Patent Publication Number: US-6991123-B2

Title: Closure with extended seal member

Description:
This application is a continuation of application Ser. No. 09/462,781 filed Jun. 15, 2000, U.S. Pat. No. 6,527,132 which is a 371 of PCT/AU98/00510, filed Jul. 3, 1998. 

   TECHNICAL FIELD 
   The present invention relates to linerless closures for containers including, but not limited to, carbonated beverage containers. More particularly, the invention relates to such closures that are formed of a synthetic plastics material and, preferably, in one piece. 
   BACKGROUND ART 
   U.S. Pat. No. 5,423,444 discloses a plastic closure for a container having an externally screw threaded neck, the closure including a top portion and an internally threaded skirt. The closure has an annular sealing rib which projects downwardly from the underside of the top portion. The rib includes a first, substantially cylindrical portion contiguous with the underside of the top portion and lying adjacent to or abutting with the skirt and a second frusto-conical portion contiguous with the end of the first portion distal to the underside of the top portion and extending radially inwardly to a circular free edge. During threaded attachment of the closure with the neck the second frusto-conical portion will be engaged by a free end of the neck and folded back against the first substantially cylindrical portion of the rib to form a gas tight seal between the neck of the container and the closure. 
   U.S. Pat. No. 5,609,263 discloses a variant of the above closure in which there is at the free end of the second portion of the rib a thick seal ring of substantially circular cross-sectional shape. The rib and the seal ring are dimensioned to engage the free end of the neck when the closure is threaded onto the neck such that when the neck is fully screwed into the closure its free end crushes the seal ring directly against the inside surface of the top portion of the closure. 
   The present invention is directed to two arrangements of closure that improve the sealing ability of closures of the type identified in the abovementioned prior art. 
   DISCLOSURE OF INVENTION 
   The present invention relates to a closure suitable for mounting onto a container having an opening defined by an end portion of the container, the closure being moulded from a synthetic plastics material and including a top portion and a skirt portion depending from the top portion all annular sealing rib projecting downwardly from an underside of the top portion the rib including a first portion which is contiguous with the top portion and having all inner surface which inner surface lies radially inwardly of the skirt portion, and a second, frusto-conical, portion contiguous with the first portion and separated from the top portion by the inner surface of the first portion, the second portion extending radially inwardly to terminate in a circular edge, the first portion having all internal diameter relative to the external diameter of the end portion of the container such that during attachment of the closure with the end portion of the container, the second frusto-conical portion of the sealing rib will be engaged by a free end of said end portion of the container and folded back at least adjacent the inner surface of the first portion of the rib, the closure being characterised in that the first portion of the rib increases in thickness as it extends away from the top portion of the closure. 
   In a second aspect, the present invention relates to a closure suitable for mounting onto a container having an opening defined by all end portion of the container, the closure being moulded from a synthetic plastics material and including a top portion and a skirt portion depending from the top portion, an annular sealing rib projecting downwardly from an underside of the top portion, the rib including a first portion which is contiguous with the top portion and having an inner surface, which inner surface lies radially inwardly of the skirt portion, and a second, frusto-conical, portion contiguous with the first portion and separated from the top portion by the inner surface of the first portion, the second portion extending radially inwardly to terminate in a circular edge, the closure being characterised in that the sealing rib has a third portion connected to the second portion at or adjacent the circular edge and extending generally in a direction away from the top portion, the third portion being substantially no thicker than the second portion and having a length longer than its thickness, the first portion having an internal diameter relative to the external diameter of the end portion of the container such that during attachment of the closure with the end portion of the container, the second frusto-conical portion of the sealing rib will be engaged by a free end of said end portion of the container and folded back at least adjacent the inner surface of the first portion of the rib, and with the third portion of the rib positioned between the neck of the container and the top portion of the closure. 
   The closures are preferably provided with a screw thread oil the inside surface of the skirt portion adapted to engage with a corresponding thread oil ail external surface of the end portion of the container. It is, however, possible for the container and the closure to be formed with other complementary attachment means. Such all arrangement could, for instance, comprise snap-on attachment means having a rib on the inside surface of the closure and a corresponding groove on the outside surface of the end portion of the container. 
   The first portion of the rib is preferably formed radially inwardly of the skirt with an annular space therebetween, it is, however, possible in other embodiments to form the first portion of the rib in abutment with the skirt in the sense that the are continuous. In one embodiment of the above aspects of the invention, the first portion of the rib is observed as a thickening of the skirt portion so that the root of the second portion of the rib is moved inwardly of the part of the skirt portion carrying the screw thread or other attachment means. 
   In each aspect, the first portion serves to form an abutment towards which the second portion is folded during attachment of the closure with the end portion of a container. Preferably, the second portion will be folded back against the first portion such that it bears against the inner surface of the first portion. This will cause the second portion to bear more strongly against the outside surface of the end portion of the container and so form a better seal with the end portion. 
