown in Fig 1 A, the outer component also has a plurality of circumferentially spaced apart features 12 projecting from its inner surface. Although of slightly different form, these have camming features 12A and thread features 12B corresponding to those described in the prior art mentioned above. Recesses 13 are formed between the spaced apart features 12. The thread features 12B shown differ from those of the prior art in that they do not extend across the recesses 13 between the respective spaced apart features 12. The upper part 10 may be substantially flat as shown on may have other forms, eg a convex or concave shape.

Figure 1 A also shows a plurality of snap-in features 14 adjacent a distal end of the skirt part 11 and a plurality of retention features 15 at spaced apart position around the interior of the cap. The function of these will be described further below. Figure 1 A also shows a seat or gland for receiving an o-ring, this being defined at its lower edge by an inclined flange 16 comprising a plurality of smaller flange parts separated from each other by slots. This flange 16 is better shown in Figure 3.

The inner component, also referred to as a collar portion 20, is shown in Figure 2.

The collar portion comprises a ring 21 and a plurality of circumferentially spaced apart radially moveable parts 22 joined at their lower ends to the ring 21. As in the prior art described above, the collar portion is used to releasably secure the cap to a container. In the embodiment described, the radially moveable parts 22 are inclined inwardly so the collar is a snap fit over the lip of a container, the radially moveable parts 22 being flexed outwardly as the collar 20 is pushed over the lip 32 of the container 30 and then snapping back inwards to as to be located beneath the lip 32 of the container. The radially moveable features also have thread features 24 on their outer faces for engaging the thread features 12B of the cap referred to above.

An important novel feature of the closure described in relation to Figs 1 to 10 in relation to the first aspect of the invention is the provision on the collar ring 21 of spaced apart upstands 23, the examples shown having an inclined upper edge so as to have a substantially triangular shape, interposed between the radially moveable parts 22. The function of these upstands 23 will be described further below.

In addition, the collar portion is provided with a plurality of circumferentially spaced apart inward projections 26, in the form of ribs projecting radially inwards from the ring 21. The example shown has sixteen such projections 26 at uniform angular intervals around the ring 21. The collar portion also has a plurality of spaced apart retention features 25 projecting radially outwards from the ring 21. The embodiment shown has four such retention features 25 spaced at 90 degree intervals around the ring 21.

The collar portion is designed to be fitted about the exterior of a container 30 beneath the lip 32 of the container, and the cap can be releasably secured thereto to close the container, the cap thus being secured to the container 30 via said collar portion rather than via a thread provided on the exterior of the container 30. Further details of such a cap-on-collar arrangement are provided in the prior art documents referred to above.

The collar portion 20 is designed to be fitted within the cap. The cap and collar portion may be pre-assembled and then fitted to a container 30. Alternatively, the collar portion 20 may be fitted to the container 30 first and the cap portion then fitted over the container mouth and the collar portion 20. The collar portion 20 is preferably a snap-fit within the cap, an outwardly projecting flange 21 A at the bottom edge of the collar ring 21 being a snap fit with the snap-in features 14 of the cap mentioned above. The cap and collar portion are assembled together first by axial movement during this snap-fitting and then by rotation of the cap relative to the collar portion about the axis A (the thread features 12B and 24 thus provide a form of bayonet-thread connection between the cap and the collar portion). As shown in the illustrated embodiment, the skirt portion of the cap preferably covers and conceals the collar portion.

The thread features mentioned above provide a multi-start threaded connection therebetween and, in the arrangement shown, having eight radially moveable parts;

rotation through about 45 degrees being sufficient to secure the cap and collar portion together. The cap is rotatable between a first rotational position, referred to herein as the 'closed' position, which is the rotational position in which the cap and collar portion are fully secured together and the closure secured to (and sealing) the container, and a second rotational position, herein referred to as the Open' position, which is the position in which the closure can be removed from the container (and re-fitted thereto).

When the cap and collar portion are in the first rotational position, the substantially radially inward facing cam surfaces 12A of the features 12 are rotationally aligned with the radially moveable parts 22 of the collar portion and interact therewith to urge and/or hold said parts to secure them beneath the lip 32 of the container 30.

