Abstract:
A tamper evident and resistant container lid of the present invention includes a lid body configured to cover the opening of a base container having a top rim and a skirt extending from the lid. The skirt has an annular score line and an annular fold line extending therearound. An outer band of the skirt extends between the score line and the fold line, and an inner band folded inwardly to be in opposing relation to the outer band extends upwardly from the fold line to an upper free edge. When the container lid is sufficiently applied to the base container such that the second portion slides downwardly past a top rim of the base container, achieving a proper closure, an attempt to remove the lid will cause a plurality of sections of the inner band to engage the top rim and impede removal of the container lid from the base container.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional of and claims priority to U.S. application Ser. No. 11/130,878 filed May 17, 2005, currently pending, entitled “Tamper Evident Container Lid,” the entire disclosure of which is incorporated herein by reference to the extent permitted by applicable law. 
    
    
     BACKGROUND OF THE INVENTION 
     There has been increasing interest in food safety on the part of consumers in recent years due to incidents of nefarious individuals tampering with prepackaged food items. Some prepackaged items have a plastic shrink-wrap type seal around a lid of a container that must be broken in order to access the contents of the container. In the case of plastic soft drink bottles and the like having a round screw-type cap, a lower ring may be attached to a skirt of the cap with a score line. Upon twisting of the cap to remove it from the bottle, the screw threads of the bottle impede the upward movement of the lower ring, thereby breaking the ring from the skirt of the cap along the score line and allowing the consumer to fully remove the cap to access the bottle contents. A consumer purchasing such a product at a retail store should notice if the ring were separated from the remainder of the cap, indicating someone has had access to the bottle contents and may have tampered with the product. 
     Various designs have also been proposed for tamper resistant or tamper evident lids for round food containers, such as ice cream containers and the like. Such tamper resistant/evident lids are designed to provide a visual indication to the purchaser as to whether the lid has been peeled back or otherwise removed from the base food container to expose the contents. One particular configuration is provided in U.S. Pat. No. 5,653,382, issued to Van De Gejin et al, which shows a container lid formed with a skirt having a sufficient downward length so that the same can be curled upward to form a return bend having a radius and an upwardly directed free end. The free end of the curled skirt serves to impede the removal of the container lid once applied by abutting with a lower edge of a rim of the base container. This design has a serious drawback, however, in that the upwardly curled portion of the skirt extending to the free end tends to become uncurled at the curved return bend when the container lid is pulled upward forcefully impacting the free end with the rim. Thus, the lid could easily be removed and reapplied to a food container with the return bend re-curled to give the appearance that the lid hadn&#39;t been removed and no tampering had taken place. Other tamper resistant/evident designs are available that incorporate lid skirts with abutting members, but unfortunately, many of these position the abutting members where they may be slid past any catching portion (e.g., the rim) of a base container. As a result, any tamper resistant or tamper evident feature of such a lid may be defeated. 
     BRIEF SUMMARY OF THE INVENTION 
     A tamper evident and resistant container lid provides an improved solution for securely covering a base container. The container lid is configured to be difficult to remove from the base container without causing noticeable modification or damage to the container lid. As such, the container lid improves the confidence of consumers in the safety of food items purchased in such containers. 
     In one aspect of the invention, a tamper evident and resistant container lid has a lid body sized to cover the opening of the base container and a convolute-wrapped skirt extending therefrom. Both an annular score line and an annular fold line extend around the skirt. A first portion of the skirt extends downwardly from the lid body to the fold line and a second portion of the skirt extends upwardly from the fold line in generally opposing relation to and inwardly of the first portion. When the container lid is sufficiently applied to the base container such that the second portion slides downwardly past a top rim of the base container, achieving a proper closure, an attempt to remove the lid will cause a plurality of sections of the inner band to engage the top rim and impede removal of the container lid from the base container. 
     The invention of another aspect includes a tamper evident and resistant container lid having a lid body sized to cover the opening of the base container, and a skirt including an upper section, an outer band and an inner band. The upper section of the skirt extends downwardly from the lid body to an annular score line below which is formed the outer band. The outer band extends between the annular score line and a lower annular fold line. Extending upwardly from the annular fold line is the inner band positioned in generally opposing relation to and inwardly of the outer band. When the container lid is sufficiently applied to the base container such that the inner band slides downwardly past a top rim of the base container, achieving a proper closure, an attempt to remove the lid will cause a plurality of sections of the inner band to engage the top rim and impede removal of the container lid from the base container. 
