WO2014177853A1

WO2014177853A1 - A closure for a container

Info

Publication number: WO2014177853A1
Application number: PCT/GB2014/051322
Authority: WO
Inventors: Anthony Henry Joseph Fraser; John Hein
Original assignee: Threadless Closures Limited
Priority date: 2013-04-30
Filing date: 2014-04-29
Publication date: 2014-11-06
Also published as: GB201407157D0; GB2513730A; US20160107806A1; EP2991912A1

Abstract

A closure for releasably securing to a container adapted for storing foodstuff or a beverage, the closure comprising closing means (14) for closing a mouth of the container and securing means (22,23) for securing it in a closed position, the closing means and the securing means being formed of a plastics material comprising polyoxymethylene so as to provide a substantial gas barrier to the passage of oxygen and/or carbon dioxide therethrough, The closure may have a sealing member (18) formed of resilient material (compared to the rigid material of the remainder of the closure) for providing a seal between the closure and the container. The sealing member may be provided on a bore component which projects into the container so that, in use, it seals against an internal surface of the container. The sealing member may be an o-ring (18) formed of an elastomer, e.g. nitrile butadiene rubber. A foodstuff or beverage container, e.g. in the shape of a wine glass or the shape of a beer glass, having such a closure is also described. The use of a plastics material comprising polyoxymethylene for closing a container provides a barrier to the ingress of oxygen and/or to the egress of carbon dioxide to improve the shelf life of the product is also described.

Description

A CLOSURE FOR A CONTAINER

FIELD OF THE INVENTION

This invention relates to a closure for a container adapted for storing foodstuff or a beverage, in particular a wide-mouthed container the contents of which may be a carbonated beverage. It also relates to the use of a closure for closing a container, particularly a container housing a foodstuff or beverage.

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 both one-part and two-part closures described in the patent specifications mentioned above are also disclosed in co-pending applications.

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 one or more of the following: improvements in the ease and/or reliability of opening, closure and/or re- closure of the closure, improvements in the storage of foodstuffs or beverages, eg the shelf- life, and/or improvements in the manufacturability of the closure, and/or simplification of its construction.

SUMMARY OF INVENTION

According to a first aspect of the invention, there is provided a closure for releasably securing to a container adapted for storing foodstuff or a beverage, the closure comprising closing means for closing a mouth of the container and securing means for securing it in a closed position, the closing means and the securing means being formed of a plastics material providing a substantial gas barrier to the passage of oxygen and/or carbon dioxide therethrough, the plastics material comprising polyoxymethylene.

As will be described further below, the use of polyoxymethylene provides a number of advantages, eg due to its strength, resiliency, low surface friction and good moulding properties. In addition, it has been discovered that it has excellent gas barrier properties and provides a substantial gas barrier to the passage of oxygen and/or carbon dioxide therethrough. These gas barrier properties make it particularly suitable for storing foodstuff or beverages which are susceptible to the ingress of oxygen and/or the egress of carbon dioxide. The ingress of oxygen causes degradation of many foodstuffs and beverages and so limits the shelf-life of a packaged product. An example of this is wine which rapidly deteriorates if exposed to too much oxygen.

Similarly, carbonated or sparkling beverages are susceptible to the egress of carbon dioxide which again limits the shelf-life of the packaged product. An example of this is beer which rapidly becomes 'flat' if too much carbon dioxide is lost.

Known plastics closures, eg of polyethylene terephthalate (PET), have to be provided with an additional gas barrier to limit the ingress of oxygen and/or the egress of carbon dioxide, eg the provision of a metal foil or a special coating such as silicon dioxide (glass), or an additive has to be added to the plastic material to improve its gas barrier properties. This adds to both the material cost and the manufacturing cost. In addition, the additional material makes it more difficult or more expensive to recycle the plastic material of the closure. Forming a closure of virgin POM enables the closure to be recycled more easily.

The container also needs to have good gas barrier properties. This is one of the reasons why metal or glass containers are often preferred. Plastic containers are often made of PET and, as mentioned above, these are typically provided with an additional gas barrier in the form of a thin silicon dioxide coating or the use of an additive to improve the gas barrier properties of the plastic material. The gas barrier properties of polyoxymethylene are particularly relevant to the closing means of the closure as this is the part of the closure providing a physical barrier between the contents of the container and the outside world. The physical properties of polyoxymethylene are particularly relevant to the securing means of the closure, as this is the part which requires the strength to securely connect the closure to the container but also the resiliency to facilitate fitting of the closure to the container and removal therefrom. The physical properties may also be relevant to the wall thickness of the closure (and hence the amount of plastics material used in the closure). The strength of POM enables the wall thickness, eg of the closing means and/or the skirt portion of the securing means, to be reduced. It is thus possible to use a thin- walled closure for applications in which the strength requirements are not as stringent, eg for non-carbonated beverage closures. This provides a significant cost saving both in terms of the amount of material used and the reduced cycle time in injection moulding of the closure and thus reduced manufacturing costs.

Thus, although POM is a more expensive material than PET, the combined cost of the material and manufacturing can be reduced to significantly reduce the price difference. The reduction in wall thickness will have little, if any, affect upon the gas barrier properties of a closure formed of POM, particularly for non-carbonated applications which merely need to resist the ingress of oxygen at atmospheric pressure. A typical PET closure may, for example, have a wall thickness in the range 1.2 - 1.5 mm whereas the wall thickness of a thin-walled POM closure may be in the range 0.8 - 1.2 mm. Such a reduction in wall thickness can thus reduce the amount of plastics material used by 20 - 30 %.

As mentioned, another advantageous property of POM is its inherent low surface friction. It can therefore be described as being self-lubricating. This is particularly advantageous in a wide-mouth closure as its low surface friction helps reduce the torque required to rotate or unscrew the closure from a container. This is also a further advantage over PET as to reduce the surface friction of PET it is necessary to add lubricant to the PET (which also adds to the cost of the material and makes it less recyclable). In addition to the above, the physical properties of POM make closures formed of POM more resistant to impact - so the closures are able to perform well in drop-tests used in the beverage container industry - and make the closures less vulnerable to be levered off a container.

Preferred embodiments of the invention may have one or more of the following features.

Preferably said securing means are adapted to snap-fit with the container when mounted thereon.

Preferably said securing means has one or more resiliently flexible portions which are flexed as the closure is fitted to the container.

