AU2015100380A4 - Pressure resistant container closure - Google Patents

Abstract

In accordance with the invention, there is provided container and metal closure combination which includes 5 a) a container with an externally threaded neck; b) a metal closure having an internal screw thread adapted to cooperate with the screw thread of the container neck in which the pitch angle of the thread is less than 300; c) a protective lining on the inner surface of the closure; and 10 d) a resilient seal liner over the top internal surface of the closure. The closure may also include the conventional wad. --------- -- Fig. 3 5 Fig. 4

Description

1 PRESSURE RESISTANT CONTAINER CLOSURE This invention relates to improvements in screw cap closures for bottles made of glass plastic or metals particularly glass and aluminium bottles. 5 Background to the invention Conventionally in glass and metal containers the closures for pressurised products are champagne corks or crown seals. 10 Wine and champagne have traditionally been packaged in glass bottles. Aluminium bottles have been proposed and USA patents 6499329 and 6354234 are examples. 15 For still wine products in glass containers the industry standard format BVS (Bague Verre Stelvin) Redraw style 'screw caps' have become popular. Although there are numerous advantages of the metal screw cap, the fundamental disadvantage is the inability of this type of seal to effectively seal 20 and maintain effervescent beverages such as carbonated /sparkling wine, energy and soft drinks as the pressure forces the cap upward and creates a dome effect whereby the inner wad of the cap will lift away from the sealing surface thus compromising the seal and the quality of the contents. 25 It is an object of this invention to provide a metal screw cap and container that can hold carbonated beverages and/or wines (still and/or sparkling and/or carbonated) and have a usable shelf life of at least 12 months and preferably more than 24 months. 30 It is an object of this invention to provide a modified container and closure combination whereby carbonated beverages and/or wines (still or carbonated) preferably have a usable shelf life of at least 24 months. The modified container and 2 closure combination will preferably withstand internal pressures greater than 2.5 bar. Brief description of the invention 5 The object of the invention is achieved by a container and metal closure combination in accordance with the independent claims. Preferred embodiments are disclosed in the dependent claims. 10 In accordance with the invention there may be provided a container and metal closure combination which includes a) a container with an externally threaded neck; b) a metal closure having an internal screw thread adapted to cooperate with the screw thread of the container neck in which the pitch angle of the thread 15 is less than 300; c) a protective lining on the inner surface of the closure; and d) a resilient seal liner over the top internal surface of the closure. The pitch angle of the thread is the angle between a plane being perpendicular to 20 the axis of the thread and the lower flange of the thread. Reference is made to Fig. 1, Fig. 3 and Fig. 6, where the pitch angle a is shown. Since the pitch angle is lower than used in known container and closure combinations, the friction between the closure and the container thread is increased such that the container and closure combination can withstand higher internal pressures. In addition the force needed to 25 lift the closure is higher such that a more reliable sealing of the content is achieved. According to the invention the pitch angle of the thread may be less than 290, preferably less than 270, more preferred less than 270, further more preferred less than 260 and most preferred about 250. 30 According to the invention the pitch angle of the thread may be greater than 150, preferably greater than 200, more preferred greater than 220, further more preferred greater than 230 and most preferred about 250.

3 In accordance with the invention there may be provided a container and metal closure combination which includes a) a container with an externally threaded neck; 5 b) a metal closure having an internal screw thread adapted to cooperate with the screw thread of the container neck; c) a protective lining on the inner surface of the closure; and d) a resilient seal liner over the top internal surface of the closure; 10 wherein the screw thread of the container neck comprises at least two portions having a different pitch angle of the thread. This container and metal closure combination may also comprise the above mentioned features regarding the pitch angle of less than 300 including the preferred 15 values. According to the invention this embodiment comprises at least two portions having a different pitch angle of the thread. Since the closure is formed to conform the neck portion of the container and the form of the thread, a deformation of the closure is needed to lift the closure. For instance the very last portion of the thread near the container may have a different thread angle such that a higher force is 20 needed when opening the closure. Thereby a greater force is needed when starting opening the container. After the portion of the closure with the different pitch angle has been deformed to conform with the rest of the thread a lower force is needed to open the container. Because of the higher force needed at the beginning of opening the container, a more reliable sealing of the content is achieved. It is clear that the 25 portion with the different pitch angle can also be provided at other parts of the thread. In addition more than one portion with different pitch angles may be provided. According to the invention the difference between the pitch angles of the at least two 30 portions can be more than 1 , preferably more than 20, more preferred more than 30 and most preferred about 50.