   The first aspect of the present invention is directed to the first portion of the rib having a thickness that increases in a direction away from the top portion of the closure. This thickening of the first portion will increase the force of the pressure of the rib against the outside surface of the end portion of the closure. The thickness of the first portion preferably increases at a uniform rate along the length of the first portion however it could do so in a non-uniform manner. The increase in the thickness of the first portion means that the inside and outside surfaces of the first portion will not necessarily be exactly cylindrical. They may respectively taper slightly inwardly and outwardly relative to the axis of the closure in a direction away from the top portion of the closure. 
   In the second aspect of the present invention, the rib includes a third portion. This third portion is preferably contiguous with the free edge of the second portion, though it may be spaced slightly radially outwardly from it. The third portion projects generally away from the top of the closure. It may join the second portion in an angular disjunction or it may join it in a smooth angular transition from the generally radially inward direction of the second portion to a generally axial direction. 
   It is of the essence of this second aspect of the present invention that the third portion of the rib be substantially no thicker than the second portion and also be relatively longer in relation to its thickness. It has been found that the sealing qualities of the closure are best improved by providing a thin extension to the second portion of the rib that will wrap around the free end of the end portion of the container from a position on a cylindrical outer surface of the end portion at least to the apex of the free end of the end portion. It has also been found that this construction also reduces the torque needed to unscrew a closure from a corresponding container to which it has been attached. 
   The closures according to the present invention may be made of any suitable synthetic plastics material, however it is preferred to form them from a suitable grade of polyethylene or polypropylene. It is also preferred to form the closure in one piece by injection or rotary mouldinig. The closures could, however, be formed in two parts with the sealing rib formed separately from the top portion and the skirt portion. 
   It will be apparent to persons skilled in the art that numerous modifications may be made to the closures described in this specification without departing from the scope of the invention as earlier defined. The closure may, for instance, be provided with a tamper evident band, for example a band such as is described in Australian patent specifications 668197 and 683598, the contents whereof are incorporated herein by reference. 
   Where the closure has a screw thread on the inner surface of the skirt, the thread can be continuous or formed of a series of thread segments. If formed from a series of thread segments, the thread segments can be arranged, starting from a first thread segment distal to the top, along a helical thread locus, as is described in Australian patent specification 668197. Each of the thread segments except the first can be formed with two substantially planar end surfaces that are inclined to the axis of the closure and face away from the top of the closure, that is they face in the direction that a mould core used to mould the closure was withdrawn. In this specification, the term “substanitially planar surface” is used to describe a surface that is nearly actually planar or that is curved provided that it all faces in the defined direction. The first of the thread segments is preferably pointed at its end distal to its one adjacent thread segment to assist in mating the thread on the closure with a complementary thread on the neck of a container. 
   The substantially planar ends of the thread segments call also be inclined to a notional radial plane of the closure extending from the longitudinal axis of the closure to the end of the respective thread segment such that the ends are inclined to the cylindrical skirt by an angle that is less than the angle that the respective notional plane makes with that skirt. 
   To assist in the venting of gas that may be present in the container, the spaces between the thread segments in adjacent turns of the thread call be aligned. A groove may also be provided oil the inside surface of the skirt of the closure extending longitudinally thereof through the aligned spaces. 
   There also call be at the line of meeting of the first and second portions of the sealing rib, a weakened zone or annular region of weakness to assist even deformation of the second portion relative to the first as the closure is applied to a container as is described in Australian patent specification 637706, the contents whereof are incorporated herein by reference. 
   The underside of the top portion of the closure call also have a continuous or segmented annular ridge radially inside of the sealing rib. The upper surface of the second portion of the rib may also be formed with an engagement means comprising a segmented or continuous annular ridge as is described in Australian patent specification 74544/94, the contents whereof are incorporated herein by reference. On attachment of the closure with the neck of a container, the engagement means engage with the underside of the top portion. 
   In accordance with the above, the closure can have a tamper evident band adapted to provide all indication of removal or attempted removal of the closure from a container. The tamper evident band can extend from the skirt portion by connection through a plurality of frangible bridges. 
   The band call also comprise a generally cylindrical body portion and a segmented rib extending inwardly of the body portion and adapted to provide a lip having all inner free edge to engage under a retaining flange extending outwardly from the end portion of the container, characterised in that the combined length of the segmented ribs is equal to at least 50% of the internal circumference of the band and the segmented ribs are separated from each other by a gap, the rib segments each having an upper surface facing generally towards the top portion of the closure and an underside facing generally away from the top portion, the inner surface of the band having a plurality of radially inward projections extending from above the free edge of the band and not extending beyond the inner free edge of the lip. 
