CA2023375C

CA2023375C - Container

Info

Publication number: CA2023375C
Application number: CA002023375A
Authority: CA
Inventors: Ian Michael Daines Gaylor; David John Livesley
Original assignee: White Cap Co
Current assignee: White Cap Co
Priority date: 1989-08-15
Filing date: 1990-08-15
Publication date: 2001-12-11
Anticipated expiration: 2010-08-15
Also published as: ES2069015T3; EP0421590A1; GB8918541D0; DE69016556D1; EP0421590B1; CA2023375A1; DE69016556T2; ATE117963T1

Abstract

Provision is made on a container to indicate whether the container has been tampered with. Release of a vacuum from within the container causes a lid of the container to become convex. This causes a coating on the lid to craze and therefore produce a visible change.

Description

_ 1 _ The present invention relates to a container, particularly one whose contents are to remain safely sealed :from -the environment, and especially to o.ne having means for rendering -tampering evident.
There is a great noel for some means o:E reliably determining whether a seal on a container has broken, either through mere failure or by deliberate -tampering. This is particularly so in the case of containers for food, drinks and medicines (which -term includes medicaments not taken by mouth). If a seal is broken the container or its contents could be contaminated by environmental bacteria by oxidation or by deliberate poisoning or by adding glass e-tc. Whilst in many cases simple failure of a seal may be noticeable, tampering may be more difficult to datect.
This is because an attempt may be made to reform -the seal to avoid det~c tion.
Many attempts have boon made to design containers such that a brolcen seal wall be permanently observable. Tho following examples may be noted.
Some containers, such as beer cans, are made such that they are in effect destroyed when they are opened.
Unobservable tampering is difficult, but such containers cannot be resealed by 'the legitimate user after partial use of their con-ten-ts.
Various proposals have been made fox containers, such as bottles, with screw-caps. For example, a cap may be provided with a band at its base, joined to the remainder of the cap 'through a line of weakness. The band is prevented from rot cling or from rising up -the screw -thread when the cap is unscrewed, and as a result it becomes detached from the remainder of the cap. In another technique a paper label is stuck across a stopper such -that the movement of the stopper causes -the paper to be torn. Heat-shrink sleeves have been shrunk around the tops o~ bottles so as to enclose -the stopper. Removal of the stopper requires the shrunk sleeve to be cwt away. A more expensive 'technique is to -trap the stopper by means of a wire 2U frame around the bottle top, tho onds of -the wire boing loc)tod by means o:E a soldor seal.
Unfortunately, each of 'those tochnlques has its dis advawtages, such as cost or ease of repair a:Eter tampering.

we have now discovered 'that a conformational change in a part of a container may be made to occur when an attempt is mado to open -the container to the environ ment, and that conformational change can be rendered observable.
Thus, the present invention provides a container comprising a first part and a second part that can be brought 'together to close 'the container to the environment, in which:
the first part can have a first conformation when it is brought -together with the second part, which first conformation changes to a second conformation on opening of -the container; and with the proviso that where 'the conformational change is reversible i-t produces an optical and/or tactile change that is not reversed on reversal of said conformational change.
The fi:cst part of the container praferably comprises a lid, by which term wa include caps and stoppers etc.
'Phe second part preferably comprises a can, box, ~ax~, flexible pack or bottlo. By conformational change, we include any suitablo chango of shape, form or ~~~j~ ~a arrangement of parts. We prefer, however, -that the change is a change in -the curvature o:E a wall, particularly a change frorn concave (as viewed from the outside of the container) to substantially flat or convex. The con:Eo:rrnation change is preferably floxur~.
The invention also provides an article for use in environrnental sealing which has a first conformation when providing an environmental seal which changes to a second conformation on breaking of the seal, -the conformational change causing a change in light-scattering and/or light-reflectance a-t a visible or machine-readable portion (which need not be an external surface) of the article. In general, the portion at which scattering or reflectance occurs will be an intermediate surface or layer of a mufti-layer coating on the article.
The invention further provides a label for applying -to a container as an ind:lcator of subsequent -tampering which comprises:
(a) a first layer bearing a visib:Le and/or machine-readable mark; and ~~~~c'g~~~