4 According to the invention the difference between the pitch angles of the at least two portions is less than 100, preferably less than 80, more preferred less than 70 and most preferred about 50. 5 According to the invention the portion of the screw thread of the container neck having the lower pitch angle can cover more than 5%, preferably more than 10%, more preferred more than 15% and most preferred about 20% of the screw thread. According to the invention the portion of the screw thread of the container neck 10 having the lower pitch angle can cover less than 40%, preferably less than 30%, more preferred less than 25% and most preferred about 20% of the screw thread. When more than one portion with a different pitch angle than the majority of the thread is provided the total percentage of these portions may be within the above 15 mentioned ranges. According to the invention the screw thread of the container neck can comprise a portion with a gradually changing pitch angle of the thread. 20 According to the invention the end of the screw thread can have a recessed edge with an angle of less than 120, and wherein the closure has a portion and/or flange to engage with said recessed edge. According to the invention the container neck can have a recessed end edge with 25 an angle of less than 120, and wherein the closure has a flange to engage with said recessed end edge. The angle of the recessed end edge is the angle between a plane being perpendicular to the axis of the thread and the recessed end edge. Reference is 30 made to Fig. 2 and Fig. 3, where the angle P of the recessed end edge is shown. Since the pitch angle is lower than used in known container and closure combinations, the friction between the closure and the container thread is increased such that the container and closure combination can withstand higher internal 5 pressures. In addition the force needed to lift the closure is higher such that a more reliable sealing of the content is achieved. According to the invention the angle of the recessed edge of the screw thread 5 and/or the recessed end edge of the container neck can be less than 11 0 and preferably of about 100. According to the invention the angle of the recessed edge of the screw thread and/or the recessed end edge of the container neck is greater than 80, preferably 10 greater than 90 and most preferred about 100. According to the invention the container and closure combination can use a thread pitch of at least 1.5 turns of thread engagement, preferably at least 1.6 turns of thread engagement and more preferred of about 1.7 turns of thread engagement. 15 According to the invention the container and closure combination can use a thread pitch of less than 2.5 turns of thread engagement, preferably less than 2 turns of thread engagement and more preferred of about 1.7 turns of thread engagement. 20 According to the invention the container and closure combination can use as the protective liner an inert acrylic based lacquer with a minimum film thickness of more than 10 gsm (gram per square meter), preferably more than 11 gsm and most preferred of about 12 gsm. 25 According to the invention the container and closure combination can use as the protective liner an inert acrylic based lacquer with a minimum film thickness of less than 20 gsm, preferably less than 16 gsm, more preferably less than 14 gsm and most preferred of about 12 gsm. 30 According to the invention the thickness of the lining of the closure may be doubled with respect to conventional closure linings.

6 According to the invention the thickness of the lining of the closure can be greater than 25 pm, preferably greater than 30 pm, more preferred greater than 35 pm and most preferred about 40 pm. 5 According to the invention the thickness of the lining of the closure can be less than 60 pm, preferably less than 50 pm, more preferred less than 45 pm and most preferred about 40 pm. According to the invention the container and closure combination can use as the 10 resilient seal liner a water based styrene butadiene polymer. According to the invention the container can be an aluminium bottle. According to the invention the dome on the base of the aluminium bottle can be 15 punted. According to the invention the container and closure combination can include a wad. For instance the closure may also include a conventional wad. However due to the use of a thicker liner and/or a cured water based flexible compound placed into the 20 top of the closure the closure does not require a wad. According to the present invention there is also provided a container and closure combination which includes e a container with an externally threaded neck in which the end of the screw 25 thread has a recessed edge with an angle of less than 120 to the horizontal, e a metal closure having an internal screw thread adapted to cooperate with the screw thread of the container neck in which the pitch angle of the thread is less than 300 and the closure has an internal flange to engage with said recessed end edge of the container neck, 30 e a protective lining on the inner surface of the closure, and e a resilient seal liner over inner surface of the top of said closure.