     A process for manufacturing the tamper evident and resistant container lid is presented in another aspect of the invention. A sheet is formed of paper stock having leading and trailing edges, top and bottom edges, and longitudinal score and fold lines extending generally from the leading edge to the trailing edge and spaced from one another. The leading edge of the sheet is wrapped over the trailing edge thereof to form an interior overlap region of the sheet proximal to the trailing edge and an exterior overlap region of the sheet proximal to the leading edge. As a next step, the exterior overlap region is sealed to the interior overlap region to form the sheet into a generally cylindrical skirt. A lid body may then be attached with the skirt to form a container lid, and a portion of the skirt below the longitudinal fold line folded inwardly and upwardly towards the lid body to form the skirt portion into an inner band positioned in generally opposing relation to an outer band defined between the longitudinal score line and the longitudinal fold line. The steps of the process are conducted such that a plurality of sections of the inner band are formed to, upon application of the container lid to the base container whereby the inner band is slid downwardly past the base container top rim, impede removal of the container lid from the base container by engaging with the top rim. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicated like elements in the various views: 
         FIG. 1  is a perspective view of one embodiment of a tamper evident container lid of the present invention applied on a base container; 
         FIG. 2  is a fragmentary bottom plan view of the tamper evident container lid and base container of  FIG. 1 ; 
         FIG. 3  is a fragmentary cross-sectional view of the tamper evident container lid and base container taken along line  3 - 3 ; 
         FIG. 4  is a fragmentary bottom perspective view, taken partially in section, of the tamper evident container lid of  FIG. 1 ; and 
         FIG. 5  is side elevational view of a template for the skirt portion of the tamper evident container lid of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, and initially to  FIG. 1 , a tamper evident and resistant container cover or lid  10  is shown applied onto an exemplary base container  100  that may house food items. Although shown as being cylindrical and having a circular cross-section, the base container  100  may also be elliptical or another shape in cross-section employing a generally curved profile. The container lid  10  includes a lid body  12  having a perimeter region  14  and an annular downwardly extending skirt  16  circumscribing the perimeter region  14 . The skirt  16  may have the same shape as the base container (e.g., cylindrical, elliptical, etc.). Preferably, the skirt  16  is die cut from a sheet of paper stock and may have registered printing applied thereon, and thereafter overlaid with varnish or other protective coating. The lid body  12  may be of similar construction (e.g., of paper stock) and may include registered printing and a protective coating if desired. 
     The lid body  12  may have a generally disc-like shape inwardly of the perimeter region  14  towards the center thereof, through other shapes may be utilized for the lid body  12 . The skirt  16  includes an interconnect portion  18  for coupling the skirt  16  with the lid body  12 , a support portion  20  extending downwardly from the interconnect portion  18  and a tamper evident portion  22  separated from the support portion  20  by a perforated annular score line  24 . Forming the tamper evident portion  22  is an outer band  26  and an inner band  28  divided along an annular fold line  30 , which may be scored in the same fashion as the score line  24 . A pull tab  32  extends from the outer band  26  at a leading edge  34  of the skirt  16 . When a consumer desires to access the contents held in the base container  100 , the tab  32  is pulled away from the remainder of the skirt  16 , as seen in  FIG. 1 , resulting in the tamper evident portion  22  breaking from the support portion  20  at the score line  24 . Continual pulling of the tab  32  all the way around the skirt  16  will completely break off the tamper evident portion  22 , leaving the interconnect portion  18  and support portion  20  of the skirt  16  behind to, with the lid body  12 , serve as a reusable lid for the base container  100 . The perforation marks remaining on the support portion  20  of the skirt  16  after removal of the tamper evident portion  22  serve as a visual indication to a purchaser of the product that someone may have had access to the contents of the base container  100 . 
       FIGS. 2-4  show more details of the construction of the container lid  10 , with the lid  10  applied on the base container  100  in  FIGS. 2 and 3 , and with the lid  10  separately in  FIG. 4 . The perimeter region  14  of the lid body  12  includes a lower edge  36  that extends with a curved profile generally matching the profile of a top rim  102  of the base container  100 . This arrangement facilitates the lid  10  essentially mating with the top rim  102  and positioning the skirt  16  to envelop the top rim  102  in an annular fashion to provide a good seal between the lid  10  and the base container  100 . 
