AU782121B2 - Container and method - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: CONTAINER AND METHOD VAli y ndtraJca P/laihcS Applicant: Ae- OPERATIONS-PTY LTD The following statement is a full description of this invention, including the best method of performing it known to me: 1 Document4 CONTAINER AND METHOD The present invention relates to a container comprising a tray and a cover moulded from thermoplastic material. The invention also relates to a method of fabricating the container.

The invention has particular application within the food industry, and most particularly as a container for food products such as cakes and pastries to be retailed in food stores or supermarkets. It will be convenient to hereinafter describe the invention in this context, however it will be appreciated that the container of the invention is not limited to this application.

Moulded thermoplastic containers comprising substantially flat trays with domed or cylindrical covers or lids are already known for use in supermarkets or food stores as containers for whole fresh-baked cakes and pastries. The cover or lid is typically transparent to also allow the cakes within the containers to be on display. The tray part of the container has a rim, which extends around a periphery of the tray and a lower edge of the cover or lid connects to the tray in a snap-on type connection over an outer surface of the rim.

2 .:.One problem with this arrangement is that the covers have a tendency to pop off the trays if they are nudged or jostled from the side during packaging in boxes or stacking on shelves. The connection between the tray and cover is also easily disturbed if the containers are handled by customers within the stores. Accordingly, there can be a significant amount of time wasted in cautiously stacking packaged produce, or in re-attaching covers to trays for those containers where the lid has become detached. Where the lids or covers oo do become detached from the trays, product damage is also a problem, as is the fact that the products become susceptible to unwanted tampering.

In view of the above, there exists a need for an improvement in containers comprising moulded thermoplastic trays and covers for food products such as cakes and pastries.

WWAELISSANOOELETECordaine and Method Reviseddoc 2 According to one aspect, the present invention provides a container moulded from a thermoplastic material for enclosing a food product, including: a tray having a substantially planar base portion for supporting the product, and a rim portion defining the periphery of the tray; and a cover adapted to engage and fasten with the rim portion of the tray to securely enclose the product; wherein the rim portion includes a wall member which is upstanding from the base portion of the tray which includes connection means for engagement of the cover to the tray, and wherein the connection means includes a region of the upstanding wall member which is of greater stiffness than the region of the wall member immediately adjacent to the base portion of the tray.

In a preferred embodiment of the invention, the region of the upstanding wall member of the connection means likewise has a greater wall thickness than the region of the upstanding wall member immediately adjacent to the base portion of the tray. The connection means is/are preferably located in an upper region of the upstanding wall member, and the upstanding wall member is preferably substantially vertical.

20 The connection means may take any form as would be recognized in the art. Preferably the connection means is provided at an inner surface of the upstanding wall portion. In a preferred embodiment of the invention, the connection means includes one or more inwardly directed projections at the inner surface of the wall member. The projection(s) is/are preferably angled or oo 25 wedge-shaped to facilitate snap-on engagement with the edge portion of the cover. Most preferably, the rim portion has a plurality of projections formed as discrete lug indentations moulded into the upstanding wall member of the tray rim portion. The projections are preferably evenly spaced around the wall o member. A plurality of discrete lug projections tend to make the cover more difficult to remove, compared with a single continuous bead projection. With a continuous bead, once the cover has been prised off at one point it is then easy to peel the cover off the tray. With a plurality of discrete lugs, however, the W AMELISSAMDOELETXCOniner ad MeUxd Reviseddoc 3 cover must be prised individually off 2 or 3 separate lugs before the container may be properly accessed.

In a preferred embodiment of the invention, the container cover has a top portion and downwardly depending sides that terminate at an edge portion. The edge portion of the cover is adapted to engage and fasten with the connection means of the upstanding rim portion of the tray. The edge portion of the cover is preferably outwardly up-turned producing an upstanding lip for engagement with the connection means at the rim portion of the tray.

