GB2454511A

GB2454511A - Tamper evident container closure with overcap

Info

Publication number: GB2454511A
Application number: GB0722052A
Authority: GB
Inventors: Roger Milner King
Original assignee: Beeson and Sons Ltd
Current assignee: Beeson and Sons Ltd
Priority date: 2007-11-09
Filing date: 2007-11-09
Publication date: 2009-05-13
Anticipated expiration: 2027-11-09
Also published as: WO2009060207A1; JP2011502894A; JP5228057B2; GB0722052D0; US20110024420A1; GB2454511B; EP2212213A1

Abstract

A container closure comprising: a plastics inner cap (2, fig 2) having a base portion (4, fig 2) and a skirt portion 5, a thread 10 on the inside of the skirt portion, a first snap fitting element (11, fig 2) on the outside of the skirt portion, and a tamper evident ring (6, fig 2) formed integrally with the skirt portion and joined to an open end of the skirt portion by severable connections; a plastics overcap 3 having a base and a skirt (26, fig 2) portion in mating engagement with the skin portion of the cap and extending beyond the open end of the skirt portion of the cap to at least partially cover the tamper-evident ring, and a second snap fitting element (31, fig 2) on the inside of the skirt that engages with the first snap fitting element on the inner cap skirt to resist separation of the overcap from the inner cap. Also provided, is a closure assembly comprising a threaded container neck and a container closure according to the invention. The overcap may be shaped to resemble the top of a champagne bottle and cork assembly. The neck and closure may be arranged to provide a vent for venting gas from the container neck upon unscrewing of the closure.

Description

I

CONTAINER CLOSURE WITH OVERCAP

The present invention relates to a container closure with an overcap, and to container assemblies sealed with such a closure.

It is known to provide a plastics overcap for conventional, metal, screw-top closures, wherein the overcap is shaped to simulate a champagne cork. The overcap forms an interference fit over the screw-top closure, and the assembly is then wrapped in foil to provide a simulated champagne cork closure assembly. These assemblies are popular for small (l75m1) champagne bottles, especially for airline service. Overcaps of this type are available under the Registered Trade Marks CHAMPLAST and TOPCAP 28.

These overcaps are quite crude. In particular, they completely cover the tamper-evident ring of the screw-top closure, whereby there is no visible indication of whether the tamper-evident ring is intact. Furthermore, the overcaps must be fitted onto the bottles in a separate step after the step of attaching the screw-top closure and securing the tamper-evident ring.

In a first aspect, the present invention provides a container closure comprising: a plastics inner cap having a base portion and a skirt portion, a thread on the inside of the skirt portion, a first snap fitting element on the outside of the skirt portion, and a tamper evident ring formed integrally with the skirt portion and joined to an open end of the skirt portion by severable connections; a plastics overcap having a base and a skirt portion in mating engagement with the skirt portion of the cap and extending beyond the open end of the skirt portion of the cap to at least partially cover the tamper-evident ring, and a second snap fitting element on the inside of the skirt that engages with the first snap fitting element on the inner cap skirt to resist separation of the overcap from the inner cap.

In a second aspect, the present invention provides a container and closure assembly comprising a plastics closure according to the first aspect of the invention, and a container having a neck, wherein the neck comprises a neck thread on an outer surface thereof and a flange located below the neck thread, and wherein the closure is secured in seating engagement on the neck by engagement of the thread on the inner cap with the neck thread, and wherein the tamper-evident ring is retained below the flange.

The use of plastics to form both the overcap and the inner cap enables the provision of snap-fitting elements to retain the overcap on the inner cap, thereby removing the need for a foil over-wrap in the final assembly. In addition, the closure can be made with a clearance between the overcap and the tamper-evident ring, whereby the tamper-evident ring is free to drop away from the closure after opening to give a clear indication of tampering. Finally, the closure can be assembled prior to capping of the bottles, and the capping can be performed in one step by screwing the closure including the overcap directly onto the bottle.