     The design of the inner band  28  of the skirt  16  enables a tamper resistant feature of the lid  10  to be realized. More specifically, a plurality of sections of the inner band  28  are formed into interference members  38 , as best seen in  FIGS. 3 and 4 . These interference members  38  extend inwardly towards the center of the container lid  10  to generate an interference with a top rim  102  of the base container  100  when the lid  10  is fully applied thereon. Upon pulling of the lid  10  upwardly to remove it from the base container  100 , the interference members  38  abut the top rim  102  and prevent lid  10  removal. Because the inner band  28 —and thus the interference members  38 —has a length defined between the fold line  30  and an upper free edge  40  of the inner band  28  that is greater than the lateral (i.e., radial) gap between the outer band  26  of the skirt  16  and a sidewall  104  of the base container  100 , the inner band  28  cannot simply be folded down at the fold line  30  to allow the skirt  16  to slip past the interference with the top rim  102 . Additionally, the fold line  30  is formed with a sharp angle between the outer and inner bands  26 ,  28 , and not a large radius curve. This design makes it very difficult to peel back the inner band  28  and facilitates maintaining the integrity of the fold line  30  (and thus the inner band  28 ) even when relatively large forces are applied to impact the interference members  38  with the top rim  102  when attempting to pull the lid  10  off of the base container  100 . Also, the spaced intervals for the interference members  38  may be, for example, an even number (e.g., every 90 degrees around the inner band  28 ) or may be varied, but should occur frequently enough around the inner right to hamper efforts to pry off the container lid  10  without tearing off the outer and inner bands  26 ,  28  at the annular score line  24 , or otherwise visibly damaging the same. 
     The interconnection between the lid body  12  and the skirt  16  is achieved by forming the perimeter region  14  with a vertically-extending leg member  42  extending from the lower edge  36  thereof, and shaping the interconnection portion  18  to mate with the leg member  42 . More specifically, the leg member  42  has a generally upside down “J” profile with a return bend  44  cradled by an upper lip  46  of the interconnect portion  18 . An annular groove  48  is also formed into the interconnect portion  18  below the upper lip  46 , and a curved arm  50  extends below the annular groove back towards the lower edge  36  to terminate in a free edge  52 . This configuration for the interconnect portion  18  and the leg member  42  provides good interlocking between the lid body  12  and the skirt  16 . 
     One method of forming the container lid  10  will now be described. The skirt  16  may be die cut from paper stock to achieve the shape necessary for the final design.  FIG. 5  shows a die cut skirt template  54  having the leading edge  34 , a trailing edge  56 , a top edge  58  and a bottom edge  60 , with the pull tab  32  extending from the leading edge  34 . The score line  24  and the fold line  30 , which may be scored as well, are preferably formed on the template  54  to be generally parallel with and spaced from one another and each extend from a point at least close to the leading edge  34  to another point at least close to the trailing edge  56 . Also, the score line  24  and fold line  30  may be aligned with the paper grain direction of the template  54  as determined by the paper stock used, which aids in the tamper evident portion  22  of the skirt  16  breaking or tearing away from the support portion  20  at the score line  24 . By providing alignment with the paper grain direction in this fashion, the present invention avoids the use of traditional spiral wound techniques often employed in the manufacture of traditional container lid configurations. If spiral wound techniques were used, an erratic tearing action would result when pulling on the tab  32  due to interruption of a ply gap of the skirt material at the score line  24 . More specifically, a diagonal gap would span through the skirt  16 , creating in weak points in the skirt material approaching, and moving away from, the score line  24 . Thus, pulling on the tab to break away the tamper evident portion  22 , with a spiral would skirt  16 , would often results in tearing of the skirt  16  away from the score line  24  upward into the support portion  20  or downward into the outer band  26 , which is clearly undesirable. Another advantage provided by convolute wrapping is that printed instructions can be applied to the skirt  16  at the pull tab  32  location. Printing in this fashion is quite difficult if spiral wound techniques were employed because random location printing is typically required. 
     Next, the template  54  is convolute wrapped, or bent in a curve fashioned to form a complete loop with the leading edge  34  overlapping the trailing edge  56 . The amount of overlap between the leading and trailing edges  34 ,  56  is chosen to achieve the initial outline of the skirt  16  with the correct dimensions to fit over the base container  100  and such that adequate surface area is presented for applying adhesive to secure or seal the region of the skirt  16  near the leading edge  34  to the region of the skirt  16  near the trailing edge  56 . Various adhesives, such as industry recognized food grade adhesives, may be used in forming the skirt as described. 
