Tamper evident container assembly

Abstract: A tamper evident container assembly (10) includes an open-ended container body (12) having a bottom wall (16) and peripheral side wall (18), the side wall (18) having an upper rim (20) protruding radially outwardly of the peripheral side wall (18). A reusable lid (14) has a top wall (24) and a depending skirt (26), the skirt (26) having a free end (28), a major portion of which is tucked under the upper rim (20) to thereby lock the lid (14) to the container body (12). The depending skirt (26) is further provided in a lower portion thereof with an annular line of weakening (30) extending about the skirt portion to thereby define an annular tear strip (36) inclusive of the free end (28) so that upon removal of the tear strip (36), the lid (14) may be removed from said container (12). A related method of assembling a tamper evident container assembly (10) the steps of: a) filling the container body (12) with contents; b) applying the lid (14) to the container body; and c) tucking a substantial portion of the lower free edge (28) under the rim (20) to thereby provide a tamper evident container.

Description: TECHNICAL FIELD This invention relates to tamper evident, reusable containers according to the preamble of claim 1 and a method of assembling such a tamper evident container assembly. BACKGROUND This invention relates to tamper proof (or "tamper evident") container assemblies, and more specifically, to a container and lid assembly in which the lid is effectively locked to the container body prior to initial use by means of a removable tear strip integrally formed with the lid, and which nevertheless permits repeated reapplication and removal of the lid to the container body. At the same time, any tampering with the cover to gain access to the interior of the container will be immediately apparent. Numerous attempts have been made in the container industry and specifically with respect to consumer oriented foodstuffs, medicines, etc. to prevent potentially harmful tampering with the contents of such containers. It is well known, for example, to heat seal a thin foil disk about the container opening prior to assembly of the lid. This approach, while successful to a large extent, nevertheless involves the addition of another component to the assembly, i.e., the foil disk, and related assembly procedures and associated costs. Other attempts to provide effective tamper proof mechanisms in container assemblies are well documented in the patent literature. U.S. Patent 4,966,294, for example, discloses a tamper evident closure for a wide mouth container wherein rim segments are formed in the skirt portion of the container lid and are arranged so that upward lifting force applied against the lid flange will cause breakage to occur at opposite ends of the flange, and a continued upward pulling on the flange will result in a pair of tear lines in the lid to facilitate removal of the lid. In U.S. Patent 2,383,760, a closure for a container includes a flat upper surface in the peripheral depending skirt portion, around which is adhesively secured a strip which extends below the container flange and includes a bent marginal flange portion extending upwardly and inwardly from the bend. The flange is a continuous, smooth flange which, after insertion over the upper portion of the container, will snap into locking engagement with the flange. The marginal portion of the sealing strip is provided with a strip of adhesive so that the marginal portion will be cemented to the inside face of the container flange. No means are provided, however, for facilitating the easy removal of the closure. In fact, it is stated that when a container is opened, the cover will be disposed of, apparently because it will be damaged or destroyed in the opening operation. In U.S. Patent 1,955,865, container closures are disclosed which are formed with depending skirt portions and integral circumferentially spaced bent tab portions. These tab portions are designed to cooperate with complementary circumferentially spaced tabs formed on the periphery of the container side wall. Locking of the lid to the container is achieved by pressing the closure down over the tabs and rotating it so that the tabs will lie behind respective tabs on the container side wall. Fairly rigid disks are required to maintain the locking engagement between the cover and the container. Other tamper proof constructions are disclosed in U.S. Patent Nos. 3,044,610; 3,997,056 and 4,602,718. These prior efforts are characterized by rather complex, and therefore costly, arrangements which are not fully satisfactory in all respects. FR-A-846072 discloses a tamper evident container assembly comprising an open ended container body having a bottom wall and a peripheral side wall having a rim flange at an upper edge thereof. A reusable lid for the container has a depending skirt lower portion of which engages the rim flange when the lid is in place on the container so as to lock the lid to the container. The lower portion of the skirt may be removed to enable removal of the lid from the container without destroying the upper portion of the depending skirt. SUMMARY OF THE INVENTION It is the principle object of the present invention to provide a simple, low cost yet effective tamper proof