Abstract:
A tamper resistant package for foods and other materials includes a container and a plug closure having a side wall and a flange spaced outwardly from the side wall. A detachable tear strip on the upper edge of the container is initially heat sealed to the edge of the flange. When the tear strip is detached, the heat seal ruptures to release the closure. The closure can thereafter be applied to cover the container with the upper edge of the container sandwiched closely between the closure wall and flange.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to containers and more particularly to a container that is constructed in a manner to visually indicate when it has been opened or tampered with. 
     BACKGROUND OF THE INVENTION 
     There have been a variety of tamper proof and tamper evident containers proposed for use in various applications. For example, in the case of foods, medicines and other consumer products, it is often desirable for the packaging to provide easily noted visual evidence when the package has been opened. The tamper evident packages that have been proposed in the past have generally been characterized by complexity that results in high costs and reliability problems. Further, many containers cannot be effectively closed again after they have been initially opened. 
     Containers with detachable tear strips have been proposed in various forms and typically provide a tear strip that must be removed in order to open the container. Thus, the presence of an intact tear strip indicates an unopened container and the absence or partial tearing of the strip indicates tampering. Although this type of construction has achieved some popularity, the techniques that have been used to construct the tear strips have resulted in high costs. Also, adequately closing and sealing the container once it has been opened has been a problem with this type of container construction. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a tamper evident container is equipped with a detachable tear strip that must be removed to open the container. The invention is characterized by a container body and a closure having a side wall that fits closely inside of the container body. The closure also includes a flange which is connected with the side wall, preferably by an annular neck. The tear strip is connected with the upper edge of the container body along a line of weakness that facilitates detachment of the tear strip when it is desired to open the container. The flange terminates in a lower edge that is heat sealed to the upper edge of the tear strip. 
     The container can be opened by tearing away the tear strip along the line of weakness which connects it with the container body. This also results in rupture of the heat seal so that the closure is released from the container body and can be removed to provide access to the contents of the container. The closure can be replaced on the container with the upper part of the container wall closely sandwiched between the flange on the outside and the closure wall on the inside. The neck on the closure seats on the upper edge of the container wall so that the closure has a tight fit on the container to effectively contain the contents. 
     Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     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 indicate like parts in the various views: 
     FIG. 1 is a perspective view of a tamper evident container constructed according to a preferred embodiment of the present invention, with the tear strip included on the upper portion of the container body shown partially detached from the container; 
     FIG. 2 is a fragmentary sectional view on an enlarged scale taken generally along line  2 — 2  of FIG. 1 in the direction of the arrows; 
     FIG. 3 is a fragmentary sectional view similar to FIG. 2, but showing the closure removed from the container after the tear strip has been detached; and 
     FIG. 4 is a fragmentary sectional view similar to FIGS. 2 and 3, but showing the closure replaced on the container after having been initially opened. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings in more detail and initially to FIG. 1, numeral  10  generally designates a container which may be used in a variety of applications, including holding various types of food items and particularly other, smaller containers which may contain foods and other materials. The container  10  includes a hollow container body  12  which holds the contents of the container. The container body has a cylindrical side wall  14  and a bottom  16  which may take the form of a disk closing the bottom of the side wall  14 . As best shown in FIGS. 2-4, the side wall  14  of the container body has an upper end portion  18  which terminates in a circular upper edge  20 . The container body  12  may be constructed of any suitable material such as paperboard coated with a thermoplastic material. 
     With reference to FIGS. 1 and 2 in particular, a detachable tear strip  22  has a lower edge  24  that is connected with the upper edge  20  of the container wall  14  along a circular line of weakness  26  which may be perforated or otherwise weakened. The tear strip  22  essentially forms an upward continuation of the side wall  14  extending above its upper end portion  18 . The tear strip  22  also has an upper edge  28 . The tear strip  22  is preferably provided with a tab  30  on one end which may be grasped with the fingers in order to detach the tear strip  22  from the container body  12 . 
     A plug closure which is generally identified by numeral  32  is used to cover the otherwise open top of the container body  12 . The closure  32  includes a discoidal lid portion  34  which is substantially flat. The closure  32  has a stepped construction and includes an inclined wall  36  which angles downwardly and outwardly from the outer periphery of the lid portion  34 . An annular shoulder  38  extends outwardly from the lower edge of the inclined wall  36 . The closure  32  has a cylindrical side wall  40  which extends downwardly from the shoulder  38  and has a size to fit closely inside of the container wall  14 , as shown in FIG.  2 . The lower edge of the side wall  40  is beveled at  42  to facilitate the fit of the side wall  40  inside of the container wall  14 . 
     The plug closure  32  has a short annular neck  44  which extends outwardly from the upper edge of the side wall  40  and essentially forms an outer continuation of the shoulder  38 . A downwardly extending flange  46  is connected at its upper end with the outer edge of the neck  44 . The flange  46  is cylindrical and is spaced outwardly from and parallel to the side wall  40 . The flange  46  is spaced away from wall  40  by the neck  44  a distance that is substantially equal to or slightly greater than the thickness dimension T (see FIG. 2) of the container wall  14 . 
     The flange  46  terminates in a circular lower edge  48  which is adjacent to and connected with the upper edge  28  of the tear strip  22  by a heat scal  50 . The closure  32  may be constructed of a suitable material such as paperboard coated with a thermoplastic which can be heated in order to provide the heat seal between the flange edge  48  and the tear strip edge  28 . 
     In order to initially open the container  10 , it is necessary to detach the tear strip  22  from the container body  12  by grasping the tab  30  and tearing the strip  22  away from the container body along the line of weakness  26 . As the tear strip  22  is detached, the heat seal  50  is ruptured so that the flange  46  is released from its initial attachment to the tear strip. This releases the closure  34  and allows it to be lifted off of the top of the container body  12 , thereby providing access to the contents of the container  10 . 
     In order to replace the closure  32 , it can simply be applied to the upper edge portion  18  of the container wall  14  by fitting the closure wall  40  inside of the container wall  14  with the flange  48  located adjacent to and outwardly of the container wall  14 . The closure  32  can be lowered onto the upper edge portion  18  of the container until the underside of the neck  44  seats on the upper edge  20  of the container wall in abutting relationship with it, as shown in FIG.  4 . The upper edge portion  18  of the container wall is closely sandwiched between the flange  46  on the outside and the closure wall  40  on the inside, with the seating of the neck  44  on edge  20  enhancing the tight fit of the closure  32  on the container body  12 . When the closure  32  is replaced on the container body in this fashion after having been initially removed, it is located at a lower position than its initial position wherein the heat seal  50  holds the flange  46  at the position shown in FIG. 2 well above the edge  20  of the container side wall. 
     In this manner, the container  10  is constructed so that the presence of the tear strip  22  in an intact condition provides visual evidence that the container is unopened and has not been tampered with. At the same time, the closure  32  can be easily removed simply by tearing away the tear strip  22 . Any remaining contents can be enclosed within the container body  12  by replacing the closure  32  and seating it in the position of FIG. 4 wherein it provides a tight fit on the top of the container to enclose the remaining contents of the container body. 
     From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.