Field of the invention

The present invention relates to the field of flowable liquid bottle closures, particularly to a closure preform for a glass container. In particular, although not exclusively, the closure preform may be for a bottle for wine, perfume, oil or spirits. Most particularly, although not exclusively, the invention relates to a glass closure preform for a wine bottle that accepts STELVIN ™ type screw caps. Additionally, the invention relates to sub-assemblies of a container closure and a method of forming a closure preform or closure sub-assembly. Background of the invention

There is a resistance to the adoption of new closure designs in the wine industry. One reason is that the wine industry is particularly conservative. Another reason is that the wine industry employs standardised bottling equipment and standardised bottle design. This places limitations on the closure designs which may be accommodated by the standardised bottling equipment.

Typically, the standardised bottling equipment is equipped to handle an over-cap over the neck of the bottle of approximately 0.25mm thickness. These over-caps are known as screw-cap closures or STELVINS™. The screw-cap closures are comprised of a top wall with a peripheral skirt which, before bottling, generally has a smooth outer profile.

During the bottling operation, threads are applied to the peripheral skirt and these threads engage with threads formed on the exterior of the bottle neck near the opening. Additionally, the bottle neck includes an annular land which defines a shoulder therebeneath. The bottling equipment also applies an annular groove in the peripheral skirt so that the screw-cap closure engages with the annular shoulder on the bottle.

During forming, a ring of perforations is made between the annular groove and the screw threads. Thus, when the consumer twists the top of the screw-cap closure, the perforations are broken and the screw-cap closure above the perforations is removable to open the bottle. The remainder of the peripheral skirt is retained on the bottle neck by the engagement of the annular groove under the annular shoulder.

This design places limitations on the metal thickness which may be accommodated by the bottling equipment and generally the metal thickness is limited to 0.25mm in order to form the screw threads, the ring of perforations and the annular groove. Therefore, it is challenging to develop new closures given wine industry constraints.

Accordingly, it is an object of the present invention to overcome or at least ameliorate the abovementioned disadvantage. An alternative object of the invention is to provide the public with the useful choice over known closure preforms, sub-closure assemblies and production methods therefor.

Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.

Summary of the invention

1. Closure preform

In accordance with a first aspect of the present invention, there is provided a closure preform for a glass container arranged to contain flowable content, the container having an opening with a peripheral surface surrounding the opening, the closure preform including: a primary sealing member made of hard material, the sealing member adapted to extend across the peripheral surface for closing the container; a retaining means to retain the sealing member in engagement with the peripheral surface of the bottle, the retaining means including an outer cap, an inner cap for insertion into the outer cap and a secondary sealing member; the outer cap having a top wall and a peripheral skirt, the top wall having an inspection window for viewing the primary sealing member; the inner cap having a top wall, a peripheral skirt and an inspection window in the top wall, the inner cap being received in or insertable into the outer cap; and a secondary sealing member disposed at least partially within the inner cap with the primary sealing member disposed at least partially within the secondary sealing member.

The closure preform as defined above may be transported from its place of manufacture to the bottling plant. Alternatively, an inner cap sub-assembly may be assembled with the outer cap at a subsequent stage, for example at the bottling plant.

2. Closure sub-assembly

Accordingly, a second aspect of the invention provides a closure sub-assembly for insertion into an outer cap of a container closure, the sub-assembly including: a primary sealing member made of hard material for sealing the container; an inner cap for insertion into the outer cap, the inner cap having a top wall and a peripheral skirt with an inspection opening in the top wall for viewing the primary sealing member; and a secondary sealing member at least partially disposed within the inner cap and retained there, with the primary sealing member at least partially disposed within the secondary sealing member and retained there.

Retaining the secondary sealing member within inner cap

The secondary sealing member may be retained within the inner cap by one or more retention features. This may be achieved by complementary structure of the inner cap and the secondary sealing member. For example, the inner cap may be folded or bent inwardly at the end opposite the inspection window to retain the secondary sealing member within the inner cap. This may define an under-roll at the edge of the inner cap. The folds or bends may be in any form such as even, fluted or with spaced folded portions (tabs). Alternatively, the retention feature(s) may be in the form of barbs or ribs formed in the inner cap which retain the secondary sealing member in position. Alternatively, the inner cap may have inward piercings which dig into the secondary sealing member. In another preferred form of the invention, the inner cap may be provided with inwardly extending indentations which resiliently deform outwardly to allow passage of the secondary sealing member and return inwardly to retain the secondary sealing member within the inner cap.

