Abstract:
A closure is for a container, for example a beverage container. In some examples the closure comprises an outer portion connectable to an opening of the container, an axially actuatable inner portion having a sealing member for restricting fluid flow through the closure with the inner portion in a first position and allowing fluid flow through the closure with the inner portion in a second position axially displaced relative to the outer portion, and an annular membrane connecting the outer and inner portions and configured to provide a returning force to resiliently bias the inner portion towards the first position. A beverage container comprises a closure. A method is for operating a closure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage application of International Application PCT/NO2013/050042, filed Mar. 1, 2013, which international application was published on Sep. 6, 2013, as International Publication WO2013/129940 in the English language. The international application is incorporated herein by reference, in entirety. The international application claims priority to Norwegian Patent Application No. 20120253 and Norwegian Patent Application No. 20120456 which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a closure for a container, for example a beverage container. 
     BACKGROUND 
     To allow for improved ease of use, beverage containers may comprise resealable closures that can be operated without the need to unscrew or otherwise remove a cap, thereby allowing for one-handed operation. Conventional resealable closures comprising such features may have a valve that is operable by pulling or pushing on a portion of the closure, thereby allowing liquid contained in the bottle to flow out. The valve may either remain in an open configuration after being opened, allowing for continued flow of liquid as required, or may be configured to return to a closed configuration thereby resealing the container. 
     Such closures are typically mass manufactured via polymer injection moulding, using multi-cavity moulds configured to form the various components that are required to operate together to form the closures. In certain types of closures, for example where an automatically resealable valve is required, it can be difficult to achieve sufficiently small manufacturing tolerances to give the resulting product a uniform functionality regardless of the specific cavity each part is moulded in. 
     Various technical aspects are influenced by the way in which a resealable valve is configured. The drinking experience is strongly influenced by the ease of response of the closure valve, i.e. a more easily opened valve tends to result in an improved drinking experience. The valve should therefore be easy to operate, but should ideally not remain open, as this can result in leakage of the contents. However, return of air back into the bottle after drinking is an important concern to avoid deformation of the bottle, since the valve will ideally be air tight once it re-closes. Air returning to the bottle after drinking should therefore be controlled by configuration of the valve. A bottle closure having a configurable resealable valve that aims to address these issues is disclosed in published patent application US 2009/0212061. Configuring the closure such that a lower force tends to return the valve to its closed position allows for control over the timing of this venting function. 
     A competing requirement, however, is that the membrane should also be resistant to damage by biting or chewing, given that the valve will tend to be operated by mouth action alone. Since users may be children, a particularly important requirement is that any small components in the closure that may represent a choking hazard are not at risk of being separated during normal use. Typical requirements involve a resistance to loosening or breaking when a force of up to 60 N is applied. Furthermore, any detached part should not be so small that it could become lodged in the throat of the user. The British Soft Drinks Association has developed standards based on such requirements. 
     The aforementioned publication US 2009/0212061 discloses a pressure activated closure device for a beverage container, in which a pressure-sealing membrane is connected between an outer portion of the closure device and a centrally located drinking orifice portion. Movement of the drinking orifice portion results in flexure of the membrane and opening of a valve, allowing the liquid contents of the bottle to flow through the drinking orifice. The elasticity of the membrane ensures that the valve returns to its pressure-sealing position when an under-pressure supplied during drinking ceases. The deformable area of the membrane element must, due to its ring-formed shape, be either very thin or have a long extent in order to provide a sufficiently high flexibility for the membrane to be practically useful. This is an inherent weakness of the type of design in which membrane flexure occurs as a result of an extensive geometrical deformation in an area that by necessity is restricted to a small diametrical extent, i.e. the width of a bottle opening. Furthermore, in one embodiment the membrane is in its periphery only loosely connected to the remaining structure of the closure by means of a snap lock. This connection method provides the membrane with an increased freedom of movement in its outer portion, but this makes it difficult to design a sufficiently strong closure so that the above mentioned regulatory requirement for tensile strength is satisfied. To address this it may be necessary to use several types of plastic materials for the membrane, for example by using a stiffer material for the snap lock zone in relation to the deformation zone. This would result in a technically more complicated solution and as a result lead to the need to use a more expensive manufacturing process. 