   The band can also comprise a generally cylindrical body portion and a segmented rib extending inwardly of the body portion and adapted to provide a lip having an inner free edge to engage under a retaining flange extending outwardly from the end portion of the container, the rib segments each having an upper surface facing generally towards the top portion of the closure and an underside facing generally away from the top portion, characterised in that the upper surface of each rib comprises a first surface contiguous with the body portion of the band, which surface slopes inwardly and downwardly away from the top portion, and a second surface which extends radially inwardly from the inner terminus of the first surface and has a slope angle substantially normal to the skirt portion of the closure. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The following description of a preferred embodiment of the present invention is provided as an example of the invention and is described with reference to the accompanying drawings, in which: 
       FIG. 1  is a diametrical sectional view through a part of a closure according to the first and the second aspects of the present invention; 
       FIG. 2  is a diametrical sectional view through a part of another embodiment of a closure according to the second aspect of the present invention; 
       FIG. 2   a  is a diametrical sectional view through a part of another embodiment of a closure according to the second aspect of the present invention; 
       FIG. 3  is a diametrical sectional view of a part of the closure of  FIG. 2  when applied to the end portion of a container; 
       FIG. 4  is a vertical sectional view through a part of an embodiment of a closure according to the first aspect of the present invention: and 
       FIG. 5  is a vertical sectional view through a part of another embodiment of a closure according to the second aspect of the present invention. 
   

   BEST MODE FOR CARRYING OUT THE INVENTION 
   The closure  10  shown in  FIG. 1  comprises a circular top  11  and a depending skirt  12 . The radially inner surface of the skirt  12  is provided with a non-segmented screw thread  13  adapted to mate with a corresponding thread on the neck of a bottle to which the closure  10  is adapted to be attached. While the embodiments of the closure depicted in  FIGS. 1  to  4  are depicted with non-segmented screw threads, other suitable means for attaching the closure to the container would be immediately apparent to a person skilled in the art. The segmented screw thread on the embodiment of the closure depicted in  FIG. 5  can also readily be envisaged as being used, if required, on the embodiments of the closure depicted in  FIGS. 1-4 . The radially outer surface of the skirt  12  carries a series of fine vertical ribs  24 . The fine ribs  24  can terminate at the lower edge of the skirt  12  in a narrow circumferential rib  25  as, for example, depicted on the closure of FIG.  5 . 
   A sealing rib  14  is provided on the underside of the top  11  of the closure  10 . The rib  14  is continuous and annular. Seen in cross-section the rib  14  has three portions  15 ,  17  and  18 . The first portion  15  is contiguous with the top  11  and is substantially cylindrical in shape. The thickness of the first portion  15  increases as the first portion  15  progresses away from the top  11 . The inside surface  16  of the first portion is thus not exactly cylindrical, at least until the closure has been applied to the neck of a bottle. The second portion  17  of the rib  14  is frusto-conical in form and tapers slightly in thickness as it extends radially inwardly from its outer edge which is contiguous with the lower end of the first portion  15 . A sharp edge  20  is formed between the first portion  15  and the second portion  17 . This sharp edge  20  defines a line of weakness between the two parts for a purpose that will be described later in this specification. The third portion  18  is contiguous with the radially inner end of the second portion  17 , the two joining in a curved transition zone  19 . The transition zone  19  changes the direction of the third portion  18  so that it projects substantially in an axial direction away from the top  11 . 
   A short downwardly extending ridge  21  is also provided on the underside of the top  11  radially inside the rib  14 . 
   The arrangement shown in  FIGS. 2 and 3  is essentially similar to that described in  FIG. 1  with the exception that the first portion  15  of the rib  14  is of constant thickness along its length and the second portion  17  and the third portion  18  join in a sharp angular disjunction rather than the smoothly curved transition zone  19  seen in FIG.  1 . As is seen in  FIG. 3  when the closure  10  is applied to the neck  22  of a bottle, a free end  23  of the neck  22  engages the radially outer side of the third portion  18  and starts to push it towards the inside surface of the top  11 . The second portion  17  is also pushed upwardly towards the top  11 . As the second portion  17  is pushed upwardly it bends relative to the first portion  15  along the line of weakness defined by the sharp edge  20 . This ensures that the folding back of the second portion  17  relative to the first portion  15  takes place evenly around the whole circumference of the rib  14 . The folding back of the second portion  17 , and with it the third portion  18 , continues until the third portion  18  is trapped between the free end  23  of the neck  22  and the inside surface of the top  11 . When this happens the second portion  15  will normally be folded back adjacent to or in contact with the inside surface  16  of the first portion  15 . In the embodiment depicted in  FIG. 3 , the first portion  15  is pushed radially outwardly and bears against the radially inner surface of the skirt  12 . A seal will then be formed between the closure  10  and the neck  22  extending from a radially outer portion of the neck  22  around to the apex of the free end  23 . While the, arrangement shown in  FIG. 3  has the first portion  15  of constant thickness it will be appreciated that if the first portion  15  were to taper outwardly in thickness towards its lower end (as is shown in  FIG. 1 ) then this would have the effect of causing the first portion  15  to bear against the inside surface of the skirt  12  sooner and thus to apply more pressure to the radially outer surface of the neck  22  and thus further improve the seal between the closure  10  and the neck  22 . 