Preferably, the closure comprises a skirt part depending from the closing means for fitting around the exterior of the container.

Said flexible portions may comprise a plurality of circumferentially spaced radially moveable members around an inner surface of the skirt portion for snap fitting with the container.

The radially moveable members may comprise arms connected at their lower ends to the skirt part. Each arm is preferably located within an aperture in the skirt part and arranged to flex about the connection at its lower end to the skirt part.

Preferably, the closure is an injection moulded closure.

Another important aspect of the closure is the provision of sealing means for providing a seal between the closure and the container. Such sealing means need to maintain a seal under stringent conditions, in particular at high temperatures and pressures (eg during pasteurisation of the contents of the closure and/or during transport in hot climates) whilst at the same time not preventing easy fitting and easy removal of the closure. These requirements are generally more difficult to achieve for wide-mouth closures due to the increased area over which a seal has to be provided (ie around the circumference of the closure).

In view of this, the closure is preferably formed of a relatively rigid material and is provided with a sealing member formed of relatively resilient material for providing a seal between the closure and the container. The sealing member also needs to have good gas barrier properties so as to resist the ingress of oxygen and/or the egress of carbon dioxide. This is particularly important for a wide mouth closure in which the area of seal material gases can pass through is much larger due to the larger circumference of the seal. The seal member should preferably also have a high resistance to compression set. Compression set is the result of a progressive stress relaxation, which is the steady decline in sealing force that results when an elastomer is compressed over a period of time. Compression set can be expressed as a percentage of original specimen thickness that is recovered after removal of the compression force. The seal member preferably has a compression set of at least 90% so that after removal of compressive forces, the seal recovers at least 90% of the thickness or shape it had prior to being compressed.

The sealing means is preferably a separate component of a different, softer material mounted on the closure, eg in the form of a 'floating' seal. However, it may also comprise a component formed of a different material, which is formed, for example by co-moulding, with the remainder of the closure.

The closure preferably has a bore component which, in use, projects through the mouth of the container, the sealing member being provided on the bore component so that, in use, it seals against an internal surface of the container.

The sealing member may comprises an o-ring and is preferably formed of an elastomer, eg nitrile butadiene rubber ( BR). A seal member comprising NBR is able to satisfy the requirements described above. A particularly advantageous embodiment thus comprises a closure formed of POM and a sealing member formed of BR. This combination of materials has been found to meet the wide range of requirements discussed above. The closure is preferably adapted to close a container having a circular opening defining an axis and having an outwardly projecting lip and the closure is preferably adapted to snap fit over the lip of the container.

A particularly advantageous arrangement comprise a one-piece, injection- moulded closure formed of polyoxymethylene, the skirt portion of the closure having resilient arms for snap-fitting beneath the lip of a container, the arms being connected at their lower ends to the skirt portion, and the closing portion of the closure comprising a bore component arranged to carry an o-ring seal for sealing with an internal surface of the container. In some arrangements, said securing means may comprise a separate component in the form of a collar arranged to fit about the exterior of the container by means of which the remainder of the closure is securable to the container, ie the closure is a two-part, capon-collar closure. A variety of cap-on-collar arrangements are possible. In one particular arrangement, the invention provides 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 wherein the outer component is formed of a plastics material comprising

polyoxymethylene.

In another arrangement, the invention provides 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 wherein the outer component is formed of a plastics material comprising polyoxymethylene. In a further two-part arrangement, the invention 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.

In this arrangement the inner component may be formed of a plastics material comprising polyethylene terephthalate.

According to a further aspect of the invention, there is provided a container and a closure therefor, the container having an opening defining an axis passing therethrough and an outwardly projecting lip around the opening and a plurality of spaced apart camming features on or adjacent an underside of the lip, the closure being in the form of a cap comprising an upper portion for closing said opening and a skirt portion depending from the upper portion for securing the cap to the container, with a substantially rigid connection between the upper portion and the skirt portion, the skirt portion of the cap having a plurality of spaced apart inwardly projecting first parts around an inner circumference thereof for locating beneath the lip of the container to secure the cap to the container, at least part of the skirt portion being sufficiently elastic such that when applied to the container said plurality of first parts can be snap-fitted over the container lip so as to be located beneath the container lip, said plurality of inwardly projecting first parts also being arranged such that upon subsequent twisting of the cap about said axis relative to the container in a loosening direction, they interact with said camming features of the container so said first parts are flexed outwards to disengage them from the underside of the lip, said closing portion also comprising a bore component having a sealing member on, or mountable on, an exterior thereof, such that, when the cap is mounted on the container, the bore component extends into the interior of the container so that the sealing member engages with an internal surface of the container to provide a seal between the closure and the container, wherein the closure is formed of a plastics material comprising polyoxymethylene.

According to yet a further aspect of the invention there is provided a container and a closure therefor, the container having an opening and an outwardly projecting lip around said opening, and the cap having a top part and a skirt part, the cap being securable to the container by snap fitting projecting parts of the skirt part over the lip and being removable by twisting relative to the container so that camming features on the container flex said projecting parts outwardly to disengage them from the lip, said top part having a bore component that extends into the container and a sealing member mounted on the bore feature for providing a seal with an internal surface of the container wherein the closure is formed of a plastics material comprising polyoxymethylene.

In a container and closure as detailed above the container is preferably formed of a plastics material comprising polyethylene terephthalate and the sealing member is preferably an o-ring seal comprising a toroid of elastomer material.

The above further aspects of the invention also relate to two-part closures.

Other aspects of the invention are relevant to both one-part and two-part closures.

The invention also relates to a foodstuff or beverage container having a closure as detailed in any of the above aspects. The container may have a wide variety of shapes and in particular may have the shape of a beverage container from which the beverage may be directly consumed. The beverage container may, for example, have the shape of a wine glass, eg in the form of a goblet comprising a bowl portion for containing the wine, a narrow stem and a relatively broad base.

In a further application, the foodstuff or beverage container may contain a carbonated beverage, and the beverage container may, for example, have the shape of a beer glass, eg having a wide mouth for the consumer to drink from and a similarly wide base. The remainder of the glass may have a wide variety of shapes including known beer glass shapes such as conical, nonic and tulip shapes. Many brewers also have their own distinctive shape of beer glass.