(b) a second layer overlying the first layer, the second layer being capable of undergoing a change of light-scattering and/or light-reflectance on conformational change of the label.
The invention may also provide apparatus for use in machine-reading such a label, optionally hav~.ng means indicating that 'the label cannot be read. For example i-t may have an output indicating -that a sale should 1U not take place or that a product has been tampered with.
A tamper-evident container may be produced by either of the following methods.
A first method comprises:
(a) applying a material to a part of the container;
'then ( b ) causing a conformational change to that part of the articl~ and consequently to the material, and closing the container to the environment; then ~~~~~"~~

(c) treating the material such that reversal of the conformational change causes an optical and/or tactilo change in -the rna-terial.
Step (c) may compriso embrittlemont, and at may be caused by crass-linking. It is desirable that such treatment be carrlod out after the conformational change has been made -to tho container since prior to treatrnent the material may be flexible.
:In another embodiment the method comprises:
(a) causing a conformational change to a part of the container and closing the container to 'the environment; -then (b) applying -to that part of the container a material such that reversal of the conformational change causes an optical and/or tactile change in the rnatorial 'that is no-t reversed 'thereby.
Apparatus, such as production line may bo provided far use :I~n the methods of tho invention. Such apparatus preferably includes means :for closing a container, means :for applying a label or material in other form, and means :Eor treating tho material for example with _ 7 _ UV or other irradiation to make it brittle e-tc. The apparatus may also include means for fitting the container and for making a vacuum inside.
The material may ba applied as part of a label or as a three-dimonsional pro-form, formed for example by in j oction-moulding.
~Jhilst the invention will have many uses, i~t will b~
described with particular reference to vacuum-packing of food in jars. The first part of -the container is -therefore a lid and the second part is the jar itself, Food is placed inside the jar, the jar and -the food are then heated to sterilise them, the lid is placed over the jar, and -the jar and food allowed to cool. On cooling a vacuum which term of course includes a partial vacuum) is created within -the jar causing the outside of -the lid to become concave. This is -the so-called first conformation referred to above. Thus, we prefer that -the conformational change is of a surface of -the first part that is in pressuro communication wl-th, and more preferably diroctly faces, the ins:Ldo of the container.