Most desirably the region of the edge portion of the container cover designed to engage with the connection means of the tray (whether the edge portion is up-turned or not) is of greater stiffness than the region of the cover adjacent to its top portion. It is preferable that this region of greater stiffness be of greater thickness than the region of the cover adjacent to its top portion.

Whilst the shape and design of the side wall of the container cover is not a crucial aspect of this invention it is preferred that it be strong enough to 20 withstand the pressure of pressing the cover onto the tray without collapsing or suffering any permanent deformation.

The substantially planar base portion of the tray is preferably in the form of a plate suitable for a cake or other comestible item to stand upon. However, the base may alternatively be dished or indented. The base portion of the tray 25 preferably includes a plurality of stiffening ribs formed therein. The stiffening gigolo ribs can depend downwardly from planar segments of the base portion, which segments together define a product-supporting surface. The planar segments typically exhibit greater material thickness than the stiffening ribs.

In one embodiment of the invention, the tray and cover have at least and preferably 8 or more sides. The more sides the tray and cover have the greater the hoop strength of the resultant container. More preferably, however, the tray for the container is substantially circular, and is so dimensioned that the W:WMELISSANODELETEContalnef and Method Revised doc 4 height of the upstanding rim portion defining the periphery of the tray is relatively small compared with the width dimension or diameter of the tray.

The tray and cover of the container may be moulded from any of a variety of thermoplastic materials, but are most preferably formed from PET.

For example, the tray may be formed from black PET while the cover is formed from transparent PET to enable the product enclosed within the container to be clearly visible to consumers.

One of the advantages of the present invention is that the cover and tray are designed to fasten together within, or inside, the outer rim portion of the tray. Another advantage is the relatively higher stiffness of the upper region of the rim portion wall member, which ensures that the connection means projections are robust and that the radial stiffness at the periphery of the tray is satisfactory without over-designing the entire tray. That is, for a commercially practical container, the amount of material used should be as economical as possible without compromising the desired container properties. Accordingly, areas of the greater material thicknesses (ie wall thickness) should desirably be 0 confined to those areas only where the higher stiffness is required. These l! factors combine to provide a light and flexible, but nevertheless robust and noteasily-tampered-with container for storage and display of cakes, pastries and other such food products on supermarket shelves.

An outward bias of the up-turned edge portion of the cover can assist to retain the container in a reliable sealed condition so that it is less susceptible to unwanted opening during handling and/or storage. However, despite such an outward bias, the cover and tray should still be able to be fitted together by simple pushing of the cover onto the tray. In the embodiment of the invention where the tray is substantially circular, the relatively higher stiffness of the upper region of the wall portion, in conjunction with the hoop strength between respective connection means, makes it more difficult to remove the cover by deformation of the tray compared with non-circular tray and lid combinations.

W:WELISSA\NOELETEXCoantarw and Method -Revsed doc Fabricating the tray for the container of the invention using conventional vacuum moulding techniques is difficult since the outer periphery of the thermoplastic web the blank material from which the tray is formed) tends to be subjected to substantial thinning on the male forms during vacuum forming, and this compromises the rigidity of the upper region of the rim portion wall member. However, in the case of the present invention, the conventional fabrication process is inverted and the tray of the container is adapted to pressure moulding on a female form. Using this technique, the periphery of the thermoplastic web experiences reduced deformation and therefore a lower degree of thinning to retain rigidity at the connection means of the tray together with radial stiffness at the rim portion.

Thus, according to another aspect, the present invention also provides a method of fabricating the container described above including the step of moulding the tray using vacuum or pressure forming. More particularly, the tray of the container is typically pressure formed in a female mould such that the material thickness at the region of the rim wall intended to engage with the cover is greater than the region immediately adjacent to the base portion of the 2 tray. The cover is typically vacuum formed in a female mould optionally using a plug assist. Likewise it is preferred that the cover is formed such that the material thickness of the region intended to engage with the tray is greater than the region of the cover adjacent to its top. Preferably the method is used to produce a tray and cover both of which are substantially circular.