7 This combination of seal liner and the pitch and recess angles of the screw threads enables the retention of pressurised contents. The periphery of the seal liner contacts the lip of the aluminium or glass bottle to provide the pressure seal. 5 A preferred embodiment of this invention is to provide aluminium can bottles in combination with a modified industry standard format BVS (Bague Verre Stelvin) Redraw style 'screw caps' (such as those sold under the brands Global Cap and New Kap) to ensure the integrity of the seal and stability, longevity of the effervescent product is maintained in excess of 24 months. 10 The aluminium closure of this invention preferably uses an acrylic based curable liner on the internal surface but the conventional epoxy phenolic lacquer may also be used to line aluminium containers and closures. Preferably the protective liner is applied in a thicker coating than is usual. The internal surface closure of this 15 invention is preferably sprayed with an acrylic based lacquer (e.g. Valspar 40Q60AA-BPA Free) or epoxy phenolic lacquer. To ensure adequate protection of the aluminium surface from the contents of the container the thickness of the coating whether it is an acrylic based curable liner or an epoxy phenolic lacquer, is also greater than conventionally used preferably in the range of 11 to 14 gsm. 20 The 'screw cap' for of this invention preferably uses a cured, water based resilient synthetic latex compound placed into the top of the closure so that the peripheral edge contacts the lip of the container. This resilient compound will compress against the rim of the neck of the can bottle and form a tight gas 25 impermeable seal - that will maintain and retain higher pressures in the can or glass bottle than are currently possible with conventional screw cap technology. The resilient compound is preferably a styrene butadiene copolymer which gives the seal resilience and therefore the ability to minimise the potential deleterious effects of any external impact damage when the screw cap is knocked or impacted. 30 In a preferred embodiment this invention uses more threads over the length of the neck to provide a more effective cap seal and the ability to maintain and withstand greater pressures (generated from within the aluminium container caused by the 8 carbonated beverages and carbonated or sparkling wine), than is currently being experienced with screw cap technology. In a preferred embodiment this invention uses a specific thread pitch of a minimum 5 of 1.5 - 2 turns of thread engagement to provide a more effective cap seal and the ability to maintain and withstand greater pressures (generated from within the aluminium container caused by the carbonated beverages and carbonated or sparkling wine), than is currently being experienced with screw cap technology. 10 Preferably this invention uses more threads per unit-thread pitch (wherein the slope of the thread is markedly decreased). This increases the number of turns required to screw the cap on or off the container. Consequently this invention provides a more effective cap seal and an improved ability to maintain and withstand greater pressures than is currently being experienced with screw cap 15 technology. This invention preferably angles the bottle thread down to improve pressure maintenance and uses a range of thread angles from 250to 300. Preferably the angle-degrees of the bottle thread is altered to improve the ability of the closure to withstand varying pressures in the filled aluminium or glass 20 bottle/container. The tuck angle of the recessed end edge of the neck portion of the container is preferably 1 00 to 120. 25 In a particularly desirable embodiment of this invention the dome on the base of the can bottle is punted as this will spread pressures away from the dome seam of the can bottle and add strength to the dome. It is particularly desirable to have the dome punted as this ensures greater internal 30 filling pressures are attainable. This is in contrast to the conventional low filling pressures. The closure of this invention provides a pressure seal that prevents possible 9 deterioration from the effects of oxygen ingress and will provide an extra barrier to wine contact with the inside of the screw cap. The advantages that accrue from this invention are: 5 1. an integrity seal that provides the wine industry and beverage manufacturers with the next generation of screw cap. 2. a solution for the need to provide a reliable, inert seal for an aluminium or glass bottle filled with a carbonated or sparkling wine. 3. a solution for the need to provide a reliable, inert seal for an aluminium or glass 10 bottle filled with a still wine. 4. a solution for the need to provide a reliable, inert seal for an aluminium or glass bottle filled with a wine product/wine based effervescent beverage. 5. the seal guarantees the essential criteria for ensuring the wines key notes and characteristic profiles are maintained during storage and transport in excess of 15 24 months. 6. the closure is resealable 7. the closure is 100% recyclable 8. the closure is easy opening and closing. 20 This invention provides a one way screw cap (one way seal application) to achieve and maintain a greater pressure in the container to allow for the storage of higher pressured products such as sparkling wines. In accordance with the invention the seal has a number of distinct advantages. The 25 One way screw cap will ensure an impermeable seal and achieve greater internal filling pressures. 1. The One way screw cap will ensure these higher pressures are constantly maintained throughout the life cycle of the product. This is in contrast to the 30 conventional low filling pressures of industry standard screw caps currently used which can result in product deterioration or failure within a short time frame such as 3 to 6 months.

