GB2225314A

GB2225314A - Container lid assembly

Info

Publication number: GB2225314A
Application number: GB8926658A
Authority: GB
Inventors: Michael C Faust; Keith Thomas Pinckney; Janelle Kay Wong
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1988-11-29
Filing date: 1989-11-24
Publication date: 1990-05-30
Anticipated expiration: 2009-11-24
Also published as: JPH02180161A; GB8926658D0; GB2225314B; CA2004052A1

Abstract

A sealable lid assembly to form a tamper evident seal for a container comprises strip means 28 attached to and extending beneath a lower rim portion 20 of a lid 18, the strip means 28 being heat-shrinkable to engage a container 10. Preferably the strip means is preformed on the lid prior to assembly. In a preferred embodiment the strip means includes a first strip 30 of pressure sensitive adhesive tape which is adhered to a lower rim of the lid, a second strip 34 of rigid heat shrinkable material adhered to a lower portion of the first strip and a tear strip 32. The pressure sensitive tape may alternatively be attached to the inner rim surface (23, Figs. 9, 10). <IMAGE>

Description

SEAL SYSTEM FOR CONTAINERS The present invention relates to tamper evident closures, which are used to verify that a container has not been opened subsequent to its sealing. More particularly, the present invention provides a tamper evident closure for a container and system for installing, which is simple to install and can be incorporated onto an existing container assembly line at a minimum of cost.

Contemporary package designs often utilize a band of tape or other tamper evident seal around a lid of a packaged article to enable a consumer to determine whether the container may possibly have been breached or contaminated prior to use. Such tamper evident seals are particularly advantageous for use with containers for storing food stuffs or the like. An example of such a seal and an apparatus which is used to apply the seal to a container is disclosed in U.S. Patent No. 3,873,018 to Donnay. In that system, an additional station was provided on a manufacturing line for applying a band of tape between a lid of the container and the container body after placement of the lid on the container. Thus, tamper evident seals for containers have in the past been installed on the containers in a manufacturing step that is performed separately and subsequent to assembly of the containers.

One disadvantage of such prior art systems is that the equipment required to place a tamper evident seal upon a container is relatively expensive to purchase and maintain. Moreover, such systems are relatively bulky and take up a substantial amount of space on a manufacturing floor.

It is clear that there has existed a long and unfilled need in the prior art for a system to apply a tamper evident seal to a container that is less expensive to purchase and maintain, and that does not take up a great deal of space on a production floor.

The present invention provides a sealable lid assembly of the type which is adapted to be placed upon a container to seal the container, comprising a lid adapted for fitting upon a container, the lid having a lower rim portion with an outer surface; and a strip assembly attached to the lower rim portion for shrinking when heat is applied thereto, the strip assembly extending beneath the lower rim portion, whereby the strip assembly will shrink to engage a container when the lid member is placed thereon, in order to form a tamper evident seal.

In order to form a tamper evident seal on a container in a compact, economical fashion, the present invention further comprehends a method comprising providing at least one prefabricated lid assembly including a lid member having a lower rim portion and a strip assembly attached to the lower rim portion for shrinking when heat is applied thereto; providing a container body having at least one upstanding wall defining an opening at an upper rim thereof; placing a prefabricated lid assembly on the container body so as to close the opening; and applying heat to the strip assembly so as to shrink the strip assembly about the container body, whereby a tamper evident seal is formed between the lid member and the container.

These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.