The vacuum or pressure moulding of the container tray or container cover according to the method of the invention preferably includes the steps of: heating a web of the thermoplastic material; positioning a female mould-form shaped for moulding a tray or a cover having the features previously described for any tray or cover made in accordance with the invention, opposite the heated thermoplastic web; deforming the heated web by differential pressure into the female mould to produce the moulded product; W:WELISSANODELETECOntan and Method Renswed wc 6 cutting any unwanted remainder of the web from the moulded product formed; and removing the moulded product from the mould.

In a preferred embodiment of the invention the tray is made by pressure forming. Pressure forming comprises the following steps, the thermoplastic web is fed onto a hot platen, the female mould positioned above the platen comes down and a knife edge formed around the periphery of the mould seals the web between the knife edge and the platen, air is blown through the mould to push the web onto the hot platen which heats the web to the forming temperature, when the web is at the correct temperature the air from the space between the web and the tool is removed by sucking out through small holes in the mould and at the same time air is blown into the space between the platen and the web to force the web into contact with the female mould. After the web has cooled the female mould is forced down onto the platen so that the knife cuts the web. The mould is lifted and the cut article and residual web is moved off the platen. The trays are transported to the operator for packing while the residual web is recycled.

S 20 The above and further features and advantages of the present invention will be more fully appreciated from the following detailed description of preferred embodiments of the container and method of this invention with reference to the accompanying drawings, in which like reference characters indicate like parts, and in which: 25 Fig 1 is a side view sketch of a container comprising a tray and cover .oto°i according to a preferred form of the invention, with the tray shown in crosssection.

Fi ig 2 is a sketch showing details of the connection between the cover *and the tray highlighted by the circle in Fig 1.

Referring to Fig 1 of the drawings, the present invention provides a container comprising a tray 10 and a cover 20 for enclosing a food product such as a cake. The container of this invention is also referred to generally herein as WWMELISSMNODELETCOntaine arid Metlod Revised.dOC 7 the "Florapak" container to distinguish it from other competing container types or configurations with which the invention will later be compared in the "Test Results" section of this description.

The tray 10 is generally circular and has a substantially planar base portion 1 for supporting the cake product. The tray 10 furthermore includes a circumferential rim portion 11 which is upstanding from the base portion 1 and defines a periphery of the tray 10. The height of the upstanding rim portion 11 is small in comparison to the diameter of the base portion 1. The rim portion 11 of the tray 10 comprises a substantially upright circumferential wall member 12 and an inner surface 13 of that wall member 12 is adapted for fastening engagement with the container cover 20. The base portion 1 of the tray includes a plurality of substantially planar segments 2 which together define a cake supporting surface. The base portion 1 further includes a plurality of stiffening ribs 3 which depend downwardly from the planar segments 2 and enhance the overall stiffness of the tray 10. The ribs 3 may be formed in any of a variety of configurations, but preferably include at least one circular rib and a plurality of radially extending ribs. The base portion 1 further includes a 2 circumferential recess 4 formed adjacent the rim portion 11 for receiving an 20 edge portion of the cover 20 when the tray and cover are connected together.

The container cover 20 has a generally cylindrical or frusto-conical shape defined by a top portion 21 and slightly outwardly diverging, downwardly depending sides 22. The top portion 21 of the cover may be slightly domed, but is preferably flat as shown to facilitate stacking of the containers one on top of a the other. The sides 22 include a plurality of ribs 23 to enhance the compressive stiffness of the cover. The sides 22 which depend downwardly from the flat top portion 21 terminate at a circular edge portion 24. The edge portion 24 is outardly up-turned to form an upstanding lip 25 for fastening engagement with the inner surface 13 of the tray rim portion 11.

