AU3509501A - Closure system - Google Patents

Description

Regulation 3.2 -1-

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT APPLICANT: AMKUR PTY. LIMITED NUMBER: PQ 6810/00 FILING DATE: 11/ 4/2000 Invention Title: CLOSURE SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me/us: -2- CLOSURE SYSTEM This invention relates to a closure system, closures made incorporating the system and a method of manufacturing such closures.

The closures of the invention are adapted to be associated with thermo-formed containers which containers are manufactured from flat sheets ofa thermo-plastics material which are located over a female tool portion whilst heated and, are then deformed by the downward movement of a male tool portion into the female tool portion. The forming can be completed by vacuum or pressure air acting to bring the material into contact with the female tool. Such closures can often be incorporated into a container for holding fruit oo•• either raw or prepared and, historically, the container is formed with an integral closure S"thereon which closure is adapted to be moved over to a position above the open end of the container and to pass therein and to engage therewith to form a closed container.

.oooo o Such containers have not been fully satisfactory as it is difficult to make a good seal and, if the contents have a liquid component, this can leak from the container and further, the container, which can be relatively thin walled, can, if deformed, often cause the closure to be released from the container.

It is the object of the invention to provide a closure system adapted to be used with such container which provides are positive seal which is unlikely to be displaced and which, at the same time, is strongly resistant to inadvertent removal whilst being readily able to be removed when required.

Another object of the invention is to provide a tamper evident system so a purchaser or a store keeper can ascertain that there has been an endeavour, at least to open the container.

K:\WP51\SPEC\AmkuiCAP.wpd 10/4/01 The invention, in its broadest sense, comprises a closure system for use in a thermoformed container wherein the container has, at its outer end, a returned portion which has formed therein an external rib and the closure has an external portion which is adapted to be located over and to engage around the periphery of the rib of the container.

The invention also includes a container of this type wherein the body of the container and the lid both have outwardly extending tabs, the tabs being interconnected so as to be not easily displaced one from the other and one of the tab having a weakened portion whereby on any attempt to displace the tabs, the weakened portion breaks thus providing S• a tamper evident arrangement.

lo The invention also provides a method of manufacturing closure systems of the S• aforementioned type wherein the tools which form the rib on the closure have at least one portion which is smaller than the desired final shape of the container whereby, the completed container can be stripped from the tool notwithstanding the fact that the diameter of the tool at the portion where removal is necessary is larger than the smallest 15 diameter of the associated metre.

The invention also includes a method of manufacturing containers having closures of the type therein before mentioned wherein the tools, where return portions of the container or the closure have a diameter less than a portion of the tool over which it must pass has a reduced diameter portion over part of its length whereby the completed item can be stripped from the tool after forming and before cooling.

The invention, in a still further aspect, provides a container of the type generally referred to hereinbefore wherein the container body and the closure both have outwardly extending tabs, the tabs having inter-engaging portions which are not readily released one from the other and one of these portions, at least, has a weakened area so that when the container is being opened this is broken thus providing, if necessary, a tamper evident arrangement.

K:\WP51 \SPEC\AmkurCAP.wpd 10/4/01 In order that the invention may be more readily understood we shall describe in relation to the accompanying drawings, one particular embodiment of the invention from which the various aspects of the invention will be able to be gathered.

Figure 1 shows a perspective of a first form of container and closure; Figure 2 shows a section of the container along line 2-2 of Figure 1; Figure 3 shows a section of the closure along line 3-3 of Figure 1; Figure 4 shows a section incorporating those of Figures 2 and 3 showing the container closed by the closure; Figure 5 shows a partial profile of the container tool; 1o Figure 6 shows a partial profile of the closure tool; Figure 7 shows a view as to how the two tools would relate; and Figure 8 shows a plan view of the container tool.

The container 20 and the associated closure 10 of the invention could be of any required shape and for illustration only, are shown as cylindrical in form and could be of the order of 110 Omm of intemrnal diameter and 70mm high. The container and closure assembly are made of sheet plastic material which can either be a food grade plastic, if the container is to be used for prepared food, or even a recycled plastic if it is to be used for, say products.

Containers of this size, shape and material are known.

K:\WP51 \SPEC\AmkurCAP.wpd 10/4/01 The desiderata for such containers is that they are of a thickness sufficient to withstand normal handling in delivery of the product to, say, supermarkets and to be placed on supermarket shelves but which are not unduly thick and thus use excess material. At the same time, they need to give a good seal and are strongly resistant to inadvertent opening.

Essentially these containers have been formed so that the closure is an insert into the container, the upper end of which is smooth, and a relatively good seal should be able to be made between these. However, it will be appreciated that when the closure is being fitted to the container, it has been filed with a product which can often be semi-liquid and portions of product can be delivered onto the surface of the container and prevent a io satisfactory seal. ooeo In the art of thermo-forming, it can be difficult to cause the plastics material to closely follow the tool portions, particularly where these cause rapid deformation as the material *eeoe has a fixed initial size and whilst it can be drawn, the degree of drawing is limited and where there is a corner it tends to follow a curve rather than any sharp edge.