The invention will now be described with reference to the accompanying drawings in which: FIGURE 1 is a cross-sectional fragmentary view of a container and lid assembly according to a first embodiment of the invention, shown prior to sealing; FIGURE 2 is a fragmentary cross-sectional view of the embodiment illustrated in FIGURE 1, with the lid assembly and container body in a sealed position; FIGURE 3 is a plan view of a seal blank used in the embodiment of FIGURES 1 and 2; FIGURE 4 is a plan view of a modified seal blank adapted for use with the embodiment of FIGURES 1 and 2; FIGURE 5 is a fragmentary cross-sectional view of a second embodiment of the invention, shown prior to sealing; FIGURE 6 is a fragmentary cross-sectional view of the embodiment illustrated in FIGURE 5, shown after sealing;; FIGURE 7 is a plan view of a seal blank adapted for use with the embodiment illustrated in FIGURES 5 and 6; FIGURE 8 is a plan view of a lid assembly constructed according to a third embodiment of the invention; FIGURE 9 is a fragmentary cross-sectional view of a container body and lid assembly constructed according to a fourth embodiment of the invention, shown prior to sealing; FIGURE 10 is a fragmentary cross-sectional view of the embodiment illustrated in FIGURE 9, shown in a sealed position; FIGURE 11 is a diagrammatical view illustrating one method step according to the invention; FIGURE 12 is a diagrammatical view illustrating a second method step according to the invention; and FIGURE 13 is a diagrammatical view illustrating a third method step according to the invention.

Referring to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and particularly referring to Figures 1-3, a container body 10 includes a cylindrical upstanding wall 12 which defines a circular opening in the top of container body 10. Wall 12 terminates at an upper rim bead portion 16 thereof, as is shown in Figure 1. In the illustrated example, container body 10 is of the type which is commonly used to store ice cream or other quiescently frozen food products.

A lid member 18 is provided for sealing the circular opening in the top of container body 10. Lid member 18 includes a top surface 22, a top edge 24 and a downwardly extending cylindrical rim portion 20 having an outside surface 21, as may b seen in Figure 2. In order to seal the opening in container body 10, lid member 18 is placed upon the container body 10 in such a way that rim portion 20 slides over the rim bead 16 and extends downwardly parallel to an outside surface 14 of container wall 12, in the position which is illustrated in Figure 2.

In the embodiment of Figures 1 and 2, lid member 18 forms part of a sealable lid assembly 26 and is provided with a seal strip 28 which extends around the circumference of rim portion 20. Seal strip 28 includes a first strip 30 of pressure sensitive adhesive tape having an adhesive layer of synthetic rubber resin or an equivalent adhesive substance on one side thereof. First strip 30 may be a commercially available tape such as those marketed by 3M as the trademarks Scotchpro and Paklon. As is shown in Figure 1, strip 30 has a first portion adhered to the outside surface 21 of rim portion 20, and a second portion which is adhered to a second strip of heat shrinkable film 34 which is relatively rigid with respect to first strip 30.The second strip 34 is preferably formed from a relatively rigid polymer which will shrink when heat is applied thereto, such as Glycol Modified Polyethylene Terephthalate (PETG) or Polyvinyl Chloride (PVC). In this preferred embodiment, strip 34 is preferably formed to have a thickness within the range of 0.19 to 0.32 mm (7.5 to 12.5 mils.) Adhered to a third portion of the adhesive surface of pressure sensitive adhesive tape 30 is a tear strip tape 32 which preferably is formed of Biaxially Oriented Polypropylene, Polyester, Tensilized Polypropylene or an equivalent material which has a relatively high tensile strength. Tear strip tape 32 may also be provided with an adhesive surface for contact with strip 30.

In order to provide a container having a tamper evident seal 36r as is illustrated in Figure 2, the prefabricated sealable lid assembly 26 including lid 18 and seal strip 28 is lowered from the position shown in Figure 1 to a closed position over container body 10. Heat is then applied to seal strip 28, which causes the rigid heat shrinkable film 34 to contract against the outside surface 14 of container body 10, as is shown in Figure 2. As a result, a tamper evident seal is formed on the container body 10 without the addition of an expensive and bulky applicator machine.

Figure 3 illustrates a seal blank 38 which may be used to form the seal strip 28 shown in the embodiment of Figures 1 and 2. As may be seen in Figure 3, an edge nick 44 is formed in an end portion of first seal strip 30 adjacent the tear strip tape 32. As a result of the edge nick 44, the pressure sensitive adhesive tape 30 will tear along its interface with top edge 42 of the tear strip 32 when the tear strip 32 is pulled. Accordingly, the entire strip 34 of rigid heat shrinkable film will be removed along with tear strip tape 32 when the tamper evident seal 36 is removed by a consumer.