Referring now to Fig 2 of the drawings, the wall member 12 of the tray rim portion includes an upper region 14 and a lower region 15 adjacent the base W:MELISSA NODELETEContaner a Method Revised.doc 8 portion 1. The wall member 12 furthermore includes a plurality of discrete inwardly directed projections 16 moulded as lug indentations evenly spaced around the rim portion in the upper region 14. These projections 16 function as connection means for fastening engagement with the rim portion 24 of the container cover 20. Importantly, the material stiffness in the wall member 12 is greater in the region 14 compared with the bottom of region 15 (adjacent to the base of the tray) providing the rim portion with superior radial stiffness for improved fastening engagement with the cover. This higher material stiffness in the upper region 14 of the wall member 12 corresponds to a higher material thickness in that region. For example, the wall thickness in the upper region 14 in this example may be about 0.38 mm, compared to a wall thickness of about 0.20 mm towards the bottom of the lower region The projections 16 are chamfered or tapered in cross-section to produce a snap-on interaction with the edge portion 24 of the cover as the upstanding lip of the edge portion is pressed down into engagement with the fastening projections 16 formed in the upper region 14 of the wall member 12.

2 Referring now to both Figs 1 and 2, the tray and cover of the container .e are fastened together by pressing the cover 20 downwardly into fastening engagement with the rim portion 11 of the tray 10. As the cover is pressed down onto the tray, the upstanding lip 25 of the cover edge portion 24 encounters the upper chamfered face of the inwardly directed locking projections 16 at the inner surface 13 of the rim portion wall member. The upstanding lip 25 is resiliently deformed inwardly by the projections 16 (there are preferably five of them) which are spaced evenly around the rim portion 11. The rim portion itself will naturally also experience some resilient deformation in a radially outward direction.

When the upstanding lip 25 passes beyond the innermost extreme of the lug indentations, the rim portion and lip snap resiliently back to an un-deformed state, and the edge portion 24 is received and retained in the recess 4 formed in the base portion 1 directly adjacent the lower region 15 of the rim portion wall W.WELSSA\ODELErE\Coainer and MothDd Reviseddoc 9 member 12. In a particular preferred form of the invention the lip 25 of the outwardly up-turned edge portion 24 maintains an outward bias against the inner surface 13 of the wall member when the tray 10 and the cover 20 are connected.

The material thickness, and thus the stiffness, of the outwardly up-turned edge portion 24 of the container cover 20 is typically greater than that near the top of the sides 22. In this example, the upstanding lip 25 which engages and fastens with the rim portion 12 has a material thickness of about 0.38 mm, compared with a material thickness of about 0.18 mm towards the top of the side 22.

In the above example, the tray 10 is made by pressure forming with contact heat, using 0.38 mm thick black PET sheet stock. The cover 20 is made by vacuum forming with radiant heat and using a plug assist, using 0.42 mm thick clear PET sheet stock.

The resultant container according to this invention is easy to close, but Sonce closed has a robust and reliable connection. This greatly assists container 20 users, such as bakers and cake manufacturers, by reducing their labour and *:effort when packaging items for sale. It also prevents the container cover from inadvertently becoming dislodged during transport and/or handling of the goods.

Test Results: The "Florapak" container of the invention was compared to a number of other cake container configurations. The cake container configurations used by the applicant for the comparisons were as follows:- ACI High S ACI Low Ultrapac S Rema-High S Rema-Low S C&A WWELISSAWODELETENConanir and Methnd R .ndo The first two products were alternatives produced by the applicant. Both utilised a tray having a base and a wall member depending downwardly from the base to provide a foot on which the tray could stand. Both included a cover having an edge portion shaped to fit over the depending wall portion of the tray.

Both were made by pressure forming using contact heat. The lid was made using 0.38 mm clear PET and the base was made from 0.38 mm black PET.

The volume, weight and dimensions of these products are set out in the tables hereafter appearing. Neither product was found to achieve satisfactory performance in terms of the cover retention.