The other aspect is that the tooling which is used for thermo-forming does not have moveable parts and as such, conventionally, the formed article must be able to be stripped from the tooling. That is, generally, there can be no part of the finished product which is smaller in diameter than any portion of the mould in the direction of stripping from which it is to be stripped.

The closure system of the present invention differs from conventional wisdom in this respect.

The body 21 of the container may be formed of any particular size or shape which can be drawn from the material used but, for the purposes of this description, it will be considered to be a truncated cone with the base 22 of a smaller diameter than the top and K:\WPS I\SPEC\AmkurCAP.wpd 10/4/01 may have vertical ribs or striations 19 to give strength to the container whilst, at the same time, giving a satisfactory external appearance.

Whilst we have referred to the container as being circular in section it can also be square or rectangular or any other shape should this be required.

At the top of the container, which of course provides one of the surfaces for sealing, the container is formed about an extension from the main part of the female tool so it has a returned portion 24 at the inner end 25 of which there can be a flat outwardly directed annular flange 26 which is, effectively, the undisturbed sheet.

o* The container has an outwardly directed annular rib 27 spaced upwardly from the flange 26.

ooooo The closure 10 is formed integrally with the container 20 from the same sheet of material and the connection between the two is by a hinge 30. The closure has a body portion 11 which may have an annular formation about its periphery which provides strengthening to the closure, an outwardly directed rib 13 and a flange 14 which is at the level of the base material.

The flanges 26 and 14 and the hinge can be cut by a cutting forme or otherwise after the moulding operation is completed.

The spacing of the rib 13 from the flange 14 is effectively the same as the spacing of the rib 27 of the container from the flange 26.

The arrangement is such that the closure can be placed over the open top of the container by rotation about the hinge 30 and can be located thereon by engagement of the ribs as can be seen in Figure 4.

K:\WP51\SPEC\AmkuxCAP.wpd 10/4/01 When closed, the flange 143 closely overlays the flange 26.

The main seal is made at area 60 where the closure tends to press strongly against the underside of the rib 27.

When the cutting is effected it is preferred to leave a tab 28 on the container and a tab s on the closure which tabs have cutouts 29,16 so that one tab can be deformed and the cutouts on the two tabs will inter-engage with each tab overlying or underlying the adjacent portion of the material.

".This arrangement, which is known, provides a lock between the container and closure and :acts to prevent inadvertent displacement of the two components.

The crux of the invention lies in the formation of the annular ribs about the top of the container.

It has not generally been considered possible to form such ribs using a thermo-forming process where the tool are solid.

In order to form these ribs, we make use of the character of thermo-forming referred to earlier, that is, that the material being deformed will tend to follow a smooth curve rather than closely abut an angular position, unless it is completely constrained to do this by the two tool portions.

Referring to Figures 5 and 8, we show in Figure 5 in solid line a first profile 70 which is the profile of the tool on either side of the area of the hinge and in broken line a second profile 71 which is the profile adjacent the tabs, opposite the hinge. This can well be seen from Figure 8.

K:\WP51\SPEC\AmkurCAP.wpd 10/4/01 When the container is being formed, the material adjacent the front of the container (away from the hinge) will tend to be closer to the relieved portion than to the solid line portion of the profile although, because of the reluctance of the material to follow rapid variations, it will not necessarily follow this closely.

The area 60 which is the area in which the seal is made. With the closure the corresponding area 61 of which is completely with the area 60 will not be displaced.

This formation serves two purposes.

Firstly, when the product is being stripped from the tool it will leave the forward area of the tool more readily than would have been the case of there was no relief and as it reaches towards the rear of the tool, removal will be straightforward as the forward portion has already been removed.

Secondly, when the container is being used, because the upper end of the rib of the container is relieved adjacent the front of the container, it is easier to bring the closure over the front of the container than would have been the case if the rib was symmetrical around the whole of its periphery.

As the portion 60 has not been displaced, the seal is as efficient as it would be if there were no relief on the rib.

Whilst we have described and illustrated the concept of relief in relation to the annular rib about the upper surface of the container, we could, if required us the same concept about the closure but in this case, whilst we could get an advantage in stripping the closure from the tool or when the container and being used and the closure closed, because the hinge side of the closure is stripped first, only one of these advantages could be achieved at a time. Of course, with other products where the closure is being stripped first, both benefits may be achieved.

K:\WP51\SPEC\AmkurCAP.wpd 10/4/01 Earlier in the specification we described how when the finished container was cut from the sheet two tabs were provided which could inter-engage which act as a deterrent to the inadvertent opening of the container, even though this may be unlikely as there may need to be quite substantial force to effect opening because of the positive engagement of the components.

It is possible to make a tamper evident closure instead of using tabs of this type.

In this form of the invention we provide a corresponding dimple on each of the tabs.