As is also shown in Figure 3, strip 34 is formed shorter in length than the strip 30 of pressure sensitive adhesive tape, which exposes an area 46 of adhesive on the rear side of pressure sensitive adhesive tape 30. The area 46 of exposed adhesive is used to fasten one end of the seal blank 38 to the other during fabrication of the sealable lid assembly illustrated in Figure 1.

Referring to Figure 4, a modified seal blank 48 for use with the embodiment of Figures 1 and 2 has a first edge nick 50 formed on one end of pressure sensitive adhesive tape 30 above tear strip 32, and a second edge nick 52 formed in the same end of pressure sensitive adhesive tape 30 immediately below tear strip tape 32. As a result, only tear strip tape 32 will be removed from seal strip 28 when the tamper evident seal 36 is broken by a consumer, thereby leaving the upper portion of pressure sensitive adhesive tape 30 ad the rigid shrinkable film 34 upon the container.

A second embodiment of a sealable lid assembly according to the invention is illustrated in Figures 5 and 6. In this embodiment, a seal strip 56 includes a first strip of pressure sensitive adhesive tape 58 and a second strip of rigid heat shrinkable film 60. The first strip 58 of pressure sensitive adhesive tape is preferably formed from materials listed above in reference to first strip 30 in the embodiment of Figures 1 and 2. Accordingly, the second strip of rigid heat shrinkable film 60 is preferably formed from the materials listed above in regard to strip 34 in the embodiment of Figures 1 and 2.

In operation, the prefabricated sealable lid assembly 54 is placed upon container body 10 in the manner described above in reference to Figures 1 and 2. Heat is then applied to seal strip 56, which causes seal strip 56 to contract, thereby creating a tamper evident seal 62 which bears against the outside surface 14 of the container wall.

Referring to Figure 7, a sealing blank 64 is provided for forming the seal strip 56 which is illustrated in Figure 5. As is shown in Figure 7, an edge nick 68 is defined in the pressure sensitive adhesive tape 58 on an end portion of sealing blank 64. Edge nick 68 is defined slightly above the top edge 66 of the heat shrinkable rigid strip 60. As a result, the pressure sensitive adhesive tape 58 will tear along its interface with the top edge 66 of the rigid heat shrinkable strip 60 when the tamper evident seal 62 is being removed by a consumer.

A third embodiment 70 of a sealable lid assembly according to the invention is depicted in Figure 8. This embodiment differs from the embodiment illustrated in Figures 5 and 6 in that a seal strip 72 is formed so as to have a greater inside diameter than the outside surface of the rim portion 20 of lid member 18. As a result, -a lid assembly constructed according to the embodiment of Figure 8 will be stackable with respect to other lid assemblies which are similarly constructed. As is shown in Figure 8, the flaring seal strips 72 fit comfortably over the top edge 24 of a lid member 18.

Referring to Figures 9 and 10, a fourth embodiment 78 of the sealable lid assembly includes a first strip 82 of pressure sensitive adhesive tape which has a first portion adhered to an inside surface 23 of the rim portion 20 of lid member 18. A second strip of rigid heat shrinkable film 84 is adhered to a second portion of pressure sensitive adhesive tape 82 that extends beneath rim portion 20, as is shown in Figure 9.

In order to create a tamper evident seal 86, the prefabricated sealable lid assembly 78 is placed upon container body 10 and heat is applied to the seal strip 80.

This causes the second strip of rigid, shrinkable film 84 to contract, which forces the pressure sensitive adhesive tape 82 to bear against the outside surface 14 of container body 10, as is shown in Figure 10.

In order to form a prefabricated sealable lid assembly of the type described above in reference to Figures 1-3, a seal blank 38 is wrapped around the rim portion 20 of a lid member 18, as is shown in Figure 11.