The Ultrapac product used for the comparisons was a commercially available product from Ultrapac Inc of the United States.

Both the Rema-High and Rema-Low packages were commercially available packages produced in Australia under the trade mark REMA.

The C&A container was a commercially available container manufactured in Australia and sold under the trade mark C&A.

oo* The comparisons related primarily to ease of opening and closing the different containers. However, dimensional comparisons were also made, in terms of the amount material used in forming the container, as well as container capacity.

25 Opening and closing tests for the various cake containers were :oooi performed on an "lnstron" testing apparatus. In each case, the container tray was secured by three screws fastened to a metal plate, which was then clamped onto the bottom plate of the Instron apparatus. The cover was held by a cable through two holes near the edges at the top portion thereof and the cable was then connected to the top jaw of the Instron apparatus. The head speed of the Instron was set at 40mm/min for each test.

W:WELISSANOOELETEIConarner and Method R1vis.doc 11 The results for the cake tray opening and closing forces (average) measured during the tests are illustrated graphically below.

Container closing force Iw Container opening force 8.00

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rOooo0 o o *oooo o *o* 4.82 1 ,o 9 2.00- 0.98 in0.6 0.98 1.03 nflI U~Ws r'u Irr U~l It will be noted that whilst the closing force required for the "Florapak" container of the invention is comparable to the other competing cake tray configurations, the opening force required is significantly greater, being more than double the force required for the next most secure configuration. This illustrates one of the primary advantages of the present invention; namely, that the cover or lid is substantially more securely attached to the tray, thereby minimising the problems associated with the covers 'popping' off during transport or handling.

W:\MELISSA\NODELETE\Container and Method Revised doc 12 a a Tables listing the overall product dimensions for the different container types, and their various wall section thicknesses are given below: Container Dimensions Product Type Volume Cover Tray Diameter Height (ml) Weight Weight (mm) (mm) ACI High 3000 20.8 20.2 220 106 ACI Low 2000 20.7 20.2 220 76 ULTRA PAC 3800 33.3 20.8 213 126 REMA- High 2300 16.5 15.6 216 91 REMA- Low 2000 16.8 15.6 216 74 C&A 2000 17.6 18.3 190 79 Florapak 2000 18.3 18.4 214 79 Container Wall Sections Product Type Cover, Corner Cover, Mid-Wall Cover, Top Tray (mm) (mm) (mm) (mm) ACI High 0.02 0.03 0.15 0.18 0.13 0.38 ACI Low 0.04 0.05 0.16 0.19 0.20 0.38 ULTRA PAC 0.03 0.04 0.19 0.21 0.25 0.29 REMA High 0.03 0.04 0.15 0.18 0.16 0.25 REMA Low 0.08 0.10 0.19 0.21 0.23 0.25 C&A 0.02 0.03 0.14 0.18 0.19 0.35 Florapak 0.02 0.04 0.10 0.18 0.16 0.30 The above tables show that the "Florapak" container of the invention is comparable in overall size and capacity to most of the competing cake container configurations tested (except the ACI-High and ULTRA PAC types which have a substantially greater volume). Furthermore, the component weights and the wall section thicknesses illustrate that the "Florapak" configuration produces vastly superior opening-closing force performance without compromising on economy of material used to produce the container.

WWELISSANODELETE\Corntiner and Method Revlsed.doc 13 An alternative embodiment of the invention includes a non-circular tray which has up to eight equal sides, and a corresponding shaped cover which also has up to eight sides. In this embodiment the lug indentations are preferably placed in the middle of each of the sides to reduce ease of tampering with the product.

While particular forms of the invention have been described in detail above, it will be apparent to persons skilled in the art that various alternations and/or additions may be made to the parts previously described without departing from the spirit or ambit of the invention as defined in the claims.