The invention also relates to a method of closing a container of the type described herein using a closure of the type described above. According to a further aspect of the invention, there is provided the use of a closure formed of a plastic material comprising polyoxymethylene for closing a container to provide a barrier to the ingress of oxygen and/or the egress of carbon dioxide through the closure. As mentioned above, it has been discovered that polyoxymethylene has good gas barrier properties and that an unexpected advantage of forming a closure of

polyoxymethylene is that additional measures do not need to be taken to improve the gas barrier properties in order to achieve a satisfactory shelf-life for a foodstuff or beverage contained in a container having a closure formed of polyoxymethylene. In turn, this improves the ability to recycle the plastic material used to form the closure.

In particular, as mentioned above, the closure may be used for closing a container housing a beverage susceptible to the ingress of oxygen, eg wine, and/or for housing a carbonated beverage, eg beer.

As used herein, the term "polyoxymethylene", abbreviated as POM, refers to a polymer comprising a repeating unit of formula (I)

or a mixture of two or more such polymers.

The or each polymer which comprises a repeating unit of formula (I) may or may not further comprise repeating units of one or more different chemical formulae, ie chemical formulae other than formula (I). Thus, the term "polyoxymethylene", as used herein, not only encompasses polyoxmethylene homopolymers but also copolymers of polyoxmethylene. Mixtures of two or more polyoxmethylene homopolymers, mixtures of two or more copolymers of polyoxmethylene, and mixtures of at least one

polyoxymethylene homopolymer and at least one copolymer of polyoxymethylene, are also encompassed by the term. The or each polymer which comprises a repeating unit of formula (I) may additionally comprise terminal groups in order to stabilise the polymer. Such terminal groups may for instance be carboxylate (eg acetate, OC(0)CH₃), carboxyl (eg acetyl, C(0)CH₃), alkyl (eg methyl) or alkoxy (eg methoxy) groups, or a mixture of such groups. Such groups can improve the thermal stability of the polyoxymethylene, as described, for instance in US Patent No. 2,998,409, which relates to polyoxymethylenes terminated by carboxyl and carboxylate groups.

In a preferred embodiment of the present invention, the polyoxymethylene employed is in homopolymer form, ie it is a polyoxymethylene homopolymer, or a mixture of two or more different polyoxymethylene homopolymers.

The term "polyoxymethylene homopolymer", as used herein, refers to a polymer in which the only repeating unit is the repeating unit of formula (I). Polyoxymethylene homopolymers include homopolymers of any monomer that yields the repeating unit of formula (I), including for instance homopolymers of formaldehyde, and homopolymers of cyclic oligomers of formaldehyde, eg, 1,3,5-trioxane and tetraoxane. Such homopolymers are commercially available, and for instance are sold by DuPont™ under the trade name Delrin®.

The terms "copolymer of polyoxymethylene" and "polyoxymethylene copolymer", as used herein, refer to a polymer which comprises a repeating unit of formula (I) and which further comprises repeating units of one or more other chemical formulae. Thus, the terms "copolymer of polyoxymethylene" and "polyoxymethylene copolymer", as used herein, not only encompass copolymers in the strict sense of the word (ie copolymers having only two kinds of repeating unit), but also terpolymers, and polymers with more than three different kinds of repeating unit.

Polyoxymethylene copolymers include copolymers of a first monomer that yields the repeating unit of formula (I), and one or more co-monomers. The first monomer may be formaldehyde or a cyclic oligomer of formaldehyde (eg trioxane or tetraoxane). The one or more co-monomers may for instance be co-monomers that yield oxyalkylene repeating units which have at least two adjacent carbon atoms, for instance C₂ (ethylene glycol) or C₄ (1,4-butanediol) units. Such units may be introduced by employing the corresponding cyclic acetal (which can be made from the diol and formaldehyde) or the corresponding cyclic ether (eg ethylene oxide) as the co-monomer.

The quantity of the one or more co-monomers in a copolymer of polyoxymethylene is generally less than or equal to about 20 weight percent, or for instance less than or equal to about 15 weight percent, for example less than or equal to about 5 weight percent, of the total weight of the POM polymer. It may for instance be about 2 weight percent. Co- monomers can be used to provide linear, branched or crosslinked polyoxymethylene copolymers.

Examples of polyoxymethylene copolymers include Hostaform® from Ticona and Ultraform® from BASF.

As mentioned above, the polyoxymethylene employed in the present invention is often in homopolymer form. It is typically a polyoxymethylene homopolymer or a mixture of two or more different polyoxymethylene homopolymers. Polyoxymethylene homopolymers (such as for instance those sold by DuPont, under the trade name Delrin®) often have superior mechanical properties, and a higher % crystallinity, as compared to polyoxymethylene copolymers (for instance, as compared to a polyoxymethylene copolymer comprising the repeating unit of formula (I) and another repeating unit of formula -CH₂CH₂O- occurring after about every 70 units of formula I). Thus, the use of a polyoxymethylene homopolymer often provides improved durability and strength.

The polyoxymethylene employed in the present invention, which is often a polyoxymethylene homopolymer, typically has a percent crystallinity of greater than 50%. Often, for instance, the percent crystallinity of the polyoxymethylene employed is at least 55%. It may for instance be from 55% to 60%.

The polyoxymethylene employed in the present invention, which is often a polyoxymethylene homopolymer, typically has a tensile modulus, as measured in accordance with test standard ISO 527-1/-2, of at least 3000 MPa. Often, the tensile modulus of the polyoxymethylene employed is at least 3200 MPa.

The polyoxymethylene employed in the present invention, which is often a polyoxymethylene homopolymer, typically has a flexural modulus, as measured in accordance with test standard ISO 527-1/-2, of at least 3000 MPa. Often, the fexural modulus of the polyoxymethylene employed is at least 3100 MPa.

Typically, the polyoxymethylene employed in the present invention, which is often a polyoxymethylene homopolymer, has a yield stress value, measured in accordance with test standard ISO 527-1/-2, of at least 68 MPa. The yield stress value of the

polyoxymethylene employed may for instance be at least 70 MPa, or for example at least 72 MPa.

The polyoxymethylene employed in the present invention, which is often a polyoxymethylene homopolymer, may have a strain at yield value, measured in accordance with test standard ISO 527-1/-2, of at least 10%. Often, the strain at yield value of the polyoxymethylene employed is at least 12%, or for instance at least 15%.

The polyoxymethylene employed in the present invention, which is often a polyoxymethylene homopolymer, typically has a Charpy Notched Impact Strength, measured at 23°C in accordance with test standard ISO 179/leA, of at least 7 kJ/m².