The secondary sealing member may be of resilient material and is oversized compared to the internal dimensions of the inner cap. This enables the secondary sealing member to be inserted into the inner cap under compression and then released to expand and engage with the inside of the peripheral skirt of the inner cap.

Retaining the primary sealing member within the secondary sealing member

The secondary sealing member retains the primary sealing member in position. The secondary sealing member is preferably in the form of an annulus adjacent to an inner side of the top wall of the inner cap and an inner side of the peripheral skirt of the inner cap. The secondary sealing member preferably receives the primary sealing member and a portion of the secondary sealing member extends beyond the primary sealing member in the direction away from the top wall of the inner cap. In the fully assembled glass container, the screw closure created during bottling will provide the force which results in a downward force to hold the top wall in contact with the secondary sealing member. The downward force is transferred through the secondary sealing member to the primary sealing member to hold the primary sealing member in contact with the peripheral surface surrounding the opening of the container. Additionally, the secondary sealing member is held in sealing contact with the primary sealing member. The combination of the inner cap and the outer cap therefore provides sufficient rigidity and strength around the inspection window for force transference.

Similarly, there is a lateral force applied by the peripheral skirt to the secondary sealing member to retain the secondary sealing member in sealing contact with the primary sealing member and the outer side wall surface of the bottle. The combination of the inner cap and the outer cap therefore provides sufficient rigidity and strength to the peripheral skirt to maintain the sealing contact.

The function of the portion of the secondary sealing member that extends beyond the primary sealing member in the direction away from the top wall of the inner cap is to seal against the outer side wall surface of the container.

The secondary sealing member is preferably in the form of an annulus of approximately C-shaped cross section to define an inward-facing annular recess to receive the primary sealing member in the annular recess. In a preferred form of the secondary sealing member, there is an annular flange which overhangs the annular recess with an annular ledge spaced below the annular flange to receive the primary sealing member between the annular flange and the annular ledge. Preferably, annular barb formations are provided on an internal periphery of the portion of the secondary sealing member extending beyond the primary sealing member in the direction away from the top wall of the inner cap. The annular barb formations discourage dislodgment of the primary sealing member from the secondary sealing member and bear against the outer side wall surface of the container, eg the neck of the bottle to provide a seal against the container. The secondary sealing member is suitably formed of resiliently deformable material to allow the primary sealing member to be pushed into position.

3. Method of forming a closure sub-assembly In accordance with a third aspect of the present invention, there is provided a method of providing a closure sub-assembly for insertion into an outer cap of a container closure, the method including: providing a primary sealing member made of hard material for sealing the container; providing an inner cap for insertion into the outer cap, the inner cap having a top wall and a peripheral skirt with an inspection opening in the top wall for viewing the primary sealing member; providing a secondary sealing member at least partially disposed within the inner cap, with the primary sealing member at least partially disposed within the secondary sealing member; and forming in the inner cap, one or more retention features on the inner cap prior to bottling for holding the secondary sealing member within the inner cap.

The retention features to retain the secondary seal within the inner cap are preferably formed after the primary and secondary seals are inserted into the cap. The retention features may be as described above in connection with the second aspect of the invention. Preferably, the sub-assembly is assembled as follows: with the secondary sealing member being inserted into the inner cap, followed by the primary sealing member being inserted into the secondary sealing member. Alternatively, the primary seal may be inserted into the secondary seal and the assembled combination inserted into the inner cap. The retention feature, such as the under-roll, is then applied to the inner cap.

Features of the inner and outer caps

Preferably, the peripheral skirt of the inner cap is shorter than the peripheral skirt of the outer cap. The inner cap thereby forms a strengthening and stiffening function for the inspection window while not interfering with bottling operations which create the screw thread and the annular groove in the outer cap.

