Abstract:
Container closures for bottles, cans, tubs, etc. having a sloping or slanted flange on the container which matches a complementary flange on a closure cap. The flange is disposed at an angle of at least 10 degrees and a preferred angle of about 20 degrees for a conventional 63 mm closure and a preferred width of about 0.125 to 0.175 inches. A foil liner carried by the cap includes an induction heat activated adhesive on at least the portion thereof facing the complementary flange on the container for greatly increasing burst, vacuum and drop impact strength of the container because the adhesion is in shear rather than peel. Provision can be made for facilitating peeling of the liner to assist the consumer in opening the container. The liner may additionally be adhered to a horizontal surface of the container for further securing the liner thereto.

Description:
[0001]    This is a continuation-in-part of PCT/US2014/11171, filed on Jan. 11, 2014 in the USPTO Receiving Office which claims priority of U.S. Provisional Application 61/768,381, filed Feb. 22, 2013 for which priority is claimed. Priority is also claimed for U.S. Provisional Application 61/999,237, filed Jul. 19, 2014. The disclosures of the foregoing are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    It has previously been disclosed to provide flexible closures for containers wherein the burst strength, internal vacuum resistance, and drop impact strength are increased by placing seals in shear without increasing the peel forces needed for consumers to open the closures and thereby gain access to the contents in the container. 
       SUMMARY OF THE INVENTION 
       [0003]    A primary feature of the present disclosure is to disclose a range of preferred flange angles and widths of seals used to form a seal between the closure and the container on an angled flange, or finish, of the closure and the container rather than merely sealing on a top edge or surface of the container as is presently done. The result is a much stronger seal which is in shear rather than peel. 
         [0004]    The improved burst performance of angled seals is documented in results of lab tests described here: 
         [0000]    
       
         
               
             
               
               
             
               
               
               
             
           
               
                   
               
               
                 Burst Tests: Heat Seal in Shear (Angled) vs. Peel (Flat) 
               
               
                 307 Diameter Plastic Bowls with Sealing Film, Heat Sealed to the Flange 
               
               
                 Standard Plant Air 
               
             
          
           
               
                 Test Results:** 
                 PSI 
               
             
          
           
               
                 Variable (Flange Angle) 
                 Average Burst 
                 Burst Range 
               
               
                   
               
               
                 Flat (Control) 
                 26 
                 18-32 
               
               
                 30 Degree Angle 
                 45 
                 41-55 
               
               
                 45 Degree Angle 
                 56 
                 53-65 
               
               
                   
               
             
          
         
       
     