Typically, the Charpy Notched Impact Strength measured at 23°C is at least 8 kJ/m², or for instance at least 9 kJ/m².

The polyoxymethylene employed in the present invention, which is often a polyoxymethylene homopolymer, typically has an Un-notched Charpy Impact Strength, measured at -30°C, in accordance with test standard ISO 179/leU, of at least 200 kJ/m². Often, the Un-notched Charpy Impact Strength of the polyoxymethylene, measured at - 30°C, is at least 225 kJ/m², or for instance at least 250 kJ/m². The polyoxymethylene employed in the present invention may for instance be Delrin®, which is commercially available from DuPont™ Typically, it is Delrin® 311DP NCOIO acetal resin, which is commercially available from DuPont™. The plastics material employed in the present invention, which provides a substantial gas barrier to the passage of oxygen and/or carbon dioxide, comprises polyoxymethylene. The plastics material may or may not further comprise other components, in addition to the polyoxymethylene. For instance, the plastics material may further comprise one or more additives, one or more filler materials, and/or one or more further polymers.

In some embodiments, the plastics material consists essentially of

polyoxymethylene. The term "consists essentially of, as used herein, refers to a composition which mostly comprises the given component, but may comprise additional components provided the additional components do not have a material effect on the function of the composition. For example, a plastics material which consists essentially of polyoxymethylene may comprise greater than or equal to, say, 90% by weight, or for instance greater than or equal to 95% by weight, of the polyoxymethylene, but further comprises one or more additional components that do not have a material effect on the function of the plastics material.

In some embodiments, the plastics material consists of polyoxymethylene. As mentioned above, this improves the ability to recycle the plastics material. As used herein, the term "nitrile butadiene rubber", abbreviated as NBR, refers to a a synthetic rubber which is a copolymer of acrylonitrile (ACN) and butadiene. NBR is also known as Buna-N, Perbunan, and nitrile rubber. Trade names include Nipol, Krynac and Europrene. Various butadiene monomers, including 1,2-butadiene and 1,3 -butadiene, may be employed together with acrylonitrile in the polymerisation reaction used to produce NBR. Nitrile butadiene rubber ( BR) therefore encompasses a family of unsaturated copolymers of acrylonitrile and various butadiene monomers.

As the skilled person would understand, NBR, being an unsaturated copolymer, may be crosslinked; the term "nitrile butadiene rubber", as used herein, also therefore encompasses crosslinked nitrile butadiene rubber (crosslinked NBR).

NBR has good gas barrier properties and resists compression set; typically being able to recover 90% of its shape when a compression force is removed. It also retains its resistance to compression set at elevated temperatures. The resistance to compression set of NBR can be improved by crosslinking. Preferably, therefore, the NBR employed in the present invention is crosslinked NBR.

Filler or reinforcing materials may also be included in NBR. Such fillers modify physical properties of the material as well as lowering cost. One filler material is carbon black which can enhance the properties of the elastomer system whilst lowering its cost. The carbon black is typically elemental carbon in the form of extremely fine particles having an amorphous molecular structure. 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). 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 two-part, cap-on-collar closure according to one aspect of the invention;

Figures 2A and 2B are perspective views from beneath and above of an inner component of a two-part, cap-on-collar closure according to this 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;

Figure 6 is a perspective view of a container and a first embodiment of a one-piece closure according to an aspect of the invention prior to the closure being fitted over a lip of the container;

Figure 7 is a cross-section of the container and closure of Fig 6 after the closure has been snap-fitted to the container;

Figure 8 is a cross-sectional view of the container and closure of Fig 7 after the closure has been lifted to a venting position;

Figure 9 is a perspective view of the closure of Figs 6 - 8 showing features on the interior of the closure; and

Figure 10A and 10B are perspective views from above and below of a second embodiment of a one-piece closure according to an aspect of the invention and Figure IOC is an enlarged, part-sectioned view of part of Figure 10B illustrating a rib feature of the third embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention will be described first in relation to a two-part closure (Figs 1 to 5) and secondly in relation to one-part closures (Figs 5 to 9 and Fig 10). These are examples of the types of closure that the invention relates to. As will be described further below, the invention may be applied to other forms of one- or two-part closures and to other forms of closure.

Figures 1 and 2 shows perspective views from above and below of an outer and an inner component of a two-part, cap-on-collar closure according to a first embodiment of one aspect of the invention.

This is a widemouth closure designed to close a container having an opening the diameter of which is typically in the range 55 - 65 mm and having an outwardly projecting lip around the opening. Preferably, the container has no other externally projecting features, or only minimal features, so that the container is comfortable to drink from.

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 circumferentially spaced apart positions 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 Figures 3 and 4.

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. The collar ring 21 has a plurality 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 beneath the lip of the container, and the cap can be releasably secured thereto to close the container, the cap thus being secured to the container via said collar portion rather than via a thread provided on the exterior of the container. 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. Alternatively, the collar portion 20 may be fitted to the container 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 of the container (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.

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 beneath the lip of the container) so they can be disengaged from the lip 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.

The function of the upstands 23 will now be described with reference to Figures 5 - 6. 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. 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. As best shown in Figs 3 and 5, the outer component also comprises a bore feature

17 which has a recess or gland in the outer surface thereof for holding an o-ring seal 18. When the closure is mounted to a container, the bore feature 17 projects into the mouth of the container so that the o-ring 18 sealingly engages an internal surface 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 recess or gland in which the o-ring 18 is located comprises an L-shaped recess or groove, having an upper surface and a rear surface, 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 as the flange 16 is sufficiently flexible that is can be sprung out of a mould. The is facilitated if the gland is formed of formed of a plastics material comprising polyoxymethylene (POM). 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 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 of the container and reaches an angled lead-in portion adjacent the mouth of the container, an elevated pressure within the container may be sufficient to lift at least part of the o-ring away from the lead-in surface so this excess pressure is vented. As the cap is further rotated from the first to the second position, the radially moveable arms 22 are driven outwards by engagement with the ramps of the cam features under the lip of the container, into the recesses 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. 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 of the container, rotation of the outer component in the loosening direction relative to the collar portion to a venting position, venting of the container, 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 of the cam features of the container, and axial disengagement of the o-ring 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. The user can then pull the closure axially upwards to withdraw the bore component (and the o-ring) from the container (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 formed of a plastics material comprising polyoxymethylene (POM) (preferably in homopolymer form), eg by injection moulding. POM is significantly stiffer than the conventional material polyethylene terephthalate (PET) that is typically used in known cap-on-collar closures, and 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. A preferred form of a cap-on- collar closure is one in which the outer component (the cap) is formed of a plastics material comprising polyoxymethylene (POM) (preferably in homopolymer form). The use of a stiffer plastics material such as POM also enables less plastic material to be used.