Preferably, the inspection windows of the inner and outer caps substantially align. The top wall of the inner cap may abut against or lie adjacent to the top wall of the outer cap. Also, it is preferred that the peripheral skirt of the inner cap abuts against or lies adjacent to the corresponding portion of the outer cap. In one preferred form of the invention, the inner cap is tapered with the peripheral skirt of the inner cap increasing in circumference in the direction extending away from the inspection window. This facilitates insertion into the outer cap and also serves to retain the inner cap within the outer cap when the circumference of the broadest part of the inner cap approximates or exceeds the internal dimensions of the outer cap, thereby engaging within the outer cap by friction or an interference fit. Additionally, the outer cap may be tapered with an increasing circumference in the direction away from the inspection window. There could be a differential in the taper between the outer cap and the inner cap so that at the desired seating location of the inner cap within the outer cap, the inner cap jams within the outer cap. The periphery of the top wall of the outer cap surrounding the inspection window may be folded or bent, preferably inwards. The periphery of the top wall of the inner cap surrounding the inspection window may also be folded or bent, preferably inwards. It is preferred that the curvature of folding or bending of the outer cap is similar to or commensurate with the curvature of folding or bending of the inner cap so that the inner cap nests within the outer cap. The folding or bending may be of a constant radius of curvature around the edge of the window. Alternatively, the periphery of the inspection windows could be fluted, wavy or crimped. A spring lip or in-turned fingers could also be provided around the inspection windows. See for instance, the spring lip or the in-turned fingers of WO2004/024584, the contents of which are incorporated herein by reference. Retention feature (retaining the inner cap within the outer cap)

As discussed above, the inner cap may be retained within the outer cap by friction or an interference fit. There may also be one or more retention features provided on the outer cap to retain the inner cap within, preferably in its seated position.

The inner cap could be retained within the outer cap by the presence of a circumferential bulge in the peripheral skirt of the outer cap, the peripheral bulge being formed relative to the remainder of the peripheral skirt so that the inner cap is received within the circumferential bulge and retained therein by virtue of the external circumference of the peripheral skirt of the inner cap being larger than the internal circumference of the remainder of the peripheral skirt of the outer cap. The remainder of the peripheral skirt is suitably below the circumferential bulge.

Preferably the inner cap is received entirely within the circumferential bulge. The length of the peripheral skirt of the inner cap may be commensurate with the length of the circumferential bulge on the outer cap.

Preferably, the circumferential bulge is created by assembling the inner cap within the outer cap and expanding the assembled inner and outer caps in the region of the inner cap to create the circumferential bulge. The folding/bending of the top wall around the inspection window could also be achieved at the same time.

In an alternative form, the retention features may comprise one or more indentations formed in the peripheral skirt of the outer cap. These indentations may be flexible to be pushed outwardly as the inner cap or closure sub-assembly is pushed into position and to spring back after passage of the inner cap or closure sub-assembly to retain the inner cap or closure sub-assembly within the outer cap.

In a further alternative form, the retention feature may comprise a peripheral rib, inwardly projecting, formed in the peripheral wall of the outer cap to retain the inner cap or closure sub-assembly in position. The peripheral rib may be form subsequent to the insertion of the inner cap into the outer cap.

Another method of retaining the outer cap within the inner cap may be to use an adhesive to bond the inner cap within the outer cap.

4. Method of forming peripheral bulge In accordance with a fourth aspect of the present invention there is provided a method of forming a closure preform or closure sub-assembly for a container arranged to contain flowable liquid, the method including: providing an outer cap having a top wall and a peripheral skirt; providing an inner cap having a top wall and a peripheral skirt, the length of the peripheral skirt of the inner cap being less than the length of the peripheral skirt of the outer cap; assembling the inner cap within the outer cap; expanding the assembled inner cap and outer cap in the region of the inner cap to create a circumferential bulge in the outer cap which seats the inner cap within the outer cap.

Preferably the inner cap and the outer cap are both of metal to accommodate the expansion. The expansion to create the circumferential bulge may extend the radius of the outer and inner caps by about one to three wall thicknesses e.g. the wall thickness is approximately 0.25mm. The inner cap and the outer cap may have inspection windows as described above and the inner cap functions to strengthen the outer cap in the region of the inspection windows. Following the creation of the circumferential bulge, the secondary sealing member is inserted into the inner cap. The primary seal is subsequently inserted into the secondary seal. Alternatively, the primary seal may be inserted into the secondary seal and the assembled combination inserted into the inner cap.

Primary sealing member The primary sealing member may be in the form of a disc which extends across the opening of the container and contacts the peripheral surface surrounding the opening as described in International Patent Application WO2014/179837, the contents of which are incorporated herein by reference. However, other shapes for the primary sealing member are possible including a plug, a dome shape as disclosed in International Patent Application WO2004/024584, the contents of which are also incorporated herein by reference. Another possible shape is the frusto-conical shape of WO2014/179837. The primary sealing member could also be in an inverted conical, inverted frusto-conical shape or parallel truncated cone.