10 2. The one way screw cap will also be re-closable therefore guaranteeing the freshness and flavour of the filled product is maintained. 3. Sealant lining Compound on the inside of the top of cap to maximise the achievable torque capability of the screw cap during application onto the 5 aluminium or glass bottle. Detailed description of the invention Preferred embodiments of the invention will be described with reference to the drawings in which 10 Fig. 1 depicts the thread angle required in a preferred embodiment; Fig. 2 depicts the tuck angle required in the preferred embodiment of figure 1; Fig. 3 is a side view of the neck portion of the container of an embodiment in accordance the invention. 15 Fig. 4 is a side view of the embodiment of Fig. 3 with a closure. Fig. 5 is a side view of the embodiment of Fig. 3. Fig. 6 is a side view corresponding to Fig. 4 of another embodiment. Fig. 7 is a side view corresponding to Fig. 5 of another embodiment. 20 The following reference numerals are used in the description: 10 container 11 neck portion 12 top of the neck portion of the container 25 20 thread of the container 21 plane perpendicular to the thread axis 22 direction of the lower flange of the thread 23 inclination of the thread 24 direction of the lower flange of the thread of the thread portion having the 30 lower pitch angle 25 thread portion having the lower pitch angle 30 recessed end edge of the neck portion 31 plane perpendicular to the thread axis 11 32 direction of the recessed end edge of the neck portion 33 flange 40 closure 41 top of the closure 5 42 thread of the closure 43 flange of the closure 44 perforation 45 liner 50 wad 10 a pitch angle P tuck angle (angle of the recessed end edge of the neck portion) y thread angle 5 pitch angle of thread portion (having smaller pitch angle) E thread angle of thread portion (having smaller thread angle) 15 In Fig.1 a portion of the neck portion 11 of the container 12 is schematically shown. In the neck portion 11 there is provided a thread. The pitch angle a is the angle between the direction 22 of the lower flange of thread 20 and a plane 21 being perpendicular to the axis of the thread. Lower flange means the side of the 20 thread facing the container in which the content is held or the side of the thread facing away from top 12 of neck portion 11. Therefore pitch angle a defines the inclination or slope of the lower flange of thread 20 against which the closure is pressed with its corresponding thread portion by the pressure of the content of the container. According to the invention this angle a is smaller than in prior art 25 container and metal closure combinations in order to provide a better protection against an undesired opening of the container due to the internal pressure in the container. Fig. 2 is similar to Fig. 1 wherein angle P of the recessed end portion 30 of the 30 neck portion 11 (tuck angle) is shown. Angle P is the angle between the direction 32 of the recessed end edge 30 of the neck portion of the container and a plane 31 being perpendicular to the axis of the thread. Therefore tuck angle P defines the inclination or slope of the recessed end edge 30 of the neck portion against which 12 a flange of the closure is pressed by the pressure of the content of the container (before the container has been opened for the first time wherein the flange of the closure will be removed) . 5 Figures 3 to 5 show the neck portion 11 of and the closure (Fig. 4) of a container and closure combination in accordance with an embodiment of the invention. The container 10 has a neck portion 11 with a top 12. In the neck portion 11 there are provided threads 20 having a lower flange extending in a direction 22 being in 10 an angle a with respect to a plane 21 perpendicular to the axis of neck portion 11 (or the axis of the threaded portion of the neck portion). The neck portion comprises at its lower end (in proximity to the container with its content) a flange 33 at which the closure 40 is held with a flange 43 after the filling 15 and before the container has been opened for the first time. When the container is opened for the first time flange 43 of closure 40 will be separated at the perforation 44. At the lower side of flange 33 neck portion 11 comprises a recessed end edge 30 20 extending (direction 32) in an angle P with respect to plane 31 being perpendicular to the axis of neck portion 11. Closure 40 has a top 41 and threads 42 conforming to threads 20 of neck portion 11 due to the way of manufacturing closure 40. At the inner face of closure 40 25 there is liner 45. Fig. 5 illustrates thread angle y. Angle y is the angle between the thread along direction 23 and plane 21 being perpendicular to the axis of neck portion 40. Angle y is smaller than the thread angle of conventional container and closure 30 combinations resulting in a higher friction force needed for turning and opening closure 40. Because of the higher friction force needed for opening the container, a more reliable and more secure sealing is provided.