Key features of the preferred embodiments described above include:

a) The cap being formed of POM and

b) The cap having a bore feature adapted to carry a seal such as an o-ring.

c) The seal being formed of a material, eg NBR, much softer than that of the closure or container. The use of POM in the closure is advantageous for several reasons: its strength, resiliency, low surface friction, good moulding properties, gas barrier properties and its recyclability.

The use of NBR for the seal is also advantageous for several reasons: eg its gas barrier properties, and its resistance to compression set.

Key features of preferred embodiments include:

d) The use of radially moveable arms to secure the closure by engaging beneath the lip of the container

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

Whilst the two-part closures described above are satisfactory in many cases, the present invention is also applicable to one-part closures. These enable the container and/or the closure to be further simplified, and reduces the cost of materials and/or the cost of manufacture whilst maintaining the performance of the closure, in particular the ease and reliability of opening and closure, re-closure (if required) and venting (if housing a carbonated beverage). Figures 6 to 9 illustrate a first embodiment of a one-piece closure according an aspect of the invention. As for the embodiment shown in Figs 1 to 5, this is designed for closing the opening of a wide-mouth container typically having a diameter in the range 55 - 65 mm. The container is typically formed of a plastics material, eg polyethylene terephthalate (PET), and formed by injection moulding followed by blow moulding, or it may be formed of glass or a wide range of other materials, eg metal formed by pressing and drawing operations. The container may also be formed of more than one material, eg the uppermost part, including the lip, may be of a first material and the lowermost part of a second material. A plastic lip may, for example, be over-moulded onto a metal container. The closure shown in Fig 6 is in the form of a cap and comprises an upper part or portion 70 which, in use, extends across the opening of a container (not shown) and a skirt part or portion 71 depending from the periphery of the upper part 10 with a substantially rigid connection between the upper part and the skirt part. In addition, the closure has a plurality of circumferentially spaced apart inwardly projecting parts 72 around the inner surface of the skirt 71 by means of which the closure can be snap-fitted over the lip of the container so that said parts 72 are located beneath the lip. These parts 72 will be described further below. The closure also has a bore component 77 (see Figs 7 and 8) projecting from said upper part 70 and which carries an o-ring seal 78. The bore component comprises a substantially cylindrical member extending from the underside of the upper part 70 of the closure. The outer surface of this bore component 77 is rigidly connected to the skirt part 71 of the closure.

The plurality of circumferentially spaced apart radially moveable parts 72 are in the form of arms joined at their lower ends to the skirt portion 71 of the closure. The radially moveable arms 722 are inclined inwardly so the closure is a snap fit over the lip 32 of the container, the radially moveable arms 72 being flexed outwardly as the closure 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 closure can thus be secured to the container 30. It will be appreciated that as the arms 72 project upwardly and are joined at their lower ends to the lower part of the skirt portion 71 which, as shown, comprises a continuous, substantially rigid collar of material. The cap is preferably formed as an integral member, eg by injection moulding. The upper part is thus integrally formed with the skirt part. The embodiment shown in Figs 6-9 has a plurality of recesses 70 A adjacent its periphery separated from each other by bracing walls 70B which also provides a rigid structure connecting the upper end of said cylindrical bore component 77 with the skirt part of the closure. It is desirable for the bottom wall IOC of each recess to be substantially level with the upper edge of apertures 72 A of the skirt portion 11, within which the radially moveable parts 72 are formed, to facilitate the manufacture of these apertures 72A and the parts 72. This provides a rigid connection between the upper part of the cap, particularly the portion which overlies the lip 32 of the container 30, and the skirt portion of the cap.

These apertures are spaced from the lower edge of the skirt part so that, as mentioned above, the lower portion of the skirt part comprises a substantially rigid collar of material, typically having a height of 3.0 - 5.0 mm, so it is resistant to flexing or twisting. The radially moveable members are resiliently moveable about their connection to the upper end of the lower portion of the skirt part rather than by flexing of the lower portion of the skirt part.

The bore component 77 has a recess or gland in the outer surface thereof for holding the o-ring seal 78. When the closure is mounted to a container 30, the bore component 77 projects into the mouth 31 of the container 30 so that the o-ring 78 sealingly engages the internal sealing surface 34 (see Fig 7) of the container 30. The bore component 77 is preferably integrally formed with the closure but may also be a separate item mounted thereto.

The gland in which the o-ring 78 is located comprise an L-shaped recess or groove in the outer surface of the bore feature 77 and an angled flange 76 at its lower end. As shown in Figs 7 and 8, the flange 76 comprises a plurality of flange parts which are angled so as to extend outwards at approximately 45 degrees to the horizontal. This arrangement is essentially similar to that described above in relation to the first embodiment and, as in the first embodiment, the gland is preferably formed of formed of a plastics material comprising polyoxymethylene (POM). The one-piece closure is preferably injection moulded. Closures for use with carbonated beverages generally need to be formed of a stiffer material than that might be used in non-carbonated applications. Preferably, the material used has a tensile modulus (Young's modulus) - which is a measure of the stiffness - of greater than 3000 MPa, a flexural modulus - which is a measure of its flexing strength (ie a measure of deformation or strain as stress is applied) - of greater than 3000 MPa, and a yield stress - the stress at which it begins to deform plastically - of greater than 70 MPa.

The use of polyoxymethylene (POM) is thus particularly advantageous for closures for carbonated beverages. It is significantly stiffer than polyethylene terephthalate (PET) and is more stable at higher temperatures and pressures. As mentioned above, it also has good de-moulding properties as it is able to 'spring' out of a mould and retains its moulded shape well. The use of polyoxymethylene (POM) is also advantageous for closures for non-carbonated beverages as its greater strength enables the wall thickness of the closure to be reduced so less plastics material is used.