When the cap and collar are in the second rotational position, the cam surfaces 12A are no longer aligned with the radially moveable parts 22. Instead, the recesses 13 are aligned therewith so that the radially moveable parts 22 can be flexed radially outwards (by interaction with the cam features 33 beneath the lip 32 of the container 30 as described below) so they can be disengaged from the lip 32 of the container.

When the cap and collar portion are initially assembled together axially, it is desirable for the cap and collar portion to be in an orientation corresponding to the second (open) rotational position, the radially moveable parts 22 in this position being aligned with the recesses 13 in the cap as mentioned above. Once axially assembled, the cap can be rotated relative to the collar portion so that the features 12 become aligned with the radially moveable parts 22 to urge and/or hold the radially moveable parts in an inward position beneath the lip of the container. These functions are similar to those described in the prior art referred to above.

As the cap is rotated to the first position, the threaded engagement with the collar portion moves the cap and collar portion together axially. In use, this draws the collar portion up tightly beneath the lip 32 of the container 30 and draws the cap downwards so an o-ring seal 18 carried thereby (described further below) engages an internal surface of the container (as described further below). Alternatively, in cases in which such an o-ring seal is not used, the cap is drawn down into engagement with the lip 33 of the container either directly or via a sealing component (not shown) therebetween. This sealing component may be provided on the cap or may be a separate component sandwiched between the cap and the container lip.

The function of the upstands 23 will now be described with reference to Figures 5 -

10. When the cap is moved from the first (closed) position to the second (open) position, ie when it is loosened so that the closure can be removed from the container, it is highly desirable that the cap and collar portion are retained in the second position so that, if required, the closure can be easily re-fitted to the container. As the cap is rotated to the second position, the cap and collar move axially relative to each other in the direction that would eventually separate them (although in practice the collar portion is held captive within the cap by the snap-in features 14) and it is desirable to keep the cap and collar portion in this axially 'separated' position (rather than the collar portion being able to move axially further into the cap or to become tilted within the cap). This is the function of the upstands 23. As the cap is rotated away from the first position, the upper edges of the respective upstands 23 engage the undersides of the features 12 as shown in Fig 6 to limit axial movement of the collar portion 20 relative to the cap.

Figure 7 shows the position following further rotation in the loosening direction (ie towards the second rotational position) and Fig 9 shows the position when the second rotational position has been reached. It will be appreciated that the engagement between the upstands 23 and the underside of the features 12 prevents the collar portion 20 moving axially into the cap and holds the cap and collar portion in the axially 'separated' position. The engagement of a plurality of upstands 23 with a plurality of the features 12 at circumferentially spaced positions also serves to prevent the collar portion 20 from tilting, ie the ring 21 of the collar is maintained parallel to the distal end of the skirt 11.

As mentioned above, the spaced apart features 12 of the skirt portion may comprise both a camming feature 12A and a thread feature 12B. In the arrangement shown, the underside of the feature 12 is provided by the underside of said thread feature 12B.

An additional function of the upstands 23 on the collar ring 21 is to limit rotation of the cap beyond the first position in the tightening direction. When the cap reaches the first position, the upstands 23 are arranged to engage sides of the spaced apart features 12 of the skirt portion as shown in Fig 5 so the cap cannot be rotated further in that direction relative to the collar portion. In use, the radially moveable parts 22 of the collar portion also engage the stop surfaces 33B of the features beneath the lip of the container in this closed position so that the further rotation of the collar portion in the tightening direction relative to the container is also prevented.

When the cap and collar portion are in the second (open) position for removal of the closure from the container, it is also desirable to releasably hold them in this position to ensure that the first and second parts are maintained in the appropriate positions relative to each other to enable the closure to be easily re-fitted to the container. This function is provided by the retention features 15 and 25 on the cap and collar portion referred to above. Their function is illustrated in Figs 8 and 10. The retention features 15 and 25 are positioned such that they engage each other (as shown in Fig 8) as the cap and collar approach the first rotational position (the cap rotating clockwise relative to the collar portion in the view from beneath shown in this Figure) and then ride over each other to the position shown in Fig 10 as the first rotational position is reached.