     It is an object of the invention to address one or more of the above mentioned problems. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the invention there is provided a closure for a container, comprising:
         an outer portion connectable to an opening of the container;   an axially actuatable inner portion having a sealing member for restricting fluid flow through the closure with the inner portion in a first position and allowing fluid flow through the closure with the inner portion in a second position axially displaced relative to the outer portion; and   an annular membrane connecting the outer and inner portions and configured to provide a returning force to resiliently bias the inner portion towards the first position such that the returning force is lower with the inner portion located at the second position relative to the first position.       

     Preferably, the annular membrane is configured such that the returning force is a maximum with the inner portion located either between the first and second positions or at the first position. 
     A closure according to the invention allows for an improvement in the responsiveness to pressure differences across the membrane during a drinking action, while at the same time providing the means to increase the thickness of the membrane element without affecting its deflection properties and/or its sensitivity, and thereby maintaining a high tolerance to mechanical stress during use, such as biting, puncturing or tear-off. 
     In certain embodiments the annular membrane may comprise a structurally weakened annular region. The weakened annular region may be provided on or adjacent to an upper edge of the outer portion and/or on or adjacent to a lower edge of the inner portion. The structurally weakened annular region may be provided by a reduction in thickness relative to an adjacent portion of the membrane. Alternatively, or additionally, the structurally weakened region may be provided by a portion of membrane material having a relatively increased flexibility, such as by use of a material having a relatively lower stiffness. 
     The annular membrane may be formed of the same or a different material as that for the inner and outer portions. In the case of a different material, the annular membrane material may have a lower stiffness than the inner and outer portion material. 
     The weakened annular region may have a radial width of between 0.1 and 10 mm, optionally between 0.1 and 1 mm or between 0.1 and 0.5 mm. 
     An advantage of the structurally weakened annular region is that adjustments can be made to the geometric elements in a mould tool, for example by changing the height, shape and/or extent of trimming of an individual forming cavity. This makes the design process significantly faster and less costly to set up to an adjusted and optimized production equipment. In addition, more uniform tolerances can be achieved when using multiple cavity moulds. 
     Furthermore, the membrane can be designed to provide a sufficiently low force when the valve is open to allow time for air to flow back through the closure before the valve reseals, while maintaining a sufficiently high closure force when the valve remains closed. 
     The closure may further comprise a protective cover removably connected to a body portion comprising the outer portion of the closure. The protective cover may be connected to the body portion by a hinge portion. One or more frangible connections may be provided connecting the protective cover to the body portion. The body portion may comprises a threaded region configured for affixing the closure to a beverage container. 
     In accordance with the invention, there may be provided a beverage container comprising a closure according to the first aspect of the invention. The container may be a bottle, or alternatively another type of container suitable for holding a liquid, such as a pouch or a laminated pack. The beverage container may contain a liquid beverage, such as a fruit-flavoured drink. 
     In accordance with a second aspect of the invention there is provided a closure for a container, comprising:
         an outer portion connectable to an opening of the container;   an axially actuatable inner portion having a sealing member for restricting fluid flow through the closure with the inner portion in a first position and allowing fluid flow through the closure with the inner portion in a second position axially displaced relative to the outer portion; and   an annular membrane connecting the outer and inner portions and configured to provide a returning force to resiliently bias the inner portion towards the first position, wherein the annular membrane comprises a structurally weakened annular region.       

     The structurally weakened annular region may be configured such that the returning force provided by the annular membrane is lower with the inner portion in the second position relative to the first position, and is preferably a maximum with the inner portion located either between the first and second positions or at the first position. 
     In accordance with a third aspect of the invention there is provided a closure for a container, comprising:
         an outer portion connectable to an opening of the container;   an axially actuatable inner portion having a sealing member for restricting fluid flow through the closure with the inner portion in a first position and allowing fluid flow through the closure with the inner portion in a second position axially displaced relative to the outer portion; and   an annular membrane connecting an upper edge of the outer portion to a lower edge of the inner portion and configured to provide a returning force to resiliently bias the inner portion towards the first position,   wherein the closure is configured such that the lower edge of the inner portion displaces past the upper edge of the outer portion when axially displaced from the first position to the second position.       