~~'~J~
_8_ The presence of a vacuum within -the container is an accepted indication that an environmental seal has been maintained. ~ione-theless, in its broader -terms -the inven-Lion includos conformational changes brought about by any change of pressure difference across a surface of the first part that is in communication with the inside of tho container.
In -the simple case of a lid being deformed by a vacuum within the container, tho conformational change may be reversible. an itself, therefore, -the presence of a concave lid is no guarantee that the container has riot been -tampered with. This is simply because the tamperer could reheat the container, replace -the lid and let it cool thus recreating the concave lid.
The invention is able to deal with this problem as follows.
In one embodiment -the ftrst part is provided with a material thereon that is forced to undergo an optical and/or tactile change as -the lid relaaces frorn tts concavo shape to a substantially flat or convex shapo.
This is the change raferrod to abovo as boing from the first corxformation to a socond conforrnation. We prefer that 'the second conformation bo stable and that the first conformation be unstab7.e and maiwtained only, for example, by -the internal vacuum.
The material may comprise a coating 'that follows the surface of -the lic3 (or other f_i.rs~t part) when in the first and when in the second conformation. The resulting conformational change of -the material will cause an optical and/or tactile change.
:LO In another embodiment, the material may bo held adj acent ( but at least partial ly separated from ) -the lid such that -the lid impacts the material on change from the first to the second conformation, the impact causing the optical and/or tactile change. In this case the lid may have a localised pop-up portion that is retracted when in the first conformation and extended when in the second conformation.
We prefer that tho conformational change causes the material to craze, i.e to produce many generally small cracks. Crazing 1.s one way by means of which a chango of light-sca't'tering and/or light reflectance can bo made 'to result from th~ conformational change. 7Lt will, in gonoral, not be revorsed, ovon if the con:Eorrnational chango is reversiblo. We p:refor a high donsity of crack-initiation silos is produced. We also prefer that stress is reduced over a wide area, and not for example -through a small number of large cracks.
In order that crazing result from the conformational change, we prefer that the material be brittle. If it is not brittle when it is applied -to the lid, it can be made brittle by a process such as cross-linking.
This may be carried ou-t by irradiation or by chemical means etc.
The optical change may be enhanced by the provision of a colourant, such as a micro-encapsulated dye that is dispersed by 'the conformational change. The dye may then travel along cracks in the material by capillary action.
In another embodiment -the conformational change causes stress-clouding of 'the material, or 'the material becomes disbonded from the first part possibly creating scattering of light at the newly-created interface.
It may b~ dosl.rablo to prevent the material from leaving the lira, especially after crazing, and a ~transparewt, preferably flexible, coating may be provided for this purpose, over or under the material.
A variety of chemical formulations may be used as tho material that provides tho optical and/or tactile change. At present a preferred material comprises a wax/resin blend. A variety of such materials are available and the desired melting point, brlttleness, hardness and colour may be chosen. At present preferred blends are those marketed by Wilkins Cambell & Co Ltd under the 'trade marks 6565, 6545 and 6566.
Other materials may be used depending upon the technique by means of which they are applied to the container. Melting and resolidification may be used in the case of hot-melt adhesives, such as polyamides and ethylene vinylacetates etc. Various cross-linkable or curable materials may be used, such as epoxy materials which may be chemically cross-linked and polyim:Ldes wh:Lch may be cross-linked using ultra violet l:Lght. Other su:Ltable polymeric mate:r:Lals include polys-tyrenos, polypropylenes and poly urethanes. Those materials are preferably used without plasticizors, and with inert fillers such as talc or chalk.

Another class of materials that may be used includes lacquers, which may be applied in solution. On evaporation of the solvent -the material cures.
The material may bo used in con,junct:ion with a visual and/or machine-readable mark. A widely usod example of a machine-readable mark is a bar code. The rnaterials may be used as a coating ovor or undex the mark such -that a change in light-scattering and/or light-reflectance of the material alters the appearance of the mark, The container may carry a second mark that is substantially unaffected by -the conformational change, the first-mentioned mark together with the second mark conveying a different message from that conveyed by the second mark alone.
The change may, for example, be deletion of -the word "not" :From a message such as "tampon not evident".
The invention may be used together with one or more other means of detecting ar rosisting tamper:Lng, for examplo, a heat-shrink sleavo or a labol or other layer etc may at loast partially covor the socond part of the container such that its rupture is required to separate the :First and sacond parts.

~2~~~~

The invention is further illustrated with reference to 'the accompanying drawings in which:
Figure 1 is a cross-section through a bottle;

Figure 2 is a cross-section -through a can;

Figure 3 .Ls a cross-section 'through a vacuum-packed plastics comta:Lner;

Figures 4(a) and 4(b) show conformational change of a lid;

Figures 5(a) and 5(b) are perspective views of 'the top of can;
a Figures 6(a) and 6(b) are plan views of the -top of a can;

Figures 7(a), 7(b) and 7(c) show ways of attaching a material a container;
to Figures 8(a), 8(b) and 8(c) show a label, and flow diagramsfor its manufacture and use;

Figures 9(a), 9(b) and 9(c) show a pop-out disc, and flow diagrams for its manufacture and use;
and Figures 10(a), 10(b) and 10(c) show a pop-out disc mouldingand tts manufacture and uso.