Suitably, both the inner cap and the overcap are formed from a thermoplastic such as polyethylene or poly propylene, for example by injection moulding. Suitably, both the inner cap and the outer cap are molded in one piece. This simplicity of manufacture is a further advantage of the assemblies according to the invention.

Suitably, at least a region of the interior surface of the overcap abuts against the base of the inner cap when the overcap is secured on the inner cap by the snap fittings. This prevents the overcap from being forced too far onto the inner cap. The overcap, and also optionally the inner cap, may be formed from gold-or silver-colored plastics andlor suitably decorated, as described further below.

Suitably, the overcap is shaped to resemble the top of a champagne bottle and cork assembly. That is to say, the base of the overcap is shaped to resemble the top of a champagne cork and the skirt of the overcap is shaped to resemble the top of a champagne bottle. In this way, the container sealed with the closure assembly can resemble a champagne bottle, especially if the overcap is formed from gold-or silver-colored plastics and/or suitably decorated. The overcap may also have a surface profile simulating the wire on a champagne bottle and cork assembly. The container and closure assemblies of the invention may further comprise a champagne-style foil over-wrap, but preferably they do not. The use of suitably coloured plastic to form the overcap and optionally also the inner cap enables the use of a foil over-wrap to be dispensed with.

Suitably, an outer surface of the skirt of the inner cap is provided with one or more longitudinally extending projections or recesses, and an inner surface of the overcap is provided with one or more complementary recesses or projections for engagement with the said projections or recesses on the inner cap to transfer rotational force from the overcap to the inner cap for opening of the assembly. Suitably, the projections on the inner cap comprise a plurality of longitudinal ribs or recesses that engage with complementary recesses or ribs on the inside of the overcap skirt.

Suitably, the first snap fitting element comprises a circumferential projection, such as a circumferential rib or flange on the inner cap, and the second snap fitting element comprises a circumferential recess on the inside of the skirt of the overcap. The circumferential projection may, for example, be located proximate to the bottom of the inner cap skirt, so that it looks like a conventional cap skirt that having a flange at the bottom. In alternative embodiments, one or more recesses may be provided on the outside of the skirt of the inner cap for snap-fitting with complementary projections on the inside of the overcap skirt.

The skirt of the overcap extends down to at least partially cover the tamper-evident ring.

This helps to give the closure assembly a more natural champagne-bottle appearance.

Suitably, there is a clearance between the skirt of the overcap and the tamper-evident ring so that the tamper-evident ring can drop clear of the overcap following separation of the ring from the skirt of the inner cap. Suitably, the container neck extends below the tamper-evident ring for a sufficient distance with a sufficiently small diameter for the tamper evident ring to drop down the neck by a distance of at least about 1mm, for example from about 2mm to about 10mm, following separation of the tamper-evident ring from the closure assembly. This clear and visible separation of the tamper-evident ring is a further advantage of the closures according to the present invention.

The tamper-evident ring is retained under the flange on the container neck when the closure is removed from the neck. Suitably, the tamper-evident ring comprises a tubular body having a plurality of partially cut-away sections and plurality of flexible tabs formed integrally with the body in the cut-away sections, wherein the tabs are inclined inwardly and upwardly from the tubular body, whereby in use the ends of the tabs abut against the underside of the flange on the container neck. Suitably, the container neck further comprises one or more projections on the container neck that engage with the tamper-evident ring to resist rotation of the tamper-evident ring in an unscrewing direction and thereby assist separation of the ring from the inner cap skirt when the closure is removed from the container neck. Tamper-evident rings of this kind are described for example in WO-A-941 1267, the entire content of which is incorporated herein by reference.