In a one-piece closure, an outer component is not provided to secure the radially moveable arms 72 beneath the lip of the container. Instead, the resilience of the radially moveable arms 72 is relied upon to hold them in the inward position. POM is a particularly suitable material for this as it gives the arms 72 sufficient strength to securely engage beneath the lip 32 yet enough resilience to enable them to be snap-fitted over the lip 32 of the container 30. Should any additional security and/or tamper evidence be required, it is also possible to provide a shrink sleeve or other form of tear-off or disruptable member or covering to inhibit access to the closure and/or inhibit rotation of the closure relative to the container until an end user wishes to open the container.

As shown in Fig 6, the container 30 has an outwardly projecting lip 32 and cam or underlip features beneath the lip 32. These underlip features each comprise a ramp 33A on one side thereof and a stop surface 33B on the other side thereof.

As will be described further below, in order to release the closure and open the container, the cap is rotated in a loosening (anti-clockwise) direction relative to the container 30, initially from a position such as that shown in Fig 7 to a venting position shown in Fig 8. Depending on the angular position at which the closure is fitted to the container, this initial rotation is typically through a few degrees up to about 20 - 30 degrees. This initial rotation of the cap also rotates the bore component 77 and hence the o-ring 78 and this help breaks the seal between the o-ring 78 and the container 30 (and thus makes it easier to withdraw the o-ring from the container).

The closure is then able to rise relative to the container 30, and if a carbonated beverage is housed in the container 30, the internal pressure may also help lift the closure, to the position shown in Figs 8. The closure may typically rise by a distance in the range 1.0 to 4.0mm, eg by approximately 2.5 mm, between the closed position and the venting position.

As the cap is rotated further anti-clockwise, typically through 5 degrees or less on a wide-mouth closure (depending on the circumferential length of the ramps 33 A) the radially moveable arms 72 are driven outwards by engagement with the ramps 33 A of the cam features 33 under the lip of the container, so engagement of the arms 72 with the underside of the lip 32 of the container is released so the closure can be removed from the container 30.

As will be seen in Fig 9, this embodiment also has a plurality of circumferentially spaced apart inwardly projecting ramp features 73 around the interior of the skirt 11 of the closure. These are preferably provided between the radially moveable arms 72. There may be the same number of ramp features 73 as there are arms 72 or there may be fewer, eg half the number of arms 72 (although at least two and preferably four ramp features 73 should be provided). The ramp features 73 each have a major surface 73 A which slopes inwardly towards the container, eg at an angle in the range 10 - 15 degrees, and an upper surface 73B having a width (in the radial direction) of 0.5 - 1.0 mm. The ramp features 73 are provided so that when the radially moveable arms 72 have been disengaged with the container lip 32 and the closure starts to lift as described above, the upper surfaces 73B of the ramp features engage under the lip 32 of the container to limit the upward movement of the closure relative to the container. The container and closure are thus in the position shown in Fig 8.

During the initial upward movement of the closure, the o-ring 78 disengages from the parallel sided portion of the inner face 34 of the container and reaches a lead-in portion 34A thereof as shown in Fig 8. If there is an elevated pressure within the container this may be sufficient to lift at least part of the o-ring 78 away from the lead-in surface 34A so this excess pressure is vented. It should be noted that this venting occurs whilst the ramp features are engaged beneath the lip 32 of the container so the closure is remains securely retained on the container.

Once venting has occurred, the closure may be rotated further in the anti-clockwise direction so that the ramp features 73 are driven outwards by engagement with the ramps 33A of the cam features under the lip 32 of the container, so engagement of the ramp features 73 with the underside of the lip 32 of the container is released whereupon the closure can be removed from the container.

As mentioned above, fitting the closure to the container involves a two-stage snap- fit. In some cases, the first snap-fit stage (ie snap fitting of the ramp features 73 over the lip) may enable the user to re-fit the closure after its initial removal from the container. Location of the o-ring seal against the lead in surface 34A may provide a liquid seal, although not necessarily a gas tight seal, to prevent or inhibit spillage from the container. However, the gas pressure in the container is likely to be much reduced after the initial opening (or of no significance if the container holds a non-carbonated beverage).

Figures 10A to IOC illustrate a second one-piece embodiment of the invention comprising a closure with an upper part 80 and a skirt part 81. The closure of this embodiment is similar to that described above but instead of ramp features 73 being provide on parts of the skirt portion between the radially moveable arms 72, rib features are provided on the arms (or at least some of them) themselves. The closure thus comprises radially moveable arms 82 in the skirt portion 81 of the closure and inwardly projecting ribs 83 are provided on substantially inwardly facing surfaces of the respective arms 82. The ribs 83 comprise an upper surface 83 A at a distance beneath an upper surface 82A of the arms 82, a lower surface 83B which is inclined to the vertical axis of the container and an inclined end surface 83 C which forms a ramp from the inwardly facing surface of the arm 82 to the upper surface 83 A. The rib 83 also preferably extends only part way across the width (in the circumferential direction) of the arm 82 so the inclined end surface 83C is spaced from an edge of the arm 82.

It will also be seen that the width of the arms 82 (in the circumferential direction) decreases to some extent towards the lower end of the arm 82. This is a preferred arrangement for a closure formed of a relatively stiff material such as POM as it increases the flexibility of the connection of the arms 82 with the lower part of the skirt portion 81 so reduces the force required to flex the arm 82 in a radial direction. To assist this further, the hinge line where the arm 82 joins the lower part of the skirt portion 81 may also be made straight rather than being an arc of the circumference of the skirt portion. The arms 82 are designed to be stiff in the vertical direction so as to resist vertical compression forces applied to their upper surfaces 82A but relatively flexible in the radial direction. Forming the closure of POM allows both of these to be achieved. The ribs 83 are preferably rigidly connected to the arms 82 so are moveable radially as the arms 82 flex about their connection with the lower part of the skirt portion 81 but in other arrangements (not shown), they may be in the form of small flexible arms connected to the inner surface of the arms 82.

As in previous embodiments, the ribs 83 function to secure the closure to the container 90 when the closure has risen to a venting position.

The vertical spacing between the upper surface 82A of the arm 82 and the upper surface 83 A of the rib feature 83 determines the distance the closure rises between the fully closed position and the venting position. This distance will depend upon the application, but for a wide mouth container might typically be in the range 2 - 3 mm. The upper surface 83A of the arm 82 would typically have a width (in the radial direction) of around 1.0 to 1.5 mm whereas the upper surface 83 A of the rib feature would typically have a smaller width (in the radial direction) of around 0.5 - 1.0 mm. When these surfaces are engaged beneath the lip 92 of the container, the overlap (in the radial direction) with the lip 92 would typically be similar (or slightly smaller) to these dimensions.