     Other optional and preferable features of the second or third aspects of the invention may be correspondent with those of the first aspect. 
     In accordance with a fourth aspect of the invention there is provided a method of operating a closure for a container comprising:
         providing a beverage container having a closure according to the first or second aspects;   actuating the inner portion relative to the outer portion to thereby open a valve comprising the sealing member and allow passage of fluid from within the beverage container through an outflow orifice, past the sealing member and out of the closure through a drinking opening.       

     The inner portion may be maintained displaced relative to the outer portion by a differential suction pressure across the membrane. When the differential suction pressure is removed, the inner portion preferably returns to the first position due to the returning force provided by the membrane to reseal the closure. 
    
    
     
       DETAILED DESCRIPTION 
       Aspects and embodiments of the invention are described in further detail below by way of example and with reference to the enclosed drawings in which: 
         FIG. 1  is an isometric view of a closure according to an aspect of the invention; 
         FIG. 2  is a side elevation view of the closure; 
         FIG. 3  is an alternative isometric view of the closure; 
         FIG. 4  is an alternative side elevation view of the closure; 
         FIG. 5  is a side elevation view of the closure with a protective cover in an opened position; 
         FIG. 6  is a detailed view of a cover removal indicator; 
         FIG. 7  is a longitudinal section through the closure; 
         FIG. 8  is a longitudinal section through a portion of the closure comprising a membrane; 
         FIGS. 9 and 10  are simplified sectional views across a membrane portion of an exemplary closure in closed and open positions respectively; 
         FIGS. 11 and 12  are simplified sectional views across a membrane portion of an alternative exemplary closure in closed and open positions respectively 
         FIGS. 13 and 14  are simplified sectional views across a membrane portion of an alternative exemplary closure in closed and open positions respectively; 
         FIGS. 15 and 16  are simplified sectional views across a membrane portion of an alternative exemplary closure in closed and open positions respectively; 
         FIGS. 17 and 18  are simplified sectional views across a membrane portion of an alternative exemplary closure in closed and open positions respectively; 
         FIGS. 19 and 20  are simplified sectional views across a membrane portion of an alternative exemplary closure in closed and open positions respectively; 
         FIG. 21  is a graphical representation of membrane deflection force as a function of actuation distance for closures having two different exemplary membranes; and 
         FIGS. 22 and 23  are longitudinal sections through a closure device according to US 2009/0212061 in a closed and open configuration respectively. 
     
    
    
       FIGS. 1 to 4  are external views of an exemplary closure device  100  according to an aspect of the invention, with  FIGS. 1 and 3  showing different isometric views of the closure device  100 ,  FIGS. 2 and 4  showing alternative side elevation views of the device  100 , and  FIG. 5  the closure device  100  with a protective cover  102  fully opened. The closure device  100  comprises a closure body portion  101  and a protective cover  102 . The protective cover  102  is connected to the closure body portion  101  by a hinge portion  103  and a pair of cover removal indicators  104 . The protective cover  102  may be opened by applying an upwards directed force using a finger placed against a finger grip zone marking  105  and an upper finger grip  106 , which breaks the cover removal indicators  104  and exposes an inner portion  107  having a drinking opening  108 , the inner portion  107  connected to an outer portion  109  of the closure  100  by a membrane  110 . 
     An outer circumferential surface of the body portion  101  of the closure  100  comprises a series of ribs  111  that serve to enhance grip during capping and removal of the closure from a container such as a bottle. Upon removal of the closure  100  from a container (not shown), a tamper evidence ring  112  will remain on the beverage container. 
     As illustrated in  FIG. 3 , the hinge portion  103  comprises protruding portion  113  extending from the outer circumferential edge of the closure body portion  101  and configured to engage with a corresponding depression  114  in the protective cover  102  on opening the cover  102  by flexing the hinge portion  103 . On opening, thinned sections  115  of the hinge  103  are stretched and bent about their upper hinge zones  116  and lower hinge zones  117 . A recess  118  on the same side of the cover  102  as the hinge portion  113  allows the protective cover  102  to fully open without interference with the body portion  101  with the hinge portion  103  fully deflected, as shown in  FIG. 5 . 