The cap cannot thus be rotated back towards the first rotational position (ie in the anti-clockwise direction in the underneath view shown in Fig 10) without applying sufficient rotational torque to enable the retention features 15 and 25 to ride back over each other (to the position shown in Fig 8). The retention features 15 and 25 thus serve to releasably retain the cap and collar portions in the second rotational position until a user provides the rotational torque required to overcome this retention.

The closure thus has features which maintain the relative axial and rotational positions of the inner and outer components in the second rotational position. As mentioned this is particularly desirable to facilitate easy re-fitting of the closure to a container after its initial removal.

In the embodiment illustrated in Fig 5 A (and Fig 6A and 7A and Fig 9), the outer component also comprises a bore feature 17 which has a groove or gland in the outer surface thereof for holding an o-ring seal 18. When the closure is mounted to a container 30, the bore feature 17 projects into the mouth of the container 30 so that the o-ring 18 sealingly engages an internal surface 34 (see Fig 11) of the container 30. The bore feature 17 is preferably integrally formed with the outer component but may also be a separate item mounted to the outer component. Such an arrangement is described further in some of the prior art documents referred to above (although in some of the prior art, a different arrangement is used in which the bore feature is part of the inner component rather than the outer component).

The gland in which the o-ring 18 is located comprise an L-shaped groove in the outer surface of the bore feature 17 and the flange 16 mentioned above. As shown in Figs 5 A and 5B, the flange 16 comprises a plurality of flange parts which are angled so as to extend outwards at approximately 45 degrees to the horizontal. Each flange portion may have a length (from its connection to the bore feature to its distal end) of 0.5 mm or less. This arrangement has two particular advantages. First, the gland and the angled flange 16 are easier to form in a moulding operation (particularly if formed of a material such as POM - see below) as the flange 16 is sufficiently flexible that is can be sprung out of a mould. The gland can thus be formed in a 'line and draw' moulding process without the need to use collapsing cores. This greatly simplifies the manufacture of the cap. Secondly, the flange 16 is designed so that the o-ring 18 is a snap-fit over the flange. The flange also acts to retain the o-ring 18 in the gland when the bore feature is withdrawn from the container (when the closure is removed from the container).

As mentioned above, the collar portion also preferably has a plurality of

circumferentially spaced inwardly projecting engagement features 26 in the form of ribs provided on the ring 21. These are provided so that when the collar portion is located about the exterior of the container (prior to fitting the outer component over the inner component), the engagement features 26 limit the axial movement of the inner component down the container neck (away from the container opening). This may be achieved by means of the engagement features engaging the exterior of the container as the diameter of the container increases away from the container opening) or engaging a shoulder (or other projection) of the container neck.

In an alternative arrangement (not shown), the engagement features may comprise a plurality of circumferentially spaced apart hook features which extend upwards from the collar portion (from the collar ring or from the radially moveable parts) so as to engage an upper surface of the container lip (so that the collar portion effectively hangs from the lip).

In a further arrangement (not shown) the upper part 10 of the cap is preferably part domed shaped as described in GB1215979.4. In this arrangement, an outer portion of the upper part 10 of the cap is preferably inclined upwardly at its periphery by an angle in the range 5 - 30 degrees and preferably in the range 10 to 20 degrees. If the upper part 10 is curved, this is the angle of a tangent to the curve at the periphery of the outer portion thereof. The central portion of the upper part may be flat. The upper part 10 thus extends away from the container opening (when mounted thereon) so the central portion thereof is spaced from (but substantially parallel to) the opening of the container.

In order to release the closure and open the container, the cap is rotated from the first position to the second position. During this rotation, the cap rises slightly (due to the threaded engagement with the collar portion). This initial rotation of the cap also rotates the bore feature and hence the o-ring and this help breaks the seal between the o-ring and the container and thus makes it easier to withdraw the o-ring from the container. If a carbonated beverage is housed in the container, the internal pressure also helps lift the cap. When the o-ring disengages from the parallel sided portion of the inner face 34 of the container and reaches the lead-in portion 34A thereof, an elevated pressure within the container may be sufficient to lift at least part of the o-ring away from the lead-in surface 34 so this excess pressure is vented.