The primary sealing member is preferably glass, ceramic, carbon, metal carbide, metal oxide or other hard material that can define a flat surface. The primary sealing member may incorporate an O-ring, seal or anti-vibration ring as described in WO2004/024584. Additionally, the primary sealing member could be domed to protrude through the central aperture.

It is preferred that the contactable surfaces of the primary sealing member and the peripheral surface surrounding the opening of the bottle are extremely flat surfaces polished to a flatness of two to three wavelengths of light as described in WO2014/179837.

Additionally, a wetting agent which is also described in that International Patent Application may be applied between the contactable surfaces before the bottling operation. The effect of the wetting agent is described in detail in the aforementioned international application and the reader is directed to that earlier specification for further information.

The secondary sealing member in use extends past the junction between the two contactable surfaces to prevent the wetting agent from escaping out from between the flat surfaces and to eliminate evaporation of any wetting agents that have high evaporative properties.

The secondary sealing member is preferably made of one or more compressible synthetic materials that have low liquid and oxygen permeability.

5. Increased thickness in region of inspection window In accordance with a fifth aspect of the present invention, there is provided a closure sub-assembly for a container arranged to contain flowable liquid, the closure sub-assembly including: a cap made of sheet metal having a top wall and a peripheral skirt with the top wall having an inspection window; wherein the top wall and the peripheral skirt adjacent the inspection window has a greater wall thickness than the remainder of the peripheral skirt.

The increase in thickness may be created by the dual skin formed by the inner cap within the outer cap as described in the foregoing aspects of the invention.

Alternatively, the cap may be formed with the increased thickness in the specified region at the time of forming/extrusion. For example, the specified region of the cap may be provided with a wall thickness increased by factor 1 .5 to 3 times the wall thickness of the remainder of the cap. The remainder of the cap preferably has a thickness able to be accommodated by standardised bottling equipment for screw-cap closures or STELVINS™. Thus, the area where the bottling equipment makes the threads and the annular groove will be of a thickness able to be readily accommodated by standardised bottling equipment.

Kit In accordance with another aspect of the present invention, there is provided, a kit for a closure preform for a glass container arranged to contain flowable content, the container having an opening with a peripheral surface surrounding the opening, the kit including: a primary sealing member made of hard material, the sealing member adapted to extend across the peripheral surface for closing the container; an outer cap having a top wall and a peripheral skirt, the top wall having an inspection window for viewing the primary sealing member; an inner cap having a top wall, a peripheral skirt and an inspection window in the top wall, the inner cap being insertable into the outer cap; and a secondary sealing member receivable within the inner cap, the secondary sealing member being shaped: to hold the primary sealing member in a position in the inner cap such that it extends across the peripheral surface of the container when the closure is assembled with the container; and to extend across the junction between primary sealing member and the

peripheral surface of the container when the closure is assembled with the container.

As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings In order that the invention may be more fully understood, some embodiments will now be described by way of example, with reference to the figures in which: Figure 1 is a perspective view of an outer cap for a closure preform in accordance with a first preferred embodiment of the present invention;

Figure 2 is a perspective view of an inner cap insertable within the outer cap of Figure 1 ; Figure 3 is an exploded view in cross-section of the components making up a closure sub-assembly in accordance with a first preferred embodiment of the present invention;

Figure 4 is longitudinal sectional view showing the outer and inner caps of Figures 1 and 2 during a preliminary assembly step; Figure 5A is a view similar to Figure 4 showing the assembled outer and inner caps with an expanding force applied;

Figure 5B is a view similar to Figure 5 showing the result of the expanding force;

Figure 6 is a longitudinal part-sectional view of the closure assembly according to the first embodiment shown on a bottle after bottling operations; Figure 7 is an exploded view in cross-section of a closure sub-assembly in accordance with a second preferred embodiment of the present invention;

Figure 8 shows the sub-assembly of Figure 7 in a partly assembled configuration, showing the operation of a bending tool;

Figure 9 is the sub-assembly according to a second preferred embodiment of the present invention, fully assembled;

Figure 10 illustrates the assembly of the sub-assembly of Figure 9 with the outer cap;