The containers in the assemblies of the present invention suitably contain a carbonated beverage. Suitably, at least the neck region of the containers is formed of thermoplastic, by injection moulding. The body of the container may be formed by blow moulding in conventional fashion. The threads on the container neck and the closure are preferably of the pressure-safety type described in WO-A-9505322, WO-A-972 1602 and WO-A- 99 19228, the entire contents of which are incorporated herein by reference. Briefly, the threads on the neck and the closure are provided with mutually engageable elements to block or restrict rotation of the closure in an unscrewing direction beyond an intermediate position when the closure is under an axial pressure in a direction emerging from the container neck, the neck and closure being constructed and arranged to provide a vent for venting gas from the container neck at least when the closure is in the intermediate position. This pressure safety feature prevents the closure from blowing off uncontrollably once unscrewing of the closure from the container neck has started. It thus allows the use of shorter, more steeply pitched or multiple-start threads in the container and closure assembly, thereby rendering the assembly much more elderly- and child-friendly without sacrificing pressure safety.

Preferably, the mutually engageable elements comprise a step or recess formed in the upper surface of one of the second screw thread segments to provide a first abutment surface against which a second abutment surface on one of the first screw thread segments abuts to block or restrict rotation of the closure in an unscrewing direction at the said intermediate position when the closure is under axial pressure in a direction emerging from the container neck.

In these embodiments, a first thread segment on the neck or the inner cap skirt may comprise a first thread portion having a first longitudinal cross section and a. second thread portion having a second longitudinal cross section narrower than the first cross section, whereby the a second thread segment on the inner cap skirt or the neck abuts against the first thread portion at the said intermediate position when the closure is under axial pressure in a direction emerging from the container neck.. The relatively broad first cross section is preferably adjacent to the circumferentially overlapping region of the first thread segments, resulting in a relatively narrow thread gap in that region.

Suitably, the closure can be moved from a fully disengaged to a fully secured position on the container neck by a single, smooth rotation through about 3600 or less, preferably about 1800 or less, for example about 90°. Suitably, the threads define a continous helical thread path so that the cap travels smoothly onto the neck, e.g. the threads are not bayonet-type threads that follow a stepped thread path.

Suitably, the first and second threads on the container neck and closure are variable pitch threads, for example as described in W097/2 1602, the entire contents of which are incorporated herein by reference. The use of a variable pitch thread renders it easier to combine fast-turn threads having a steep average pitch that are elderly-and child-friendly with pressure safety. A problem that could arise with fast-turn threads is that they are steeply pitched, which results in a tendency to back off from the fully secured position on the container neck when the container is pressurized. This problem can be overcome by using bayonet-type threads, but the use of bayonet-type threads results in a number of different problems, as described above. In contrast, the variable pitch threads solve the problem of backing off of the closure under pressure, whilst retaining all of the advantages of continuous, fast-turn threads.

Preferably, the container neck and the inner cap skirt further comprise complementary locking elements that block or resist unscrewing of the closure from the fully secured position on the container neck until a predetermined minimum opening torque is applied.

In certain embodiments, the locking elements comprise a longitudinal locking rib on one of the container neck or the inner cap skirt, and a complementary locking ramp on the other of the container neck and the inner cap skirt, said locking rib abutting against the retaining edge of the locking ramp when the closure is fully secured on the container neck. Preferably, the complementary locking elements are provided on the same surfaces as the threads, that is to say on the internal surface of the inner cap skirt and the outside surface of the container neck.

The locking arrangement helps to prevent the closure from backing off under pressure from inside the container. It also provides a positive click that indicates to the user when the closure has been screwed onto the neck sufficiently to achieve a pressure-tight seal.

Accordingly, at least one, and preferably both of the complementary locking projections on the neck and/or the closure is substantially separate from the thread segments and can flex substantially independently of the thread segments in order to provide the snap-fitting and clearly audible click as the fully secured position of the closure on the neck is reached. In general, a radially innermost vertex of the locking element on the neck rides over a radially outermost vertex of the locking element on the inner cap skirt as the fully secured position is approached. The neck locking element then rides back over the skirt locking element when the closure is removed from the secured position, for example when opening the assembly.