     The lid body  12  may also be die cut as previously described to have a shape that will fit within the formed skirt  16 . The leg member  42  of the lid body  12  may be shaped as shown in  FIG. 3  by crimping the lid body  12  having a disc-like shape to form the curved lower edge  36  and the leg member  42 , and also crimping the leg member  42  near the terminus thereof to form the return bend  44 . Similarly, the shape of the interconnect portion  18  of the skirt  16  may be attained by crimping the template  54  in the form of the skirt  16  above the score line  24  to form the curved upper lip  46 , and again crimping portions of the skirt  16  between the upper lip  46  and the template top edge  58  to form the annular groove  48  and curved arm  50 . One technique that may be employed is to crimp the skirt interconnect portion  18  over the leg member  42  after the leg members  42  has been finally formed, resulting in interlocking of the lid body  12  with the skirt  16 . However, those of skill in the art will appreciate that other sequences may be employed to cause interlocking between the lid body  12  and the skirt  16 . 
     At this point, the portion of the skirt  16  below the fold line  30  may be folded inwardly and upwardly along the fold line  30  towards the lid body  12  to form the inner band  28 . The inner band  28  is thereby positioned in opposing relation to the outer band  30  formed between the score line  24  and the fold line  30 . 
     In the steps of convolute wrapping and sealing the leading edge  34  over the trailing edge  56 , adhesive is preferably not applied to the pull tab  32  such that the tab  32  extends freely and essentially tangentially from the leading edge  34  of the skirt  16 . This facilitates easy grasping of the pull tab  32  by a user to tear off the tamper evident portion  22  along the score line  24 . Additionally, the aforementioned configuration encourages outward pulling of the tab  32  to increase the probability of a clean break along the score line  24  and avoid erratic tearing along the skirt  16  upwards or downwards from the score line  24 . 
     The interference members  38  may be formed by pulling on the inner band  28  at spaced intervals, which may have a consistent value around the inner band  28  if desired (e.g., every 30 degrees, 60 degrees, 90 degrees, etc.). Preferably, the pulling forms a pair of creases  62  running diagonally along the inner band  28  from the upper free edge  40  thereof to the fold line  30  to establish the shape of the interference members  38  with an impact edge  64 , as seen in  FIGS. 2 and 4 . Because of the cross-sectional shape of the interference members  38 , and likewise the profile of the upper free edge  40  of the inner band  28 , the members  38  are afforded a degree of lateral stability to resist buckling or collapsing when an attempt is made to pull the container lid  10  away from the base container  100  and impact the edge  64  with the container top rim  102 . Additionally, the creases  62  bias the impact edge  64  inwardly away from the opposing relation with the outer band  26  (and away from the remainder of the inner band  28 ) towards the base container  100  when mounted thereon. This ensures that a good interference is maintained between the interference members  38  and the top rim  102  of the base container  100 . 
     The container lid  10  may thus be manufactured with a tamper evident feature already in place, merely requiring that the lid  10  be applied or mounted onto the base container  100  for full activation. One suitable application method for the container lid  10  is by wipe on in the same fashion as standard food container lids are applied (e.g., cylindrical ice cream container lids). The interference members  38  are oriented such that the inner band  28  can easily slide past the container top rim  102  as the container lid  10  is pushed onto the base container  100  from above. Once the inner band upper free edge  40  passes by the container top rim  102  during container lid  10  application, the interference members  38  snap inward towards the base container sidewall  104  to form the interference with the top rim  102 . This provides the advantage of requiring no other post activation by the user once the desired product is placed in the base container  100  and the container lid  10  is “wiped on”. 
     From the forgoing, it can be seen that the container lid  10  of the present invention provides an effective device for alerting consumers of attempts to remove the covering from a base container, while also serving to thwart such attempts. The tamper evident portion  22  is also easy to remove by the purchasing consumer so that once the tamper evident nature of the lid  10  have served their purpose, the consumer is not significantly impeded in accessing the product in the base container  100 . Furthermore, since certain changes may be made in the above invention without departing from the scope hereof, it is intended that all matter contained in the above description or shown in the accompanying drawing be interpreted as illustrative and not in a limiting sense.