Figure 11 illustrates the manner in which the sub-assembly and the outer cap are assembled; Figure 12 illustrates the closure assembly according to the second preferred embodiment, after bottling operations; Figure 13 illustrates the assembly of the sub-assembly of Figure 9 with the outer cap according to a third preferred embodiment;

Figure 14 illustrates the manner in which the sub-assembly and the outer cap are assembled; Figure 15 illustrates the assembly of Figure 14 with a peripheral groove applied to retain the sub-assembly within the outer cap;

Figure 16 is a detail from Figure 15;

Figure 17 illustrates the closure assembly according to the third preferred embodiment, after bottling operations; Figure 18 illustrates an outer cap according to a fourth preferred embodiment of the present invention; and

Figures 19 and 20 illustrate the assembly of the outer cap of Figure 13 with the sub-assembly of Figure 9.

Detailed description of the embodiments In the first preferred embodiment shown in Figures 1 to 6, the closure preform 10 comprises an outer cap 12, an inner cap 14, a primary sealing member 16 and a secondary sealing member 18. As shown in Figures 1 and 4, the outer cap 12 comprises a substantially cylindrical shell having a top wall 20 and a peripheral skirt 22 which is annular in form. The lower end of the cylindrical shell is open. The transition between the peripheral wall 22 and the top wall 20 is radiused as shown in Figure 4. The top wall 20 includes an inspection window 24 for viewing the primary sealing member 16 and/or the contents of the bottle 1 1 . The outer cap has a longitudinal axis 26 and the inspection window 24 is centrally arranged relative to the longitudinal axis 26. The outer cap 12 is radially symmetrical relative to the central longitudinal axis 26. The outer cap 12 is formed by extrusion and thus, while the peripheral skirt 22 is a substantially constant cross section, there may be a slight taper to enable withdrawal of the outer-cap 12 from the extrusion tool. The outer cap is typically extruded metal such as aluminium. As shown in Figure 4, the periphery of the inspection window 24 is bent or folded to form an in-turned lip 28. The in-turned lip on both the internal and external caps also acts to structurally stiffen the top section of the caps. Preferably these lips are between 0.5mm and 2mm in height. The form of the inner cap is shown in Figures 2, 3 and 4. The inner cap 14 also comprises a cylindrical shell which is symmetrical about a central longitudinal axis 30. The inner cap 14 is receivable in the outer cap 12 and is substantially commensurate in circumference. However, the inner cap 14 is substantially shorter than the outer cap 12. The inner cap is about 7mm in height whereas the outer cap 12 is about 60mm in height. As can be seen from Figure 6, the inner cap 14 is only intended to reside within the outer cap above the region where the screw threads 32 are formed in the outer cap 12. This increase in thickness in this region of the closure preform will add strength around the inspection window 24 while not adding to the thickness of the outer cap 12 in the region where the screw threads 32 are formed in the outer cap 12. As shown in Figure 3, the inner cap 14 has a peripheral skirt 34 which is open at its lower end and has a top wall 36 which has an inspection window 38 centrally disposed relative to the longitudinal axis 30. Like the outer cap 12, the periphery of the inspection window 38 has a downturned lip 40 which projects inwardly. The downturned lip 40 is commensurate in size and curvature with the in-turned lip 28 on the outer cap 12. When the inner cap 14 is assembled with the outer cap 12, the top wall 36 on the inner cap 14 will abut the underside of the top wall 20 on the outer cap 12. The down-turned lip 40 will nest behind and below the in-turned lip 28 on the outer cap 12. Additionally, the peripheral skirt 34 of the inner cap 14 will lie in close abutting relationship with the inner side of the peripheral skirt 22 of the outer cap 12. The peripheral skirt 34 of the inner cap may also be tapered with a matching taper to the peripheral skirt 22 of the outer cap 12.

The inner cap 14 may be formed in a similar process to the outer cap 12 in extruded aluminium.

As an initial assembly step, the inner cap 14 is assembled with the outer cap 12 so that the inner cap 14 nests at the top of the outer cap 12. As shown in Figure 5A, a force is applied from within the inner cap to expand the circumference of the inner cap and the outer cap in the region of the inner cap. The force may be applied by hydraulics. This creates a circumferential bulge in the region of the inner cap so that the circumference of the outer cap in this region is greater than the circumference of the remainder of the peripheral skirt 22 below this region. Similarly, the inner cap also has a circumference greater than the circumference of the peripheral skirt 22 below this region and will thereby be retained in its position at the top of the outer cap 12. It is also possible that the in-turned lip 28 and the down-turned lip 40 may be created during this process. Additionally, an under roll 44 may be created at the lower end of the inner cap 14 during this step, or after insertion of the secondary seal. The under roll preferably extends inwardly by about 0.5mm. The expansion of the inner and outer cap has the effect of increasing the radius of each by about 1 mm.