As the cap is further rotated to the second position, the radially moveable arms 22 are driven outwards by engagement with the ramps 33 A of the cam features 33 under the lip 32 of the container, into the recesses 13 in the cap so engagement of the collar with the underside of the lip of the container is released. It should be noted that this occurs after the venting referred to above. Thus, while venting takes place, the collar, and hence the closure, is still securely retained on the container.

In some cases, the engagement of the upstands 23 with the underside of the features 12 may also help lift the cap as the cap is rotated in the loosening direction.

Figures 12 to 14 show a modified form of the container 40. The principal modification is the provision of venting grooves 44B in a lead-in surface 44A to further promote venting as the o-ring is withdrawn from the container 40. It is likely that the venting will be audible so the user is aware that the excess pressure is being released. The user can thus wait until this venting has completed before rotating the outer component further in the loosening direction.

It is important to note that in this venting position, the collar portion remains secured beneath a lip 42 of the container 40 so there is no risk of the inner component (and hence the closure) being ejected in an uncontrolled manner due to the excess pressure within the container or as this is released. The venting grooves 44B referred to above are shown in Fig 12. A plurality of grooves 44B are provided at spaced apart positions around the circumference of the lead-in surface 44A. Each groove is typically 0.5 to 1.0 mm wide (and the upper end may be wider than the lower end as shown) and approx 2 to 3mm long and have a depth of around 0.2 mm (the ratio of the width to depth typically being in the range 3 : 1 to 4: 1). It is found that these grooves 44B facilitate a more reliable and controllable venting of the container 40 as the o-ring moves from the parallel sided surface 44 to the lead-in surface 44A as the o-ring is withdrawn from the container 40.

Once venting has completed, or has subsided to a safe level, the outer component can be rotated further to effect disengagement of the inner component from the lip of the container and subsequent removal of both the inner and outer components.

The closure is thus arranged to enable it to securely close the container whilst being relatively easy to remove, removal being effected by initial rotation of the closure in a loosening direction until the inner component engages the cam features 43 of the container 40, rotation of the outer component in the loosening direction relative to the collar portion to a venting position, venting of the container 40, further rotation of both the inner and outer components together in the loosening direction, whereby the collar portion is disengaged from the container by the cam surfaces 43 A of the cam features 43 of the container, and axial disengagement of the o-ring from the container 40.

The container is shown in more detail in Figs 13 and 14. As mentioned above, a plurality of spaced apart cam features 43 are provided beneath the lip 42 of the container 40. The cam features 43 comprise two side faces, one 43 A substantially perpendicular to the outer surface of the container 40 and the other 43B inclined thereto, and a small outwardly facing surface 43C joining these two side faces 43 A, 43B. As described above, the cam features 43 provide two main functions. First, they limit the rotation of the inner component in the tightening direction (clockwise in the example shown) by virtue of the side faces 43 A that extend radially and thus lie substantially perpendicular to the outer surface of the container. As the inner component is rotated in the tightening direction, the sides of the radially moveable arms engage these side faces 43 A so that further rotation of the inner component in the tightening direction is arrested. Second, they drive the radially moveable arms of the inner component outwards as the inner component is rotated in the loosening direction (anticlockwise in the example shown) by virtue of the cam surfaces 43B, eg in the form of ramps, on the other side of the cam feature 43. As the inner component is rotated in the loosening direction, the radially moveable arms engage and ride up these ramps 43B until they rest on the outwardly facing surface 43 C. This outwardly facing surface 43C blends with the contour of the container lip 42 and is at a diameter corresponding to (or marginally greater) the maximum external diameter of the container lip 42.

The radially moveable arms are thus driven outwards (against the resilience of the arms and/or their connection to the ring of the collar portion) to a position in which they are disengaged from the underside of the lip and rest on the outer surfaces 43C of the cam features 43. The inner component is thus released from its securement beneath the lip of the container 40 and is free to move axially in an upward direction and thus to be removed from the container 40. This upward movement is preferably assisted by the contour of the lip 42 the diameter of which decreases towards the open end of the container 40. As the radially moveable arms are flexed outwards, they have a natural tendency to revert to their unstressed positions so have a tendency to slide upwards on the surfaces 43 C and lip 42 to move to a more inward radial position. If the container houses a sparkling drink, the pressure within the container may also assist is moving the inner component upwards once the radially moveable arms have disengaged from the underside of the container lip.