At least one, and preferably both of the complementary locking projections on the neck and/or the closure has a length in the longitudinal direction (i.e. along the rotational axis of the closure assembly) of from about 1 mm to about 6mm, for example from about 2mm to about 4mm. At least one, and preferably both of the complementary locking projections on the neck and/or the closure has a height of from about 0.25mm to about 2mm, for example from about 0.5mm to about 1.5mm. In any case the height of the locking projections is normally less than the average height of the respective thread segments. At least one, and preferably both of the complementary locking projections on the neck and/or the closure has a maximum width (i.e. around the circumference of the neck or closure skirt) of from about 0.5mm to about 3mm, for example from about 1mm to about 2mm. At least one, and preferably both of the complementary locking projections on the neck and/or the closure has a ratio of the maximum height to the maximum width of at least about 0.5, more preferably at least 1, for example from about I to about 5.

The assemblies according to the present invention may comprise more than one pair of complementary locking projections on the container neck and the closure. Preferably there are at least two such complementary pairs radially spaced around the neck and the inner cap skirt. There will normally be at least one pair for each thread start, for example there may be four pairs radially spaced around the neck and inner cap skirt.

Preferably, the locking projections on the neck and the inner cap skirt are radially positioned such that they are in abutment when the closure is at the fully closed and sealing position on the container neck. That is to say, the projection on the inner cap skirt has ridden over one side of, and is resting in abutment with the opposite side of, the corresponding projection on the container neck at said fully closed and sealing position.

This ensures that there is no play in the cap at said closed and sealing position that could allow leakage from the seal. Preferably, when the projections are in abutment at the closed and sealing position, the inner cap skirt and/or the projections are still slightly distorted such that a resilient force is exerted between the projections in abutment. This resilient force is leveraged by the abutment into a closing torque between the closure and the neck that urges the closure into the fully closed and sealing position. This can ensure that the respective sealing surfaces of the container neck and the closure are automatically seated against each other, even though the closure may not be screwed down especially tightly. Furthermore, the locking projections allow for considerably lower manufacturing tolerances in the moulding of the assembly, since effective sealing is achieved over a broader range of radial sealing positions due to the interaction between the locking projections and the radial deformation of the closure skirt.

The advantages of such locking projections that urge the closure into the sealing position are discussed in detail in W093/01098, the entire content of which is incorporated herein by reference.

The complementary locking elements according to the present invention provide a number of other important advantages, besides urging the closure into the fully secured and sealing position as described above. Firstly, they prevent accidental backing off of the closure from the fully engaged and sealing position on the container neck due to pressure from inside the container. These elements enable more steeply pitched threads and free running (parallel) threads to be used without risk of the closure unscrewing spontaneously. The use of more steeply pitched threads in turn makes it easier to remove and resecure the closure. This system can also ensure that exactly the right degree of compression is applied between respective sealing surfaces on the container and closure to achieve an effective airtight seal when the closure is on the fully secured position on the neck.

The closure assembly according to the present invention may further comprise a projecting stop surface on one of the container neck and the closure for abutment against a second stop or a thread segment on the other of the container neck or the closure to block over-tightening of the closure beyond a predetermined angular sealing position of the closure on the container neck. The stop means acts in conjunction with the locking arrangement to ensure that exactly the right degree of screwing of the closure is achieved in order to provide a pressure-tight seal with the sealing arrangement of the present invention. Preferably, the complementary stop means are provided on the outer surface of the container neck and the inside surface of the inner cap skirt.

Suitable locking and stop arrangements for use with assemblies according to the present invention are described in detail in WO 91/18799 and WO 95/053 22, the entire contents of which are expressly incorporated herein by reference.

The assemblies according to the invention preferably comprise sealing elements on the container neck and/or on the closure for sealing the container when the closure is secured on the container neck. The sealing elements may comprise a sealing liner, for example a liner of elastomeric material, inside the base of the inner cap. The liner is pressed against the lip of the container neck to form the seal. However, the sealing elements preferably comprise one or more circumferential sealing projections on the container neck and/or the inside of the inner cap. Preferably, the sealing projections are provided only on the inner cap, so that the surface of the neck remains smooth to enhance its user-friendliness.