       FIG. 5  illustrates the closure  100  as viewed from the side and in a fully opened condition. The cover removal indicators  104  are broken and the cover  102  is rotated nearly 180 degrees about the hinge portion  103  relative to the body portion  101  of the closure  100 . In this configuration the protruding portion  113  is engaged with the depression  114  and the thinned sections  115  are stretched and bent on their upper hinge portions  116  and lower hinge portions  117 . As described above, the recess  118  on the cover  102  allows for a larger hinge deflection. 
       FIG. 6  illustrates in detail the components that form the cover removal indicator mechanism  104  for providing a tamper evidence function on the closure  100 . The indicator mechanism  104  consists of a frangible connecting portion  601  in the form of an indicator string connected at a first end  602  to the closure body portion  101  and at a second opposing end  603  to the cover  102 . During the initial opening of the cover  102 , the indicator string  601  breaks somewhere between its first and second ends  602 ,  603 , so that opening of the cover  102  is unambiguously indicated. 
       FIG. 7  illustrates a longitudinal section through the closure device  100  described above. A valve  701  is formed by a sealing member  704  sealing against an outflow orifice  702  of an inner wall  703  of the body portion  101  of the closure  100 , the sealing member  704  extending through the outlet orifice  702  in the body portion  101 . The sealing member  704  is connected to, and forms part of, the inner portion  107  of the closure  100 . As indicated in  FIG. 7 , the inner portion  107  comprises longitudinal ribs  706  connecting to the sealing member  704 , with fluid flow paths  707  provided between adjacent ribs  706 . Actuation of the inner portion  107  in an axial direction, indicated by arrow  705 , causes the membrane  110  connecting the inner portion  107  to the outer portion  109  to flex (as indicated schematically in subsequent figures), causing the sealing member  704  to disengage from the inner wall  703  and thereby allow fluid to flow through the closure  100  through the outlet orifice  702  and drinking opening  108 . Elasticity of the membrane  110  provides a biasing force that, on releasing of an actuation force in the inner portion  107 , tends to return the inner portion  107  to the closed position indicated in  FIG. 7 , resealing the sealing member  704  against the inner wall  703  and closing the outlet orifice  702 . 
       FIG. 7  also illustrates part of a threaded region  708  for affixing the closure  100  to a beverage container. The tamper evidence ring  112  is provided with several weakened zones  709  that are configured to break when an inner ridge  710  acts to retain the ring  112  on the beverage container by engaging with a complementary slot in the container (not shown). Upon unscrewing the closure  100  from the container, the weakened sections  709  will break and the indicator ring  112  will remain on the beverage container. 
       FIG. 8  illustrates a longitudinal section of an actuatable portion  800  of the closure  100  as described above, the actuatable portion  800  comprising the inner portion  107  with sealing member  704 , the outer portion  109  and the connecting membrane  110 . The drinking opening  108  extends through the centre of the inner portion  107 . The membrane  110  extends radially between a lower edge  801  of the inner portion  107  and an upper edge  802  of the outer portion  109 , the outer portion  109  forming a circumferential wall  803  of the body portion  101  of the closure  100 . 
     In the embodiment illustrated in  FIG. 8 , the membrane  110  comprises a weakened annular region  804  adjacent the upper edge  802  of the outer portion  109 , the weakened annular region  804  being provided by a reduction in thickness of the membrane  110  relative to the immediately adjacent wall  803  and the adjacent portion of the membrane  110 . 
     In the embodiment illustrated in  FIG. 8 , the wall  803  forming the outer portion  109  comprises a fastening foot  805  at a lower end  806  of the outer portion  109 , the foot  805  serving to permanently connect the wall to the rest of the body portion  101  of the closure  100 . 
       FIG. 9  illustrates a partial sectional view of an actuatable portion  900  having a membrane  910  without a weakened wall section, in which the membrane  910  comprises a substantially uniform thickness between the outer portion  109  and the inner portion  107 . On actuation of the inner portion  107  relative to the outer portion  109 , the membrane  110  flexes into the configuration indicated in  FIG. 10 . Because the membrane  910  is not provided with a thinned or weakened annular region, flexure of the membrane is substantially stiffened, and the resulting flexed form is in a characteristic S-shape. This results firstly in a substantially increased actuation force required to displace the inner portion  107 , resulting in a poorer drinking experience. 