or tamper evident container assembly which permits repeated application and removal of the container lid even after one time use of the tamper evident mechanism by the consumer upon initial opening. According to a first aspect of the present invention there is provided a tamper evident container assembly comprising: an open-ended container body having a bottom wall and a peripheral side wall having a rim flange at an upper edge thereof; a reusable lid having a top wall and a depending skirt having upper and lower portions, said depending skirt incorporating first means in said lower portion of said depending skirt engaging said rim flange when said lid is in place on the container body for locking said lid to said container body, and second means for separating said upper and lower portions without destroying said upper portion of said depending skirt characterized in that said depending skirt is formed of spiral wound paper stock and said second means comprises a substantially horizontal, annular line of weakening in said spiral wound stock between said upper and lower portions of said depending skirt, and an integral gripping tab in said lower portion spaced from said peripheral side wall so as to allow removal of said lid from said container body; wherein said first means is in substantially continuous engagement with said rim except in an area defined by said gripping tab. According to a second aspect of the present invention there is provided a method of assembling a tamper evident container assembly including a container body having a bottom wall and a peripheral side wall including a radially outwardly projecting rim at an upper end thereof, and a reusable lid having a top wall and an axially extending depending skirt, having a line of weakening formed therein extending annularly around said skirt intermediate an upper end and a lower free edge thereof to thereby define a removable tear strip which, when removed, permits said lid to be removed from said container body; the method comprising the steps of: a) filling said container body with contents; b) applying said lid to said container body; said method being characterized by said depending skirt being constructed of spiral wound stock and by comprising the further steps of: c) tucking at least a major portion of said lower free edge under said rim so that said portion of said free edge engages said rim; and d) leaving a minor portion of said lower free edge untucked such that the minor portion is spaced from the peripheral side wall of the container body to provide a gripping area facilitating tearing and removal of said tear strip. In an exemplary embodiment of the invention, there is provided a container and lid assembly partially removed or otherwise deformed to allow separation of the lid from the container, any tampering with the container prior to its initial use will be immediately apparent from visual inspection. Accordingly, the present invention provides a significant improvement over prior art tamper proof containers, and particularly those which result in the effective destruction of the lid during the initial opening of a container. The tamper proof assembly of this invention thus provides the following advantages: 1) the tamper proof mechanism is integrally incorporated into the lid; 2) the previously required foil disk is eliminated; 3) a reclosing feature for the lid is retained; and 4) the assembly of this invention can be utilized by, for example, food stuffs distributors, with only minor modifications and/or additions to existing equipment. Additional objects and advantages of the invention will become apparent from the detailed description which follows. BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of a tamper proof container/lid assembly in accordance with an exemplary embodiment of the invention; FIGURE 2 is a partial side view of the upper portion of a container body of the type shown in Figure 1; FIGURE 3 is a partial sectional view illustrating the connection between the container body and lid; FIGURE 4 is a sectional view of another exemplary embodiment of the invention prior to curling the free end of the skirt; and FIGURE 5 is a partial sectional view of the container lid illustrated in Figure 4 but after the free end of the skirt has been curled and after the gripping tab has been cut into the skirt. DETAILED DESCRIPTION OF THE DRAWINGS With reference to Figure 1, a tamper proof container assembly 10 includes a container body 12 and a lid 14. The container body 12 is formed with a bottom wall 16 and a peripheral side wall 18. At the upper end of the container body, there is a radially outwardly extending flange or rim 20 (see Figures 2 and 3), formed by rolling the free edge of the peripheral side wall outwardly onto the container body peripheral side wall and compressing it against the side wall in a conventional manner. The rim 20 has a lower edge 22 which extends about the entire periphery of the container body. The lid 14 includes a top wall 24 and a depending skirt 26. In a preferred arrangement, top wall 24 and depending skirt 26 are separate components which may be roll seamed to each other about a line 25. The depending skirt 26 is of spiral wound construction, i.e., formed by a slicing a spiral tube made of conventional spiral wound lid