         [0005]    To achieve the time, temperature and pressure needed in the process, an angled section under, and at the outer, internal edge of the closure is added. The shape of this section can vary depending upon the geometry of the container flange but is intended, in all cases, to exert pressure on the angled liner and container flange as the closure is twisted or snapped into place. 
         [0006]    While the angle section is generally around the entire inner corner or circumference, 360 degrees of the closure, some designs change the shape, or reduce the angle, over a small section to prevent a full section heat seal on the periphery to facilitate a pull tab, or peel opening feature. This technique of providing a pull tab helps to initiate the peel opening, and also reduces tearing of the liner or of the lid when opened from the outside by a consumer. The force needed to peel the pull tab is, ideally, in the range of 2 to 6 pounds. The necessary force could be higher, on the order of 10 to 12 pounds, but that risks tearing of the liner or inducing the consumer to use a sharp instrument to tear the liner for opening the container. 
         [0007]    All current liners are flat and are pushed into the closure as a component, or are cut from a web of liner material and pressed into the closure. The liner contemplated by the present invention may also be flat and may be inserted into the closure the same as with existing liners. Or, the liner may be preformed before insertion into the closure. Preforming has two advantages. First, since the outside diameter of an angled liner could well be greater than flat liners, preforming would allow clearance past the closure threads or snap ring as the liner is being inserted. Second, because of a requirement to angle the full periphery of the liner, preforming would avoid wrinkles which could impede effective seals. 
         [0008]    Those skilled in the container and packaging art will recognize that the invention is suitable for use with the three different types of closure caps, namely, (1) push on—push off, (2) twist on—twist off, and (3) push on—twist off. Thus, the container closures and/or the containers can be provided with helical threads, or with circumferential snap rings. 
         [0009]    A major trend in the container industry is to blow the bottle finish into the mold rather than use an injection molded finish. Injection has been used in the early days where finish diameters were small (such as with soft drinks) and the small diameter allowed more parisons per mold. Now, especially with bigger diameters (such as 63 mm) the finishes are blown and the injection molded top of the preform is cut off and recycled as plant scrap. The net impact is thinner top finishes which are harder to seal effectively. Therefore, adding the angled flange gives a good sealing surface and adds the shear feature, rather than peel, if angled correctly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view of a prior art closure cap for closing a container. 
           [0011]      FIG. 2  is a vertical section of the prior art closure cap of  FIG. 1  and shows a liner contained therein. 
           [0012]      FIG. 3  is a fragmentary section of a container provided with an inwardly turned top flange portion having a slanted engagement surface having an angle α. 
           [0013]      FIG. 4  illustrates the fragmentary section of  FIG. 3  positioned within a closure cap that is provided with a matching slanted engagement surface for capturing a peripheral portion of a liner along the slanted flange portion of the container. 
           [0014]      FIG. 5  illustrates a modification of the top portion of a container wherein a downwardly and outwardly slanted surface is provided having an angle α. 
           [0015]      FIG. 6  illustrates the fragmentary section of  FIG. 5  positioned within a closure cap that is provided with a matching slanted engagement surface for capturing a peripheral portion of a liner along the slanted flange portion of the container, with an outermost portion of a liner for providing a pull tab aiding a consumer in removing the liner from the container after removal of the closure cap. 
           [0016]      FIG. 7  illustrates a modified form of the invention wherein the container flange is provided with a horizontal, flat sealing surface and a downwardly and outwardly slanted sealing surface cooperating with matching surfaces on the container cap for securing an outer periphery of a liner there between. 
           [0017]      FIG. 8  illustrates another modified form of the invention wherein the container flange is provided with a horizontal, flat sealing surface and a downwardly and outwardly slanted sealing surface cooperating with surfaces on the container cap for securing an outer periphery of a liner there between wherein the slanted surface on the closure cap is foreshortened to avoid sealing a pull tab portion of the liner against the container flange. 
           [0018]      FIG. 9  illustrates a modified snap-on closure cap and a modified container flange with an externally turned and downwardly angled surface matched or slightly greater angle than a corresponding angle on the underside of the cap and liner. 