13 Fig. 6 illustrates another embodiment according to the invention. This embodiment mainly corresponds to the above mentioned and described embodiments. The same reference signs have been used to describe the same features and/or parts. Accordingly reference is made to the description thereof and only the differences 5 between this embodiment and the other embodiments are described. At the very end of the thread of neck portion 11 of container 10 there is thread portion 25 having a smaller pitch angle 5 than pitch angle a of thread 20. Pitch angle 5 is the angle between direction 24 of the lower flange of thread portion 25 10 and plane 21 being perpendicular to the axis of neck portion 11. When opening the container for the first time after filling, closure 40 must be deformed because the portion of thread 42 conforming to thread portion 25 having a smaller pitch angle must be deformed to conform with the following thread of 15 neck portion. After the deformation the closure can be unscrewed without the need of further deformation. According to the invention the increased force needed to deform the closure when the container is opened for the first time ensures the integrity and reliability of the 20 sealing of the container. According to a preferred embodiment the first time opening of the container requires overcoming a higher friction force (smaller pitch angle of the thread of the neck portion in comparison with the conventional pitch angles) and requires 25 deforming the closure in a portion corresponding to the thread portion 25 having a different pitch angle. Due to the need of overcoming a higher friction force and the need to deform the closure the force needed to open the container is higher. Accordingly the integrity and the sealing reliability are enhanced. 30 Clearly the thread portion needs to have a pitch angle being different to the other part of the thread such that a deformation is required to open the container. Accordingly the pitch angle of the thread portion can be greater or smaller than the pitch angle of the other portion of the thread.

14 Preferably the portion with the different pitch angle is provided at the end of the thread being next to the container (opposite to the top of the neck portion) such that no further deformation is needed after starting opening the container. 5 However, to provide a higher force needed for opening the container the thread portion having a different pitch angle can be provided anywhere in the thread portion of the neck portion and can also be provided in separate portions being divided over the threaded portion of the neck portion. This will provide a container and closure combination requiring a high force for the first part of opening the 10 container. Therefore the object of the invention to provide a reliable sealing and closure of the container even when filled with pressurized liquids is achieved. However after the deformation has taken place a further deformation might be needed because the deformed closure section needs to be deformed another time when approaching a thread portion with a different pitch angle. This is a minor 15 disadvantage compared to the object achieved. Fig. 7 illustrates another embodiment according to the invention. This embodiment mainly corresponds to the above mentioned and described embodiments. The same reference signs have been used to describe the same features and/or parts. 20 Accordingly reference is made to the description thereof and only the differences between this embodiment and the other embodiments are described. At the very end of the thread of neck portion 11 of container 10 there is thread portion 27 having a smaller thread angle E than thread angle y of thread 20. 25 Thread angle E is the angle between direction 26 of thread portion 27 and plane 21 being perpendicular to the axis of neck portion 11. When opening container 10 by unscrewing closure 40 from neck portion 11 the closure needs to be deformed similar to the way as described in connection with 30 the embodiment of Fig. 6. Accordingly a greater force is needed resulting in a more reliable and secure closure of container 40.

