BASE STRUCTURE, KIT OF PARTS AND A METHOD

Abstract

A base structure for a container, the base structure including a base volume; and a flange defining an opening of the base volume, the flange extending from the base volume about the perimeter of the base volume; the flange including at least one projection, wherein the at least one projection extends away from the base volume, and further wherein the at least one projection extends around a majority of the perimeter of the base volume.

Claims

1. A base structure for a container, said base structure comprising a base volume; and a flange defining an opening of the base volume, said flange extending from the base volume about the perimeter of the base volume; said flange comprising at least one projection, wherein said at least one projection extends away from said base volume, and further wherein said at least one projection extends around a majority of said perimeter of said base volume.

2. The base structure of claim 1, wherein said at least one projection extends around at least 90% of said perimeter of said base volume.

3. The base structure of claim 2, wherein said at least one projection extends continuously around said perimeter of said base volume.

4. The base structure of claim 1, wherein said flange comprises at least two projections separated by a channel.

5. The base structure of claim 4, wherein said flange comprises a central projection, a first outer projection located between said central projection and said base volume, and a second outer projection located between said central projection and an outer perimeter of said flange.

6. The base structure of claim 5, wherein said central projection is separated from said first outer projection by a first channel, and further wherein said central projection is separated from said second outer projection by a second channel.

7. The base structure of claim 6, wherein said first channel and said second channel are of substantially equal width.

8. The base structure of claim 5, wherein said first outer projection and said second outer projection are angled towards one another.

9. The base structure of claim 5, wherein the first outer projection comprises a first face and a second face, the first face located closer to the base volume than the second face, wherein the angle between the normal to the flange and the first face is greater than the angle between the normal to the flange and the second face.

10. The base structure of claim 5, wherein the second outer projection comprises a first face and a second face, the first face located closer to the outer perimeter of the flange than the second face, wherein the angle between the normal to the flange and the first face is greater than the angle between the normal to the flange and the second face.

11. The base structure of claim 4, wherein said two or more projections are of substantially the same height.

12. The base structure of claim 1, wherein said at least one projection tapers in height.

13. The base structure of claim 1, wherein said flange extends in substantially the same plane as the opening of said base volume.

14. The base structure of claim 1, wherein said flange is arranged to extend at an acute angle to a wall defining the base volume.

15. The base structure of claim 1, wherein said at least one projection is located centrally on said flange.

16. A kit of parts comprising a film lid and the base structure of claim 1.

17. A method, the method comprising providing the base structure of claim 1; placing at least one product in the base volume of said base structure; and sealing said base volume with a film lid by affixing said film lid to said at least one projection.

18. The method of claim 17, wherein the method further comprises the step of introducing a modified atmosphere into said base volume prior to sealing said base volume with said film lid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

[0030] FIG. 1 depicts a perspective view of a base structure in accordance with the claimed invention;

[0031] FIG. 2 depicts a top view of the base structure of FIG. 1;

[0032] FIG. 3 depicts a deconstructed view of the base structure of FIG. 1;

[0033] FIG. 4A depicts a deconstructed side view of the base structure of FIG. 1 with a film lid affixed to the base structure;

[0034] FIG. 4B depicts a magnified view of the flange of the base structure of FIG. 4A;

[0035] FIG. 5A depicts a side view of a film lid affixed with a rounded seal to the flange of a second embodiment of the base structure of the first aspect of the invention;

[0036] FIG. 5B depicts a side view of a film lid affixed with a flat seal to the flange of a second embodiment of the base structure of the first aspect of the invention; and

[0037] FIG. 6 depicts a method in accordance with the third aspect of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In the following description, it is understood that contaminants present on the flange particularly include goods and contents housed within the base volume which have been splashed, spilt or are otherwise loose and present on the flange, and are not limited to external contaminants. Contaminants present on the flange prior to affixing the lid film are common, in particular in the filling and packaging process, wherein movement of the base structure and vessels used to pour contents into the base structure and manual handling of the base structure may cause accidental spillage onto the flange.