           [0019]      FIG. 10  shows the closure cap and container of  FIG. 9  in a closed position wherein the peripheral portion of a liner is captured between the closure cap and an outwardly and downwardly sloping surface of the container. 
           [0020]      FIG. 11  illustrates a modified flange on a container, which may be formed of metal, the edge portion being curled for avoiding a hazardous sharp edge. 
           [0021]      FIG. 12  shows apparatus for providing a sealing line for closing a plurality of containers with an opposing conveyor belt to snap the closure onto the container and hold it while an induction heating device and a cooling device create the sealing process. 
           [0022]      FIG. 13  is a fragmentary, sectional view of a closure cap which includes a small circumferential ring member for engaging the peripheral edge of a liner for centering and hold the liner in place prior to closing of the container with the closure cap. The closure in  FIG. 13  is snapped in place instead of relying on threads. 
           [0023]      FIG. 14  depicts an “Existing”, or “Prior Art” example of a traditional “twist-on, twist-off” threaded cap and conventional flat liner. 
           [0024]      FIG. 15  illustrates a “Push-On, Push-Off” closure cap with a liner that is induction heat-sealed to the slanted finish of a container. 
           [0025]    The lines A and B shown on  FIGS. 14 and 15  represent the identical fill level for both designs of finish and closures. 
           [0026]      FIG. 16  is a fragmentary showing of a production line for inserting liners into a closure cap of the type shown in  FIG. 17 . 
           [0027]      FIG. 17  shows a modified container closure having a slanted surface for cooperating with a slanted surface of a liner and the container finish, and being provided with screw threads for attaching the closure cap to a container. 
           [0028]      FIG. 18  illustrates a prior art closure cap wherein the top of the cap and the side wall of the cap are joined at a right angle corner and a flat, molded annular gasket is located at the corner. 
           [0029]      FIG. 19  is a further example of a prior art closure cap joined at a right angle corner, and a gasket of moldable resilient material is applied within the corner. 
           [0030]      FIG. 20  is a fragmentary section of a novel form of closure cap wherein the top and side wall of the cap are joined at an angle, similar to  FIG. 17 , and a moldable resilient material forms a gasket that conforms under pressure to an angled surface of the container. 
           [0031]      FIG. 21  is a fragmentary section of a blow molded container and a closure cap wherein the container terminates at its open end with a horizontal, inwardly directed flange. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]      FIG. 1  is a perspective view of a closure member also referred to as a cap or lid known in the prior art, generally indicated by the numeral  10 , and includes a central end closure panel  12  and a depending skirt portion  14  for closing a conventional container, such as a metal, glass or plastic can or bottle. 
         [0033]      FIG. 2  is a vertical section of the prior art closure member  10  of  FIG. 1  and illustrates a series of internal threaded portions  16  which can be used for pushing on, and twisting off the closure member  10 , and includes a flat liner  18 —which may be made of paper, foil or plastic or be multilayer—underlying the central end closure panel  12 . 
         [0034]      FIG. 3  shows a fragmentary, vertical, upper container section  20  of a container  22  which is provided with an external, helical threaded portion  24 . It is to be understood that a snap ring can be used in lieu of helical threads. A tongue member or flange  26  extends upwardly and inwardly at the uppermost portion of top section  20  and includes a slanted, non-horizontal, upper surface  28  which extends circumferentially about the container  22 . The slanted upper surface  28  is shown slanted at a flange angle a and having a width B. This flange angle for a well known standard 63 millimeter (mm) closure can be in a range of preferably at least about 10 degrees to about 50 degrees, more likely in a range of 15-25 degrees, and preferred at about 20 degrees, plus or minus up to 5 degrees. For larger containers this flange angle can and should be increased to an angle in the range of 25 to 50 degrees. The width B of the flange 28 is in the range of about 0.050 to 0.250 inches with a preferred width of about 0.125 to 0.175 inches. 