W:AMELSSANODELETE\Container and Method Revised doc 14

Claims (10)

1. A container moulded from a thermoplastic material for enclosing a food product, including: a tray having a substantially planar base portion for supporting the product, and a rim portion defining the periphery of the tray; and a cover adapted to engage and fasten with the rim portion of the tray to securely enclose the product; wherein the rim portion includes a wall member which is upstanding from the base portion of the tray which includes connection means for engagement of the cover to the tray, and wherein the connection means includes a region of the upstanding wall member which is of greater stiffness than the region of the wall member immediately adjacent to the base portion of the tray.

2. A container according to claim 1, wherein the region of the upstanding wall member of the tray of the connection means has a greater wall thickness than the region of the upstanding wall member immediately adjacent to the base portion of the tray. S.

3. A container according to claim 1 or claim 2, wherein the connection o means is/are located in the upper region of the upstanding wall member of the tray. *1

4. A container according to any one of the preceding claims, wherein the connection means includes one or more inwardly directed projections at the

9.. inner surface of the upstanding wall member of the tray. 5. A container according to claim 4, wherein the projections are 9 ::indentations moulded into the upstanding wall member of the tray rim portion. 6. A container according to claim 4 or claim 5, wherein the projections are angled or wedge-shaped to facilitate snap-on engagement with the cover, and comprise discrete lugs that are evenly spaced around the wall member. W:WELSSAV4ODELETECon±anef and Medo Reviseddoc 16 7. A container according to any one of the preceding claims, wherein the container cover has a top portion and downwardly depending sides which terminate at an edge portion, the edge portion being adapted to engage and fasten with the connection means of the tray. 8. A container according to claim 7, wherein the region of the edge portion of the cover designed to engage with the connection means of the tray is of greater stiffness than the region of the cover adjacent to its top portion. 9. A container according to claim 8, wherein the region of the edge portion of the cover designed to engage with the connection means of the tray has a greater wall thickness than the region of the cover adjacent to its top portion.

10. A container according to any one of claims 7 to 9, wherein the edge 15 portion of the cover is outwardly up-turned producing an upstanding lip for engagement with the connection means at the rim portion of the tray. S"11. A container according to any one of the preceding claims, wherein the planar base portion is in the form of a plate suitable for a cake or other comestible item to stand upon. S12. A container according to any one of the preceding claims, wherein the tray for the container is substantially circular, and wherein the height of the upstanding rim portion which defines the periphery of the tray is relatively small 25 compared with a width dimension or diameter of the tray.

13. A container according to any one of the preceding claims, wherein the base portion of the tray includes a plurality of stiffening ribs formed therein, the stiffening ribs depending downwardly from planar segments of the base portion that together define a product-supporting surface.

14. A container according to any one of the preceding claims, wherein the tray and cover of the container are moulded from PET.

15. A container moulded from a thermoplastic material for enclosing a food product substantially as herein described with reference to the accompanying drawings. H:\]u1iaI\keep\SpecI\9 7

245-01 amen.ded pages.doc 28/02/05 17 16. A method of fabricating a tray or a container cover as claimed in any one of the preceding claims, the method including the steps of: heating a web of the thermoplastic material; positioning a female mould-form shaped for moulding a tray or a cover as defined in any one of the preceding claims opposite the heated thermoplastic web; deforming the heated web by differential pressure into the female mould to produce the moulded product; cutting any unwanted remainder of the web from the moulded product formed; and ejecting the moulded product from the mould. 17. A method according to claim 16, wherein the female mould-form is 15 placed over the thermoplastic web positioned on the platen, and wherein air is injected through the platen to deform the heated web into the female mould. 18. A method of fabricating a container substantially as herein described with reference to the accompanying drawings. Dated this 2 8 th day of February 2005 VISY INDUSTRIAL PLASTICS PTY LTD By their Patent Attorneys o: 25 GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H:\julial\keep\Speci\8 7 245-01 amended pages.doc 28/02/05