stock. Located toward the lower free edge 28 of the skirt 26, there is an annular line of perforations 30 which extends about the entire circumference of the skirt. Prior to filling, the depending skirt 26 extends downwardly relative to the top wall 24 at substantially right angles thereto. Thus, the lower free edge 28 of the depending skirt does not interfere with the assembly of the lid to the container. Upon filling of the container body with contents, substantially the entire free edge 28 of the depending skirt 26 is mechanically curled or rolled under the lower edge 22 of the rim or flange 20 to a position best seen in Figure 3. This arrangement insures secure locking of the lid to the container body. However, it is advantageous to leave a small portion of the free edge untucked to thereby provide a gripping tab or area 32 for a purpose explained below. With reference again to Figure 1, the annular line of weakening 30 is preferably (but not necessarily) formed by a plurality of circumferentially spaced perforations 34 which thereby define a tear strip 36 having a width extending from the perforations 34 to the free edge 28 of the depending skirt, and a length corresponding to the circumference of the skirt 26. Other means may be employed to facilitate removal of the tear strip 36, such as a weakened score line or the like. To open the container initially after purchase, the gripping area 32 is pulled upwardly at a slit or perforation 38, thereby causing a vertical tear to the perforation line 30. Continued pulling of the tab in the direction indicated by arrow A will result in peripheral tearing about the perforation line 30 (indicated in phantom in Figure 1), resulting in complete separation and removal of the strip 36 from the lid 14. It will be understood that other means may be provided to facilitate removal of the tear strip. For example, an integral or separate pull tab could be provided on the tear strip, with the lower edge 28 tucked about the entire circumference of the lid. When using spiral wound lid stock, it is important that the tear strip be torn in a direction which does not intersect a downwardly extending portion of a spiral seam. By locating the slit or perforation 38 to one side of the gripping area, the user will naturally tend to grip the larger portion to one side of the slit or perforation and continue to pull the strip 36 away from the slit in the desired direction. Printed or graphic instructions may also be utilized to insure proper manipulation. It will be readily appreciated from the above description that any tampering with the container on the shelf or prior to consumer use will be readily ascertained merely by visual inspection. It will also be appreciated from the drawing figures, that even after the tear strip 36 has been torn away from the container lid 14, there is sufficient length to the depending skirt 26 to enable effective and repeated use of the lid 14 with the container body 12. It is also a feature of this invention to provide a novel method of filling and sealing a container assembly of the type described above which comprises the steps of a) filling the container body 12 with contents; b) applying the lid 14 to the container body; and c) tucking a substantial portion of the lower free edge 28 of the lid skirt 26 under the edge 22 of container rim 20, while leaving a minor portion untucked so as to a provide a gripping area 32 to facilitate removal of the tear strip 36 from the skirt 26. With reference now to Figures 4 and 5, a slightly modified lid 114 is shown which includes a top wall 124 and a depending skirt 126. Here again, the top wall 124 and depending skirt 126 are separate components, roll seamed to each other about the line 125. The depending skirt 126 is also constructed from spiral wound paper, but in this embodiment, it is preferable that the skirt be of double layer construction, with the spiral seams (e.g., 135) of one layer offset from the spiral seams (e.g., 137) of the other. Located intermediate the upper and lower ends of the skirt, there is an annular line of weakening 130 which extends about the entire circumference of the skirt 126. The line of weakening may be formed by a series of horizontally aligned perforations 134, thus defining a removable tear strip 136. With specific reference to Figure 5, a gripping tab or pull tab 132 is defined on one side by a knife cut edge 131, and on an opposite side by an uncurled portion, joined to the curled edge along fold line 133. The knife cut edge 131 and the free edge 128 form a right angle tab which facilitates tearing of the strip 136 from the remainder of the skirt 126 in a counterclockwise direction. Note also that knife cut 131 intersects a perforation 134 to further facilitate the tearing action. The strength of the double layer spiral wound skirt, in combination with the offset spiral seams, provides a relatively rigid skirt which is able to withstand tearing without unravelling the seamed skirt. Thus, the tear strip 136 may be removed without damage to the remainder of the skirt 126 so that the lid 114 may be reused as desired. It will be appreciated that the manner of assembly of the lid illustrated in Figures 4 and 5 to an associated container is the same as described above with respect to the lid illustrated in Figures 1 and 3.