         [0035]      FIG. 4  shows a novel container closure, lid or cap member  30  including a non-horizontal, circumferential, slanted surface  32  which cooperates with the slanted, upper surface  28  on the tongue member  28  of container  22 . Closure  30  has a skirt portion  34  which may include internal thread or threads  36  for adapting closure  30  to be threaded onto, or pushed on and twisted off, the top portion  20  of container  22 . A liner  38  includes a thin layer of heat-sensitive adhesive  39  on the underside thereof that comes into contact with the slanted surface  28  of the tongue  26  on the top section  20  of the container  22 . Liner  38  is preferably of metal foil and the underlying, thin layer of adhesive  39  is heat sensitive such that during closure of the container, induction heating causes the adhesive  39  to seal the liner  38  to the slanted surface  28  on the container  22 . As is shown in  FIG. 4 , a peripheral portion  40  of liner  38  is disposed between the slanted surface  28  of tongue  26  and the slanted surface  32  on the underside of closure member  30 . While the parts are shown partly separated for clarity, it is to be understood that when tightly assembled by threads  24  and  36 , liner  38  has its peripheral portion  40  tightly pressed against slanted surface  28 . While the slanted surfaces  28  and  32  are shown as having flat, or planar, surfaces, it is to be understood that one surface may be slightly domed and the other surface slightly concave thereby having a smooth even grip on the peripheral portion  40  of liner  38 . After filling and sealing, when the closure member  30  is removed during opening of the container  22 , the liner  38  is adhered in shear rather than peel, and the consumer&#39;s opening motion is in peel. 
         [0036]      FIGS. 5 and 6  show an upper container section  42  of a container  44  having exterior threads  46 . Container  44  may be formed of plastic, glass or metal, and at its uppermost portion, or finish, is topped with a non-horizontal, slanted surface  48 . In a manner similar to  FIG. 3 , slanted surface  48  forms a flange angle a which for the standard 63 mm closure has the same ranges described above with the preferred angle being about 20 degrees, plus or minus a couple of degrees. Slanted surface  48  has a width B in the range of 0.050 to 0.250 inches and a presently preferred width of about 0.125 to 0.175 inches for a 63 mm closure. As is shown in  FIG. 6 , a peripheral portion  40  of liner  38  is disposed between slanted surface  32  of closure  30  with the heat-sensitive adhesive side  39  disposed for contact with slanted surface  48  of container  44 . During closure of container  44 , closure  30  presses the peripheral portion  40 , of liner  38 , against slanted surface  48 , and induction heat is applied for causing adhesive  39  to secure liner  28  to slanted surface  48 . When the closure member  30  is removed during opening of the container  44 , the liner  38  is adhered in shear rather than peel. It is shown in  FIG. 6  that the peripheral portion  40 , of liner  38 , includes an over-hanging portion forming a pull tab  50  for assisting a consumer in opening the container  44  by peeling liner  38  from container  44 . 
         [0037]      FIG. 7  illustrates a different embodiment of a closure, cap or lid  52 , and container  54  wherein an inwardly sloping container tongue  56  includes a slanted surface  58  and flat upper surface  60  for increasing the area of contact with the peripheral portion of liner  38 . A portion  62  of liner  38  overhangs the tongue  56  to provide a pull tab for assisting a consumer to peel the liner  38  from container  54  after the closure  52  is removed. 
         [0038]      FIG. 8  is similar to  FIG. 7  but includes a closure  64  having a shortened slanted surface  66  and a horizonal flat portion  68  such that a peripheral portion  70  of the liner  38  is free of the tongue  56  to provide a pull tab. It is to be understood that the flat portion  68  may only extend about  10  degrees about the circumference of container  54 . 
         [0039]      FIG. 9  shows a modified closure  94  and a liner  38  having complementary outwardly and downwardly slanted surfaces. As previously described, liner  38  has a thin layer of adhesive on the side thereof that comes into contact with the related container. A container  95 , which may be formed of metal, paper or plastic, has an outwardly and downwardly extending flange  96  which comes into contact with liner  38  when pressed together as indicated by the arrow in  FIG. 9 , and as shown in  FIG. 10 . Closure  94  has an inwardly extending cam surface  97  which deflects container flange  96  inwardly during assembly and the flange  96  then snaps into contact with liner  38  as is shown in  FIG. 10 . The parts are shown slightly spaced for clarity but it is to be understood that the flange  96  and liner  38  are in firm contact with each other during the step of induction heating for sealing the container  95  with the adhesive layer  39  of liner  38 . 
         [0040]      FIG. 11  is a fragmentary portion of a modified metal container  98  having an outwardly and downwardly slanted flange  99  which is intended to cooperate with the closure  94 , as in  FIGS. 9 and 10 . Flange  99  terminates in a curl to protect against a sharp peripheral edge. 