It is desirable to minimise the size of the cam features 43 so they have minimal, or negligible, effect upon the drinking experience of the user. The outer surface 43 C of the cam features 43 is thus preferably less then 2mm wide and more preferably less than 1mm wide so that, when viewed from beneath, the cam features 43 have an essentially triangular form (as shown in Fig 13B). It is found that with cam features of this small size they are not noticed or felt by the user's lip when drinking from the container.

As described above, to release the closure from the container, the outer component is rotated in the loosening direction relative to the inner component. This causes the cam surfaces to move out of engagement with the radially movable arms and brings the deep pockets in alignment therewith so the arms are able to move outwards. The arms can then be driven outwards to disengage them from the underside of the lip 42. The user can then pull the closure axially upwards to withdraw the bore component (and the o-ring) from the container 40 (if it is not ejected by pressure within the container). The inner and outer components are thus removed as one component, the snap-in features of the outer component engaging the underside of the outwardly projecting flange of the inner component so an upward force applied to the outer component applies an upward force to the inner component.

The closure is preferably formed of plastics material, eg by injection moulding, suitable materials include polyethylene terephthalate (PET). A preferred material is a stiffer plastics material, eg polyoxymethylene (POM) (preferably in homopolymer form). POM is significantly stiffer than PET, is more heat stable (so retains it strength better at high temperatures, which is important if the container and its contents are subject to pasteurisation) and is self-lubricating. It also has good moulding properties as it is able to 'spring' out of a mould and retains its moulded shape well. Indeed, the third aspect of the invention is for a cap-on-collar closure in which the outer component (the cap) is formed of a plastics material comprising polyoxymethylene (POM) (preferably in homopolymer form).

The closure may also be formed of other materials, eg metal.

The use of a stiffer plastics material such as POM also enables less plastic material to be used. Another way to minimise the use of plastics material is for the skirt portion of the cap to have a substantially uniform wall thickness so the external shape follows closely the shape of features described above on the interior of the skirt portion. The shape of the features 12 and recesses 13 thus, in effect, provide the external shape of the cap which assist the user in gripping and rotating the cap.

Key features of the embodiments described above and the second aspect of the invention include:

a) The cap having a bore feature adapted to carry an o-ring;

b) The interaction of the camming surfaces in the skirt of the cap with the radially moveable arms so as to secure these under the lip of the container; c) Venting grooves being provided in a lead-in surface of the container to

facilitate controlled venting as the o-ring is withdrawn from the container. Preferably with one or more of the following features:

d) The radially moveable arms being biased inwards so the collar portion is a snap-fit over the container lip; e) The provision of cam features under the container lip for driving the radially moveable arms outwards when the cap is rotated in the loosening direction; f) The cap being formed of POM and/or;

g) Means for retaining the inner and outer components in a desired axial and/or rotational position relative to each other upon removal of the closure so as to facilitate re-fitting of the closure to the container by the user.

Key features of the embodiments described above and the further aspect of the invention include:

h) The collar portion being a snap-fit within the cap;

i) The cap having a bore feature adapted to carry an o-ring;

j) The cap being formed of POM;

k) The radially moveable arms being biased inwards so the collar portion is a snap-fit over the container lip.

The provision of cam features under the container lip for driving the radially. For the avoidance of doubt, the verb "comprise" as used herein has its normal dictionary meaning, ie to denote non-exclusive inclusion. The use of the word "comprise" (or any of its derivatives) does not therefore exclude the possibility of further features being included.

All of the features disclosed in this specification (including the accompanying claims, and drawings) may also be combined in any combination (other than combinations where the features are mutually exclusive).

Each feature disclosed in this specification (including the accompanying claims and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is just an example of a generic series of features providing an equivalent or similar function.

The invention is not restricted to the details of the embodiments described. The invention extends to a cap-on-collar closure which comprises inner and outer components and one or more of the key features referred to above, or any other novel concept, feature, or combination of the features disclosed herein.

Also, should any of the claimed inventions only be entitled to partial priority, the relevant claim is to be interpreted as comprising two parts, a first part relating to matter entitled to a first priority date and a second part relating to matter entitled to a second priority date.