Subsequently, the secondary seal 18 is inserted into the inner cap 14 in the region of the circumferential bulge. The secondary seal 18 may be retained in position by the under roll 44 on the inner cap 14. The secondary seal 18 is made of resilient material and is annular in form as shown in Figure 3. The secondary seal 18 is the same in most respects as the secondary seal 18' shown in Figure 7. For the sake of clarity the features of the secondary seal will be explained in conjunction with Figure 7. It will be understood that the secondary seal 18 is upside down in Figure 7 and the following description refers to its in-use orientation. As mentioned, the secondary seal 18 is annular in form and symmetrical about a central longitudinal axis 48. The secondary seal 18 includes an annular flange 50 which defines a central opening 52. As can be seen from Figure 6, the central opening 52 aligns with the inspection windows in the outer and inner caps 12, 14. The annular flange 50 includes an annular nose portion 54 which will rest on the upper face of the primary sealing member 16. Additionally, the underside of the nose portion 54 may include one or more annular ribs (not shown) to assist with sealing against the primary sealing member. The annular portion 50 also includes a radiused portion 56 which conforms to the internal curvature of the down-turned lip 40 of the inner cap 14. The nose portion 54 is a bulbus portion projecting slightly from the radiused portion 56. The secondary seal 18 is approximately C-shaped in cross section throughout. This C-shaped cross section creates an annular recess 58 in which the primary sealing member 16 is seated. Spaced from the annular flange 50 is an annular ledge 60 which supports the primary sealing member 16. Overall, the annular recess 58 is undersized for the primary sealing member 16 so that when the primary sealing member 16 is inserted into the annular recess, the resilient nature of the secondary seal 18 holds the primary sealing member 16 firmly in position.

The secondary seal 18 is also open at its lower end to receive the primary sealing member 16. Below the ledge 60 is a series of annular protrusions 62 which essentially function as annular barbs or ribs. The annular barbs or ribs 62 project inwardly and upwardly (in the in-use orientation) so that the primary sealing member 16 may be pushed passed the annular barbs or ribs 62 into position until it is seated in the annular recess 54. The annular barbs or ribs 62 discourage dislodgement of the primary sealing member 16 from its seated position. The annular barbs or ribs 62 assist with sealing agains the edge of the glass disc 16 and also against the outer side wall surface of the neck of the bottle.

The outer circumference of the secondary seal 18 may also be tapered so that the circumference gradually increases in the downward direction. This ensures a good fit within the inner cap 14. Ideally, the secondary seal 18 could also be over-sized for the inner circumference of the inner cap 14. Thus, on insertion, the secondary seal 18 would need to be compressed for insertion into the inner cap 14, following which the expansion holds the secondary seal 18 in abutting position against the inner periphery of the inner cap. Thus, the under roll 44 is merely optional and need not be required to retain the secondary seal 18 in position. As shown, the lower end of the secondary seal 18 is radiused to conform to the under roll 44.

Reverting to Figure 6, once the secondary seal 18 has been inserted, the primary sealing member 16 may be inserted into position as already explained. Alternatively, the primary sealing member 16 may be inserted into position in secondary seal 18 prior to insertion into the inner cap 14. The primary sealing member 16 is preferably in the form of a glass disc although other hard inert materials are also possible. The glass disc 16 is circular in plan and of constant thickness and thus is plate-like in form. The closure preform is then ready for transportation from the place of manufacture to the bottling plant. Due to the circumferential bulge, the inner cap will be retained in position within the outer cap. Additionally, the secondary seal 18 will be retained in position either by the hoop stresses created from being over-sized and/or due to the under roll 44. Additionally, the glass disc 16 is retained in position by being seated within the annular recess 58 in the secondary seal 18. Thus, the closure preform 10 is robust and fit for transportation without the likelihood of components dislodging.

In this embodiment, it is also conceivable that the glass disc 16 may be inserted at the bottling plant. This may be the winemaker's preference to ensure sterility or cleanliness of the glass disc 16 so as not to introduce any contaminants into the wine.