         [0041]      FIG. 12  shows a closing line, generally indicated by the numeral  100 , wherein a plurality of containers  102  are shown moving under a conveyor belt  104  for pressing caps  106  onto the containers  102  and holding them together while an induction heater  108  causes adhesive on the liner contained within the cap  106  to seal the container  102 . The adhesive can then be cooled by a cooling unit  110 . 
         [0042]      FIG. 13  shows a further modification wherein a closure, cap or lid  90  includes a ring or series of nibs  92  extending circumferentially about the underside of closure  90  for being contacted by the peripheral edge of liner  38  to center the liner  38  and maintain it in proper position while the closure is placed upon a container during the closing operation. 
         [0043]      FIG. 14  illustrates an existing, prior art, traditional threaded container  72 , threaded closure  73  and liner  74 . In accord with the present invention, it is seen that a bottom part of the circumferential, tamper-band skirt  75  is to be eliminated because tamper evidence is provided by the aluminum sealed liner; also eliminated is an upper part of the container finish  76 . The result is shown in  FIG. 15  wherein liner  38  has its adhesive side  39  heat sealed to a container tongue  78  and closure  80  is a “Push-On, Push-Off” closure. The weight reduction of the container finish  76  is approximately 5 grams for a container of 63 mm finish and the closure skirt portion  75  is also a meaningful change resulting in significant cost savings. 
         [0044]    The lines A and B shown on  FIGS. 14 and 15  represent the identical fill level for both designs of finish and closures. The savings in material through utilizing the closure cap and container of  FIG. 15 , rather than the prior art structures of  FIG. 14 , is economically meaningful. 
         [0045]      FIG. 16  is a fragmentary showing of a production line for preforming liners  38  from a web of liner material  82  that on its upperside is coated with a thin layer of adhesive  83 . Web  82  moves in the direction of arrow  84  and passes beneath a forming tool  86  which shapes the outline of a desired liner  38 . The web  82  continues and is acted upon by a punch  88  that inserts liner  38  into an underlying closure  52  first shown in  FIG. 7  and shown in cross section in  FIG. 17 . It is to be understood that the same procedure may be used for inserting a liner  38  into closures  30 ,  52 ,  64 ,  80 ,  90  and  94  described above. 
         [0046]      FIGS. 18 and 19  are both examples of prior art closures wherein the end panels wherein the central end panel closures  12  are joined to depending skirt portions  14  at right angles  15 . In the embodiment of  FIG. 18  there is provided a preformed gasket  17 , generally rectangular in section, that extends circumferentially about the skirt  14 . In the embodiment of  FIG. 19 , a gasket  19  of moldable resilient material is applied within the right angle corner where the end panel closure  12  meets the skirt portion  14 . 
         [0047]      FIG. 20  is an improvement over the embodiments of  FIGS. 18 and 19 . A gasket  25  of moldable resilient material is provided where the end panel  21  meets with the depending skirt portion  23 . In view of the tapered tongue  56  on the container  54 , similar to the showing in  FIG. 8 , the gasket  25  is caused to conform to the tapered tongue  56  and capture and press a peripheral portion of liner  38  and place it in shear. A pull tab  70  assists the consumer in initially pealing the liner from the container  54 . 
         [0048]      FIG. 21  illustrates a closure cap  120  for a blow molded container  122  having a substantially horizontally, plus or minus 5 degrees, inwardly, extending flange  124 . Closure cap  120  holds liner  38  against flange  124  during induction heating for causing adhesive  39  to secure the liner  38  to flange  124 . This embodiment of the invention is useful for vacuum packed products wherein liner  38  tends to be drawn into the container  122  but is securely held, in shear, to the top surface of flange  124 . 
         [0049]      FIG. 21  also illustrates a feature of the invention with respect to the width of the container flanges and the sealing area between the respective liners  38  and adhesive layer  39  of the various disclosed embodiments. The dimension D in  FIG. 21  may be in the range of 0.050 to 0.250 inches, or wider for larger containers. For the well known standard 63 mm closure, the width of dimension D may typically be in the range of about 0.125 to 0.250 inches and a presently preferred width of about 0.175 inches. For larger closures, the width of dimension D would likely be increased. These dimensions are suitable for hot packed or 
         [0000]                                                                               
retorted product, or for vacuum packed products, and maintains the liners adhered to the container flanges in shear condition.
 
         [0050]    Modifications and variations as would be apparent to those skilled in the art are deemed to be within the scope of the present invention as defined by the appended claimed subject matter.