Figure 1 shows a glass or p:Lastics bottlo or other container ~. having a cap 2 sealad thereto. Z'he bo~t~tle 1 con-talns food 3 ~thav has been heat s~torllisod. Tho cap :Ls spawn in its so-called first configuration.

~~~~~'~

Note the concave shape ~ when viewed from the outside.
The concave shape 4 results from a vacuum 5 inside °the container. An outer surface of the cap has been coated with a rna-terial, such as a lacquer, that will craze when -the cap 2 is relaased from its concave configuration. Th~.s will, of course, occur when 'the container is opened, at 'the cap or elsewhere and 'the vacuum is released. 'i'he cap 2 may be pravlded alone or it may be used with another closure part such as cover 6. Cover 6 may be -transparen-t such that 'the state of the lacquer 7 may bo viewed without its removal.
Figure 2 shows a tin can 8 having a lid 2 sealed to it by means of a sealed seam 9. The -tin contains a perishable foodstuff 3 under vacuum 5. The lid is in 'the first conformation having a concave portion ~ duo ~to the vacuum 5. Before generation of -the vacuum 5 the lid was substantially flat or convex. On release of the vacuum 'the plastic energy in the lid wall cause it to spring outward and become again flat or convex.
The concavo portion ~l has on it a mark 10 such as a bar code o:r visual messag~. 2'hat mark is coverod by a material 7 as ila.ustrated in flguro 1. If dos:trod, a transparent layer may be provided over tho material 7 as shown by the dotted line. This transparent layer may be provided to prevent fragmentation and removal of material 7 after crazing.
Figure ~ shows a plastics vacuum pack 11 containing perishablo goods 3 under vacuum 5. An insert 12 is placed on 'the goods 3. The insert has perforations or is otherwise constructed such ~tha~t pressure within It equals the pressure within the pack 3. The insert which, together with the film 2, constitutes 'the so-called first part of the invention, has a concave portion 4 resulting from the 'vacuum 5 within the pack 11. On release of 'the vacuum 5 the presently concave portion of the insert 12 pops outwards and becomes substantially flat or convex. This causes the lacquer 7 to craze as described above. Preferably the top of the insert is aligned with the top edges of the pack 11 in order that the film 2 can cause concave portion 4 -to be formed in the insert as the vacuum 5 develops in the pack 11.
Figure 4(a) shows a lid 2 having a coating of a :Lacguer 7 in Sts concave conformation brought about by vacuum 5. The arrows 13 represent some agency such as ultra-violet ligtnt which causes ~tho lacquer 7 to cure and become brittle after 'the concave conformatl.on has been achieved. In figure ~(b) the vacuum 5 has been released and the lid has popped upwards and become convex. This has caused the :Lacquer 7 ~to become crazed and to scatter or reflect light.
't'echniques other than irradiation by ultra-vio7.et light carr be used. For exarnple, the lacquor or other material % may bo melted by -the application of heat and allowed to cool to become a bri't'tle solid which can be caused to craze in a way that is not reversed by any reasonable -treatment. In a further alternative the material 7 is applied in solution and -the solvent removed whilst the lid 2 is in the concave conformation.
l5 The concave portion of the lid may bear some marl, as mentioned above, or it may merely b~ coloured in a colour -tha-t is distinctive from -that of the crazed or otherwise altered material 7.
Figuro 5(a) shows the prosenco of a bar code 1~6 on a lid 10 of a can ~3. The material 7 may bo coated above or below tho bar codo :L~k. Whon tho material 7 is clear tho code can be read easily, but aftor crazing as shown in figure 5(b) the material becomo crazed as shown at l5 and 'the codo l~ can no longer be read.

Th:is lack of ability of the bar code to be read will cause the goods to be rejected at 'the point of sale.
The fault in -the goods w:Lll be readily apparent to both buyer and seller. The crazing will not be reversed on resealing.
Figures 6(a) and 6(b) show how a messago can be alter~d in meaning by crazing of material 7 to produce a generally opaque covering 15. A first mark 7 and two second marks 17 are shown on a lid 2. Beforo 'the conformational change the message read "'tamper not evident" and after the conformational change, brought about by loss of vacuum within -the container, -the message reads "-tamper evident".