       FIG. 11  illustrates a partial sectional view of an actuatable portion  800  of a closure  100  in a form similar to that shown in  FIG. 8 , in which the membrane  110  is provided with annular structurally weakened zone  804  in region of the membrane adjacent to the upper edge  802  of the outer portion  109 .  FIG. 12  illustrates the actuatable portion  800  with the inner portion  107  axially displaced relative to the outer portion  109 , resulting in flexing of the connecting membrane  110 . In comparison with the membrane  910  of  FIGS. 9 and 10 , the membrane  110  is substantially more flexible as a result of the structurally weakened zone  804 , resulting in a different flexed form. The actuating force required for maintaining the inner portion  107  in the actuated position is thereby reduced due to the reduced stiffness of the membrane  110 , without substantially compromising the integrity of the closure. 
     A differential suction pressure during drinking that applies across the membrane  110  in the actuated position shown in  FIG. 12  would, without the structurally weakened zone  804 , need to be higher to maintain the membrane in the flexed configuration in order to keep the valve open. Using the structurally weakened zone, however, the suction pressure required to maintain the valve open is reduced, while still retaining a high closing force with the actuatable portion  800  in the closed position ( FIG. 11 ). 
       FIG. 13  illustrates a partial sectional view of an alternative embodiment of an actuatable portion  1300  of a closure  100 , in which the membrane element  1310  is provided with a second structurally weakened annular region  1304   b  in addition to a first structurally weakened annular region  1304   a , the first weakened annular region  1304   a  being similar to that described above in relation to  FIGS. 11 and 12 . In this embodiment the second weakened annular region  1304   b  is provided on the membrane  1310  adjacent the lower edge  801  of the inner portion  107 , and is in the form of a reduction in thickness relative to an adjacent portion of the membrane  1310 . A force applied to the inner portion  107  to actuate the valve will apply a higher bending stress at both weakened annular regions  1304   a ,  1304   b , causing the membrane to flex in a different way, illustrated in  FIG. 14  with the inner portion  107  in the actuated position. As can be seen in this figure, deformation of the membrane is now largely confined to the weakened regions  1304   a ,  1304   b . A differential suction pressure required to maintain the valve open is thereby further reduced while maintaining a returning force on the inner portion  107  in the closed position. 
       FIG. 15  illustrates a partial sectional view of a further alternative embodiment of an actuatable portion  1500  of a closure  100 , in which a structurally weakened annular region  1504  is provided on the upper edge  802  of the outer portion  109 . The effect of this, as can be seen in  FIG. 16  illustrating the actuatable portion  1500  with the inner portion  107  in the opened position, is similar to that of providing the weakened annular region in the membrane adjacent the upper edge  802  of the outer portion. In this embodiment, the deformation in the membrane is now concentrated in the outer edge, which can allow the valve opening to be increased due to less deformation of the membrane  1510 . 
       FIG. 17  illustrates a partial sectional view of a further alternative embodiment of an actuatable portion  1700  of a closure  100 , in which a structurally weakened annular region  1704  is provided on the lower edge  801  of the inner portion  107  adjacent to the membrane  1710 . The effect of this, as can be seen in  FIG. 18  illustrating the actuatable portion  1700  with the inner portion  107  in the opened position, is to provide a reduction in the applied force required to actuate the valve between that of the unmodified version ( FIGS. 9 and 10 ) and the version with a structurally weakened annular region along the outer edge of the membrane ( FIGS. 11 and 12 ). 
       FIG. 19  illustrates a partial sectional view of a further alternative embodiment of an actuatable portion  1900  of a closure  100 , in which a structurally weakened annular regions  1904   a ,  1904   b  are provided on both the lower edge  801  of the inner portion  107  and the upper edge  802  of the outer portion  109 , in this case the weakened annular regions  1904   a ,  1904   b  being defined by a difference in internal and external radii at the edges where the membrane  1910  joins the inner and outer portions  107 ,  109 , in each case the internal radius being smaller than the external radius. If this difference is sufficiently large then the resulting structurally weakened zones can provide a significant contribution to the reduction in force required to maintain the valve open and an increase in the possible valve displacement.  FIG. 20  illustrates the actuatable portion  1900  of  FIG. 19  with the inner portion  107  in the axially displaced position, with the membrane  1910  fully flexed. The shape of the flexed membrane in this embodiment is similar to that of the embodiment described above in relation to  FIGS. 13 and 14 . Deformation in the membrane  1910  is concentrated at the peripheral edges in the structurally weakened regions  1904   a ,  1904   b  and the valve displacement is increased due to less deformation of the membrane being required. 