15 The aluminium screw cap of the embodiments (closure 40) is typically manufactured from 0.5m2 to 1 m2 sheets of fine grain aluminium alloy grade-801 1, 1100 or 3105. 5 The thickness of the sheets is typically between 0.18 and 0.25 mm (preferably 0.23mm+/-0.01 mm). Tensile strength: 135 to 142 mPa to the bottle/container. Elongation: 2.5 to 3% The outside of the aluminium sheet is coated with a food grade epoxy or polyester 10 in order to be able to accept a paint for decoration, then the base colour and the end decoration applied prior to the sheet being cut and punched into discs. The inside of the sheet is sprayed with an inert non phenolic , acrylic based polymer- BPA free lacquer (e.g. Valspar 40Q60AA-BPA Free) that complies with International legislation e.g. FDA, with a minimum preferred film thickness range of 15 11-14gsm. The discs are then punched into a cylindrical capsule via a graduated extrusion process and finally the skirt is trimmed in order to attain the finished product. During the screw cap application process the screw cap (non threaded) is fitted to 20 the neck of the threaded container and compressed onto to the surface of the container rim by a high- pressure central metal pressure block, the outside edge of the pressure block moves down the neck of the container -approximately 1 mm, drawing the screw cap downward and effectively increasing the sealing area. The addition of a flexible, resilient sealant compound on the inside of the cap in 25 addition to the liner further ensures that an additional level of seal integrity is maintained and the pressure from within the container is not compromised. A resilient food grade water based synthetic rubber compound such as Fukuoka S1 0P-56 or Actega (WBC-RB-1 006-22) is suitable. 30 In the third stage the primary rollers used to run down the outside of the cap embed the blank aluminium cap onto the threaded grooves of the container neck to allow for the pitch of the cap threads to be shaped in a manner that provides an upward angle of less than 300 preferably 250. This is illustrated in figure 1.

16 In a similar manner the maximum angle of the bead angle of the neck (tuck under angle of the mouth of the cap), is less than 12 0 and preferably 100. This reduces the likelihood of the cap coming off the container because of higher 5 internal container pressures. As shown in figure 2, in the final stage the secondary rollers make a small tuck in the base of the screw cap directly below the screw thread- securing the bottom skirt of the seal. 10 When the container is then pressurised the cap is forced up against the neck thread of the container in an upward motion forcing the cap thread to engage up into the neck thread and thus providing a greater seal and preventing the escape of pressure that would occur if the cap thread was greater than 300 and bead 15 angle of the neck thread were greater than 120. The placement of the flexible food grade water based resilient compound into the top of the closure over the internal lacquer will ensure that a tight impermeable seal is maintained during the compression stage at the filler and continues to 20 maintain the impermeable seal after sealing when the secured cap flexes due to increased pressures encountered from within the container. The closure of this invention also allows for a greater pressure to be applied into the container to allow products requiring above 2.5 bar in pressure to be 25 packaged. The manufacturing stages of the Screw cap of this invention: 1. Raw materials 2. Lacquering and litho. The sheets are lacquered inside and out. The centre 30 portion of the blank that forms the top of the cap is now decorated. 3. The external surface of the screw cap is sprayed with an epoxy -phenolic lacquer 17 4. The internal surface of the closure is sprayed with an inert (non - phenolic) acrylic based polymer- BPA free lacquer(e.g. Valspar 40Q60AA-BPA Free) that complies with International legislation e.g. FDA, with a minimum preferred film thickness range of 11-14gsm. 5 5. Lubrication and Drawing: The cap is punched into discs and the skirt trimmed. Side decoration of the drawn piece. Decoration of the skirt of the cap is optional at this stage of the process. 6. Beading. The cap in its final form producing the knurl, the groove containing the sealing liner and the bridge line. 10 7. Placement of the water based resilient Styrene/Butradene synthetic rubber material such as Fukuoka S1 0P-56 or Actega (WBC-RB-1 006-22) on the inside of the top of the cap. 8. Placement of the Liner wad (multi layered wad) such as Pechiney EPE SU38, EPE 40 or Corelen@3020. 15 9. Using this method of screw cap application during the cap/container sealing process creates the ability for screw cap to push up hard onto the head of the container and into the container thread when the pressure inside the container is increased thus providing a better seal for products that require pressurisation be maintained or increased as part of the product profile (e.g. 20 Carbonated products). 10. Final inspection. Tests for Opening torque, Bridge Performance upon capping and Varnish performance upon capping. The combination of the thicker lacquer, the resilient sealant with the method of 25 screw cap production and application method delivers a far greater pressure seal to the container. The use of the resilient sealant liner in combination with the increased threads per unit-thread pitch and decreased thread angle, allows for higher pressure to be 30 applied to the product in the container. The resilient seal liner extends beyond the periphery of the wad to ensure it seats on the lip of the glass or aluminium container opening.