   While the third portion  18  is contiguous with the radial inner end of the second portion  17  in  FIG. 2 , an alternative embodiment is depicted in  FIG. 2   a  in which the third portion  18  extends downwardly from the second portion  17  adjacent its inner end. While the third portion  18  is in a slightly different position, the manner in which the second portion  17  of the sealing rib  14  will fold back towards the inner surface  16  of the first portion  15  is substantially identical to that depicted in FIG.  3 . 
     FIGS. 4 and 5  show respectively a part of a closure according to the first aspect of the present invention and a part of a closure according to the second aspect of the invention. In the case of  FIG. 4  the closure  10  has a first portion  15  which increases in thickness away from the top  11  but without a third portion  18 . In  FIG. 5  the closure  10  has a rib  14  in which there is a transition zone  19  between the second portion  17  and the third portion  18  that is of relatively large radius. 
   In  FIG. 4 , the closure also has a short downwardly extending ridge  21  provided on the underside of the top  11  radially inside the rib  14 . On the upper surface of the second portion  17  of the sealing rib  14  and adjacent its inner end, there is also provided a continuous annular ridge  26 . When the closure  10  is attached to the neck  22  of a container and the second portion  17  is folded back towards the first portion  15 , the annular ridge  26  engages with the underside of the top portion  11 . In some cases, the annular ridge  26  call also interlock with the downwardly extending ridge  21  provided on the underside of the top  11  of the closure  10 . While ridges  21 ,  26  are each depicted as continuous, the ridges can be readily envisaged as being comprised of a plurality of segments separated by short gaps. 
   As depicted in  FIG. 5 , the closure  10  includes a band  30  attached by frangible bridges  31  to the lower edge of the skirt  12 . The band  30  includes a rib  32  about its inside surface being sized and shaped so as to provide an inwardly extending lip which will engage under the retaining flange  33  (see  FIG. 3 ) of the neck  22  of the container once the closure  10  is fully closed onto the neck  22 . 
   The rib  32  is made up of a series of rib segments  37  separated by short breaks  38  and in the depicted embodiment constitutes about 85% of the circumference of the band  30 . The short breaks  38  provide circumferential flexibility to the band  30  and allow the rib  32  to pass over the retaining flange  33  without creating a stress sufficient to break the frangible bridges  31 . 
   The rib  32  has an upper side directed towards the top  11  of the closure  10  and all under side directed away from it. The upper side includes a radially outer frusto-conical surface  34  and a radially inner annular surface  35 . The annular surface  35  lies in a plane normal to a longitudinal axis of the closure  10  while the frusto-conical surface  34  is inclined inwardly and downwardly away from the top portion  11  and makes an angle of about 20° with the plane normal to the longitudinal axis of the closure. The presence of the frusto-conical surface  34  assists in the moulding of the closure  10  as it prevents or at least substantially reduces the production of closures having deformed ribs  32 . 
   Below the rib  32  and still on the inside surface of the band  30  is an arrangement of a plurality of inward extending projections  36  each having a long axis generally aligned with the longitudinal axis of the closure  10 . The projections  36  serve to help prevent a person from introducing a device such as a knife blade radially inwardly of the body portion  12  of the band  30  and progressively moving the device circumferenitially around the band in an effort to gradually prise the rib  32  up and over the flange  33  on the container. 
   In  FIG. 5 , the thread  13  is made up of a plurality of thread segments  39  arranged in spaced apart array along the locus of the thread. Each thread segment, except the first segment  40 , is bounded at each end by a planar surface  41 . Each of the planar surfaces  41  are inclined to the longitudinal axis of the closure  10  so that it faces away from the top  11 . Each planar surface  41  is also inclined relative to a notional radial plane extending from the axis of the closure  10  to the planar surface  41  in question such that the minimum included angle between the planar surface  41  and the skirt  12  is acute and is less than the angle that a notional radial plane makes with the skirt  12 . 
   The first thread segment  40  is formed with a planar surface  41  on its trailing edge, however, it is formed with a point  42  on its leading edge to assist in mating the thread with a corresponding thread on the neck  22  of a container. 
   The thread segments  39  in each turn of the thread are aligned as are the spaces between them. A groove  43  is formed on the inside surface of the skirt  12  in each of the aligned spaces between adjacent thread segments  39 . The grooves  43  serve to assist in venting any gas that may be present in the container and, in particular, gases from carbonated beverages as the closure  10  is unscrewed from the container. 
   It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.