The fully assembled preform 10 is assembled with the bottle 1 1 at the bottling plant or the winery. Generally, standard bottling equipment is used in the wine industry and likewise, the form of the bottle neck is also standardised. The form of the bottle neck is illustrated in Figure 6. The bottle neck has an upper opening (not shown) with a peripheral surface surrounding the opening. The peripheral surface is ideally formed as an extremely flat surface and likewise the contacting surface of the glass disc 16 also has an extremely flat surface. The degree of required flatness is of the order of 2-3 wavelengths of light. The extremely flat surfaces may be achieved by polishing or by laser cutting. These extremely flat surfaces form a surface tension seal when they are pressed into parallel abutting contact. The rest of the closure preform 10 functions as a retaining means to prevent relative lateral movement of the glass disc 16 and the peripheral surface. A full description of the surface tension seal is contained in WO 2004/024584. Additionally, a wetting agent may be applied between the extremely flat surfaces as described in WO2014/179837.

The function of the secondary seal 18 is thus a) to hold the glass disc 16 in position during transit b) holding the glass disc 16 in position during use, by transmitting the force of the closure to firstly hold the glass disc 16 against the peripheral surface of the bottle opening and secondly to hold the glass disc 16 against lateral movement of the glass disc 16 relative to the peripheral surface surrounding the bottle opening, c) to form a secondary seal as a supplementary seal to the primary seal, sealing against the egress of the bottle's contents from between the secondary seal and the primary seal and also between the secondary seal and the outer surface of the bottle neck adjacent the opening . Thus, the secondary seal 18 extends from above the glass disc 16 across the junction of the extremely flat surfaces and therebelow onto the side of the neck of the bottle adjacent to the upper opening.

The neck of the bottle is also provided with integral threads 64, a circumferential land 66 and an annular shoulder 68 below the circumferential land 66. During bottling operations, the closure preform 10 is placed over the neck of the bottle and the bottling equipment forms threads 32 in the outer cap 12 which mate with the integral threads 64 on the neck of the bottle. The bottling equipment also compresses the outer cap in the region below the annular shoulder 68. This may be by way of an annular groove. Alternatively, the whole of the peripheral skirt 22 below the annular shoulder 68 may be compressed to conform to the contour to the bottle neck.

As will be understood by those familiar with wine bottle closures, the outer cap is perforated in a ring (not shown) which lies between the threads 32 and the shoulder 68. This perforated ring may be provided in the preformed outer cap or created during bottling operations. Thus, once the consumer twists the top of the closure preform 10, the upper part of the closure preform 10 will sever from the lower part of the peripheral skirt 22 at the perforated ring. Thus, the upper part of the closure preform 10 can be removed to consume the contents of the bottle while the lower part of the peripheral skirt 22 remains on the bottle.

During bottling a downward force of about 60 kilograms is applied to the top of the cap before the threads are formed and after bottling is completed there must be a retained downward force of the cap against the secondary sealing member of at least 20kg to retaining the secondary sealing member in compression to keep the bottle seal intact. Thus, it will be appreciated that the inner cap 14 forms the function of strengthening and stiffening the upper region of the closure preform, particularly around the inspection window 24. Otherwise, the upward force of the compressed seal leads to distortion of the cap around the inspection window and to loss of downward force. The downward force also assists with retaining the secondary seal 18 in position during transit. However, the increased wall thickness in the upper region of the closure preform 10 is confined to the region above the threads 32 so that this region of the outer cap 12 can co-operate with standardised bottling equipment which can only cope with limited thicknesses in the metal cap.

Some changes may be required to the standard bottling equipment to accommodate the preform 10 according to the present invention. For example, the standard bottling equipment uses rollers create the thread 32 and the under roll 68 and height adjustments may be required to these rollers. Alternatively, in order to minimise the number of changes required to the bottling equipment, the capping top pressure plate, or anvil, could be easily replaced with an anvil that is shorter than the standard Stelvin™ anvil by the thickness of the primary seal 16 and the additional height of the secondary seal. Additionally the 'redraw' function required for Stelvin caps that rolls the Stelvin sealing wadding around the sides of the top of the bottle could be removed from the anvil as that feature is not required in this invention. Alternatively, the height of the circumferential land 66 on the bottle 1 1 could be reduced from the standard dimension by the heights discussed above so that the rollers creating the under roll 68 will not require adjustment.