The sealing projections may comprise a circumferential sealing skirt and/or one or more circumferential sealing ribs and/or sealing fins for sealing against the lip or the the inside or outside surface of the container neck.

In certain embodments, a cylindrical sealing plug extends from the base portion of the inner cap inside the container neck for sealing engagement against an inside surface of the neck proximate to the lip and above the first thread segments. The cylindrical sealing plug may comprise at least one circumferential sealing rib on an outer surface of said sealing plug for engagement with the inner surface of the container neck proximate to the lip when the closure is secured on the container neck. The sealing means may alternatively or additionally comprise at least one flexible sealing fin extending from the base of the inner cap for engagement with the lip of the container when the closure is secured on the container neck. The sealing means may alternatively or additionally comprise a circumferential sealing skirt extending around the inner cap for engagement with the lip or the outside surface of the container neck. In these embodiments, at least one circumferential sealing rib may further be provided on the skirt for engagement with the outer surface of the container neck when the closure is secured on the container neck.

Where present, at least one of the sealing ribs suitably has a substantially triangular cross-section, for example substantially equilateral triangular. This enables the sealing force to be concentrated in the tip of the sealing rib to maximise sealing effectiveness.

Suitably, at least one of the sealing ribs has a height in the range of 10 to 500 micrometers, more preferably 50 to 250 micrometers. Such micro sealing ribs are especially effective to concentrate the sealing force and achieve an effective seal with a substantially smooth sealing surface on the container neck. Furthermore, such micro ribs are especially easy to mould in high-speed cap moulding equipment, and to bump off the mould mandrel of the equipment after moulding. Preferably, two circumferential sealing ribs are located in facing relationship at substantially the same height above the base of the inner cap so that, in use the closure applies the sealing ribs symmetrically on either side of the container lip to apply a symmetrical sealing pinch.

The sealing fins may have their base in the base of the inner cap between the skirt and the sealing plug, or they may extend inwardly or outwardly and downwardly from the base of the skirt or the sealing plug. Preferably, at least one of the sealing fins extends in a direction downwardly and outwardly from the base of the inner cap between the sealing plug and the closure skirt. Preferably, the closure comprises two or four sealing fins extending around the inner cap in concentric fashion.

Preferably, the height of the sealing fins is greater than their width at their base.

Preferably, the cross-section of the sealing fins is substantially in the shape of an isosceles triangle. Preferably, at least one sealing fin has a height of from ito 4mm.

Sealing arrangements of this type incorporating symmetrically disposed sealing ribs and fins are described in more detail in W002/42171, the entire content of which is incorporated herein by reference.

Preferably, the torque required to secure the closure in a sealing position on the container neck is less than 1.2 Nm, more preferably less than I Nm and most preferably from about 0.7 to about 0.9 Nm. This is the torque required to engage the complementary locking arrangement (where present) at the sealing position, or otherwise the force required to substantially eliminate gas leakage at normal carbonated beverage pressure differentials.

The closure assemblies of the present invention are especially suitable for carbonated beverage containers for consumption by children on account of their attractive appearance, low cost, and high safety. The venting of gas when the closure is opened for the first time gives a noise somewhat similar to that provided by opening a conventional champagne cork, but with little or no risk of missiling of the cap under pressure. In addition, the all-plastic construction eliminates the sharp metal edges produced by prior art overcap systems based on metal inner caps.

An embodiment of the present invention will now be described further by way of example with reference to the accompanying drawings, in which:-Figure 1 shows a side elevation of a container neck and closure assembly according to the present invention with the closure secured on the neck; Figure 2 shows a side elevation view partially cut away of the container neck and closure assembly of Fig. 1 with the overcap, inner cap and neck shown separately, prior to securing the closure on the neck; and Figure 3 shows a longitudinal cross-sectional view of the container neck and closure assembly according to Fig. I with the closure secured on the neck.