Whilst these could be provided on the type of tab illustrated, it may be preferred that the tabs are adapted to directly overlie each other rather than to lie side by side and interoooo lo engaging.

One of the tabs, at least, can be provided with a weakened portion, possibly by the provision of a score line thereacross and this can be done by the cutting forme when excess material is removed from the container and the tabs are formed. The arrangement S.is such that when the closure is closed the two tabs come into alignment and the dimples can be engaged.

That is, for handling and transport, the container achieves the same benefit of the tabs ooooo previously described.

However, when there is an attempt to open the container, the two dimples can be formed to provide an extremely close connection and the attempt to open the container will cause fracture of the weakened portion so it can readily be seen that there has been an endeavour to open the container and thus, the closure is one which has tamper evidence associated therewith. Of course, when the container is legitimately opened the same effect will occur.

K:\WP51 \SPEC\AmkurCAP.wpd 10/4/01 Whilst we have described one particular form of container we believe that the general feature of the invention can readily be ascertained herefrom and it would be simple for persons skilled in the art to be able to design other forms of containers which have the features of the invention. In particular, it is not necessary that the container be circular in section, the invention can well be applied to containers having other shapes.

K:\WP51\SPEC\AmkurCAPwpd 10/4/01

Claims (19)

1. A closure system for a thermo-formed container and a closure wherein one of the the container or the closure has, at its outer end, a returned portion which has formed therein an outwardly directed external rib and the other has an external portion which is adapted to be located over and to engage around the periphery of the rib of the said one.

2. A closure system for a thermo-formed container wherein the container has, at its outer end, a returned portion which has formed therein an outwardly directed :external rib and the closure has an external portion which is adapted to be located .000 10 over and to engage around the periphery of the rib of the container.

3. A closure systems claimed in claim 2 wherein the returned portion of the container has an outwardly directed flange below the external rib.

4. A closure system as claimed in either claim 2 or claim 3 wherein the closure has Sege and outwardly directed internal recess which generally corresponds with the outwardly directed external rib of the container.

A closure system as claimed in any one of claims 2 to 4 wherein the external portion of the closure has an outwardly directed flange below the outwardly directed recess.

6. A closure system as claimed in claims 4 and 5 wherein the outwardly directed flanges are adapted to be in contact when the closure is positioned.

7. A closure system as claimed in any preceding claim wherein the closure is formed integral with the container and is connected thereto by way of a flexible hinge. I\SPEC\AmkurCAP.wpd 10/4/01

8. A closure system as claimed in any one of claims 1 to 7 wherein the body of the container and the lid each have outwardly extending tabs, the tabs being adapted for interconnection to retain the closure in position on the container.

9. A closure system as claimed in claim 8 wherein the tabs are extensions from the flanges of the container and the closure. A closure system as claimed in claim 8 or claim 9 wherein the tabs are formed so as to be not easily displaced one from the other and one of the tab has a weakened •portion whereby on any attempt to displace the tabs, the weakened portion breaks thus providing a tamper evident arrangement. e0g.

C. *0 0

11. A method of manufacturing closure systems for thermo-formed containers as claimed in any preceding claim wherein the tool which forms the rib on at least one of the container or the closure has at least one portion which is smaller in o o diameter than the desired final shape of the container, the arrangement being such 0 0 that after forming and cooling the completed container can be stripped from the *e 15s mould by deformation notwithstanding the fact that the diameter of portion of the tools at the portion where removal is necessary is larger than the smallest o diameter of the associated part.

12. A method of manufacturing containers having closures of the type therein before mentioned wherein the tools, where return portions of the container or the closure have a diameter less than a portion of the tool over which it must pass has a reduced diameter portion over part of its length whereby the completed item can be stripped from the tool after forming and before cooling.

13. A method as claimed in claim 12 wherein after forming, the flanges are cut from the material which extends outwardly from the container and the closure. K:\WP51\SPEC\AmkurCAP.wpd 10/4/01

14. A method as claimed in claim 13 wherein whilst the flanges are being formed tabs are formed on each of the container and the closure which tabs are adapted to interlock when the container is filled and closed in use.

A method as claimed in claim 14 wherein when the tabs are being formed at least one can be weakened so that on opening the container, the tab breaks to indicate that the container has been opened.

16. A tool for manufacturing containers as claimed in any one of claims 1 to 10 or to apply the method of claims 11 to 15 in which part of the tool which forms an annular rib is relieved over part of its surface so that as the material is being to formed, the material generally follows tool shape but the form of the relief is such S• that the completed article can readily be stripped from the tool.

17. A container and closure substantially as hereinbefore described with reference to the accompanying drawings.

18. A method of making a container and closure substantially as hereinbefore s described with reference to the accompanying drawings. *oo

19. A tool for making a container and closure substantially as hereinbefore described with reference to the accompanying drawings. DATED this 10 day of April, 2001 AMKUR PTY. LIMITED By Its Patent Attorneys A TATLOCK ASSOCIATES 1\SPEC\AmkurCAPwpd