[0039] It is also understood that a film lid may be any suitable lid structure and is not limited to a plastic film. The film lid may comprise a plurality of layers, but in particular may be a film lid less than 1 mm in thickness, or more preferably less than 500 ?m in thickness. It is envisaged that the film lid is unperforated such that an airtight seal can be formed over the base volume when a film lid is affixed to the base structure. In this way, a modified atmosphere can be introduced and maintained within the base structure.

[0040] With reference to FIGS. 1-4, there is illustrated a base structure 100 comprising a base volume 105 and a flange 110 defining an opening of the base volume 105. In this embodiment, the base volume 105 is substantially cuboid with a substantially rectangular cross section. However the shape of the base volume 105 is not particularly limited and may be, for example, cylindrical or another type of prism. In use, the base structure can be filled with goods or other contents, such as food stuffs, such that the contents of the base structure 100 occupy the base volume 105 but do not overflow the base volume 105.

[0041] The flange 110 extends from the base volume 105 about the perimeter 145 of the base volume 105, such that any overflowing contents from the base volume 105 overflow onto the flange 110. As shown in the figures, the flange 110 extends in substantially the same plane as the opening of the base volume 105 and is located centrally on the flange 110.

[0042] The flange 110 comprises three projections 115 with each projection 115 extending away from the base volume 105. The three projections 115 extend continuously around the perimeter 145 of the base volume 105. The three projections 115 comprise a central projection 115b, a first outer projection 115a located between the central projection 115b and the base volume 105, and a second outer projection 115c located between the central projection 115b and an outer perimeter 120 of the flange 110. The first outer projection 115a and the second outer projection 115c are angled towards one another.

[0043] The central projection 115b is separated from the first outer projection 115a by a first channel 150a, and the central projection 115b is separated from the second outer projection 115c by a second channel 150b. The first channel 150a and the second channel 150b are of substantially equal width and have an triangular cross section along their length. The cross section of each channel 150a, 150b is constant along their length. The movement of any contaminants trapped within the first channel 150a or second channel 150b is substantially unhindered about the perimeter 145 of the base volume 105.

[0044] The first outer projection 115a comprises a first face 155a and a second face 155b, the first face 155a located closer to the base volume 105 than the second face 155b, wherein the angle between the normal N to the flange 110 and the first face 155a is greater than the angle between the normal N to the flange 110 and the second face 155b. The second outer projection 115c comprises a first face 160a and a second face 160b, the first face 160a located closer to the outer perimeter 120 of the flange 110 than the second face 160b, wherein the angle between the normal N to the flange 110 and the first face 160a is greater than the angle between the normal N to the flange 110 and the second face 160b. As can be seen from FIGS. 4A and 4B, the second faces 155b, 160b of the outer projections 115a, 115c are steeper than their inner faces 155a, 160a. The cross section of the central projection 115b is symmetrical about the normal N to the flange 110 and is constant along the length of the central projection 115b.

[0045] All three projections 115a, 115b, 115c are of substantially the same height and each projection 115a, 115b, 115c tapers in height with distance from the base volume 105. In this embodiment, each projection 115a, 115b, 115c tapers to a point. As shown in FIGS. 1 and 3, the projections 115a, 115b, 115c are planar and this plane is parallel to the opening of the base volume 105. In this way, a film lid affixed to the projections 115a, 115b, 115c will also sit planar and parallel to the opening of the base volume 105.

[0046] In this embodiment, the base structure 100 is made entirely from PET (polyethylene terephthalate), although the type of material is not particularly limited.

[0047] The flange 110 further comprises a lipped surface 130 extending from the outer perimeter 120. The lipped surface 130 comprises a lip 135 extending continuously around the perimeter 145 of the base volume 105. The lipped surface 130 of the flange 110 is arranged to extend at an acute angle to a side wall 140 defining the base volume 105.