Referring to the drawings, the assembly comprises a container neck 1, an inner cap 2 of, and an overcap 3. The container neck 1 is formed from polyethylene terephthalate (PET) by injection molding. The neck is normally integrally formed with a container body (not shown) shaped by blow molding. The inner cap 2 and overcap 3 are also molded in one piece by injection molding from polyethylene or similar thermoplastics.

The inner cap 2 comprises a base 4, a skirt 5 and a tamper-evident ring 6 joined to the skirt by integral, frangible bridges 7. The outer surface of the skirt 5 is ribbed. At the bottom of the skirt 5 there is a circumferential snap-fitting projection 11.

The neck 1 is provided with an integral circumferential flange 8 for retaining the tamper-evident ring after opening of the assembly. A second, larger flange 9 is provided below the flange 8 for clamping the container neck during filling and handling. The vertical spacing between flanges 8 and 9 is at least about 1mm greater than the vertical height of the tamper-evident ring, whereby the ring drops at least about 1mm to rest on the second flange 9 after opening of the assembly, thereby giving a clear visual indication that the assembly has been opened.

The neck I and inner cap 2 are provided with integrally molded, fast-turn, steeply-pitched threads incorporating a pressure safety feature, as described in detail in our International patent application WO-A-972 1602, the entire content of which is expressly incorporated herein by reference.

Briefly, on the inside of the inner cap skirt 5 there is provided a four-start first screw thread made up of four first thread segments 10 as shown in phantom on Fig. 3. The thread segments extend a total of about 170 degrees around the skirt 5, whereby adjacent thread segments overlap around the circumference of the skirt 5. A substantially continuous, approximately helical thread gap is defined between overlapping regions of the first thread segments on the skirt 5.

The container neck 1 is provided on its outer surface with a second screw thread formed from four short second thread segments 13, each of which is a substantially continuous helical thread extending about 20 degrees around the container neck.

A feature of this assembly is the profiling of the upper surface of the thread segments 10 on the inner cap skirt 5, which is described in more detail in WO-A-9721602.

The thread segments 10 on the inner cap skirt 5 also include a pressure safety feature similar to that described and claimed in our International Patent Publication W095/05322. Briefly, a step 14 is provided in the upper surface of the thread segment to abut against an end of the neck thread segments 13 and block unscrewing of the inner cap 2 from the neck I when the neck thread segments 13 are in abutment with the upper surface of the skirt threads, i.e. when there is a net force on the cap in an axial direction out of the container neck. This abutment acts to block further unscrewing of the closure until venting of gas pressure from inside the container is substantially complete, so that the cap can drop down to bring the thread 13 out of abutment with the step 14. A region of the upper surface of the inner cap skirt thread segments 10 situated adjacent to the step 14 has a low pitch of about 6 degrees to reduce the risk of the pressure safety feature being over-ridden by high pressure inside the container.

Each of the thread segments 10 on the inner cap skirt includes a longitudinally upwardly projecting portion 15 that defines a longitudinal stop surface against which a second end of one of the short thread segments 13 on the neck may abut when the closure is fully secured on the neck to block over-tightening of the closure on the neck.

The assembly is also provided with complementary locking elements on the container neck I and the inner cap 2 to block unscrewing of the cap from the fully engaged position on the container neck unless a minimum unscrewing torque is applied. Briefly, the locking elements comprise four equally radially spaced first locking projections 16 on the container neck, and four equally radially spaced second locking projections 17 on the inside of the inner cap skirt. The projections 16 on the container neck are located below the short neck thread segments 13, where they are least noticeable to a person drinking directly from the container neck. The locking projections 17 on the inner cap skirt are located level with, and radially spaced by about 2mm from, the bottom of the thread segments 10 on the skirt. The locking projections 17 on the inner cap skirt form a continuation of the helical thread path defined by inner cap threads 10 whereby the short thread segments 13 on the neck can pass smoothly past the locking projections 17 on the closure as the cap is secured on the neck. Locking projections of this type are described and claimed in our International Patent Publication W02005/058720, the entire content of which is incorporated herein by reference.