Figures 7-12 illustrate a second preferred embodiment of the closure preform 70. In this closure preform 70, a sub-assembly 72 is formed which includes the inner cap 14, the secondary seal 18' and the glass disc 16. The sub assembly 72 may then be inserted into the outer cap 12 either at the manufacturing plant for the sub-assembly and the outer cap 12 or alternatively at the bottling plant.

In the second embodiment, many components are substantially identical to those in the first embodiment. There may be some subtle differences but these are noted in the text. Thus, like numerals are used to represent like parts, with the prime symbol (') indicating where a part has been changed to suit the new embodiment.

Figure 7 is an exploded view of the sub-assembly 72 showing the orientation the components adopt during assembly. In this embodiment, the secondary seal 18' and the glass disc 16 are assembled within the inner cap 14', prior to the inner cap 14' being inserted into the outer cap 12. The inner cap 14' is substantially the same as described above for the first embodiment. Additionally, the inner cap includes a ring of perforations or scorings 74 to facilitate bending as will be explained. This ring 74 lies approximately 1 mm from the bottom of the inner cap 14 (considered from the in-use orientation). On assembly, the glass disc 16 is inserted into the secondary seal 18 in the manner described above for the first embodiment. The assembled secondary seal 18 and the glass disc 16 are then inserted into the inner cap 14'. As shown in Figure 8, a forming tool 76 is pressed on to the bottom of the inner cap 14' to create the under roll 44' as shown in Figure 9.

The sub-assembly 72 can be assembled with the outer cap 12 or alternatively, with a standard screw closure such as a STELVIN ™. The sub-assembly can be inserted immediately into the outer cap 12 to form the assembled closure preform 70. Alternatively, the sub-assembly 72 can be transported to another location such as the bottling plant for insertion into the outer cap 12. It is anticipated that the inner cap 14' will have a taper such that the circumference gradually increases in the downward direction (in-use orientation) away from the inspection window. Accordingly, this will create frictional engagement with the inside of the peripheral skirt 22 of the outer cap 12 to assist with retaining the inner cap 14' in position. It is anticipated that the inner cap 12 will also have a slight taper to assist with removal from the forming tool. There could be a differential in taper between the inner cap 14' and the outer cap 12 to create a jamming effect. Alternatively, the sizing of the inner cap may be such that there is an interference fit with the outer cap 12 in the home or seated position. Figure 10 illustrates the insertion of the sub assembly 72 into the outer cap 12 and Figure 1 1 illustrates the home or seated position. Figure 12 illustrates the closure preform 70 assembled onto the neck of the bottle 1 1 . The process at the bottling plant is substantially identical as that described above for the first embodiment.

The third embodiment of Figures 13 to 17 is substantially the same as the second embodiment and like reference numerals indicate like features. The closure subassembly 72 is inserted into the outer cap 12 as with the previous embodiment. Once in the seated or home position shown in Figure 14, a peripheral groove is created by a roller which creates an internal circumferential rib 78 in the peripheral wall 22 to retain the sub-assembly securely in position. The rib 78 is located at the change in curvature of the peripheral skirt of the inner cap 14' created by the forming tool 76. The fourth embodiment of Figure 18 to 20 is substantially the same as the second embodiment and like reference numerals indicate like features. The closure sub-assembly 72 is inserted into the outer cap 12 as with the previous embodiment. However, the peripheral wall 22' of the outer cap 12' is provided with sprung indentations 80 which protrude into the interior of the outer cap 12'. The indentations 80 are formed by cutting and pressing into the peripheral wall 22'. The indentations 80 have two angled facets, the length of which is greater than the length of the cut-out in which they sit, creating a bias towards the inside of the outer cap 12 '. Thus when the sub-assembly 72 is inserted into the outer cap 12', the indentations 80 are pushed out of the way until the sub-assembly reaches the home or seated position and then the indentations 80 will spring back. The indentations 80 are in circumferentially and evenly spaced disposition around the peripheral skirt 22 of the outer cap 12'. The indentations lie at the level of the change in curvature of the peripheral skirt of the inner cap 14' created by the forming tool 76. The indentations 80 serve to retain the sub-assembly securely in position. Similar indentations may also be provided in the inner cap 14 or 14' to retain the secondary seal 18, 18' in position.

The foregoing describes only some embodiments of the present invention and modifications may be made thereto without departing from the scope of the present invention. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.