[0048] The base volume 105 further comprises a number of impressions 125. The type, size and number of impressions 125 is dependent on the application and contents of the base structure 100. In this embodiment, some of the impressions 125 extend into the base volume 105, reducing the total volume of the base volume 105, and some of the impressions 125 extend away from the base volume 105, increasing the total volume of the base volume 105. The function of the impressions 125 is to improve ease of handling the base structure, improve rigidity of the base structure 100 and/or reduce the risk of warping and bursting when a film lid 200 is affixed to the base structure 100.

[0049] A method 600 is shown in FIG. 6, the method 600 including the steps of PROVIDE BASE STRUCTURE 601, wherein the base structure 100 is provided. There follows a PLACE PRODUCT 602 step, wherein at least one product is placed in the base volume 105 of the base structure 100. Finally, there follows a SEAL 603 step, comprising sealing the base volume 105 with a film lid 200 by affixing the film lid 200 to the projections 115a, 115b, 115c. In this way, a hermetic seal is formed over the base volume 105 such that the product held within the base volume 105 is held within an airtight atmosphere.

[0050] FIGS. 5A and 5B depict a second embodiment of the base structure 100 of FIGS. 1-4 and in the following description similar numerals will be used for similar parts of the second embodiment of the present invention. As shown in FIGS. 5A and 5B, a film lid 200 can be affixed to the base structure 500 in a number of configurations. In FIGS. 5A and 5B heat sealing is employed, wherein the film lid 200 and base structure 500 are subjected to high temperature and pressure along their points of contact such that they are affixed together.

[0051] In FIG. 5A, a rounded seal is illustrated. Namely, the film lid 200 is affixed to each tapered end of the outer projections 515a, 515c. The film lid 200 is further affixed to the first face 555a of the first outer projection 515a and to the first face 560a of the second outer projection 515c. In this embodiment, the film lid 200 does not contact the central projection 515b, although sealing of the film lid 200 against the central projection 515b is envisaged in some embodiments. In this way, the film lid 200 crosses the tapered ends of the projections and is pressed downward on the outermost faces 555a, 560a of the outer projections 515a, 515c. As such, the film lid 200 forms a rounded, dome like seal over the three projections 515a, 515b, 515c. Contaminants trapped within the first channel 550a and second channel 550b are free to move between channels 550a, 550b and about the perimeter of the base volume.

[0052] In FIG. 5B, a flat seal is illustrated. Herein, the film lid 200 is affixed to the tapered end of each of the three projections 515a, 515b, 515c only. The film lid 200 thus maintains a planar line across all ends of the projections 515a, 515b, 515c and consequently the base volume.

Burst Testing

[0053] A base structure in accordance with the present invention was compared to a known flat flange base structure. It is understood that a flat flange base structure is well known in the art and is a base structure that has a substantially flat flange without any projections. The test conditions were kept constant across experiments, and in each case a base structure measuring 132 mm by 122 mm was used alongside a polyethylene terephthalate (PET) film lid with a 500 ?m thickness. Examples 1-4 comprise the base structure of the present invention and Comparative Examples 1-4 comprise a known flat flange base structure.

[0054] Each sample was partially filled with a volume water and no modified atmosphere was added. A PET film lid (KM Packaging PET-3G 25/P21) was heat-sealed to each base structure to produce a flat seal, as shown in FIG. 5B, using a six spring, 2997N force seal at 160? C. for 0.5 seconds such that a hermetic seal was formed. Each sample was then tested using a vacuum pressure tank. The vacuum in the vacuum pressure tank was increased slowly to ?30 kPa and held at ?30 kPa for 30 seconds. If the sealed sample withstood the 30 seconds at ?30 kPa then the vacuum pressure was increased slowly to the point at which the sample fails.

[0055] Each sealed sample was tested for either burst or leak. A burst failure is shown by a mass of air appearing in the water and the pack deflating quickly. A leak failure is shown by a constant stream of bubbles from one or more areas of the base structure. Further, a sealed sample can fail in two ways; as a seal failure or as a film failure. A seal failure is shown by the film lid lifting from the base structure in the area it was sealed in and a film failure is shown by a break or fracture inside the seal line. In the case of a film failure, the seal made between the film lid and the base structure remains intact.