Key features of the one-piece embodiments described above are that the closure a) the one-piece closure is in the form of a cap formed of POM

b) the cap has a bore component adapted to carry a sealing member, eg o-ring; c) the cap is a snap-fit over a projecting lip of the container, and

d) rotation of the cap relative to the container causes the snap-fit features to be disengaged from the container lip so the cap can be removed.

Thus, the closure comprises a snap-on, twist-off, one piece cap formed of POM with an o-ring seal arranged to engage an internal surface of the container.

In other embodiments (not shown) of a one-piece closure, the closure may be drawn down onto the container by engagement of features on the closure with features on the container as the closure is rotated (in a tightening direction) relative to the container.

Another preferred key feature of both of the one-piece closures described above is the provision of an intermediate venting position, in which the sealing member is moved to a position which enables excess pressure to be released whilst a feature of the closure is remains engaged with the lip of the container to retain the closure on the container until this engagement is released, eg by further rotation of the closure relative to the container.

As will be apparent from the above description, fitting and/or removal of the closure involves twisting of the closure through relatively small angles, depending at least in part on the number of inwardly projecting parts provided around the inner circumference of the closure. In all cases, this rotation is less than 180 degrees and in most cases less than 90 degrees and preferably less than 45 degrees.

Fitting of the closure by snap-fitting over the lip will generally be carried out by a capping machine once the container has been filled whereas removal of the closure is generally carried out by hand by the end user. Some embodiments may, however, be designed so that the closure can be re-fitted by the user by snap-fitting and/or rotation relative to the container.

The invention has been described above in relation to one- and two-part closures having a variety of features. The invention is not however restricted to use with closures having all the features described in these embodiments and may be used with a variety of other forms of closure including one- and two-part closures having only some of the features of the embodiments described. As mentioned above, the use of polyoxymethylene provides a number of advantages, eg due to its strength, resiliency, low surface friction and its good moulding properties, as well as its gas barrier which make it make it particularly suitable for storing foodstuff or beverages which are susceptible to the ingress of oxygen and/or the egress of carbon dioxide.

Typical benchmarks required in the beverage industry for the gas barrier properties of a container over a given period (ie the shelf life of the product) are:

Oxygen: less than 1 ppm oxygen uptake

Carbon dioxide: less than 10% loss of carbon dioxide

If the oxygen uptake is greater than 1 ppm, the product typically has a spoilt flavour. If the carbon dioxide loss is greater than 10%, the beverage is regarding as having gone 'flat' .

Tests were carried out with closures formed of closures formed of POM and the following tables show the mean uptake of oxygen and the mean loss of carbon dioxide at time intervals up to 28 weeks. The test were carried out at ambient temperature and pressure. In both cases, the container was formed of PET with a silicon dioxide gas barrier coating and a black BR o-ring was used. Table 1 : POM Closure - Oxygen uptake

It will thus be seen that the oxygen uptake of 0.338 ppm at 28 weeks is well within the bench mark of an uptake of less than 1.0 ppm.

Table 2: POM Closure - carbon dioxide loss

A typical carbonated beverage contains approximately 6.5 g of carbon dioxide per litre and, as mentioned above, it is desirable for less than 10% of this to be lost, ie a loss of less than 0.65 g/l. The loss of 0.28 g/l after 28 weeks was thus also well within the benchmark of a loss of less than 0.65g/l.

Tests using the same type of closure and container but with the closure formed of PET instead of POM, gave the following results after 28 weeks:

Oxygen uptake: 0.4 ppm

Carbon dioxide loss: -0.65 g/l (10%?)

As will be seen from the above results, the gas barrier property of a closure formed of POM was approximately 10% better than for PET for oxygen uptake and approximately twice as good as for PET for carbon dioxide loss. Extrapolation of the results for POM also suggest a potential shelf life of at least nine months before the oxygen uptake or carbon dioxide loss reach the industry benchmarks mentioned above. The gas barrier properties of polyoxymethylene are particularly relevant to the closing means of the whereas the physical properties of polyoxymethylene are particularly relevant to the overall strength of the closure and, in particular, the securing means of the closure. The use of polyoxymethylene is thus particularly advantageous for securing means, such as the resiliently moveable arms described above, that are adapted to snap-fit with the container when mounted thereon and particularly in relation to closures for carbonated beverage containers such as wide mouth containers which have the dual function of storing the beverage prior to sale and use as a beverage glass by the consumer.

However, in some applications, eg for non-carbonated beverages, the closure need not have resiliently movable arms as described above and so may not be a snap-fit with the container. Nevertheless, as mentioned above, in such applications the physical properties of POM are advantageous as they allow a thin walled closure to be provided so that less plastics material is used (compared to a similar closure made of PET) whilst having strength characteristics similar to those of a closure formed of PET. In such an application, the thin walled closure may thus comprise closing means for closing a mouth of the container, securing means for securing it in a closed position, eg in relation to an outwardly projecting lip of the container, a bore component which, in use, projects through the mouth of the container, and a sealing member, such as an o-ring, provided on the bore component so that, in use, it seals against an internal surface of the container.

As mentioned above another important aspect of the closure is the provision of sealing means for providing a seal between the closure and the container which are each formed of relatively rigid material. The use of a sealing member such as that described above formed of relatively resilient material, eg an o-ring formed of an elastomer such as nitrile butadiene rubber and carried on a bore component of the closure, for providing a seal between the closure and the container, is particularly advantageous. As discussed above, the closure is preferably adapted to close a container having a circular opening and having an outwardly projecting lip and the closure is preferably adapted to snap fit in one or two stages over the lip of the container, in particular for closing a container which has minimal features on the lip or its external surface so that it is comfortable to drink from. The closure may be snap-fitted over the lip by axial movement and/or rotational movement relative thereto.

The embodiments described above use a variety of arrangements (on the closure and/or the container) for facilitating fitting (and re-fitting) of the closure to a container and removal therefrom, in particular for assisting in moving the bore component (and o-ring seal) axially into and out of the container, eg by converting rotational movement of the closure, or a part thereof, into axial movement of the bore component and the provision of features of the container lip for assisting with this and/or assisting disengagement of the closure form the container as it is rotated in a loosening direction. The invention is not restricted to the particular arrangements described and other arrangements of the closure and/or the container lip for carrying out similar functions may be used.