       FIG. 21  illustrates in graphical form a series of measurements of the deflection forces necessary to mechanically actuate (i.e. open) two exemplary closure embodiments, having a membrane without (curve A) and with (curve B) an annular structurally weakened region according to an aspect of the invention. Curve B represents the force required to actuate the valve as a function of displacement for an actuatable portion of the form illustrated in  FIGS. 11 and 12 , whereas curve A represents the force required for an actuatable portion of the form illustrated in  FIGS. 9 and 10 . As can be seen, the force necessary to move the valve differs dramatically, even when only one structurally weakened annular region is incorporated. In each case, the force required to actuate the valve, which largely corresponds to the returning force provided by the membrane, reaches a maximum  211 ,  212  between a first closed position at a lower (but non-zero) displacement and a second open position at a maximum displacement. The maximum displacement may be limited by an end stop, such as when the inner portion  107  contacts the inner wall  703  of the body portion  101  ( FIG. 7 ), resulting in the returning force provided by the membrane being a maximum with the inner portion  107  located between the first (closed) and second (open) positions. The closure may be configured such that the maximum returning force is applied when the valve is in the closed position, so as to maximise the sealing force. An advantage of the form of force-displacement profile illustrated in  FIG. 21  is that the force required to retain the valve in the open position can be reduced compared to that required to open the valve. Given the viscoelastic nature of the polymeric materials that may be used for the actuatable portion of the closure, the reduction in returning force at maximum displacement allows time for air to return through the closure prior to the inner portion returning to the closed position after a differential suction pressure across the membrane is removed. By appropriate design of the membrane, a sufficiently low return force can be designed to allow enough time for air to return while maintaining a sufficiently high return force with the valve in the closed position, thereby keeping the closed valve sealed. The closure may even be configured such that the valve is stable in both the open and closed positions, although this is less preferable due to the possibility of leakage as the valve remains open after drinking. 
       FIG. 22  illustrates a longitudinal section through a closure constructed according to previously published patent application US 2009/0212061. In this closure, a thinned and flexible area  44  is connected by a relatively rigid membrane  42  which, at its middle section, is connected to an inner portion  38  having a drinking opening  32 . The thinned region  44  is connected to an annular flange portion designed with a snap fitting connecting it to the rest of the construction. 
       FIG. 23  illustrates a longitudinal section through the closure of  FIG. 22 , but in an opened configuration. The thinned and flexible area  44  is now deformed and has changed its shape. The rest of the membrane  42  has, however, due to its rigidity, not been deformed. As described above, when large deformations need to take place across a small annular area, this leads to a high resistance to deformation. The forces required to move the membrane is in this case are non-linear and tend to increase exponentially as the axial movement of the inner portion  38  increases. This results in difficult requirements for the material making up the closure. To achieve sufficient movement in the deformation zone  44 , the material must be relatively soft, but at the same time should be stiff enough to transfer forces from the remaining membrane  42  without severe deformations. One solution is to let the difference between the material thickness of the rigid membrane  42  and the flexible area  44  be as large as possible. In that case, however, the ability to uniformly mould the closure will be affected and the product is more likely to fail in mass production. 
     A further difference of the closure according to the invention compared with that disclosed in US 2009/0212061 is that the lower edge  801  of the inner portion  107  of the closure (see, for example,  FIGS. 11 and 12 ) displaces past the upper edge  802  of the outer portion  109  when actuating the inner portion from the first (closed) position to the second (open) position. This feature is associated with the different flexed shape of the membrane connecting the inner and outer portions, which allows for a lower returning force with the inner portion in the displaced second position. 
     Other embodiments are intentionally within the scope of the invention, which is defined by the appended claims.