Figure 7(a) shows a moulding that may be produced off-line, i.e separate7.y from container manufacture and filling. The moulding is -then bonded to the first part of 'the container after 'the first and second parts have been secured ~toge~thor and, if necessary, an intornal vacuum has beon gonoratod. Tho moulding 1fi comprises a central part 19 having an adhesive coating 20 around the button 23 and if dosired a hot foal 2:1 on its opposite s:ido . A stress ring 22 or other l:lno of woakness :Ls provided so that a conformational change o:f the f:Lrst part of -the container acting on button 23 causes a cen-tral part of -the moulding -to pop-up to produce a visual and tactile change. The hot foil 21 provides a further security feature since it will become visibly fragmented. This would prevent a tamperer re-melting the moulding in an attempt to recreate i-ts original shape. The adhesive 20 may additionally have 'the function of providing some flexibility such that thermal expansion and contraction of the container or changes due to changes of humidity etc. do not put undue strain on the moulding. The material chosen for the part 19 is not critical and many -thermoplastic or other polymeric materials will be suitable.
In Figure 7(b) a moulding 24 is produced on a lid 2 of a container by means of an injection moulding head 25.
In this case the moulding operation will generally be carried on-line. As before, the moulding may incor-porate a line of weakness as shown by 'the "V" shaped grooves in cross-section. The line of weaknoss may allow a portion, such as a central disc, to pop out and bocom~ dotachod from the romaindor a:~ 'the mou:1 d:Cng .

Figure 7(c) shows a self-adhesive paper label comprising a paper backing 26 having a hot :foil coating 21. The area 24 is acted on by the first part of the container when it changes its conformation.
The label may be butt cut or otherwise provided with a lane of weakness to provide a pop-out disc above ~tY~e area 24. Diagonal cuts 27 may be made to allow the label to conform to tho :Lid of the container. Instoad of hot foil 21, or additional to i-t, a brittle material may be provided. The brittle material and/or the hot foil are ruptured as the part 24 of the label is displaced by the conformational change of the lid.
Figure 8(a) shows a wax/resin pop-out disc manufactured as a label pre-form. A release layer such as a paper backing strip 28 carries a series of labols 29. The backing strip and labels may be supplied as a roll. Figure 8(a) shows 'the label in plan view and in longitudinal cross-section. The longitudinal cross-suction shows a wax/resin 30 wj.thin a cavity of a label stock 31, individual labels being defined by the bu't't cuts 32. The labels are temporarily adhored to tho backing strip by moans of a pressure-sonsitive or other adhosive 33.

Figure 8(b) describes a manufacturing process for the disc of figure 8(a) and figure 8(c) describes a method of application of the disc. Figures 8(b) and 8(c) are self-explanatory.
Figure 9(a) shows a wax/resin pop-out disc having an in~ec~tlon-moulded plastics rim togethor with a security foil. Preferred dimensions in millimetres are shown. The disc 3.s preferably substantially circular in plan view and -the drawing is a cross-soction through a diamoter. The wax/resin body 30 of -the disc is coated with a hot foil 21. An annulus of the disc comprises a ring 34 coated on i-ts lower edge with an adhesive 33. The conformational change of a lid on which the dlsC iS bonded causes the wax/resin 30 to pop up leaving behind the rim 33. Figures 9(b) and 9(c) show manufacturing and application methods appropriate to 'the disc of figure 9(a).
Figure 10(a) shows a pop-out disc formod as a moulding 35 having a wax coat:Lng 36 thereon. Again tho disc is substantially circular in plan vlow, a cross-section of its diamotor being shown. A rim 3~ of the ckisc as ;Jolnod to tho central portion by means of an a~t~tachrnorrt spoke 3 % or other l:lne of weakness . An annular groove 38 at the line of weakness may be filled with the wax 36. The rim of the disc is bonded to a lid by means of adhes>ive 33. Dimensions in millimetres for one particular embodiment are shown, and for many cases we prefor ranges of From 0.5 to 2.0 -tunes to those shown.
Figures 10(b) and 10(c) show manufacturing and application methods appropriate to 'the disc of :~igur~
10(a).

Claims

1. A method for packing food in a container which is tamper-indicating, which comprises the steps of:
providing a container including a body and a closure for application to the body which closure includes a flexible end panel having a sealing state indicating area which is capable of flipping from a seal indicating position to a non-seal indicating position due to the release of energy stored in the panel;
placing food inside the body and heating the body and the food therein;