Similarly, the embodiments described above use a variety of arrangements for facilitating controlled venting of the container as the closure is removed therefrom, in particular for retaining the closure on the container in an intermediate venting position prior to release of the closure from the container. The invention is not restricted to the particular arrangements described and other arrangements for carrying out similar functions may be used. Whilst this application is directed towards the closure for a container, it will be appreciated that the preferred embodiments described, particularly in relation to a wide- mouth closure, are designed to fit onto a container having an outwardly projecting lip and, in preferred arrangements, are arranged to be a snap-fit over the container lip. The snap-fit features are also arranged to be driven outwards so as to be disengaged from the lip by engagement with features of the container as the closure is rotated in the loosening direction relative to the container. 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 closures formed of polyoxymethylene which comprise one or more of the 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 (or more) parts, a first part relating to matter entitled to a first priority date and a second (or further) part relating to matter entitled to a second (or further) priority date.

Claims

1. A closure for releasably securing to a container adapted for storing foodstuff or a beverage, the closure comprising closing means for closing a mouth of the container and securing means for securing it in a closed position, the closing means and the securing means being formed of a plastics material providing a substantial gas barrier to the passage of oxygen and/or carbon dioxide therethrough, the plastics material comprising polyoxymethylene.

A closure as claimed in claim 1 in which said securing means are adapted to engage with the container by rotation relative thereto and/or a snap-fit therewith when mounted thereon.

A closure as claimed in claim 2 in which said securing means has one or more resiliently flexible portions which are flexed as the closure is fitted to the container.

4. A closure as claimed in claim 3 comprising a skirt part depending from the closing means for fitting around the exterior of the container.

5. A closure as claimed in claim 4 in which said flexible portions comprise a plurality of circumferentially spaced radially moveable members around an inner surface of the skirt portion for snap fitting with the container.

6. A closure as claimed in claim 5 in which the radially moveable members

comprise arms connected at their lower ends to the skirt part.

7. A closure as claimed in claim 6 in which each arm is located within an aperture in the skirt part and arranged to flex about the connection at its lower end to the skirt part

8. A closure as claimed in any preceding claim which is an injection moulded closure.

9. A closure as claimed in any preceding claim in which the closure is formed of a relatively rigid material and is provided with a sealing member formed of relatively resilient material for providing a seal between the closure and the container.

10. A closure as claimed in claim 9 which has a bore component which, in use, projects through the mouth of the container, the sealing member being provided on the bore component so that, in use, it seals against an internal surface of the container.

11. A closure as claimed in claims 9 in which the sealing member comprises an o- ring.

12. A closure as claimed in claim 9, 10 or 11 in which the sealing member is

formed of an elastomer, eg nitrile butadiene rubber.

13. A closure as claimed in any preceding claim adapted to close a container having a circular opening defining an axis and having an outwardly projecting lip.

14. A closure as claimed in claim 13 and claim 2, or any claim dependent thereon, adapted to snap fit over the lip of the container.

15. A closure as claimed in any preceding claim in which said securing means comprises a separate component in the form of a collar arranged to fit about the exterior of the container by means of which the remainder of the closure is securable to the container.

16. 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 wherein the outer component is formed of a plastics material comprising polyoxymethylene.

17. 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 wherein the outer component is formed of a plastics material comprising polyoxymethylene.

18. 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.

19. A closure as claimed in claim 18 in which the inner component is formed of a plastics material comprising polyethylene terephthalate.

20. A container and a closure therefor, the container having an opening defining an axis passing therethrough and an outwardly projecting lip around the opening and a plurality of spaced apart camming features on or adjacent an underside of the lip, the closure being in the form of a cap comprising an upper portion for closing said opening and a skirt portion depending from the upper portion for securing the cap to the container, with a substantially rigid connection between the upper portion and the skirt portion, the skirt portion of the cap having a plurality of spaced apart inwardly projecting first parts around an inner circumference thereof for locating beneath the lip of the container to secure the cap to the container, at least part of the skirt portion being sufficiently elastic such that when applied to the container said plurality of first parts can be snap- fitted over the container lip so as to be located beneath the container lip, said plurality of inwardly projecting first parts also being arranged such that upon subsequent twisting of the cap about said axis relative to the container in a loosening direction, they interact with said camming features of the container so said first parts are flexed outwards to disengage them from the underside of the lip, said closing portion also comprising a bore component having a sealing member on, or mountable on, an exterior thereof, such that, when the cap is mounted on the container, the bore component extends into the interior of the container so that the sealing member engages with an internal surface of the container to provide a seal between the closure and the container, wherein the closure is formed of a plastics material comprising polyoxymethylene.

21. A container and a closure therefor, the container having an opening and an

outwardly projecting lip around said opening, and the cap having a top part and a skirt part, the cap being securable to the container by snap fitting projecting parts of the skirt part over the lip and being removable by twisting relative to the container so that camming features on the container flex said projecting parts outwardly to disengage them from the lip, said top part having a bore component that extends into the container and a sealing member mounted on the bore feature for providing a seal with an internal surface of the container wherein the closure is formed of a plastics material comprising

polyoxymethylene.

22. A container and closure as claimed in claim 20 or 21 in which the container is formed of a plastics material comprising polyethylene terephthalate.

23. A container and closure as claimed in claim 20, 21 or 22 in which the sealing member is an o-ring seal comprising a toroid of elastomer material.

24. A closure substantially as hereinbefore described with reference to and/or as shown in one or more of the accompanying drawings.

25. A foodstuff or beverage container having a closure as claimed in any preceding claim.

26. A beverage container as claimed in claim 25 having the shape of a wine glass.

27. A foodstuff or beverage container as claimed in claim 26 or 27 containing a carbonated beverage.

28. A beverage container as claimed in claim 28 having the shape of a beer glass.

29. The use of a closure formed of a plastic material comprising polyoxymethylene for closing a container to provide a barrier to the ingress of oxygen and/or the egress of carbon dioxide through the closure.

30. The use of a closure as claimed in claim 29 for closing a container housing a carbonated beverage, eg beer.

31. The use of a closure as claimed in claim 29 or 30 for closing a container

housing a beverage susceptible to the ingress of oxygen, eg wine.

32. A method of closing a container using a closure as claimed in any of claims 1 to 23.