Each of the locking projections 16,17 is substantially in the form of a triangular prism having its long axis aligned with the axis of the assembly. The height of each locking projection is about 1.5mm, and the base width is about 1.5mm. This ensures that the projections have sufficient strength to snap over each other without permanent deformation. The complementary locking elements signal to the user by means of an audible "click" when the sealing position has been reached. The complementary locking elements resist "backing-off" of the closure, which is especially advantageous for the steeply pitched threads when the contents of the container are pressurized.

The tamper-evident ring 6 on the inner cap 2 comprises a tubular body 19 having a plurality of cut-away regions 21, and a plurality of integrally formed, flexible, radially inwardly pointing retaining tabs 20 located in cut-away regions 21 of the tamper-evident ring body. The tamper-evident ring construction is described in more detail in W094/l 1267. Briefly, the inside diameter of the ring 6 is greater than the maximum diameter of the neck flange 8, but the tabs 20 project inwardly of the maximum diameter of the neck flange 8 whereby the tamper-evident ring can be snap-fitted over the flange 8 without stretching the tamper- evident ring 6, but merely be resilient flexing of the tabs 20. However, the abutment of the tops of the tabs 20 against the underside of the flange 8 prevents removal of the tamper-evident ring from the neck and thereby causes separation of the tamper-evident ring when the inner cap 2 is unscrewed from the neck for the first time.

Referring to Figure 3, the inner cap comprises a cylindrical sealing plug 24. The closure further comprises a cylindrical sealing skirt 22 that is substantially concentric with to the sealing plug. The sealing plug 24 and the sealing skirt 22 are concentric with the threaded inner cap skirt 5 and located inside the threaded skirt 5 for sealing abutment against opposite sides of the container neck I proximate to the container lip.

The overcap 3 comprises an overcap skirt 26 and hollow top 28. The top 28 is formed in the shape of a champagne cork top, including integrally molded, simulated champagne cork wires 29. The overcap skirt 26 fits tightly over the inner cap skirt 5. The overcap skirt 26 has a ribbed internal surface, whereby the ribs on the overcap internal surface engage with the ribs on the outer surface of the inner cap skirt to transfer rotational force from the overcap 3 to the inner cap 2. A circumferential recess 31 is provided on the internal surface of the overcap skirt 26, which receives the flange on the bottom of the inner cap skirt to retain the overcap 3 on the inner cap 2 by snap-fitting. The inside surface of the overcap tapers inwardly above the overcap skirt 26 to form a ledge 30 against which the base of the inner cap 2 abuts to prevent the overcap 3 from being pushed too far down on the inner cap 2. The bottom of the overcap skirt 26 partially covers the tamper-evident nng but does not contact the tamper-evident ring, whereby the tamper-evident ring is free to drop down after it has been severed from the inner cap skirt. A further advantage of this arrangement is that the outer cap skirt 26 blocks access to the tabs 20 of the tamper-evident ring, thereby increasing the security of the tamper-evident ring.

It is an advantage of the caps according to the present invention that they can be assembled by pushing the overcap over the inner cap prior to securing the caps on the container neck, since the overcap does not interfere with the fitting of the tamper-evident ring onto the container neck. In contrast, the prior art overcaps for use with metal screw closures had to be fitted after the step of securing the metal closure and tamper-evident ring on the neck.

In use, the cap is secured on the container neck as shown in Figure 3. The cap assembly is screwed directly onto the container neck. The flexible tabs on the tamper-evident ring flex radially outwardly to pass over the retaining flange on the container neck without substantially stressing the tamper-evident ring.