applying the closure to the body while the container and food are hot and allowing them to cool and develop a vacuum therein, whereby the sealing state indicating area is caused to flip to its seal indicating position in which energy is stored in the panel; and wherein the sealing state indicating area has applied to it a hardenable material which is caused to become brittle after the sealing state indicating area has flipped to its seal indicating position so as to provide a brittle layer which provides an irreversible tamper indicating system which is actuable by the indicating area flipping to its non-seal indicating position whereupon the brittle layer is caused to rupture and provide an indication that the container has been opened.

2. The method of claim 1, in which in the seal indicating position, the end panel is concave or substantially flat when viewed from the outside of the container and the non-seal-indicating position is respectively substantially flat or convex.

3. The method of claim 1 or 2, wherein the brittle layer comprises a material which has been cross-linked in order to render it brittle.

4. The method of claim 3, wherein the brittle layer comprises a material which is a photo-curable resin or lacquer.

5. The method of any preceding claim, wherein the brittle layer has a colourant therein that is dispersed when the area flips from its seal indicating position to the non-seal-indicating position.

6. The method of any preceding claim, wherein the tamper-indicating system includes indicia means underlying the brittle layer so that when the brittle layer ruptures the visibility of the indicia is altered.

7. The method of any preceding claim, wherein the food within the container is heat sterilized.

8. The method of any preceding claim, wherein the body is a glass bottle and the closure is a cap seal to the bottle.

9. The method of any of claims 1 to 6, wherein the body is a plastics bottle and the closure is a cap sealed to the bottle.

10. The method of any of claims 1 to 7, wherein the body is a can and the closure is a lid sealed to the can.

11. A container including a body, a closure sealingly applied to the body, a flexible end panel comprised in the closure that has an area that when the container is opened flips from a seal-indicating position to a non-seal indicating position due to release of internally stored energy within the end panel, and a tamper indicating system carried by the end panel that comprises a brittle layer irreversibly rupturable in response to flipping of the end panel area to provide an indication that the container has been opened;
characterized in that:
the brittle layer comprises a material which is a ultra-violet-light-photo-curable resin or lacquer and has been cross-linked to render it brittle.

12. A container including a body, a closure sealingly applied to the body, a flexible end panel comprised in the closure that has an area that when the container is opened flips from a seal-indicating position to a non-seal-indicating position due to release of internally stored energy within the end panel, and a tamper indicating system carried by the end panel that comprises a brittle layer irreversibly rupturable in response to flipping of the end panel area to provide an indication that the container had been opened;
characterized in that:
the brittle layer has been cross-linked to render it brittle and has a colourant therein that is dispersed when the area flips from its seal indicating position to the non-seal-indicating position.

13. A container including a body, a closure sealingly applied to the body, a flexible end panel comprised in the closure that has an area that when the container is opened flips from a seal-indicating position to a non-seal indicating position due to release of internally stored energy within the end panel, and a tamper indicating system carried by the end panel that comprises a brittle layer irreversibly rupturable in response to flipping of the end panel area to provide an indication that the container has been opened;
characterized in that:

the brittle layer has been cross-linked to render it brittle and tamper-indicating system includes indicia means under-lying the brittle layer so that when the brittle layer ruptures the visibility of the indicia is altered.

14. The container of claim 11, 12 or 13, in which in the seal indicating position, the end panel is concave or substantially flat when viewed from the outside of the container, and the non-seal-indicating position is respectively substantially flat or convex.

15. The container of any of claims 11 to 14, in which there is present food, drink or medicine.

16. The container of any of claims 11 to 15, which is under vacuum.

17. The container of any of claims 11 to 16, the contents of which are sterile.

18. The container of any of claims 11 to 17, wherein the body is a glass bottle and the closure is a cap sealed to the bottle.

19. The container of any of claims 11 to 17, wherein the body is a plastics bottle and the closure is a cap sealed to the bottle.

20. The container of any of claims 11 to 17, wherein the body is a can and the closure is a lid sealed to the can.