Claims: A tamper evident container assembly comprising: an open-ended container body (12) having a bottom wall (16) and a peripheral side wall (18) having a rim flange (20) at an upper edge thereof; a reusable lid (14) having a top wall (24) and a depending skirt (26) having upper and lower portions, said depending skirt (26) incorporating first means (36) in said lower portion of said depending skirt (26) engaging said rim flange (20) when said lid (14) is in place on the container body (12) for locking said lid (14) to said container body (12), and second means (32) for separating said upper and lower portions without destroying said upper portion of said depending skirt characterized in that said depending skirt (26) is formed of spiral wound paper stock and said second means comprises a substantially horizontal, annular line of weakening (30) in said spiral wound stock between said upper and lower portions of said depending skirt (26), and an integral gripping tab (32) in said lower portion spaced from said peripheral side wall so as to allow removal of said lid (14) from said container body (12); wherein said first means (36) is in substantially continuous engagement with said rim (20) except in an area defined by said gripping tab (32). The assembly of Claim 1 wherein said first means (36) includes substantially annular surface means extending under a lower edge of said rim flange (20). The assembly of Claim 2 wherein said annular surface means includes a free edge of said depending skirt (26). The assembly of Claim 1 wherein said annular line of weakening (30) comprises a plurality of circumferentially spaced perforations. The assembly of Claim 3 wherein said integral gripping area is formed by a portion of said free edge which does not extend under a lower edge of said rim flange (20). The assembly of Claim 5 wherein said gripping tab (32) includes a slit or perforation arranged to initiate tearing of the strip in a predetermined direction. The assembly of Claim 1 wherein: said rim flange (20) protrudes radially outwardly of said peripheral side wall (18); said depending skirt portion (26) having a free end (28), said line of weakening (30) defining an annular removable tear strip (36) inclusive of said free end (28); said first means (36) comprises a major peripheral portion of said free end tucked under said rim flange (20), said depending skirt (26) including the tucked portion being in substantially continuous engagement with said rim flange (20) to thereby lock said lid (14) to said container body (12); and said second means (32) comprises a minor portion of said free end which is left untucked such that said minor portion is spaced from the peripheral side wall (18) of the container body (12) to thereby provide said gripping tab (32) to facilitate tearing of said tear strip (36). The assembly of Claim 7 wherein said top wall (24) and said depending skirt portion (26) of said lid (14) are separate components seamed together about an upper edge of said depending skirt portion (26). The assembly of Claim 7 wherein said rim flange (20) comprises an outwardly rolled free edge of said peripheral side wall (18). The assembly of Claim 7 wherein said container (12) and said lid (14) are constructed of paper board. A method of assembling a tamper evident container assembly (10) including a container body (12) having a bottom wall (16) and a peripheral side wall (18) including a radially outwardly projecting rim (20) at an upper end thereof, and a reusable lid (14) having a top wall (24) and an axially extending depending skirt (26), having a line of weakening (30) formed therein extending annularly around said skirt (26) intermediate an upper end and a lower free edge thereof to thereby define a removable tear strip (36) which, when removed, permits said lid (14) to be removed from said container body (12); the method comprising the steps of: a) filling said container body (12) with contents; b) applying said lid (14) to said container body (12); said method being characterized by said depending skirt (26) being constructed of spiral wound stock and by comprising the further steps of: c) tucking at least a major portion of said lower free edge under said rim (20) so that said portion of said free edge engages said rim (20); and d) leaving a minor portion of said lower free edge untucked such that the minor portion is spaced from the peripheral side wall (18) of the container body (12) to provide a gripping area facilitating tearing and removal of said tear strip (36).

Inventors: EARNEST EDWARD, EARNEST, EDWARD
Applicants: SWEETHEART CUP CO, SWEETHEART CUP COMPANY, INC.
Application year: 1992
Main classification: B65D43
IPC codes: B65D43, B65D17, B65D41