The exposed adhesive portion 46 is then laminated onto the opposite end of seal blank 38, while the pressure sensitive adhesive tape in the seal blank 38 adheres to the rim portion 20 of the lid member 18.

As is shown in Figure 12, the prefabricated sealable lid assembly 26 is then placed upon a container body 10 so as to seal the opening defined by the upper rim of the container wall, to form a presealing container assembly 94.

The presealing container assemblies 94 are then passed through a shrinking station 88 which in the preferred embodiment includes an endless conveyor belt 90 and a heat tunnel 92, as is shown in Figure 13. Heat tunnel 92 preferably heats the strips on the containers to a temperature of 220-250"F in the preferred embodiment wherein the thickness and material of the strips are as stated above. The container assemblies 94 are passed through heat tunnel 92, thereby forming the tamper evident seal 36 between the lid member and container body of the container. Although the process illustrated in Figures 1113 has been described with reference to the embodiment shown in Figures 1 and 2, it should be understood that the process is applicable to any of the embodiments disclosed herein.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

CLAIMS:

1. A sealable lid assembly of the type which is adapted to be placed upon a container to seal the container, comprising: lid means adapted for fitting upon a container, said lid means having a lower rim portion with an outer surface; and strip means attached to said lower rim portion for shrinking when heat is applied thereto, said strip means extending beneath said lower rim portion, whereby said strip means will shrink to engage a container when said lid means is placed thereon, in order to form a tamper evident seal.

2. A sealable lid assembly according to claim 1, wherein said strip means is attached to said outer surface of said rim portion.

3. A sealable lid assembly according to claim 2, wherein said strip means comprises a first strip of pressure sensitive adhesive tape having a first portion adhered to said outer surface, and a second strip of heat shrinkable material adhered to a second portion of said first strip.

4. A sealable lid assembly according to claim 3, wherein said second strip is more rigid than said first strip.

5. A sealable lid assembly according to claim 3, wherein said strip means further comprises a tear strip tape adhered to a third portion of said pressure sensitive adhesive tape which is between said first portion and said second portion.

6. A sealable lid assembly according to claim 5, wherein said first strip has an edge nick defined in an end portion thereof adjacent said tear strip tape, whereby gripping of said tear strip tape is facilitated.

7. A sealable lid assembly according to claim 6, wherein said edge nick is defined above said tear strip tape.

8. A sealable lid assembly according to claim 7, wherein said first strip further has a second edge nick defined in said end portion beneath said tear strip tape.

9. A sealable lid assembly according to claim 3, wherein said first strip is longer than said second strip, and said first strip overlaps itself about said outer surface of said rim portion.

10. A sealable lid assembly according to claim 1, wherein said lower rim portion has an inner surface opposite said outer surface, and said strip means is attached to said inner surface.

11. A sealable lid assembly according to claim 10, wherein said strip means comprises a first strip of pressure sensitive adhesive tape having a first portion adhered to said inner surface of said lower rim portion, and a second strip of heat shrinkable material adhered to a second portion of said first strip.

12. A sealable lid assembly according to claim 1, wherein said strip means has an inner diameter which is greater than an outer diameter of said rim portion at a lower portion thereof, whereby said lid assembly is stackable with respect to like lid assemblies.

13. A sealable lid assembly according to claim 3, wherein said second strip is formed of a heat shrinkable polymer selected from the group including Polyethylene Terephthalate Glycol Modified and Polyvinyl Chloride.

14. A sealable lid assembly according to claim 11, wherein said second strip is formed of a heat shrinkable polymer selected from the group including Polyethylene Terephthalate Glycol Nodified and Polyvinyl Chloride.

15. A sealable lid assembly according to claim 5, wherein said tear strip tape is formed of Tensilized Polypropylene.

16. A sealable lid assembly as claimed in Claim 1, substantially as herein described with reference to any one of the accompanying drawings.