18 The selected sealant liner is effective under a variety of temperature fluctuations that may impact the level of pressure inside the container due to the product being in a variety of transport and storage conditions. This invention can not only extend the shelf life of pressurised products but also 5 maintain the products integrity inside the container. The results of shelf life testing of this preferred embodiment of the invention is shown in table 1. 10 TABLE 1. Pressure Assessment Pressure initial 3 months 6 months 12 months 18 months 20 OC 1 Bar (14.5 psi) 1.5 - 2.0 Good Bubbles Retained Pressure Retained Retained Retained Pressure Pressure Pressure 2.0 - 3.0 Good Bubbles Retained Pressure Retained Retained Retained Pressure Pressure Pressure 3.0-4.0 Good Bubbles Retained Pressure Retained Retained Retained Pressure Pressure Pressure 4.0-5.0 Good Mousse Retained Pressure Retained Retained Retained Pressure Pressure Pressure From the above it can be seen that the present invention solves the problem of using metal screw caps on aluminium or glass containers for carbonated or pressurised products particularly wines and sparkling wines. 15 Those skilled in the art will realise that this invention may be implemented in embodiments other than those illustrated without departing from the core teachings of the invention. 20 The term 'comprising' as used in this specification and claims means 'consisting at least in part of'. When interpreting statements in this specification and claims which include the term 'comprising', other features besides the features prefaced by this term in each 19 statement can also be present. Related terms such as 'comprise' and 'comprised' are to be interpreted in similar manner. In this specification where reference has been made to patent specifications, other external 5 documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art. 10

Claims (5)

1. Container and metal closure combination which includes a) a container with an externally threaded neck; 5 b) a metal closure having an internal screw thread adapted to cooperate with the screw thread of the container neck in which the pitch angle of the thread is less than 300; and wherein preferably the pitch angle of the thread is less than 290, preferably less than 270, more preferred less than 270, further more preferred less than 260 and most preferred about 250, and/or is greater than 10 150, preferably greater than 200, more preferred greater than 220, further more preferred greater than 230 and most preferred about 250, c) a protective lining on the inner surface of the closure; and d) a resilient seal liner over the top internal surface of the closure. 15

2. Container and metal closure combination, in particular according to any of the preceding claim, which includes a) a container with an externally threaded neck; b) a metal closure having an internal screw thread adapted to cooperate with the screw thread of the container neck; 20 c) a protective lining on the inner surface of the closure; and d) a resilient seal liner over the top internal surface of the closure; wherein the screw thread of the container neck comprises at least two portions having a different pitch angle (a, 5) of the thread, wherein preferably 25 the difference between the pitch angles (a, 5) of the at least two portions is more than 10, preferably more than 20, more preferred more than 30 and most preferred about 50, and/or is less than 100, preferably less than 80, more preferred less than 70 and most preferred about 5*. 30

3. Container and metal closure combination according to claim 2, wherein the portion of the screw thread of the container neck having the lower pitch angle covers more than 5%, preferably more than 10%, more preferred more than 15% and most preferred about 20% of the screw thread, and/or , wherein the 21 portion of the screw thread of the container neck having the lower pitch angle covers less than 40%, preferably less than 30%, more preferred less than 25% and most preferred about 20% of the screw thread. 5

4. Container and metal closure combination according to any of the preceding claims, wherein the screw thread of the container neck comprises a portion with a gradually changing pitch angle of the thread.

5. Container and metal closure combination according to any of the preceding 10 claims wherein the end of the screw thread has a recessed edge with an angle of less than 120, and wherein the closure has a portion and/or flange to engage with said recessed edge, and/or wherein the container neck has a recessed end edge with an angle of less than 120, and wherein the closure has a flange to engage with said recessed end edge, and wherein preferably 15 the angle of the recessed edge of the screw thread and/or the recessed end edge of the container neck is less than 11 0 and preferably of about 100, and preferably the angle of the recessed edge of the screw thread and/or the recessed end edge of the container neck is greater than 80, preferably greater than 90 and most preferred about 100. 20