[0056] The samples were tested with both an uncontaminated seal, namely no contaminants present on the flange of the base structure, and a seal contaminated with chicken fats.

[0057] While the burst test result is representative of the geometry of the tray and volume of air in the pack, standard measurements seen through testing are shown in Table 1.

TABLE-US-00001 TABLE 1 Force (kPa) Pass Rate >?20 Fail ?25 Low ?30 Acceptable ?35 Substantial ?40 Good ?45 Firm <?50 Obvious Pass

[0058] The test results for a non-contaminated flange seal are shown in Table 2. The type of failure observed with each sample was also noted.

TABLE-US-00002 TABLE 2 % Improvement Failure over Base Structure Force Comparative Failure Material Sample (kPa) Pass Rate Example Type Recycled Example 1 ?75 Obvious 0 No Polyethylene Pass Failure Terephthalate Comparative ?75 Obvious No Example 1 Pass Failure Recycled Example 2 ?35 Substantial ?19 Leaked/ Polyethylene Burst Terephthalate Comparative ?43 Good Burst Anti-Block Example 2 Commercially Example 3 ?35 Substantial ?22 Burst Available Comparative ?45 Firm Burst Polyethylene Example 3 Product (TDX SealPET) Recycled Example 4 ?36 Substantial ?17 Burst Polyethylene Comparative ?43 Good Burst Terephthalate Example 4 with Resin

[0059] The results of the uncontaminated flange seal tests show that Examples 1-4 performed above an acceptable level on burst testing, with failure occurring above-30 kPa. In particular, Example 1 performed well, meeting an obvious pass standard. As such, the present invention performs more than adequately when no contaminants are present on the flange of the base structure.

[0060] The test results for a contaminated flange seal (using chicken fat as the contaminant) are shown in Table 3.

TABLE-US-00003 TABLE 3 % Improvement Failure over Base Structure Force Comparative Failure Material Sample (kPa) Pass Rate Example Type Recycled Example 1 ?61 Obvious +21 Leaked/ Polyethylene Pass Burst Terephthalate Comparative ?51 Obvious Leaked/ Example 1 Pass Burst Recycled Example 2 ?30 Acceptable +7 Leaked/ Polyethylene Burst Terephthalate Comparative ?28 Low Burst Anti-Block Example 2 Commercially Example 3 ?34 Acceptable +18 Leaked/ Available Burst Polyethylene Comparative ?29 Low Leaked/ Product (TDX Example 3 Burst SealPET) Recycled Example 4 ?34 Acceptable +10 Leaked/ Polyethylene Burst Terephthalate Comparative ?31 Acceptable Leaked/ with Resin Example 4 Burst

[0061] The results of the contaminated flange seal tests show that Examples 1-4 achieved higher pressure before sample failure occurred than each corresponding Comparative Example. As such, the seal provided by the base structure of the claimed invention is superior in preventing both burst and leak failure when contaminants are present on the flange of the base structure. As such, the present invention provides a superior seal as shown with improved results in burst tests.

[0062] Further embodiments within the scope of the present invention may be envisaged that have not been described above, for example, there may be different shapes of the base structure and base volume. Additionally, the base structure may be made of a recycled polyethylene terephthalate (rPET) and resin composition, providing improved adhesion characteristics between the film lid and the base structure. Polyethylene (PE) films typically provide a better adhesion on contaminated surfaces, however adhesion of PE with polyethylene terephthalate (PET) may reduce or spoil the recyclability of the packaging materials. The present invention provides an improved solution for recyclability of mono-polyethylene terephthalate (mono-PET) base structures by allowing use with a like PET film lid, while also reducing waste by reducing sealing malfunctions. The invention is not limited to the specific examples or structures illustrated, a greater number of components than are illustrated in the figures could be used, for example.