Both the sealing skirt 22 and the sealing plug 24 are radially slightly flexible to engage the sealing lip. The circumferential sealing skirt and the plug engage opposite sides of the neck 1, and pinch the neck between them to form a highly effective seal by concentrating pressure at the sealing ribs. Further details of the sealing arrangement may be found in W02007/057706, the entire content of which is incorporated herein by reference.

The assembly of Fig. 3 is opened by unscrewing. The ribs on the inside of the overcap skirt engage with the ribs on the outside of the inner cap skirt to transmit the unscrewing torque. The snap-fitting between the inner cap and the overcap prevents separation of the inner cap and overcap. The tops of the flexible tabs on the tamper-evident ring abut against the underside of the flange on the container neck, thereby causing the tamper-evident ring to separate from the inner skirt and drop down the neck onto the lower flange, giving a visible indication that the tamper-evident ring has separated. This visual indication may be accentuated by making the inner skirt and tamper-evident ring from a plastic of different color from the overcap and neck.

The above embodiment has been described by way of example only. Many other embodiments falling within the scope of the accompanying claims will be apparent to the skilled reader.

Claims

1. A container closure comprising: a plastics inner cap having a base portion and a skirt portion, a thread on the inside of the skirt portion, a first snap fitting element on the outside of the skirt portion, and a tamper evident ring formed integrally with the skirt portion and joined to an open end of the skirt portion by severable connections; a plastics overcap having a base and a skirt portion in mating engagement with the skirt portion of the cap and extending beyond the open end of the skirt portion of the cap to at least partially cover the tamper-evident ring, and a second snap fitting element on the inside of the skirt that engages with the first snap fitting element on the inner cap skirt to resist separation of the overcap from the inner cap.

2. A closure according to claim I, wherein at least a region of the interior surface of the overcap abuts against the base of the inner cap when the overcap is secured on the inner cap by the snap fittings.

3. A closure according to any preceding claim, wherein the base of the overcap is shaped to resemble the top of a champagne cork and the skirt of the overcap is shaped to resemble the top of a champagne bottle, whereby the overcap resembles the top of a champagne bottle and cork assembly.

4. A closure according to any preceding claim, wherein an outer surface of the skirt of the inner cap is provided with one or more longitudinally extending projections or recesses, and an inner surface of the overcap is provided with one or more complementary recesses or projections for engagement with the said projections or recesses on the inner cap to transfer rotational force from the overcap to the inner cap.

5. A closure according to any preceding claim, wherein the first snap fitting element comprises a circumferential projection or recess on the inner cap, and the second snap fitting element comprises a circumferential recess or projection on the inside of the skirt of the overcap.

6. A closure according to any preceding claim, wherein the tamper-evident ring comprises a tubular body having a plurality of cut-away regions, and a plurality of flexible tabs located in the cut- away regions and formed integrally with the tubular body and inclined inwardly and upwardly from the tubular body.

7. A container and closure assembly comprising a plastics closure according to any of claims 1 to 5 and a container having a neck, wherein the neck comprises a neck thread on an outer surface thereof and a flange located below the neck thread, and wherein the closure is secured in sealing engagement on the neck by engagement of the thread on the inner cap with the neck thread, and wherein the tamper-evident ring is retained below the flange.

8. A container and closure assembly according to claim 7, wherein the tamper-evident ring can drop down the neck by a distance of at least about 1mm following separation of the tamper-evident ring from the closure assembly.

9. A container and closure assembly according to claim 7 or 8, wherein the threads on the neck and the inner cap are provided with mutually engageable elements to block or restrict rotation of the closure in an unscrewing direction beyond an intermediate position when the closure is under an axial pressure in a direction emerging from the container neck, the neck and closure being constructed and arranged to provide a vent for venting gas from the container neck at least when the closure is in the intermediate position.

10. A container and closure assembly according to any of claims 7 to 9, wherein the overcap is gold-or silver-colored, and the assembly does not comprise a foil over-wrap.